<span class="tx-comment"># 기본 CSV 구조</span>
<span class="tx-string">name,age,city,score</span>
<span class="tx-string">Alice,30,Seoul,95.5</span>
<span class="tx-string">Bob,25,Busan,88.0</span>
<span class="tx-string">Carol,28,Incheon,92.3</span>

<span class="tx-keyword">import</span> csv
<span class="tx-keyword">import</span> json

<span class="tx-keyword">def</span> <span class="tx-func">csv_to_json_basic</span>(csv_file_path, json_file_path, encoding=<span class="tx-string">'utf-8'</span>):
    <span class="tx-string">"""
    가장 기본적인 CSV → JSON 변환 함수
    첫 번째 행을 헤더로 사용하여 배열 of 객체 형태로 변환
    """</span>
    result = []
    
    <span class="tx-keyword">with</span> <span class="tx-func">open</span>(csv_file_path, <span class="tx-string">'r'</span>, encoding=encoding, newline=<span class="tx-string">''</span>) <span class="tx-keyword">as</span> csv_file:
        <span class="tx-comment"># DictReader: 첫 행을 헤더로 자동 인식</span>
        reader = csv.DictReader(csv_file)
        
        <span class="tx-keyword">for</span> row <span class="tx-keyword">in</span> reader:
            <span class="tx-comment"># OrderedDict → 일반 dict로 변환</span>
            result.append(<span class="tx-func">dict</span>(row))
    
    <span class="tx-keyword">with</span> <span class="tx-func">open</span>(json_file_path, <span class="tx-string">'w'</span>, encoding=<span class="tx-string">'utf-8'</span>) <span class="tx-keyword">as</span> json_file:
        json.<span class="tx-func">dump</span>(result, json_file, ensure_ascii=<span class="tx-keyword">False</span>, indent=<span class="tx-num">2</span>)
    
    <span class="tx-func">print</span>(<span class="tx-string">f"✅ 변환 완료: {len(result)}개 행 처리됨"</span>)
    <span class="tx-keyword">return</span> result

<span class="tx-comment"># 사용 예시</span>
data = <span class="tx-func">csv_to_json_basic</span>(<span class="tx-string">'input.csv'</span>, <span class="tx-string">'output.json'</span>)

<span class="tx-keyword">import</span> csv
<span class="tx-keyword">import</span> json

<span class="tx-keyword">def</span> <span class="tx-func">auto_convert_type</span>(value):
    <span class="tx-string">"""문자열 값을 적절한 타입으로 자동 변환"""</span>
    <span class="tx-keyword">if</span> value == <span class="tx-string">''</span> <span class="tx-keyword">or</span> value <span class="tx-keyword">is</span> <span class="tx-keyword">None</span>:
        <span class="tx-keyword">return</span> <span class="tx-keyword">None</span>
    
    <span class="tx-comment"># 불리언 체크</span>
    <span class="tx-keyword">if</span> value.lower() <span class="tx-keyword">in</span> (<span class="tx-string">'true'</span>, <span class="tx-string">'yes'</span>, <span class="tx-string">'1'</span>):
        <span class="tx-keyword">return</span> <span class="tx-keyword">True</span>
    <span class="tx-keyword">if</span> value.lower() <span class="tx-keyword">in</span> (<span class="tx-string">'false'</span>, <span class="tx-string">'no'</span>, <span class="tx-string">'0'</span>):
        <span class="tx-keyword">return</span> <span class="tx-keyword">False</span>
    
    <span class="tx-comment"># 정수 체크</span>
    <span class="tx-keyword">try</span>:
        int_val = <span class="tx-func">int</span>(value)
        <span class="tx-keyword">return</span> int_val
    <span class="tx-keyword">except</span> ValueError:
        <span class="tx-keyword">pass</span>
    
    <span class="tx-comment"># 실수 체크</span>
    <span class="tx-keyword">try</span>:
        float_val = <span class="tx-func">float</span>(value)
        <span class="tx-keyword">return</span> float_val
    <span class="tx-keyword">except</span> ValueError:
        <span class="tx-keyword">pass</span>
    
    <span class="tx-comment"># 그 외는 문자열 그대로</span>
    <span class="tx-keyword">return</span> value


<span class="tx-keyword">def</span> <span class="tx-func">csv_to_json_typed</span>(csv_path, json_path, encoding=<span class="tx-string">'utf-8'</span>):
    <span class="tx-string">"""타입 자동 변환이 포함된 CSV → JSON 변환"""</span>
    result = []
    
    <span class="tx-keyword">with</span> <span class="tx-func">open</span>(csv_path, <span class="tx-string">'r'</span>, encoding=encoding, newline=<span class="tx-string">''</span>) <span class="tx-keyword">as</span> f:
        reader = csv.DictReader(f)
        
        <span class="tx-keyword">for</span> row <span class="tx-keyword">in</span> reader:
            typed_row = {
                key: <span class="tx-func">auto_convert_type</span>(value)
                <span class="tx-keyword">for</span> key, value <span class="tx-keyword">in</span> row.items()
            }
            result.append(typed_row)
    
    <span class="tx-keyword">with</span> <span class="tx-func">open</span>(json_path, <span class="tx-string">'w'</span>, encoding=<span class="tx-string">'utf-8'</span>) <span class="tx-keyword">as</span> f:
        json.<span class="tx-func">dump</span>(result, f, ensure_ascii=<span class="tx-keyword">False</span>, indent=<span class="tx-num">2</span>)
    
    <span class="tx-keyword">return</span> result

<span class="tx-keyword">import</span> csv
<span class="tx-keyword">import</span> json
<span class="tx-keyword">import</span> chardet  <span class="tx-comment"># pip install chardet</span>

<span class="tx-keyword">def</span> <span class="tx-func">detect_encoding</span>(file_path):
    <span class="tx-string">"""파일 인코딩 자동 감지"""</span>
    <span class="tx-keyword">with</span> <span class="tx-func">open</span>(file_path, <span class="tx-string">'rb'</span>) <span class="tx-keyword">as</span> f:
        raw = f.<span class="tx-func">read</span>(<span class="tx-num">10000</span>)  <span class="tx-comment"># 처음 10KB만 읽어서 감지</span>
    result = chardet.<span class="tx-func">detect</span>(raw)
    <span class="tx-keyword">return</span> result[<span class="tx-string">'encoding'</span>]


<span class="tx-keyword">def</span> <span class="tx-func">csv_to_json_smart</span>(csv_path, json_path=<span class="tx-keyword">None</span>, 
                       delimiter=<span class="tx-string">','</span>, encoding=<span class="tx-keyword">None</span>):
    <span class="tx-string">"""
    스마트 CSV → JSON 변환
    - 인코딩 자동 감지
    - BOM 처리
    - 커스텀 구분자 지원
    - json_path가 None이면 결과만 반환
    """</span>
    <span class="tx-keyword">if</span> encoding <span class="tx-keyword">is</span> <span class="tx-keyword">None</span>:
        encoding = <span class="tx-func">detect_encoding</span>(csv_path)
        <span class="tx-func">print</span>(<span class="tx-string">f"🔍 감지된 인코딩: {encoding}"</span>)
    
    <span class="tx-comment"># utf-8-sig는 BOM을 자동으로 처리해줌</span>
    <span class="tx-keyword">if</span> encoding <span class="tx-keyword">and</span> encoding.lower() == <span class="tx-string">'utf-8'</span>:
        encoding = <span class="tx-string">'utf-8-sig'</span>
    
    result = []
    
    <span class="tx-keyword">with</span> <span class="tx-func">open</span>(csv_path, <span class="tx-string">'r'</span>, encoding=encoding, newline=<span class="tx-string">''</span>) <span class="tx-keyword">as</span> f:
        reader = csv.DictReader(f, delimiter=delimiter)
        
        <span class="tx-comment"># 헤더 공백 제거</span>
        reader.fieldnames = [
            field.<span class="tx-func">strip</span>() <span class="tx-keyword">for</span> field <span class="tx-keyword">in</span> reader.fieldnames
        ]
        
        <span class="tx-keyword">for</span> row <span class="tx-keyword">in</span> reader:
            cleaned = {
                k.<span class="tx-func">strip</span>(): v.<span class="tx-func">strip</span>() <span class="tx-keyword">if</span> v <span class="tx-keyword">else</span> <span class="tx-keyword">None</span>
                <span class="tx-keyword">for</span> k, v <span class="tx-keyword">in</span> row.items()
                <span class="tx-keyword">if</span> k <span class="tx-keyword">is</span> <span class="tx-keyword">not</span> <span class="tx-keyword">None</span>
            }
            result.append(cleaned)
    
