/* */
/* CRC LOOKUP TABLE */
/* ================ */
/* The following CRC lookup table was generated automagically */
/* by the Rocksoft^tm Model CRC Algorithm Table Generation */
/* Program V1.0 using the following model parameters: */
/* */
/* Width : 4 bytes. */
/* Poly : 0x1EDC6F41L */
/* Reverse : TRUE. */
/* */
/* For more information on the Rocksoft^tm Model CRC Algorithm, */
/* see the document titled "A Painless Guide to CRC Error */
/* Detection Algorithms" by Ross Williams */
/* (ross@guest.adelaide.edu.au.). This document is likely to be */
/* in the FTP archive "ftp.adelaide.edu.au/pub/rocksoft". */
/* */
pub const CRC32C_TAB: [u32; 256] = [
    0x00000000, 0xF26B8303, 0xE13B70F7, 0x1350F3F4, 0xC79A971F, 0x35F1141C, 0x26A1E7E8, 0xD4CA64EB,
    0x8AD958CF, 0x78B2DBCC, 0x6BE22838, 0x9989AB3B, 0x4D43CFD0, 0xBF284CD3, 0xAC78BF27, 0x5E133C24,
    0x105EC76F, 0xE235446C, 0xF165B798, 0x030E349B, 0xD7C45070, 0x25AFD373, 0x36FF2087, 0xC494A384,
    0x9A879FA0, 0x68EC1CA3, 0x7BBCEF57, 0x89D76C54, 0x5D1D08BF, 0xAF768BBC, 0xBC267848, 0x4E4DFB4B,
    0x20BD8EDE, 0xD2D60DDD, 0xC186FE29, 0x33ED7D2A, 0xE72719C1, 0x154C9AC2, 0x061C6936, 0xF477EA35,
    0xAA64D611, 0x580F5512, 0x4B5FA6E6, 0xB93425E5, 0x6DFE410E, 0x9F95C20D, 0x8CC531F9, 0x7EAEB2FA,
    0x30E349B1, 0xC288CAB2, 0xD1D83946, 0x23B3BA45, 0xF779DEAE, 0x05125DAD, 0x1642AE59, 0xE4292D5A,
    0xBA3A117E, 0x4851927D, 0x5B016189, 0xA96AE28A, 0x7DA08661, 0x8FCB0562, 0x9C9BF696, 0x6EF07595,
    0x417B1DBC, 0xB3109EBF, 0xA0406D4B, 0x522BEE48, 0x86E18AA3, 0x748A09A0, 0x67DAFA54, 0x95B17957,
    0xCBA24573, 0x39C9C670, 0x2A993584, 0xD8F2B687, 0x0C38D26C, 0xFE53516F, 0xED03A29B, 0x1F682198,
    0x5125DAD3, 0xA34E59D0, 0xB01EAA24, 0x42752927, 0x96BF4DCC, 0x64D4CECF, 0x77843D3B, 0x85EFBE38,
    0xDBFC821C, 0x2997011F, 0x3AC7F2EB, 0xC8AC71E8, 0x1C661503, 0xEE0D9600, 0xFD5D65F4, 0x0F36E6F7,
    0x61C69362, 0x93AD1061, 0x80FDE395, 0x72966096, 0xA65C047D, 0x5437877E, 0x4767748A, 0xB50CF789,
    0xEB1FCBAD, 0x197448AE, 0x0A24BB5A, 0xF84F3859, 0x2C855CB2, 0xDEEEDFB1, 0xCDBE2C45, 0x3FD5AF46,
    0x7198540D, 0x83F3D70E, 0x90A324FA, 0x62C8A7F9, 0xB602C312, 0x44694011, 0x5739B3E5, 0xA55230E6,
    0xFB410CC2, 0x092A8FC1, 0x1A7A7C35, 0xE811FF36, 0x3CDB9BDD, 0xCEB018DE, 0xDDE0EB2A, 0x2F8B6829,
    0x82F63B78, 0x709DB87B, 0x63CD4B8F, 0x91A6C88C, 0x456CAC67, 0xB7072F64, 0xA457DC90, 0x563C5F93,
    0x082F63B7, 0xFA44E0B4, 0xE9141340, 0x1B7F9043, 0xCFB5F4A8, 0x3DDE77AB, 0x2E8E845F, 0xDCE5075C,
    0x92A8FC17, 0x60C37F14, 0x73938CE0, 0x81F80FE3, 0x55326B08, 0xA759E80B, 0xB4091BFF, 0x466298FC,
    0x1871A4D8, 0xEA1A27DB, 0xF94AD42F, 0x0B21572C, 0xDFEB33C7, 0x2D80B0C4, 0x3ED04330, 0xCCBBC033,
    0xA24BB5A6, 0x502036A5, 0x4370C551, 0xB11B4652, 0x65D122B9, 0x97BAA1BA, 0x84EA524E, 0x7681D14D,
    0x2892ED69, 0xDAF96E6A, 0xC9A99D9E, 0x3BC21E9D, 0xEF087A76, 0x1D63F975, 0x0E330A81, 0xFC588982,
    0xB21572C9, 0x407EF1CA, 0x532E023E, 0xA145813D, 0x758FE5D6, 0x87E466D5, 0x94B49521, 0x66DF1622,
    0x38CC2A06, 0xCAA7A905, 0xD9F75AF1, 0x2B9CD9F2, 0xFF56BD19, 0x0D3D3E1A, 0x1E6DCDEE, 0xEC064EED,
    0xC38D26C4, 0x31E6A5C7, 0x22B65633, 0xD0DDD530, 0x0417B1DB, 0xF67C32D8, 0xE52CC12C, 0x1747422F,
    0x49547E0B, 0xBB3FFD08, 0xA86F0EFC, 0x5A048DFF, 0x8ECEE914, 0x7CA56A17, 0x6FF599E3, 0x9D9E1AE0,
    0xD3D3E1AB, 0x21B862A8, 0x32E8915C, 0xC083125F, 0x144976B4, 0xE622F5B7, 0xF5720643, 0x07198540,
    0x590AB964, 0xAB613A67, 0xB831C993, 0x4A5A4A90, 0x9E902E7B, 0x6CFBAD78, 0x7FAB5E8C, 0x8DC0DD8F,
    0xE330A81A, 0x115B2B19, 0x020BD8ED, 0xF0605BEE, 0x24AA3F05, 0xD6C1BC06, 0xC5914FF2, 0x37FACCF1,
    0x69E9F0D5, 0x9B8273D6, 0x88D28022, 0x7AB90321, 0xAE7367CA, 0x5C18E4C9, 0x4F48173D, 0xBD23943E,
    0xF36E6F75, 0x0105EC76, 0x12551F82, 0xE03E9C81, 0x34F4F86A, 0xC69F7B69, 0xD5CF889D, 0x27A40B9E,
    0x79B737BA, 0x8BDCB4B9, 0x988C474D, 0x6AE7C44E, 0xBE2DA0A5, 0x4C4623A6, 0x5F16D052, 0xAD7D5351,
];

