use std::io::{Cursor, Read, Seek, SeekFrom, Write};
let ori_filename = "./files/zip_file.zip";

let data_bytes = fs::read(ori_filename).unwrap();

// 确保文件至少有固定大小的文件头部分
if data_bytes.len() < 30 {
    return Err("文件太小，不是zip".to_string());
}

// 提取各个字段
let local_file_header_signature = &data_bytes[0..4];
let version_needed_to_extract = &data_bytes[4..6];
let general_purpose_bit_flag = &data_bytes[6..8];
let compression_method = &data_bytes[8..10];
let last_mod_file_time = &data_bytes[10..12];
let last_mod_file_date = &data_bytes[12..14];
let crc_32 = &data_bytes[14..18];
let compressed_size = &data_bytes[18..22];
let uncompressed_size = &data_bytes[22..26];
let file_name_length = &data_bytes[26..28];
let extra_field_length = &data_bytes[28..30];

// 打印各个字段
println!("本地文件头签名 (Local File Header Signature): {:?}", local_file_header_signature);
println!("版本需要 (Version Needed to Extract): {:?}", version_needed_to_extract);
println!("通用位标志 (General Purpose Bit Flag): {:?}", general_purpose_bit_flag);
println!("压缩方法 (Compression Method): {:?}", compression_method);
println!("最后修改文件时间 (Last Mod File Time): {:?}", last_mod_file_time);
println!("最后修改文件日期 (Last Mod File Date): {:?}", last_mod_file_date);
println!("CRC-32校验 (CRC-32): {:?}", crc_32);
println!("压缩后大小 (Compressed Size): {:?}", compressed_size);
println!("未压缩大小 (Uncompressed Size): {:?}", uncompressed_size);
println!("文件名长度 (File Name Length): {:?}", file_name_length);
println!("额外字段长度 (Extra Field Length): {:?}", extra_field_length);

// 根据文件名长度和额外字段长度提取并打印文件名和额外字段
let file_name_length = u16::from_le_bytes([file_name_length[0], file_name_length[1]]) as usize;
let extra_field_length = u16::from_le_bytes([extra_field_length[0], extra_field_length[1]]) as usize;

let file_name = &data_bytes[30..30 + file_name_length];
let extra_field = &data_bytes[30 + file_name_length..30 + file_name_length + extra_field_length];

println!("文件名 (File Name): {:?}", file_name);
println!("额外字段 (Extra Field): {:?}", extra_field);


println!("=========zip结尾存放中央目录============");


// 查找结束中央目录记录的签名
let eocd_signature = b"\x50\x4b\x05\x06";
if let Some(eocd_pos) = data_bytes.windows(4).position(|window| window == eocd_signature) {
    // 本磁盘上中央目录记录的文件数量
    let num_entries = u16::from_le_bytes([data_bytes[eocd_pos + 8], data_bytes[eocd_pos + 9]]);
    // 中央文件的起始位置
    let central_dir_offset = u32::from_le_bytes([
        data_bytes[eocd_pos + 16],
        data_bytes[eocd_pos + 17],
        data_bytes[eocd_pos + 18],
        data_bytes[eocd_pos + 19],
    ]) as usize;

    // 遍历中央目录记录
    let mut offset = central_dir_offset;
    for _ in 0..num_entries {
        let central_dir_record = &data_bytes[offset..];

        // 解析中央目录记录
        let file_name_length = u16::from_le_bytes([central_dir_record[28], central_dir_record[29]]) as usize;
        let extra_field_length = u16::from_le_bytes([central_dir_record[30], central_dir_record[31]]) as usize;
        let file_comment_length = u16::from_le_bytes([central_dir_record[32], central_dir_record[33]]) as usize;
        // extra_field：额外字段，根据需求放入信息，例如，文件的扩展属性，例如文件的创建时间、修改时间、访问时间。
        // extra_field：结构通常由两部分组成：一个两字节的标识符（Header ID）和一个两字节的数据长度字段（Data Size），后面跟随实际的数据（Data）。标识符用于标明extra_field的类型或用途，数据长度字段指示随后的数据部分的长度。
        // file_comment：文件的文本注释，


        // 提取文件名
        let file_name = &central_dir_record[46..46 + file_name_length];

        // 打印文件名
        println!("文件名: {}", String::from_utf8_lossy(file_name));

        // 更新offset以跳转到下一条目录记录
        offset += 46 + file_name_length + extra_field_length + file_comment_length;
    }