    <span class="tx-keyword">if</span> json_path:
        <span class="tx-keyword">with</span> <span class="tx-func">open</span>(json_path, <span class="tx-string">'w'</span>, encoding=<span class="tx-string">'utf-8'</span>) <span class="tx-keyword">as</span> f:
            json.<span class="tx-func">dump</span>(result, f, ensure_ascii=<span class="tx-keyword">False</span>, indent=<span class="tx-num">2</span>)
    
    <span class="tx-keyword">return</span> result

<span class="tx-keyword">import</span> pandas <span class="tx-keyword">as</span> pd
<span class="tx-keyword">import</span> json

<span class="tx-keyword">def</span> <span class="tx-func">csv_to_json_pandas</span>(csv_path, json_path=<span class="tx-keyword">None</span>, orient=<span class="tx-string">'records'</span>):
    <span class="tx-string">"""
    pandas를 이용한 CSV → JSON 변환
    orient 옵션:
      'records' : [{col1:val, col2:val}, ...]  ← 가장 일반적
      'index'   : {idx: {col1:val, ...}, ...}
      'columns' : {col1: {idx:val, ...}, ...}
      'values'  : [[val1, val2, ...], ...]
      'split'   : {columns:[...], index:[...], data:[[...]]}
    """</span>
    <span class="tx-comment"># 인코딩 자동 처리 (utf-8-sig로 BOM 처리)</span>
    <span class="tx-keyword">try</span>:
        df = pd.<span class="tx-func">read_csv</span>(csv_path, encoding=<span class="tx-string">'utf-8-sig'</span>)
    <span class="tx-keyword">except</span> UnicodeDecodeError:
        df = pd.<span class="tx-func">read_csv</span>(csv_path, encoding=<span class="tx-string">'cp949'</span>)
    
    <span class="tx-comment"># NaN을 None으로 변환 (JSON null로 직렬화됨)</span>
    df = df.<span class="tx-func">where</span>(pd.<span class="tx-func">notnull</span>(df), <span class="tx-keyword">None</span>)
    
    <span class="tx-comment"># 컬럼명 공백 제거</span>
    df.columns = df.columns.<span class="tx-func">str.strip</span>()
    
    json_str = df.<span class="tx-func">to_json</span>(orient=orient, force_ascii=<span class="tx-keyword">False</span>, indent=<span class="tx-num">2</span>)
    
    <span class="tx-keyword">if</span> json_path:
        <span class="tx-keyword">with</span> <span class="tx-func">open</span>(json_path, <span class="tx-string">'w'</span>, encoding=<span class="tx-string">'utf-8'</span>) <span class="tx-keyword">as</span> f:
            f.<span class="tx-func">write</span>(json_str)
    
    <span class="tx-keyword">return</span> json.<span class="tx-func">loads</span>(json_str)


<span class="tx-comment"># 사용 예시</span>
data = <span class="tx-func">csv_to_json_pandas</span>(<span class="tx-string">'users.csv'</span>, <span class="tx-string">'users.json'</span>)
<span class="tx-func">print</span>(<span class="tx-string">f"총 {len(data)}개 레코드 변환 완료 🎉"</span>)

<span class="tx-comment"># 터미널에서 바로 실행 가능한 원라이너</span>
python3 -c <span class="tx-string">"
import csv, json, sys
with open(sys.argv[1], 'r', encoding='utf-8-sig') as f:
    print(json.dumps(list(csv.DictReader(f)), ensure_ascii=False, indent=2))
"</span> input.csv > output.json

<span class="tx-comment">/**
 * 브라우저에서 CSV 문자열을 JSON으로 변환
 * 파일 업로드 후 FileReader로 읽은 텍스트를 넘겨주면 됨
 */</span>
<span class="tx-keyword">function</span> <span class="tx-func">csvToJson</span>(csvText, delimiter = <span class="tx-string">','</span>) {
  <span class="tx-keyword">const</span> lines = csvText
    .<span class="tx-func">trim</span>()
    .<span class="tx-func">split</span>(<span class="tx-string">'\n'</span>)
    .<span class="tx-func">map</span>(line => line.<span class="tx-func">replace</span>(<span class="tx-string">/\r$/</span>, <span class="tx-string">''</span>)); <span class="tx-comment">// CRLF 처리</span>
  
  <span class="tx-keyword">if</span> (lines.length === <span class="tx-num">0</span>) <span class="tx-keyword">return</span> [];
  
  <span class="tx-comment">// 헤더 파싱</span>
  <span class="tx-keyword">const</span> headers = <span class="tx-func">parseCSVLine</span>(lines[<span class="tx-num">0</span>], delimiter);
  
  <span class="tx-comment">// 데이터 행 파싱</span>
  <span class="tx-keyword">return</span> lines
    .<span class="tx-func">slice</span>(<span class="tx-num">1</span>)
    .<span class="tx-func">filter</span>(line => line.<span class="tx-func">trim</span>() !== <span class="tx-string">''</span>) <span class="tx-comment">// 빈 행 제거</span>
    .<span class="tx-func">map</span>(line => {
      <span class="tx-keyword">const</span> values = <span class="tx-func">parseCSVLine</span>(line, delimiter);
      <span class="tx-keyword">return</span> headers.<span class="tx-func">reduce</span>((obj, header, index) => {
        obj[header.<span class="tx-func">trim</span>()] = <span class="tx-func">autoType</span>(values[index] ?? <span class="tx-string">''</span>);
        <span class="tx-keyword">return</span> obj;
      }, {});
    });
}

<span class="tx-comment">/**
 * CSV 한 줄을 파싱 (따옴표 처리 포함)
 */</span>
<span class="tx-keyword">function</span> <span class="tx-func">parseCSVLine</span>(line, delimiter = <span class="tx-string">','</span>) {
  <span class="tx-keyword">const</span> result = [];
  <span class="tx-keyword">let</span> current = <span class="tx-string">''</span>;
  <span class="tx-keyword">let</span> inQuotes = <span class="tx-keyword">false</span>;
  
  <span class="tx-keyword">for</span> (<span class="tx-keyword">let</span> i = <span class="tx-num">0</span>; i < line.length; i++) {
    <span class="tx-keyword">const</span> char = line[i];
    <span class="tx-keyword">const</span> nextChar = line[i + <span class="tx-num">1</span>];
    
    <span class="tx-keyword">if</span> (char === <span class="tx-string">'"'</span>) {
      <span class="tx-keyword">if</span> (inQuotes && nextChar === <span class="tx-string">'"'</span>) {
        <span class="tx-comment">// 이스케이프된 따옴표 ("")</span>
        current += <span class="tx-string">'"'</span>;
        i++;
      } <span class="tx-keyword">else</span> {
        inQuotes = !inQuotes;
      }
    } <span class="tx-keyword">else if</span> (char === delimiter && !inQuotes) {
      result.<span class="tx-func">push</span>(current);
      current = <span class="tx-string">''</span>;
    } <span class="tx-keyword">else</span> {
      current += char;
    }
  }
  result.<span class="tx-func">push</span>(current);
  <span class="tx-keyword">return</span> result;
}

<span class="tx-comment">/**
 * 문자열 값을 적절한 타입으로 변환
 */</span>
<span class="tx-keyword">function</span> <span class="tx-func">autoType</span>(value) {
  <span class="tx-keyword">if</span> (value === <span class="tx-string">''</span>) <span class="tx-keyword">return</span> <span class="tx-keyword">null</span>;
  <span class="tx-keyword">if</span> (value.toLowerCase() === <span class="tx-string">'true'</span>) <span class="tx-keyword">return</span> <span class="tx-keyword">true</span>;
  <span class="tx-keyword">if</span> (value.toLowerCase() === <span class="tx-string">'false'</span>) <span class="tx-keyword">return</span> <span class="tx-keyword">false</span>;
  <span class="tx-keyword">if</span> (!<span class="tx-func">isNaN</span>(value) && value !== <span class="tx-string">''</span>) <span class="tx-keyword">return</span> <span class="tx-func">Number</span>(value);
  <span class="tx-keyword">return</span> value;
}

<span class="tx-comment">// HTML: <input type="file" id="csvFile" accept=".csv"></span>

document.<span class="tx-func">getElementById</span>(<span class="tx-string">'csvFile'</span>)
  .<span class="tx-func">addEventListener</span>(<span class="tx-string">'change'</span>, <span class="tx-keyword">function</span>(event) {
    <span class="tx-keyword">const</span> file = event.target.files[<span class="tx-num">0</span>];
    <span class="tx-keyword">if</span> (!file) <span class="tx-keyword">return</span>;
    