/// 计算CRC32校验和
/// 参数 crc 初始值
/// 参数 buf 缓冲区
/// 参数 size 缓冲区大小
/// 参数 tab 查找表
pub fn crc32(crc: u32, buf: &[u8], size: u32, tab: &[u32]) -> u32 {
    let mut crc = crc;
    let mut p = buf;
    let mut size = size as usize;

    // 循环更新crc值
    while size > 0 {
        crc = tab[(crc as u8 ^ p[0]) as usize] ^ (crc >> 8);
        p = &p[1..];
        size -= 1;
    }

    crc
}

pub fn ext4_crc32c(crc: u32, buf: &[u8], size: u32) -> u32 {
    crc32(crc, buf, size, &CRC32C_TAB)
}

/// 检查位图中的某一位是否被设置
/// 参数 bmap 位图缓冲区
/// 参数 bit 要检查的位
pub fn ext4_bmap_is_bit_set(bmap: &[u8], bit: u32) -> bool {
    bmap[(bit >> 3) as usize] & (1 << (bit & 7)) != 0
}

/// 检查位图中的某一位是否被清除
/// 参数 bmap 位图缓冲区
/// 参数 bit 要检查的位
pub fn ext4_bmap_is_bit_clr(bmap: &[u8], bit: u32) -> bool {
    !ext4_bmap_is_bit_set(bmap, bit)
}

/// 设置位图中的某一位
/// 参数 bmap 位图
/// 参数 bit 要设置的位
pub fn ext4_bmap_bit_set(bmap: &mut [u8], bit: u32) {
    bmap[(bit >> 3) as usize] |= 1 << (bit & 7);
}

/// Clears a specific bit in a bitmap.
/// 参数 bmap: Mutable reference to the bitmap array.
/// 参数 bit: The bit index to clear.
pub fn ext4_bmap_bit_clr(bmap: &mut [u8], bit: u32) {
    bmap[(bit >> 3) as usize] &= !(1 << (bit & 7));
}

