#![allow(non_snake_case)]
use std::os::raw::c_char;

/// Matches `ZSTD_ErrorCode` / `ERR_enum` from the C API.
#[repr(i32)]
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub enum ZstdErrorCode {
    NoError = 0,
    Generic = 1,
    PrefixUnknown = 10,
    VersionUnsupported = 12,
    FrameParameterUnsupported = 14,
    FrameParameterWindowTooLarge = 16,
    CorruptionDetected = 20,
    ChecksumWrong = 22,
    LiteralsHeaderWrong = 24,
    DictionaryCorrupted = 30,
    DictionaryWrong = 32,
    DictionaryCreationFailed = 34,
    ParameterUnsupported = 40,
    ParameterCombinationUnsupported = 41,
    ParameterOutOfBound = 42,
    TableLogTooLarge = 44,
    MaxSymbolValueTooLarge = 46,
    MaxSymbolValueTooSmall = 48,
    CannotProduceUncompressedBlock = 49,
    StabilityConditionNotRespected = 50,
    StageWrong = 60,
    InitMissing = 62,
    MemoryAllocation = 64,
    WorkSpaceTooSmall = 66,
    DstSizeTooSmall = 70,
    SrcSizeWrong = 72,
    DstBufferNull = 74,
    NoForwardProgressDestFull = 80,
    NoForwardProgressInputEmpty = 82,
    FrameIndexTooLarge = 100,
    SeekableIO = 102,
    DstBufferWrong = 104,
    SrcBufferWrong = 105,
    SequenceProducerFailed = 106,
    ExternalSequencesInvalid = 107,
    MaxCode = 120,
}

/// Encode an error as a size_t-style error code: `(size_t)-(code)`.
#[inline]
pub fn ERROR(code: ZstdErrorCode) -> usize {
    (-(code as i32)) as usize
}

/// Returns true if `code` is an error (same as C `ERR_isError`).
#[inline]
pub fn ERR_isError(code: usize) -> bool {
    code > ERROR(ZstdErrorCode::MaxCode)
}

/// Extract the numeric `ZSTD_ErrorCode` from a size_t error value.
///
/// C permits error-shaped values which aren't named enum variants, and
/// `ERR_getErrorCode()` preserves those numeric values. Returning the ABI's
/// integer representation avoids constructing an invalid Rust enum.
#[inline]
pub fn ERR_getErrorCode(code: usize) -> i32 {
    if !ERR_isError(code) {
        return ZstdErrorCode::NoError as i32;
    }
    0usize.wrapping_sub(code) as i32
}

#[inline]
pub fn ERR_getErrorName(code: usize) -> *const c_char {
    ERR_getErrorString(ERR_getErrorCode(code))
}

/// C ABI: `ERR_getErrorString` (error_private.c).
#[no_mangle]
pub extern "C" fn ERR_getErrorString(code: i32) -> *const c_char {
    match code {
        0 => c"No error detected".as_ptr(),
        1 => c"Error (generic)".as_ptr(),
        10 => c"Unknown frame descriptor".as_ptr(),
        12 => c"Version not supported".as_ptr(),
        14 => c"Unsupported frame parameter".as_ptr(),
        16 => c"Frame requires too much memory for decoding".as_ptr(),
        20 => c"Data corruption detected".as_ptr(),
        22 => c"Restored data doesn't match checksum".as_ptr(),
        24 => c"Header of Literals' block doesn't respect format specification".as_ptr(),
        30 => c"Dictionary is corrupted".as_ptr(),
        32 => c"Dictionary mismatch".as_ptr(),
        34 => c"Cannot create Dictionary from provided samples".as_ptr(),
        40 => c"Unsupported parameter".as_ptr(),
        41 => c"Unsupported combination of parameters".as_ptr(),
        42 => c"Parameter is out of bound".as_ptr(),
        44 => c"tableLog requires too much memory : unsupported".as_ptr(),
        46 => c"Unsupported max Symbol Value : too large".as_ptr(),
        48 => c"Specified maxSymbolValue is too small".as_ptr(),
        49 => c"This mode cannot generate an uncompressed block".as_ptr(),
        50 => c"pledged buffer stability condition is not respected".as_ptr(),
        60 => c"Operation not authorized at current processing stage".as_ptr(),
        62 => c"Context should be init first".as_ptr(),
        64 => c"Allocation error : not enough memory".as_ptr(),
        66 => c"workSpace buffer is not large enough".as_ptr(),
        70 => c"Destination buffer is too small".as_ptr(),
        72 => c"Src size is incorrect".as_ptr(),
        74 => c"Operation on NULL destination buffer".as_ptr(),
        80 => c"Operation made no progress over multiple calls, due to output buffer being full"
            .as_ptr(),
        82 => c"Operation made no progress over multiple calls, due to input being empty".as_ptr(),
        100 => c"Frame index is too large".as_ptr(),
        102 => c"An I/O error occurred when reading/seeking".as_ptr(),
        104 => c"Destination buffer is wrong".as_ptr(),
        105 => c"Source buffer is wrong".as_ptr(),
        106 => c"Block-level external sequence producer returned an error code".as_ptr(),
        107 => c"External sequences are not valid".as_ptr(),
        _ => c"Unspecified error code".as_ptr(),
    }
}

/// C ABI: public `ZSTD_getErrorString` from zstd_errors.h.
#[no_mangle]
pub extern "C" fn ZSTD_getErrorString(code: i32) -> *const c_char {
    ERR_getErrorString(code)
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::ffi::CStr;

    #[test]
    fn size_t_error_encoding_matches_c() {
        let error = ERROR(ZstdErrorCode::DstSizeTooSmall);
        assert!(ERR_isError(error));
        assert_eq!(ERR_getErrorCode(error), 70);
        assert!(!ERR_isError(0));
        assert_eq!(ERR_getErrorCode(usize::MAX - 1), 2);
        assert_eq!(ERR_getErrorCode(ERROR(ZstdErrorCode::MaxCode)), 0);
    }

    #[test]
    fn error_names_match_the_public_api() {
        let name = unsafe { CStr::from_ptr(ERR_getErrorName(ERROR(ZstdErrorCode::ChecksumWrong))) };
        assert_eq!(name.to_bytes(), b"Restored data doesn't match checksum");

        let unknown = unsafe { CStr::from_ptr(ERR_getErrorString(2)) };
        assert_eq!(unknown.to_bytes(), b"Unspecified error code");
    }
}