    <span class="tx-keyword">const</span> reader = <span class="tx-keyword">new</span> <span class="tx-func">FileReader</span>();
    
    reader.onload = <span class="tx-keyword">function</span>(e) {
      <span class="tx-keyword">const</span> csvText = e.target.result;
      <span class="tx-keyword">const</span> jsonData = <span class="tx-func">csvToJson</span>(csvText);
      
      console.<span class="tx-func">log</span>(<span class="tx-string">'변환 결과:'</span>, jsonData);
      console.<span class="tx-func">log</span>(<span class="tx-string">'JSON 문자열:'</span>, JSON.<span class="tx-func">stringify</span>(jsonData, <span class="tx-keyword">null</span>, <span class="tx-num">2</span>));
      
      <span class="tx-comment">// 다운로드 기능</span>
      <span class="tx-keyword">const</span> blob = <span class="tx-keyword">new</span> <span class="tx-func">Blob</span>(
        [JSON.<span class="tx-func">stringify</span>(jsonData, <span class="tx-keyword">null</span>, <span class="tx-num">2</span>)],
        { type: <span class="tx-string">'application/json'</span> }
      );
      <span class="tx-keyword">const</span> url = URL.<span class="tx-func">createObjectURL</span>(blob);
      <span class="tx-keyword">const</span> a = document.<span class="tx-func">createElement</span>(<span class="tx-string">'a'</span>);
      a.href = url;
      a.download = <span class="tx-string">'output.json'</span>;
      a.<span class="tx-func">click</span>();
    };
    
    reader.<span class="tx-func">readAsText</span>(file, <span class="tx-string">'UTF-8'</span>);
  });

<span class="tx-comment">// npm install csv-parse  ← 검증된 CSV 파싱 라이브러리</span>
<span class="tx-keyword">const</span> { parse } = <span class="tx-func">require</span>(<span class="tx-string">'csv-parse/sync'</span>);
<span class="tx-keyword">const</span> fs = <span class="tx-func">require</span>(<span class="tx-string">'fs'</span>);
<span class="tx-keyword">const</span> path = <span class="tx-func">require</span>(<span class="tx-string">'path'</span>);

<span class="tx-keyword">function</span> <span class="tx-func">csvToJsonFile</span>(inputPath, outputPath) {
  <span class="tx-comment">// BOM 제거 후 읽기</span>
  <span class="tx-keyword">let</span> content = fs.<span class="tx-func">readFileSync</span>(inputPath, <span class="tx-string">'utf-8'</span>);
  <span class="tx-keyword">if</span> (content.<span class="tx-func">charCodeAt</span>(<span class="tx-num">0</span>) === <span class="tx-num">0xFEFF</span>) {
    content = content.<span class="tx-func">slice</span>(<span class="tx-num">1</span>); <span class="tx-comment">// BOM 제거</span>
  }
  
  <span class="tx-keyword">const</span> records = <span class="tx-func">parse</span>(content, {
    columns: <span class="tx-keyword">true</span>,        <span class="tx-comment">// 첫 행을 헤더로</span>
    skip_empty_lines: <span class="tx-keyword">true</span>, <span class="tx-comment">// 빈 줄 스킵</span>
    trim: <span class="tx-keyword">true</span>,           <span class="tx-comment">// 앞뒤 공백 제거</span>
    cast: <span class="tx-keyword">true</span>,           <span class="tx-comment">// 타입 자동 변환</span>
    cast_date: <span class="tx-keyword">false</span>      <span class="tx-comment">// 날짜 자동 변환은 끔 (의도치 않은 변환 방지)</span>
  });
  
  <span class="tx-keyword">const</span> jsonStr = JSON.<span class="tx-func">stringify</span>(records, <span class="tx-keyword">null</span>, <span class="tx-num">2</span>);
  
  <span class="tx-keyword">if</span> (outputPath) {
    fs.<span class="tx-func">writeFileSync</span>(outputPath, jsonStr, <span class="tx-string">'utf-8'</span>);
    console.<span class="tx-func">log</span>(<span class="tx-string">`✅ ${records.length}개 레코드 → ${outputPath}`</span>);
  }
  
  <span class="tx-keyword">return</span> records;
}

<span class="tx-comment">// 실행</span>
<span class="tx-keyword">const</span> data = <span class="tx-func">csvToJsonFile</span>(<span class="tx-string">'./data/input.csv'</span>, <span class="tx-string">'./data/output.json'</span>);

<span class="tx-comment"><!-- pom.xml --></span>
<span class="tx-keyword"><dependency></span>
    <span class="tx-string"><groupId></span>com.opencsv<span class="tx-string"></groupId></span>
    <span class="tx-string"><artifactId></span>opencsv<span class="tx-string"></artifactId></span>
    <span class="tx-string"><version></span>5.7.1<span class="tx-string"></version></span>
<span class="tx-keyword"></dependency></span>
<span class="tx-keyword"><dependency></span>
    <span class="tx-string"><groupId></span>com.fasterxml.jackson.core<span class="tx-string"></groupId></span>
    <span class="tx-string"><artifactId></span>jackson-databind<span class="tx-string"></artifactId></span>
    <span class="tx-string"><version></span>2.15.2<span class="tx-string"></version></span>
<span class="tx-keyword"></dependency></span>

<span class="tx-keyword">import</span> com.fasterxml.jackson.databind.ObjectMapper;
<span class="tx-keyword">import</span> com.opencsv.CSVReader;
<span class="tx-keyword">import</span> com.opencsv.exceptions.CsvException;
<span class="tx-keyword">import</span> java.io.*;
<span class="tx-keyword">import</span> java.nio.charset.StandardCharsets;
<span class="tx-keyword">import</span> java.util.*;

<span class="tx-keyword">public class</span> <span class="tx-func">CsvToJsonConverter</span> {
    
    <span class="tx-keyword">private final</span> ObjectMapper objectMapper = <span class="tx-keyword">new</span> <span class="tx-func">ObjectMapper</span>();
    
    <span class="tx-comment">/**
     * CSV 파일을 JSON 문자열로 변환
     * @param csvFilePath CSV 파일 경로
     * @return JSON 문자열
     */</span>
    <span class="tx-keyword">public</span> String <span class="tx-func">convertToJson</span>(String csvFilePath) 
            <span class="tx-keyword">throws</span> IOException, CsvException {
        
        List<Map<String, String>> result = <span class="tx-keyword">new</span> ArrayList<>();
        
        <span class="tx-keyword">try</span> (
            InputStreamReader isr = <span class="tx-keyword">new</span> <span class="tx-func">InputStreamReader</span>(
                <span class="tx-keyword">new</span> <span class="tx-func">FileInputStream</span>(csvFilePath),
                StandardCharsets.UTF_8
            );
            CSVReader reader = <span class="tx-keyword">new</span> <span class="tx-func">CSVReader</span>(isr)
        ) {
            <span class="tx-comment">// 헤더 읽기</span>
            String[] headers = reader.<span class="tx-func">readNext</span>();
            <span class="tx-keyword">if</span> (headers == <span class="tx-keyword">null</span>) <span class="tx-keyword">return</span> <span class="tx-string">"[]"</span>;
            
            <span class="tx-comment">// BOM 제거</span>
            <span class="tx-keyword">if</span> (headers[<span class="tx-num">0</span>].<span class="tx-func">startsWith</span>(<span class="tx-string">"\uFEFF"</span>)) {
                headers[<span class="tx-num">0</span>] = headers[<span class="tx-num">0</span>].<span class="tx-func">substring</span>(<span class="tx-num">1</span>);
            }
            
            <span class="tx-comment">// 헤더 공백 제거</span>
            <span class="tx-keyword">for</span> (<span class="tx-keyword">int</span> i = <span class="tx-num">0</span>; i < headers.length; i++) {
                headers[i] = headers[i].<span class="tx-func">trim</span>();
            }
            
            <span class="tx-comment">// 데이터 행 처리</span>
            String[] row;
            <span class="tx-keyword">while</span> ((row = reader.<span class="tx-func">readNext</span>()) != <span class="tx-keyword">null</span>) {
                Map<String, String> rowMap = <span class="tx-keyword">new</span> LinkedHashMap<>();
                <span class="tx-keyword">for</span> (<span class="tx-keyword">int</span> i = <span class="tx-num">0</span>; i < headers.length; i++) {
                    String value = (i < row.length) ? row[i].<span class="tx-func">trim</span>() : <span class="tx-string">""</span>;
                    rowMap.<span class="tx-func">put</span>(headers[i], value.isEmpty() ? <span class="tx-keyword">null</span> : value);
                }
                result.<span class="tx-func">add</span>(rowMap);
            }
        }
        
        <span class="tx-keyword">return</span> objectMapper
            .<span class="tx-func">writerWithDefaultPrettyPrinter</span>()
            .<span class="tx-func">writeValueAsString</span>(result);
    }
    
