//! This module mainly contains functionality replicating the miniz higher level API.

use std::default::Default;
use std::{fmt, mem};

use libc::c_ulong;

use crate::tdef::Compressor;
use miniz_oxide::deflate::core::{
    create_comp_flags_from_zip_params, deflate_flags, CompressionStrategy, CompressorOxide,
};
use miniz_oxide::deflate::stream::deflate;
use miniz_oxide::inflate::stream::{inflate, InflateState};

use miniz_oxide::*;

const MZ_DEFLATED: i32 = 8;

pub use miniz_oxide::MZ_ADLER32_INIT;

pub enum InternalState {
    Inflate(Box<InflateState>),
    Deflate(Box<Compressor>),
}

impl fmt::Debug for InternalState {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let name = match &self {
            InternalState::Inflate(_) => "Decompressor",
            InternalState::Deflate(_) => "Compressor",
        };
        write!(f, "{}", name)
    }
}

pub type MZResult = Result<MZStatus, MZError>;

/// Enum to keep track of what type the internal state is when moving over the C API boundary.
#[repr(C)]
#[derive(Debug, Copy, Clone, PartialEq)]
pub enum StateTypeEnum {
    None = 0,
    InflateType,
    DeflateType,
}

/// Trait used for states that can be carried by BoxedState.
pub trait StateType {
    const STATE_TYPE: StateTypeEnum;
    fn from_enum(value: &mut InternalState) -> Option<&mut Self>;
}

impl StateType for InflateState {
    const STATE_TYPE: StateTypeEnum = StateTypeEnum::InflateType;
    fn from_enum(value: &mut InternalState) -> Option<&mut Self> {
        if let InternalState::Inflate(state) = value {
            Some(state.as_mut())
        } else {
            None
        }
    }
}

impl StateType for Compressor {
    const STATE_TYPE: StateTypeEnum = StateTypeEnum::DeflateType;
    fn from_enum(value: &mut InternalState) -> Option<&mut Self> {
        if let InternalState::Deflate(state) = value {
            Some(state.as_mut())
        } else {
            None
        }
    }
}

#[derive(Default)]
pub struct StreamOxide<'io, ST: StateType> {
    pub next_in: Option<&'io [u8]>,
    pub total_in: c_ulong,

    pub next_out: Option<&'io mut [u8]>,
    pub total_out: c_ulong,

    pub(crate) state: Option<Box<InternalState>>,

    pub adler: u32,
    pub(crate) state_type: std::marker::PhantomData<ST>,
}

impl<'io, ST: StateType> StreamOxide<'io, ST> {
    pub fn state(&mut self) -> Option<&mut ST> {
        StateType::from_enum(self.state.as_mut()?.as_mut())
    }
}

/// Returns true if the window_bits parameter is valid.
fn invalid_window_bits(window_bits: i32) -> bool {
    (window_bits != MZ_DEFAULT_WINDOW_BITS) && (-window_bits != MZ_DEFAULT_WINDOW_BITS)
}

/// Try to fully decompress the data provided in the stream struct, with the specified
/// level.
///
/// Returns MZResult::Ok on success.
pub fn mz_compress2_oxide(
    stream_oxide: &mut StreamOxide<Compressor>,
    level: i32,
    dest_len: &mut c_ulong,
) -> MZResult {
    mz_deflate_init_oxide(stream_oxide, level)?;
    let status = mz_deflate_oxide(stream_oxide, MZFlush::Finish as i32);
    mz_deflate_end_oxide(stream_oxide)?;

    match status {
        Ok(MZStatus::StreamEnd) => {
            *dest_len = stream_oxide.total_out;
            Ok(MZStatus::Ok)
        }
        Ok(MZStatus::Ok) => Err(MZError::Buf),
        _ => status,
    }
}

