//go:build !disable_format_tta && !disable_codec_tta

package tta

import (
	"bytes"
	"errors"
	"git.gammaspectra.live/S.O.N.G/Kirika/audio"
	"git.gammaspectra.live/S.O.N.G/Kirika/audio/format"
	"git.gammaspectra.live/S.O.N.G/Kirika/vector"
	libtta "git.gammaspectra.live/S.O.N.G/go-tta"
	"io"
	"math"
	"runtime"
	"unsafe"
)

const BlockSize = 1024 * 128

type Format struct {
}

func (f Format) Name() string {
	return "tta"
}

func (f Format) DecoderDescription() string {
	return "S.O.N.G/go-tta"
}

func (f Format) EncoderDescription() string {
	return f.DecoderDescription()
}

func NewFormat() Format {
	return Format{}
}

type fakeReadWriteSeeker struct {
	r io.ReadSeekCloser
}

func (i fakeReadWriteSeeker) Read(p []byte) (n int, err error) {
	return i.r.Read(p)
}
func (i fakeReadWriteSeeker) Seek(offset int64, whence int) (int64, error) {
	return i.r.Seek(offset, whence)
}
func (i fakeReadWriteSeeker) Close() error {
	return i.r.Close()
}
func (i fakeReadWriteSeeker) Write(_ []byte) (n int, err error) {
	return 0, io.ErrShortWrite
}

type fakeReadWriteSeeker2 struct {
	w io.WriteCloser
}

func (i fakeReadWriteSeeker2) Read(_ []byte) (n int, err error) {
	return 0, io.ErrNoProgress
}
func (i fakeReadWriteSeeker2) Seek(_ int64, _ int) (int64, error) {
	return 0, io.ErrNoProgress
}
func (i fakeReadWriteSeeker2) Close() error {
	return i.w.Close()
}
func (i fakeReadWriteSeeker2) Write(p []byte) (n int, err error) {
	return i.w.Write(p)
}

func (f Format) Open(r io.ReadSeekCloser) (audio.Source, error) {
	decoder := libtta.MakeDecoder(fakeReadWriteSeeker{r})
	if decoder == nil {
		return nil, errors.New("invalid decoder")
	}

	info := &libtta.Info{}
	if err := decoder.GetInfo(info, 0); err != nil {
		return nil, err
	}

	source := audio.NewSource[int32](int(info.Bps), int(info.Sps), int(info.Nch))

	go func() {
		defer source.Close()

		smpSize := int(info.Nch) * ((int(info.Bps) + 7) / 8)
		buffer := make([]byte, BlockSize*smpSize)

		var writeLen int
		for {
			if writeLen = int(decoder.ProcessStream(buffer, nil)) * smpSize; writeLen == 0 {
				break
			}

			source.IngestInt32(vector.BytesToInt32(buffer[:writeLen], int(info.Bps)), int(info.Bps))
		}
	}()

	return source, nil
}

func (f Format) OpenAnalyzer(r io.ReadSeekCloser) (audio.Source, format.AnalyzerChannel, error) {
	return format.NewAnalyzerChannel(f.Open(r))
}

func (f Format) Encode(source audio.Source, writer io.WriteCloser, options map[string]interface{}) error {

	var bitsPerSample = 16

	if options != nil {
		var val interface{}
		var ok bool
		var intVal int
		if val, ok = options["bitdepth"]; ok {
			if intVal, ok = val.(int); ok {
				bitsPerSample = intVal
			}
		}
	}

	var encoder *libtta.Encoder

	if writeSeeker, ok := writer.(io.ReadWriteSeeker); ok {
		encoder = libtta.MakeEncoder(writeSeeker)
	} else {
		encoder = libtta.MakeEncoder(fakeReadWriteSeeker2{w: writer})
	}

	if encoder == nil {
		return errors.New("could not create encoder")
	}

	defer encoder.Close()

	err := encoder.SetInfo(&libtta.Info{
		Format:  1,
		Nch:     uint32(source.GetChannels()),
		Bps:     uint32(bitsPerSample),
		Sps:     uint32(source.GetSampleRate()),
		Samples: math.MaxUint32,
	})

	if err != nil {
		return err
	}

	switch bitsPerSample {
	case 32:
		for block := range source.ToInt32(32).GetBlocks() {
			encoder.ProcessStream(unsafe.Slice((*byte)(unsafe.Pointer(unsafe.SliceData(block))), len(block)*4), nil)
			runtime.KeepAlive(block)
		}
	case 24:
		for block := range source.ToInt32(24).GetBlocks() {
			samples := vector.Int32ToBytes(block, 24)
			encoder.ProcessStream(unsafe.Slice((*byte)(unsafe.Pointer(unsafe.SliceData(samples))), len(samples)), nil)
			runtime.KeepAlive(samples)
		}
	case 16:
		for block := range source.ToInt16().GetBlocks() {
			encoder.ProcessStream(unsafe.Slice((*byte)(unsafe.Pointer(unsafe.SliceData(block))), len(block)*2), nil)
			runtime.KeepAlive(block)
		}
	case 8:
		for block := range source.ToInt32(8).GetBlocks() {
			samples := vector.Int32ToBytes(block, 8)
			encoder.ProcessStream(unsafe.Slice((*byte)(unsafe.Pointer(unsafe.SliceData(samples))), len(samples)), nil)
			runtime.KeepAlive(samples)
		}
	default:
		return errors.New("not supported bits per sample")

	}

	encoder.Finalize()

	return nil
}

func (f Format) Identify(peek [format.IdentifyPeekBytes]byte, extension string) bool {
	return bytes.Compare(peek[:4], []byte{'T', 'T', 'A', '1'}) == 0 || extension == "tta"
}