    <span class="tx-comment">// 파일로 저장하는 버전</span>
    <span class="tx-keyword">public void</span> <span class="tx-func">convertToJsonFile</span>(String csvPath, String jsonPath)
            <span class="tx-keyword">throws</span> IOException, CsvException {
        String json = <span class="tx-func">convertToJson</span>(csvPath);
        <span class="tx-keyword">try</span> (FileWriter fw = <span class="tx-keyword">new</span> <span class="tx-func">FileWriter</span>(jsonPath, StandardCharsets.UTF_8)) {
            fw.<span class="tx-func">write</span>(json);
        }
        System.out.<span class="tx-func">println</span>(<span class="tx-string">"✅ 변환 완료: "</span> + jsonPath);
    }
    
    <span class="tx-keyword">public static void</span> <span class="tx-func">main</span>(String[] args) <span class="tx-keyword">throws</span> Exception {
        CsvToJsonConverter converter = <span class="tx-keyword">new</span> <span class="tx-func">CsvToJsonConverter</span>();
        converter.<span class="tx-func">convertToJsonFile</span>(<span class="tx-string">"input.csv"</span>, <span class="tx-string">"output.json"</span>);
    }
}

<span class="tx-keyword">package</span> main

<span class="tx-keyword">import</span> (
    <span class="tx-string">"encoding/csv"</span>
    <span class="tx-string">"encoding/json"</span>
    <span class="tx-string">"fmt"</span>
    <span class="tx-string">"os"</span>
    <span class="tx-string">"strings"</span>
    <span class="tx-string">"strconv"</span>
)

<span class="tx-comment">// autoConvert: 문자열을 적절한 타입으로 변환</span>
<span class="tx-keyword">func</span> <span class="tx-func">autoConvert</span>(s string) <span class="tx-keyword">interface</span>{} {
    s = strings.<span class="tx-func">TrimSpace</span>(s)
    
    <span class="tx-keyword">if</span> s == <span class="tx-string">""</span> {
        <span class="tx-keyword">return</span> <span class="tx-keyword">nil</span>
    }
    
    <span class="tx-comment">// 불리언 체크</span>
    lower := strings.<span class="tx-func">ToLower</span>(s)
    <span class="tx-keyword">if</span> lower == <span class="tx-string">"true"</span> || lower == <span class="tx-string">"yes"</span> {
        <span class="tx-keyword">return</span> <span class="tx-keyword">true</span>
    }
    <span class="tx-keyword">if</span> lower == <span class="tx-string">"false"</span> || lower == <span class="tx-string">"no"</span> {
        <span class="tx-keyword">return</span> <span class="tx-keyword">false</span>
    }
    
    <span class="tx-comment">// 정수 체크</span>
    <span class="tx-keyword">if</span> i, err := strconv.<span class="tx-func">ParseInt</span>(s, <span class="tx-num">10</span>, <span class="tx-num">64</span>); err == <span class="tx-keyword">nil</span> {
        <span class="tx-keyword">return</span> i
    }
    
    <span class="tx-comment">// 실수 체크</span>
    <span class="tx-keyword">if</span> f, err := strconv.<span class="tx-func">ParseFloat</span>(s, <span class="tx-num">64</span>); err == <span class="tx-keyword">nil</span> {
        <span class="tx-keyword">return</span> f
    }
    
    <span class="tx-keyword">return</span> s
}

<span class="tx-comment">// CsvToJson: CSV 파일을 JSON으로 변환</span>
<span class="tx-keyword">func</span> <span class="tx-func">CsvToJson</span>(csvPath, jsonPath string) error {
    <span class="tx-comment">// CSV 파일 열기</span>
    csvFile, err := os.<span class="tx-func">Open</span>(csvPath)
    <span class="tx-keyword">if</span> err != <span class="tx-keyword">nil</span> {
        <span class="tx-keyword">return</span> fmt.<span class="tx-func">Errorf</span>(<span class="tx-string">"CSV 파일 열기 실패: %w"</span>, err)
    }
    <span class="tx-keyword">defer</span> csvFile.<span class="tx-func">Close</span>()
    
    reader := csv.<span class="tx-func">NewReader</span>(csvFile)
    reader.TrimLeadingSpace = <span class="tx-keyword">true</span>
    
    <span class="tx-comment">// 헤더 읽기</span>
    headers, err := reader.<span class="tx-func">Read</span>()
    <span class="tx-keyword">if</span> err != <span class="tx-keyword">nil</span> {
        <span class="tx-keyword">return</span> fmt.<span class="tx-func">Errorf</span>(<span class="tx-string">"헤더 읽기 실패: %w"</span>, err)
    }
    
    <span class="tx-comment">// BOM 제거</span>
    <span class="tx-keyword">if</span> len(headers) > <span class="tx-num">0</span> {
        headers[<span class="tx-num">0</span>] = strings.<span class="tx-func">TrimPrefix</span>(headers[<span class="tx-num">0</span>], <span class="tx-string">"\uFEFF"</span>)
    }
    
    <span class="tx-keyword">var</span> result []map[string]<span class="tx-keyword">interface</span>{}
    
    <span class="tx-comment">// 데이터 행 처리</span>
    <span class="tx-keyword">for</span> {
        row, err := reader.<span class="tx-func">Read</span>()
        <span class="tx-keyword">if</span> err != <span class="tx-keyword">nil</span> {
            <span class="tx-keyword">break</span> <span class="tx-comment">// EOF 또는 에러</span>
        }
        
        rowMap := make(map[string]<span class="tx-keyword">interface</span>{})
        <span class="tx-keyword">for</span> i, header := <span class="tx-keyword">range</span> headers {
            <span class="tx-keyword">if</span> i < len(row) {
                rowMap[strings.<span class="tx-func">TrimSpace</span>(header)] = <span class="tx-func">autoConvert</span>(row[i])
            } <span class="tx-keyword">else</span> {
                rowMap[strings.<span class="tx-func">TrimSpace</span>(header)] = <span class="tx-keyword">nil</span>
            }
        }
        result = <span class="tx-func">append</span>(result, rowMap)
    }
    
    <span class="tx-comment">// JSON 파일 저장</span>
    jsonFile, err := os.<span class="tx-func">Create</span>(jsonPath)
    <span class="tx-keyword">if</span> err != <span class="tx-keyword">nil</span> {
        <span class="tx-keyword">return</span> fmt.<span class="tx-func">Errorf</span>(<span class="tx-string">"JSON 파일 생성 실패: %w"</span>, err)
    }
    <span class="tx-keyword">defer</span> jsonFile.<span class="tx-func">Close</span>()
    
    encoder := json.<span class="tx-func">NewEncoder</span>(jsonFile)
    encoder.<span class="tx-func">SetIndent</span>(<span class="tx-string">""</span>, <span class="tx-string">"  "</span>)
    encoder.<span class="tx-func">SetEscapeHTML</span>(<span class="tx-keyword">false</span>) <span class="tx-comment">// 한글 이스케이프 방지</span>
    
    <span class="tx-keyword">if</span> err := encoder.<span class="tx-func">Encode</span>(result); err != <span class="tx-keyword">nil</span> {
        <span class="tx-keyword">return</span> fmt.<span class="tx-func">Errorf</span>(<span class="tx-string">"JSON 인코딩 실패: %w"</span>, err)
    }
    
    fmt.<span class="tx-func">Printf</span>(<span class="tx-string">"✅ 변환 완료: %d개 레코드\n"</span>, len(result))
    <span class="tx-keyword">return</span> <span class="tx-keyword">nil</span>
}

<span class="tx-keyword">func</span> <span class="tx-func">main</span>() {
    <span class="tx-keyword">if</span> err := <span class="tx-func">CsvToJson</span>(<span class="tx-string">"input.csv"</span>, <span class="tx-string">"output.json"</span>); err != <span class="tx-keyword">nil</span> {
        fmt.<span class="tx-func">Fprintf</span>(os.Stderr, <span class="tx-string">"에러: %v\n"</span>, err)
        os.<span class="tx-func">Exit</span>(<span class="tx-num">1</span>)
    }
}

<span class="tx-keyword"><?php</span>

<span class="tx-comment">/**
 * CSV 파일을 JSON으로 변환하는 함수
 * 
 * @param string $csvPath CSV 파일 경로
 * @param string|null $jsonPath 저장할 JSON 파일 경로 (null이면 반환만)
 * @param string $encoding 파일 인코딩 (기본: UTF-8)
 * @param string $delimiter 구분자 (기본: 쉼표)
 * @return array 변환된 데이터 배열
 */</span>
<span class="tx-keyword">function</span> <span class="tx-func">csvToJson</span>(
    string $csvPath,
    ?string $jsonPath = <span class="tx-keyword">null</span>,
    string $encoding = <span class="tx-string">'UTF-8'</span>,
    string $delimiter = <span class="tx-string">','</span>
): array {
    