/// Initialize the wrapped compressor with the requested level (0-10) and default settings.
///
/// The compression level will be set to 6 (default) if the requested level is not available.
pub fn mz_deflate_init_oxide(stream_oxide: &mut StreamOxide<Compressor>, level: i32) -> MZResult {
    mz_deflate_init2_oxide(
        stream_oxide,
        level,
        MZ_DEFLATED,
        MZ_DEFAULT_WINDOW_BITS,
        9,
        CompressionStrategy::Default as i32,
    )
}

/// Initialize the compressor with the requested parameters.
///
/// # Params
/// stream_oxide: The stream to be initialized.
/// level: Compression level (0-10).
/// method: Compression method. Only `MZ_DEFLATED` is accepted.
/// window_bits: Number of bits used to represent the compression sliding window.
///              Only `MZ_DEFAULT_WINDOW_BITS` is currently supported.
///              A negative value, i.e `-MZ_DEFAULT_WINDOW_BITS` indicates that the stream
///              should be not be wrapped in a zlib wrapper.
/// mem_level: Currently unused. Only values from 1 to and including 9 are accepted.
/// strategy: Compression strategy. See `deflate::CompressionStrategy` for accepted options.
///           The default, which is used in most cases, is 0.
pub fn mz_deflate_init2_oxide(
    stream_oxide: &mut StreamOxide<Compressor>,
    level: i32,
    method: i32,
    window_bits: i32,
    mem_level: i32,
    strategy: i32,
) -> MZResult {
    let comp_flags = deflate_flags::TDEFL_COMPUTE_ADLER32
        | create_comp_flags_from_zip_params(level, window_bits, strategy);

    let invalid_level = !(1..=9).contains(&mem_level);
    if (method != MZ_DEFLATED) || invalid_level || invalid_window_bits(window_bits) {
        return Err(MZError::Param);
    }

    stream_oxide.adler = MZ_ADLER32_INIT;
    stream_oxide.total_in = 0;
    stream_oxide.total_out = 0;

    let mut compr: Box<Compressor> = Box::default();
    compr.inner = Some(CompressorOxide::new(comp_flags));
    stream_oxide.state = Some(Box::new(InternalState::Deflate(compr)));

    Ok(MZStatus::Ok)
}

pub fn mz_deflate_oxide(stream_oxide: &mut StreamOxide<Compressor>, flush: i32) -> MZResult {
    let state: &mut Compressor = {
        let enum_ref = stream_oxide.state.as_mut().ok_or(MZError::Stream)?;
        StateType::from_enum(enum_ref)
    }
    .ok_or(MZError::Stream)?;
    let next_in = stream_oxide.next_in.as_mut().ok_or(MZError::Stream)?;
    let next_out = stream_oxide.next_out.as_mut().ok_or(MZError::Stream)?;

    let flush = MZFlush::new(flush)?;

    let ret = if let Some(compressor) = state.inner.as_mut() {
        deflate(compressor, next_in, next_out, flush)
    } else {
        return Err(MZError::Param);
    };

    *next_in = &next_in[ret.bytes_consumed as usize..];
    *next_out = &mut mem::replace(next_out, &mut [])[ret.bytes_written as usize..];
    // Wrapping add to emulate miniz_behaviour, will wrap around >4 GiB on 32-bit.
    stream_oxide.total_in = stream_oxide
        .total_in
        .wrapping_add(ret.bytes_consumed as c_ulong);
    stream_oxide.total_out = stream_oxide
        .total_out
        .wrapping_add(ret.bytes_written as c_ulong);
    stream_oxide.adler = state.adler32();
    ret.into()
}

/// Free the inner compression state.
///
/// Currently always returns `MZStatus::Ok`.
pub fn mz_deflate_end_oxide(stream_oxide: &mut StreamOxide<Compressor>) -> MZResult {
    stream_oxide.state = None;
    Ok(MZStatus::Ok)
}