// 查找位图中第一个为0的位
pub fn ext4_bmap_bit_find_clr(bmap: &[u8], sbit: u32, ebit: u32, bit_id: &mut u32) -> bool {
    let mut i: u32;
    let mut bcnt = ebit - sbit;

    i = sbit;

    while i & 7 != 0 {
        if bcnt == 0 {
            return false;
        }

        if ext4_bmap_is_bit_clr(bmap, i) {
            *bit_id = sbit;
            return true;
        }

        i += 1;
        bcnt -= 1;
    }

    let mut sbit = i;
    let mut bmap = &bmap[(sbit >> 3) as usize..];
    while bcnt >= 8 {
        if bmap[0] != 0xFF {
            for i in 0..8 {
                if ext4_bmap_is_bit_clr(bmap, i) {
                    *bit_id = sbit + i;
                    return true;
                }
            }
        }

        bmap = &bmap[1..];
        bcnt -= 8;
        sbit += 8;
    }

    for i in 0..bcnt {
        if ext4_bmap_is_bit_clr(bmap, i) {
            *bit_id = sbit + i;
            return true;
        }
    }

    false
}

/// Clears a range of bits in a bitmap.
/// 参数 bmap: Mutable reference to the bitmap array.
/// 参数 start_bit: The start index of the bit range to clear.
/// 参数 end_bit: The end index of the bit range to clear.
pub fn ext4_bmap_bits_free(bmap: &mut [u8], start_bit: u32, end_bit: u32) {
    for bit in start_bit..=end_bit {
        ext4_bmap_bit_clr(bmap, bit);
    }
}

pub fn ext4_path_skip<'a>(path: &'a str, skip: &str) -> &'a str {
    let path = &path.trim_start_matches(skip);
    path
}

use alloc::string::String;
use alloc::string::ToString;
use alloc::vec::Vec;

pub fn ext4_path_check(path: &str, is_goal: &mut bool) -> usize {
    for (i, c) in path.chars().enumerate() {
        if c == '/' {
            *is_goal = false;
            return i;
        }
    }
    let path = path.to_string();
    *is_goal = true;
    return path.len();
}

// A function that takes a &str and returns a &[char]
pub fn get_name(name: [u8; 255], len: usize) -> Result<String, alloc::string::FromUtf8Error> {
    let mut v: Vec<u8> = Vec::new();
    for i in 0..len {
        v.push(name[i]);
    }
    let s = String::from_utf8(v);
    s
}

pub fn path_check_new(path: &str, is_goal: &mut bool) -> usize {
    // 遍历字符串中的每个字符及其索引
    for (i, c) in path.chars().enumerate() {
        // 检查是否到达文件名的最大长度限制
        if i >= 255 {
            break;
        }

        // 检查字符是否是路径分隔符
        if c == '/' {
            *is_goal = false;
            return i;
        }

        // 检查是否达到字符串结尾
        if c == '\0' {
            *is_goal = true;
            return i;
        }
    }

    // 如果没有找到 '/' 或 '\0'，且长度小于最大文件名长度
    *is_goal = true;
    return path.len();
}

#[cfg(test)]
mod path_tests {
    use super::*;
    #[test]
    fn test_ext4_path_check() {
        let mut is_goal = false;

        // 测试根路径
        assert_eq!(path_check_new("/", &mut is_goal), 0);
        assert!(!is_goal, "Root path should not set is_goal to true");

        // 测试普通路径
        assert_eq!(path_check_new("/home/user/file.txt", &mut is_goal), 0);
        assert!(!is_goal, "Normal path should not set is_goal to true");

        // 测试没有斜杠的路径
        let path = "file.txt";
        assert_eq!(path_check_new(path, &mut is_goal), path.len());
        assert!(is_goal, "Path without slashes should set is_goal to true");

        // 测试路径末尾的 null 字符
        let path = "home\0";
        assert_eq!(path_check_new(path, &mut is_goal), 4);
        assert!(
            is_goal,
            "Path with null character should set is_goal to true"
        );

        // // 测试超长文件名
        // let long_path = "a".repeat(EXT4_DIRECTORY_FILENAME_LEN + 10);
        // assert_eq!(ext4_path_check(&long_path, &mut is_goal), EXT4_DIRECTORY_FILENAME_LEN);
        // assert!(!is_goal, "Long filename should not set is_goal to true and should be truncated");
    }
}