    <span class="tx-keyword">if</span> (!<span class="tx-func">file_exists</span>($csvPath)) {
        <span class="tx-keyword">throw new</span> <span class="tx-func">RuntimeException</span>(<span class="tx-string">"파일을 찾을 수 없습니다: $csvPath"</span>);
    }
    
    <span class="tx-comment">// 파일 내용 읽기</span>
    $content = <span class="tx-func">file_get_contents</span>($csvPath);
    
    <span class="tx-comment">// BOM 제거</span>
    $content = <span class="tx-func">ltrim</span>($content, <span class="tx-string">"\xEF\xBB\xBF"</span>);
    
    <span class="tx-comment">// 인코딩 변환 (EUC-KR → UTF-8)</span>
    <span class="tx-keyword">if</span> (<span class="tx-func">strtoupper</span>($encoding) !== <span class="tx-string">'UTF-8'</span>) {
        $content = <span class="tx-func">mb_convert_encoding</span>($content, <span class="tx-string">'UTF-8'</span>, $encoding);
    }
    
    <span class="tx-comment">// 임시 파일로 처리 (메모리 효율)</span>
    $tempFile = <span class="tx-func">tmpfile</span>();
    <span class="tx-func">fwrite</span>($tempFile, $content);
    <span class="tx-func">rewind</span>($tempFile);
    
    $result = [];
    $headers = <span class="tx-keyword">null</span>;
    
    <span class="tx-keyword">while</span> (($row = <span class="tx-func">fgetcsv</span>($tempFile, <span class="tx-num">0</span>, $delimiter)) !== <span class="tx-keyword">false</span>) {
        <span class="tx-comment">// 빈 행 스킵</span>
        <span class="tx-keyword">if</span> (<span class="tx-func">count</span>($row) === <span class="tx-num">1</span> && $row[<span class="tx-num">0</span>] === <span class="tx-keyword">null</span>) <span class="tx-keyword">continue</span>;
        
        <span class="tx-keyword">if</span> ($headers === <span class="tx-keyword">null</span>) {
            <span class="tx-comment">// 헤더 행 처리</span>
            $headers = <span class="tx-func">array_map</span>(<span class="tx-string">'trim'</span>, $row);
        } <span class="tx-keyword">else</span> {
            <span class="tx-comment">// 데이터 행 처리</span>
            $rowData = [];
            <span class="tx-keyword">foreach</span> ($headers <span class="tx-keyword">as</span> $index => $header) {
                $value = isset($row[$index]) ? <span class="tx-func">trim</span>($row[$index]) : <span class="tx-keyword">null</span>;
                $rowData[$header] = <span class="tx-func">autoConvertType</span>($value);
            }
            $result[] = $rowData;
        }
    }
    
    <span class="tx-func">fclose</span>($tempFile);
    
    <span class="tx-comment">// JSON 파일 저장</span>
    <span class="tx-keyword">if</span> ($jsonPath !== <span class="tx-keyword">null</span>) {
        $jsonStr = <span class="tx-func">json_encode</span>(
            $result,
            JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES
        );
        <span class="tx-func">file_put_contents</span>($jsonPath, $jsonStr);
        <span class="tx-func">echo</span> <span class="tx-string">"✅ 변환 완료: "</span> . <span class="tx-func">count</span>($result) . <span class="tx-string">"개 레코드\n"</span>;
    }
    
    <span class="tx-keyword">return</span> $result;
}

<span class="tx-comment">/**
 * 문자열을 적절한 타입으로 변환
 */</span>
<span class="tx-keyword">function</span> <span class="tx-func">autoConvertType</span>(?string $value): mixed {
    <span class="tx-keyword">if</span> ($value === <span class="tx-keyword">null</span> || $value === <span class="tx-string">''</span>) <span class="tx-keyword">return</span> <span class="tx-keyword">null</span>;
    
    $lower = <span class="tx-func">strtolower</span>($value);
    <span class="tx-keyword">if</span> ($lower === <span class="tx-string">'true'</span>)  <span class="tx-keyword">return</span> <span class="tx-keyword">true</span>;
    <span class="tx-keyword">if</span> ($lower === <span class="tx-string">'false'</span>) <span class="tx-keyword">return</span> <span class="tx-keyword">false</span>;
    
    <span class="tx-keyword">if</span> (<span class="tx-func">is_numeric</span>($value)) {
        <span class="tx-keyword">return</span> <span class="tx-func">strpos</span>($value, <span class="tx-string">'.'</span>) !== <span class="tx-keyword">false</span>
            ? (<span class="tx-keyword">float</span>) $value
            : (<span class="tx-keyword">int</span>) $value;
    }
    
    <span class="tx-keyword">return</span> $value;
}

<span class="tx-comment">// 사용 예시</span>
$data = <span class="tx-func">csvToJson</span>(<span class="tx-string">'input.csv'</span>, <span class="tx-string">'output.json'</span>);

<span class="tx-comment">// EUC-KR 파일 처리</span>
$data = <span class="tx-func">csvToJson</span>(<span class="tx-string">'korean.csv'</span>, <span class="tx-string">'korean.json'</span>, <span class="tx-string">'EUC-KR'</span>);

<span class="tx-comment">// TSV(탭 구분) 파일 처리</span>
$data = <span class="tx-func">csvToJson</span>(<span class="tx-string">'data.tsv'</span>, <span class="tx-string">'data.json'</span>, <span class="tx-string">'UTF-8'</span>, <span class="tx-string">"\t"</span>);

<span class="tx-keyword">import</span> chardet

<span class="tx-keyword">def</span> <span class="tx-func">safe_read_csv</span>(file_path):
    <span class="tx-string">"""인코딩 자동 감지 + 안전한 CSV 읽기"""</span>
    
    <span class="tx-comment"># 1단계: 바이너리로 읽어서 인코딩 감지</span>
    <span class="tx-keyword">with</span> <span class="tx-func">open</span>(file_path, <span class="tx-string">'rb'</span>) <span class="tx-keyword">as</span> f:
        raw_data = f.<span class="tx-func">read</span>()
    
    detected = chardet.<span class="tx-func">detect</span>(raw_data)
    encoding = detected[<span class="tx-string">'encoding'</span>]
    confidence = detected[<span class="tx-string">'confidence'</span>]
    
    <span class="tx-func">print</span>(<span class="tx-string">f"감지된 인코딩: {encoding} (신뢰도: {confidence:.1%})"</span>)
    
    <span class="tx-comment"># 2단계: 감지된 인코딩으로 시도, 실패시 대안 시도</span>
    encodings_to_try = [encoding, <span class="tx-string">'utf-8-sig'</span>, <span class="tx-string">'cp949'</span>, <span class="tx-string">'euc-kr'</span>, <span class="tx-string">'latin-1'</span>]
    
    <span class="tx-keyword">for</span> enc <span class="tx-keyword">in</span> encodings_to_try:
        <span class="tx-keyword">if</span> enc <span class="tx-keyword">is</span> <span class="tx-keyword">None</span>:
            <span class="tx-keyword">continue</span>
        <span class="tx-keyword">try</span>:
            text = raw_data.<span class="tx-func">decode</span>(enc)
            <span class="tx-func">print</span>(<span class="tx-string">f"✅ {enc}으로 성공적으로 디코딩"</span>)
            <span class="tx-keyword">return</span> text
        <span class="tx-keyword">except</span> (UnicodeDecodeError, LookupError):
            <span class="tx-keyword">continue</span>
    
    <span class="tx-comment"># 최후의 수단: errors='replace'로 강제 디코딩</span>
    <span class="tx-func">print</span>(<span class="tx-string">"⚠️ 인코딩 감지 실패, 대체 문자로 처리"</span>)
    <span class="tx-keyword">return</span> raw_data.<span class="tx-func">decode</span>(<span class="tx-string">'utf-8'</span>, errors=<span class="tx-string">'replace'</span>)

<span class="tx-keyword">from</span> datetime <span class="tx-keyword">import</span> datetime
<span class="tx-keyword">import</span> re

