import re


def fix_line(lines, line_number):
    """
    修复CSV行，确保text字段中的引号和换行符正确处理。

    参数:
        lines (list): 输入的行列表，可能包含多行
        line_number (int): 当前处理的行号（用于调试）
    返回:
        str: 修复后的单行CSV字符串
    """
    full_line = ''.join(lines)

    # 正则匹配完整行
    match = re.search(r'^([^,]+),"(.+?)","([A-Z][a-z]{2} \d{1,2}, \d{1,2}:\d{2}:\d{2} (AM|PM) E[SD]T)"$', full_line,
                      re.DOTALL)
    if match:
        id_part = match.group(1)
        text_content = match.group(2)
        created_at = match.group(3)

        # 修复text字段中的引号
        fixed_text = text_content.replace('"', '""')

        # 调试第4375行附近
        if 4370 <= line_number <= 4380:
            print(f"Line {line_number}:")
            print(f"  Original text: {repr(text_content)}")
            print(f"  Fixed text: {repr(fixed_text)}")
            print(f"  Contains newline: {'\\n' in text_content}")

        # 重建CSV行
        fixed_line = f'{id_part},"{fixed_text}","{created_at}"'
        return fixed_line
    else:
        # 如果格式不匹配，返回原始内容并警告
        print(f"Line {line_number} format error: {repr(full_line)}")
        return full_line


def process_file(input_file, output_file):
    """
    处理整个CSV文件，修复每一行。
    """
    with open(input_file, 'r', encoding='utf-8') as f_in, open(output_file, 'w', encoding='utf-8') as f_out:
        f_out.write("id,text,created_at\n")
        buffer = []
        line_number = 0

        for line in f_in:
            line = line.rstrip('\n')  # 仅移除行尾换行符，保留字段内的换行符
            if line.startswith('id,text,created_at'):
                continue

            line_number += 1
            buffer.append(line)

            # 检查是否到达完整行
            if line.endswith('"') and re.search(r'"[A-Z][a-z]{2} \d{1,2}, \d{1,2}:\d{2}:\d{2} (AM|PM) E[SD]T"$', line):
                fixed_line = fix_line(buffer, line_number)
                f_out.write(fixed_line + '\n')
                buffer = []

        # 处理剩余未完成行
        if buffer:
            fixed_line = fix_line(buffer, line_number)
            f_out.write(fixed_line + '\n')

    print(f"文件已修复，保存为 {output_file}")


# 处理文件
input_file = 'original.csv'
output_file = 'fixed.csv'
process_file(input_file, output_file)