/// Reset the compressor, so it can be used to compress a new set of data.
///
/// Returns `MZError::Stream` if the inner stream is missing, otherwise `MZStatus::Ok`.
// TODO: probably not covered by tests
pub fn mz_deflate_reset_oxide(stream_oxide: &mut StreamOxide<Compressor>) -> MZResult {
    stream_oxide.total_in = 0;
    stream_oxide.total_out = 0;
    stream_oxide.adler = 0;
    stream_oxide.next_in = None;
    stream_oxide.next_out = None;
    let state = stream_oxide.state().ok_or(MZError::Stream)?;
    state.reset();
    Ok(MZStatus::Ok)
}

pub fn mz_inflate_init_oxide(stream_oxide: &mut StreamOxide<InflateState>) -> MZResult {
    mz_inflate_init2_oxide(stream_oxide, MZ_DEFAULT_WINDOW_BITS)
}

pub fn mz_inflate_init2_oxide(
    stream_oxide: &mut StreamOxide<InflateState>,
    window_bits: i32,
) -> MZResult {
    if invalid_window_bits(window_bits) {
        return Err(MZError::Param);
    }

    stream_oxide.adler = 0;
    stream_oxide.total_in = 0;
    stream_oxide.total_out = 0;

    stream_oxide.state = Some(Box::new(InternalState::Inflate(
        InflateState::new_boxed_with_window_bits(window_bits),
    )));

    Ok(MZStatus::Ok)
}

pub fn mz_inflate_oxide(stream_oxide: &mut StreamOxide<InflateState>, flush: i32) -> MZResult {
    let state: &mut InflateState = {
        let enum_ref = stream_oxide.state.as_mut().ok_or(MZError::Stream)?;
        StateType::from_enum(enum_ref)
    }
    .ok_or(MZError::Stream)?;

    let next_in = stream_oxide.next_in.as_mut().ok_or(MZError::Stream)?;
    let next_out = stream_oxide.next_out.as_mut().ok_or(MZError::Stream)?;

    let flush = MZFlush::new(flush)?;
    let ret = inflate(state, next_in, next_out, flush);
    *next_in = &next_in[ret.bytes_consumed as usize..];
    *next_out = &mut mem::replace(next_out, &mut [])[ret.bytes_written as usize..];
    // Wrapping add to emulate miniz_behaviour, will wrap around >4 GiB on 32-bit.
    stream_oxide.total_in = stream_oxide
        .total_in
        .wrapping_add(ret.bytes_consumed as c_ulong);
    stream_oxide.total_out = stream_oxide
        .total_out
        .wrapping_add(ret.bytes_written as c_ulong);
    stream_oxide.adler = state.decompressor().adler32().unwrap_or(0);
    ret.into()
}

pub fn mz_uncompress2_oxide(
    stream_oxide: &mut StreamOxide<InflateState>,
    dest_len: &mut c_ulong,
) -> MZResult {
    mz_inflate_init_oxide(stream_oxide)?;
    let status = mz_inflate_oxide(stream_oxide, MZFlush::Finish as i32);
    mz_inflate_end_oxide(stream_oxide)?;

    let empty_in = stream_oxide
        .next_in
        .map_or(true, |next_in| next_in.is_empty());
    match (status, empty_in) {
        (Ok(MZStatus::StreamEnd), _) => {
            *dest_len = stream_oxide.total_out;
            Ok(MZStatus::Ok)
        }
        (Err(MZError::Buf), true) => Err(MZError::Data),
        (status, _) => status,
    }
}

pub fn mz_inflate_end_oxide(stream_oxide: &mut StreamOxide<InflateState>) -> MZResult {
    stream_oxide.state = None;
    Ok(MZStatus::Ok)
}

/*
#[test]
fn roundtrip_oxide() {
    use miniz_oxide_c_api::{mz_inflate_oxide, mz_inflateInit_oxide,
                            StreamOxide};
    let mut stream = StreamOxide::default();
    let data = get_test_data();

}*/