<span class="tx-keyword">def</span> <span class="tx-func">parse_date</span>(value):
    <span class="tx-string">"""다양한 날짜 형식을 ISO 8601로 통일"""</span>
    date_formats = [
        <span class="tx-string">'%Y-%m-%d'</span>,        <span class="tx-comment"># 2024-01-15</span>
        <span class="tx-string">'%Y/%m/%d'</span>,        <span class="tx-comment"># 2024/01/15</span>
        <span class="tx-string">'%d/%m/%Y'</span>,        <span class="tx-comment"># 15/01/2024</span>
        <span class="tx-string">'%m/%d/%Y'</span>,        <span class="tx-comment"># 01/15/2024</span>
        <span class="tx-string">'%Y.%m.%d'</span>,        <span class="tx-comment"># 2024.01.15</span>
        <span class="tx-string">'%Y-%m-%dT%H:%M:%S'</span>, <span class="tx-comment"># ISO 8601</span>
        <span class="tx-string">'%Y년 %m월 %d일'</span>,  <span class="tx-comment"># 한국식</span>
    ]
    
    <span class="tx-keyword">for</span> fmt <span class="tx-keyword">in</span> date_formats:
        <span class="tx-keyword">try</span>:
            dt = datetime.<span class="tx-func">strptime</span>(value.<span class="tx-func">strip</span>(), fmt)
            <span class="tx-keyword">return</span> dt.<span class="tx-func">isoformat</span>()  <span class="tx-comment"># ISO 8601로 통일</span>
        <span class="tx-keyword">except</span> ValueError:
            <span class="tx-keyword">continue</span>
    
    <span class="tx-keyword">return</span> value  <span class="tx-comment"># 파싱 실패시 원본 반환</span>


<span class="tx-comment"># 날짜 컬럼을 지정해서 변환하는 예시</span>
<span class="tx-keyword">def</span> <span class="tx-func">csv_to_json_with_dates</span>(csv_path, date_columns=None):
    <span class="tx-keyword">import</span> csv, json
    date_columns = date_columns <span class="tx-keyword">or</span> []
    result = []
    
    <span class="tx-keyword">with</span> <span class="tx-func">open</span>(csv_path, <span class="tx-string">'r'</span>, encoding=<span class="tx-string">'utf-8-sig'</span>) <span class="tx-keyword">as</span> f:
        reader = csv.DictReader(f)
        <span class="tx-keyword">for</span> row <span class="tx-keyword">in</span> reader:
            processed = {}
            <span class="tx-keyword">for</span> key, value <span class="tx-keyword">in</span> row.items():
                <span class="tx-keyword">if</span> key <span class="tx-keyword">in</span> date_columns:
                    processed[key] = <span class="tx-func">parse_date</span>(value)
                <span class="tx-keyword">else</span>:
                    processed[key] = value
            result.append(processed)
    
    <span class="tx-keyword">return</span> result

<span class="tx-comment"># 사용: 'birth_date', 'created_at' 컬럼을 날짜로 처리</span>
data = <span class="tx-func">csv_to_json_with_dates</span>(<span class="tx-string">'users.csv'</span>, [<span class="tx-string">'birth_date'</span>, <span class="tx-string">'created_at'</span>])

<span class="tx-keyword">def</span> <span class="tx-func">deduplicate_headers</span>(headers):
    <span class="tx-string">"""중복 헤더를 자동으로 처리 (name → name_1, name_2 ...)</span>
<span class="tx-string">    """</span>
    seen = {}
    result = []
    
    <span class="tx-keyword">for</span> header <span class="tx-keyword">in</span> headers:
        header = header.<span class="tx-func">strip</span>()
        <span class="tx-keyword">if</span> header <span class="tx-keyword">in</span> seen:
            seen[header] += <span class="tx-num">1</span>
            result.append(<span class="tx-string">f"{header}_{seen[header]}"</span>)
        <span class="tx-keyword">else</span>:
            seen[header] = <span class="tx-num">0</span>
            result.append(header)
    
    <span class="tx-keyword">return</span> result

<span class="tx-comment"># 예시: ['name', 'age', 'name', 'name']</span>
<span class="tx-comment"># 결과: ['name', 'age', 'name_1', 'name_2']</span>

<span class="tx-keyword">import</span> csv
<span class="tx-keyword">import</span> json

<span class="tx-keyword">def</span> <span class="tx-func">csv_to_json_streaming</span>(csv_path, json_path, chunk_size=<span class="tx-num">1000</span>):
    <span class="tx-string">"""
    스트리밍 방식으로 대용량 CSV를 JSON으로 변환
    메모리 사용량을 최소화하면서 처리
    """</span>
    total_rows = <span class="tx-num">0</span>
    
    <span class="tx-keyword">with</span> <span class="tx-func">open</span>(csv_path, <span class="tx-string">'r'</span>, encoding=<span class="tx-string">'utf-8-sig'</span>, newline=<span class="tx-string">''</span>) <span class="tx-keyword">as</span> csv_file, \
         <span class="tx-func">open</span>(json_path, <span class="tx-string">'w'</span>, encoding=<span class="tx-string">'utf-8'</span>) <span class="tx-keyword">as</span> json_file:
        
        reader = csv.DictReader(csv_file)
        
        <span class="tx-comment"># JSON 배열 시작</span>
        json_file.<span class="tx-func">write</span>(<span class="tx-string">'[\n'</span>)
        
        first = <span class="tx-keyword">True</span>
        
        <span class="tx-keyword">for</span> row <span class="tx-keyword">in</span> reader:
            <span class="tx-keyword">if</span> <span class="tx-keyword">not</span> first:
                json_file.<span class="tx-func">write</span>(<span class="tx-string">',\n'</span>)
            
            <span class="tx-comment"># 각 행을 즉시 직렬화하여 파일에 씀</span>
            json_str = json.<span class="tx-func">dumps</span>(
                <span class="tx-func">dict</span>(row),
                ensure_ascii=<span class="tx-keyword">False</span>
            )
            json_file.<span class="tx-func">write</span>(<span class="tx-string">f'  {json_str}'</span>)
            
            first = <span class="tx-keyword">False</span>
            total_rows += <span class="tx-num">1</span>
            
            <span class="tx-comment"># 진행 상황 출력 (chunk_size마다)</span>
            <span class="tx-keyword">if</span> total_rows % chunk_size == <span class="tx-num">0</span>:
                <span class="tx-func">print</span>(<span class="tx-string">f"⏳ {total_rows:,}행 처리 중..."</span>, end=<span class="tx-string">'\r'</span>)
        
        <span class="tx-comment"># JSON 배열 종료</span>
        json_file.<span class="tx-func">write</span>(<span class="tx-string">'\n]'</span>)
    
    <span class="tx-func">print</span>(<span class="tx-string">f"\n✅ 완료! 총 {total_rows:,}행 처리됨"</span>)
    <span class="tx-keyword">return</span> total_rows


<span class="tx-comment"># pandas 청크 처리 방식</span>
<span class="tx-keyword">def</span> <span class="tx-func">csv_to_json_pandas_chunks</span>(csv_path, json_path, chunksize=<span class="tx-num">10000</span>):
    <span class="tx-string">"""pandas chunksize를 이용한 대용량 처리"""</span>
    <span class="tx-keyword">import</span> pandas <span class="tx-keyword">as</span> pd
    
    all_data = []
    
    <span class="tx-keyword">for</span> i, chunk <span class="tx-keyword">in</span> <span class="tx-func">enumerate</span>(
        pd.<span class="tx-func">read_csv</span>(csv_path, encoding=<span class="tx-string">'utf-8-sig'</span>, chunksize=chunksize)
    ):
        <span class="tx-comment"># NaN → None 변환</span>
        chunk = chunk.<span class="tx-func">where</span>(pd.<span class="tx-func">notnull</span>(chunk), <span class="tx-keyword">None</span>)
        all_data.extend(chunk.<span class="tx-func">to_dict</span>(orient=<span class="tx-string">'records'</span>))
        <span class="tx-func">print</span>(<span class="tx-string">f"⏳ 청크 {i+1} 처리 완료 ({len(all_data):,}행)"</span>, end=<span class="tx-string">'\r'</span>)
    
    <span class="tx-keyword">with</span> <span class="tx-func">open</span>(json_path, <span class="tx-string">'w'</span>, encoding=<span class="tx-string">'utf-8'</span>) <span class="tx-keyword">as</span> f:
        json.<span class="tx-func">dump</span>(all_data, f, ensure_ascii=<span class="tx-keyword">False</span>)
    
    <span class="tx-func">print</span>(<span class="tx-string">f"\n✅ 완료! 총 {len(all_data):,}행"</span>)
    <span class="tx-keyword">return</span> all_data

<span class="tx-keyword">const</span> fs = <span class="tx-func">require</span>(<span class="tx-string">'fs'</span>);
<span class="tx-keyword">const</span> { parse } = <span class="tx-func">require</span>(<span class="tx-string">'csv-parse'</span>);
<span class="tx-keyword">const</span> { stringify } = <span class="tx-func">require</span>(<span class="tx-string">'JSONStream'</span>); <span class="tx-comment">// npm install JSONStream</span>

<span class="tx-keyword">function</span> <span class="tx-func">csvToJsonStream</span>(inputPath, outputPath) {
  <span class="tx-keyword">return new</span> <span class="tx-func">Promise</span>((resolve, reject) => {
    <span class="tx-keyword">let</span> count = <span class="tx-num">0</span>;
    
    <span class="tx-keyword">const</span> readStream = fs.<span class="tx-func">createReadStream</span>(inputPath, { encoding: <span class="tx-string">'utf8'</span> });
    <span class="tx-keyword">const</span> writeStream = fs.<span class="tx-func">createWriteStream</span>(outputPath, { encoding: <span class="tx-string">'utf8'</span> });
    
    <span class="tx-keyword">const</span> csvParser = <span class="tx-func">parse</span>({
      columns: <span class="tx-keyword">true</span>,
      skip_empty_lines: <span class="tx-keyword">true</span>,
      trim: <span class="tx-keyword">true</span>,
      cast: <span class="tx-keyword">true</span>
    });
    
    <span class="tx-keyword">const</span> jsonStringifier = stringify.<span class="tx-func">stringify</span>(<span class="tx-string">'*'</span>);
    
    csvParser.<span class="tx-func">on</span>(<span class="tx-string">'data'</span>, () => {
      count++;
      <span class="tx-keyword">if</span> (count % <span class="tx-num">10000</span> === <span class="tx-num">0</span>) {
        process.stdout.<span class="tx-func">write</span>(<span class="tx-string">`\r⏳ ${count.toLocaleString()}행 처리 중...`</span>);
      }
    });
    
    writeStream.<span class="tx-func">on</span>(<span class="tx-string">'finish'</span>, () => {
      console.<span class="tx-func">log</span>(<span class="tx-string">`\n✅ 완료! 총 ${count.toLocaleString()}행`</span>);
      <span class="tx-func">resolve</span>(count);
    });
    
    readStream
      .<span class="tx-func">pipe</span>(csvParser)
      .<span class="tx-func">pipe</span>(jsonStringifier)
      .<span class="tx-func">pipe</span>(writeStream);
    
    readStream.<span class="tx-func">on</span>(<span class="tx-string">'error'</span>, reject);
    csvParser.<span class="tx-func">on</span>(<span class="tx-string">'error'</span>, reject);
  });
}

<span class="tx-comment">// 실행</span>
<span class="tx-func">csvToJsonStream</span>(<span class="tx-string">'./big_data.csv'</span>, <span class="tx-string">'./big_data.json'</span>)
  .<span class="tx-func">then</span>(count => console.<span class="tx-func">log</span>(<span class="tx-string">`처리 완료: ${count}행`</span>))
  .<span class="tx-func">catch</span>(console.error);

<span class="tx-comment"># JSONL: 각 행이 독립적인 JSON 객체 (줄바꿈으로 구분)</span>
<span class="tx-comment"># {"name":"Alice","age":30,"city":"Seoul"}</span>
<span class="tx-comment"># {"name":"Bob","age":25,"city":"Busan"}</span>
<span class="tx-comment"># {"name":"Carol","age":28,"city":"Incheon"}</span>

<span class="tx-keyword">def</span> <span class="tx-func">csv_to_jsonl</span>(csv_path, jsonl_path):
    <span class="tx-string">"""CSV를 JSONL(JSON Lines) 형식으로 변환 — 대용량 최적"""</span>
    <span class="tx-keyword">import</span> csv, json
    
    count = <span class="tx-num">0</span>
    <span class="tx-keyword">with</span> <span class="tx-func">open</span>(csv_path, <span class="tx-string">'r'</span>, encoding=<span class="tx-string">'utf-8-sig'</span>) <span class="tx-keyword">as</span> csv_f, \
         <span class="tx-func">open</span>(jsonl_path, <span class="tx-string">'w'</span>, encoding=<span class="tx-string">'utf-8'</span>) <span class="tx-keyword">as</span> jsonl_f:
        
        reader = csv.DictReader(csv_f)
        <span class="tx-keyword">for</span> row <span class="tx-keyword">in</span> reader:
            <span class="tx-comment"># 각 행을 한 줄의 JSON으로 즉시 기록</span>
            jsonl_f.<span class="tx-func">write</span>(
                json.<span class="tx-func">dumps</span>(<span class="tx-func">dict</span>(row), ensure_ascii=<span class="tx-keyword">False</span>) + <span class="tx-string">'\n'</span>
            )
            count += <span class="tx-num">1</span>
    
    <span class="tx-func">print</span>(<span class="tx-string">f"✅ JSONL 변환 완료: {count:,}행"</span>)
    <span class="tx-keyword">return</span> count

<span class="tx-keyword">import</span> csv
<span class="tx-keyword">import</span> json
<span class="tx-keyword">import</span> os
<span class="tx-keyword">from</span> typing <span class="tx-keyword">import</span> Optional, List, Dict, Any, Callable
<span class="tx-keyword">from</span> datetime <span class="tx-keyword">import</span> datetime


<span class="tx-keyword">class</span> <span class="tx-func">CsvToJsonConverter</span>:
    <span class="tx-string">"""
    프로덕션 레디 CSV → JSON 변환기
    
    Features:
    - 인코딩 자동 감지 (chardet)
    - BOM 자동 처리
    - 타입 자동 변환
    - 커스텀 변환 함수 지원
    - 스트리밍 모드 (대용량)
    - 진행 상황 콜백
    - 에러 핸들링
    """</span>
    
    <span class="tx-keyword">def</span> <span class="tx-func">__init__</span>(
        self,
        delimiter: str = <span class="tx-string">','</span>,
        encoding: Optional[str] = <span class="tx-keyword">None</span>,
        auto_type: bool = <span class="tx-keyword">True</span>,
        skip_empty_rows: bool = <span class="tx-keyword">True</span>,
        strip_whitespace: bool = <span class="tx-keyword">True</span>
    ):
        self.delimiter = delimiter
        self.encoding = encoding
        self.auto_type = auto_type
        self.skip_empty_rows = skip_empty_rows
        self.strip_whitespace = strip_whitespace
        self._custom_converters: Dict[str, Callable] = {}
    
    <span class="tx-keyword">def</span> <span class="tx-func">add_converter</span>(self, column: str, func: Callable):
        <span class="tx-string">"""특정 컬럼에 커스텀 변환 함수 등록"""</span>
        self._custom_converters[column] = func
        <span class="tx-keyword">return</span> self  <span class="tx-comment"># 메서드 체이닝 지원</span>
    
    <span class="tx-keyword">def</span> <span class="tx-func">_detect_encoding</span>(self, file_path: str) -> str:
        <span class="tx-keyword">try</span>:
            <span class="tx-keyword">import</span> chardet
            <span class="tx-keyword">with</span> <span class="tx-func">open</span>(file_path, <span class="tx-string">'rb'</span>) <span class="tx-keyword">as</span> f:
                raw = f.<span class="tx-func">read</span>(<span class="tx-num">50000</span>)
            result = chardet.<span class="tx-func">detect</span>(raw)
            enc = result.get(<span class="tx-string">'encoding'</span>, <span class="tx-string">'utf-8'</span>)
            <span class="tx-keyword">return</span> <span class="tx-string">'utf-8-sig'</span> <span class="tx-keyword">if</span> enc <span class="tx-keyword">and</span> <span class="tx-string">'utf'</span> <span class="tx-keyword">in</span> enc.lower() <span class="tx-keyword">else</span> enc
        <span class="tx-keyword">except</span> ImportError:
            <span class="tx-keyword">return</span> <span class="tx-string">'utf-8-sig'</span>
    
    <span class="tx-keyword">def</span> <span class="tx-func">_convert_value</span>(self, key: str, value: str) -> Any:
        <span class="tx-comment"># 커스텀 변환기 우선 적용</span>
        <span class="tx-keyword">if</span> key <span class="tx-keyword">in</span> self._custom_converters:
            <span class="tx-keyword">return</span> self._custom_converters[key](value)
        
        <span class="tx-keyword">if</span> self.strip_whitespace <span class="tx-keyword">and</span> value:
            value = value.<span class="tx-func">strip</span>()
        
        <span class="tx-keyword">if</span> value == <span class="tx-string">''</span>:
            <span class="tx-keyword">return</span> <span class="tx-keyword">None</span>
        
        <span class="tx-keyword">if</span> <span class="tx-keyword">not</span> self.auto_type:
            <span class="tx-keyword">return</span> value
        
        lower = value.lower()
        <span class="tx-keyword">if</span> lower <span class="tx-keyword">in</span> (<span class="tx-string">'true'</span>, <span class="tx-string">'yes'</span>): <span class="tx-keyword">return</span> <span class="tx-keyword">True</span>
        <span class="tx-keyword">if</span> lower <span class="tx-keyword">in</span> (<span class="tx-string">'false'</span>, <span class="tx-string">'no'</span>): <span class="tx-keyword">return</span> <span class="tx-keyword">False</span>
        
        <span class="tx-keyword">try</span>: <span class="tx-keyword">return</span> <span class="tx-func">int</span>(value)
        <span class="tx-keyword">except</span> ValueError: <span class="tx-keyword">pass</span>
        
        <span class="tx-keyword">try</span>: <span class="tx-keyword">return</span> <span class="tx-func">float</span>(value)
        <span class="tx-keyword">except</span> ValueError: <span class="tx-keyword">pass</span>
        
        <span class="tx-keyword">return</span> value
    
    <span class="tx-keyword">def</span> <span class="tx-func">convert</span>(
        self,
        csv_path: str,
        json_path: Optional[str] = <span class="tx-keyword">None</span>,
        indent: int = <span class="tx-num">2</span>,
        progress_callback: Optional[Callable] = <span class="tx-keyword">None</span>
    ) -> List[Dict]:
        <span class="tx-string">"""메인 변환 메서드"""</span>
        
        <span class="tx-keyword">if</span> <span class="tx-keyword">not</span> os.path.<span class="tx-func">exists</span>(csv_path):
            <span class="tx-keyword">raise</span> <span class="tx-func">FileNotFoundError</span>(<span class="tx-string">f"파일 없음: {csv_path}"</span>)
        
        encoding = self.encoding <span class="tx-keyword">or</span> self.<span class="tx-func">_detect_encoding</span>(csv_path)
        result = []
        
        <span class="tx-keyword">with</span> <span class="tx-func">open</span>(csv_path, <span class="tx-string">'r'</span>, encoding=encoding, newline=<span class="tx-string">''</span>) <span class="tx-keyword">as</span> f:
            reader = csv.DictReader(f, delimiter=self.delimiter)
            
            <span class="tx-keyword">if</span> reader.fieldnames:
                reader.fieldnames = [
                    h.<span class="tx-func">strip</span>() <span class="tx-keyword">for</span> h <span class="tx-keyword">in</span> reader.fieldnames
                ]
            
            <span class="tx-keyword">for</span> i, row <span class="tx-keyword">in</span> <span class="tx-func">enumerate</span>(reader):
                <span class="tx-keyword">if</span> self.skip_empty_rows:
                    <span class="tx-keyword">if</span> <span class="tx-func">all</span>(v == <span class="tx-string">''</span> <span class="tx-keyword">or</span> v <span class="tx-keyword">is</span> <span class="tx-keyword">None</span> <span class="tx-keyword">for</span> v <span class="tx-keyword">in</span> row.values()):
                        <span class="tx-keyword">continue</span>
                
                converted = {
                    k: self.<span class="tx-func">_convert_value</span>(k, v <span class="tx-keyword">or</span> <span class="tx-string">''</span>)
                    <span class="tx-keyword">for</span> k, v <span class="tx-keyword">in</span> row.items()
                    <span class="tx-keyword">if</span> k <span class="tx-keyword">is</span> <span class="tx-keyword">not</span> <span class="tx-keyword">None</span>
                }
                result.append(converted)
                
                <span class="tx-keyword">if</span> progress_callback <span class="tx-keyword">and</span> (i + <span class="tx-num">1</span>) % <span class="tx-num">1000</span> == <span class="tx-num">0</span>:
                    <span class="tx-func">progress_callback</span>(i + <span class="tx-num">1</span>)
        
        <span class="tx-keyword">if</span> json_path:
            <span class="tx-keyword">with</span> <span class="tx-func">open</span>(json_path, <span class="tx-string">'w'</span>, encoding=<span class="tx-string">'utf-8'</span>) <span class="tx-keyword">as</span> f:
                json.<span class="tx-func">dump</span>(result, f, ensure_ascii=<span class="tx-keyword">False</span>, indent=indent)
        
        <span class="tx-keyword">return</span> result


<span class="tx-comment"># ===== 사용 예시 =====</span>

<span class="tx-comment"># 기본 사용</span>
converter = <span class="tx-func">CsvToJsonConverter</span>()
data = converter.<span class="tx-func">convert</span>(<span class="tx-string">'input.csv'</span>, <span class="tx-string">'output.json'</span>)

<span class="tx-comment"># 고급 사용: 커스텀 변환기 + 진행 상황 출력</span>
<span class="tx-keyword">from</span> datetime <span class="tx-keyword">import</span> datetime

converter = (
    <span class="tx-func">CsvToJsonConverter</span>(delimiter=<span class="tx-string">','</span>, auto_type=<span class="tx-keyword">True</span>)
    .<span class="tx-func">add_converter</span>(<span class="tx-string">'birth_date'</span>, <span class="tx-keyword">lambda</span> v: datetime.<span class="tx-func">strptime</span>(v, <span class="tx-string">'%Y-%m-%d'</span>).<span class="tx-func">isoformat</span>() <span class="tx-keyword">if</span> v <span class="tx-keyword">else</span> <span class="tx-keyword">None</span>)
    .<span class="tx-func">add_converter</span>(<span class="tx-string">'phone'</span>, <span class="tx-keyword">lambda</span> v: v.<span class="tx-func">replace</span>(<span class="tx-string">'-'</span>, <span class="tx-string">''</span>) <span class="tx-keyword">if</span> v <span class="tx-keyword">else</span> <span class="tx-keyword">None</span>)
)

data = converter.<span class="tx-func">convert</span>(
    <span class="tx-string">'users.csv'</span>,
    <span class="tx-string">'users.json'</span>,
    progress_callback=<span class="tx-keyword">lambda</span> n: <span class="tx-func">print</span>(<span class="tx-string">f"⏳ {n:,}행 처리 중..."</span>, end=<span class="tx-string">'\r'</span>)
)
<span class="tx-func">print</span>(<span class="tx-string">f"\n🎉 완료! {len(data):,}개 레코드"</span>)

<span class="tx-keyword">from</span> flask <span class="tx-keyword">import</span> Flask, request, jsonify
<span class="tx-keyword">import</span> csv, json, io

app = <span class="tx-func">Flask</span>(__name__)

<span class="tx-comment"># POST /convert  →  CSV 파일 업로드 → JSON 반환</span>
@app.<span class="tx-func">route</span>(<span class="tx-string">'/convert'</span>, methods=[<span class="tx-string">'POST'</span>])
<span class="tx-keyword">def</span> <span class="tx-func">convert_csv</span>():
    <span class="tx-keyword">if</span> <span class="tx-string">'file'</span> <span class="tx-keyword">not in</span> request.files:
        <span class="tx-keyword">return</span> <span class="tx-func">jsonify</span>({<span class="tx-string">'error'</span>: <span class="tx-string">'파일이 없습니다'</span>}), <span class="tx-num">400</span>
    
    file = request.files[<span class="tx-string">'file'</span>]
    
    <span class="tx-keyword">if</span> <span class="tx-keyword">not</span> file.filename.<span class="tx-func">endswith</span>(<span class="tx-string">'.csv'</span>):
        <span class="tx-keyword">return</span> <span class="tx-func">jsonify</span>({<span class="tx-string">'error'</span>: <span class="tx-string">'CSV 파일만 허용됩니다'</span>}), <span class="tx-num">400</span>
    
    <span class="tx-keyword">try</span>:
        content = file.<span class="tx-func">read</span>().<span class="tx-func">decode</span>(<span class="tx-string">'utf-8-sig'</span>)
        reader = csv.DictReader(io.<span class="tx-func">StringIO</span>(content))
        result = [<span class="tx-func">dict</span>(row) <span class="tx-keyword">for</span> row <span class="tx-keyword">in</span> reader]
        
        <span class="tx-keyword">return</span> <span class="tx-func">jsonify</span>({
            <span class="tx-string">'success'</span>: <span class="tx-keyword">True</span>,
            <span class="tx-string">'total'</span>: <span class="tx-func">len</span>(result),
            <span class="tx-string">'data'</span>: result
        })
    <span class="tx-keyword">except</span> Exception <span class="tx-keyword">as</span> e:
        <span class="tx-keyword">return</span> <span class="tx-func">jsonify</span>({<span class="tx-string">'error'</span>: <span class="tx-func">str</span>(e)}), <span class="tx-num">500</span>

<span class="tx-keyword">if</span> __name__ == <span class="tx-string">'__main__'</span>:
    app.<span class="tx-func">run</span>(debug=<span class="tx-keyword">True</span>)