//go:build cgo

package replaygain

import (
	"errors"
	"git.gammaspectra.live/S.O.N.G/Kirika/audio"
	libebur128 "git.gammaspectra.live/S.O.N.G/go-ebur128"
	"sync"
)

const referenceLevel = -18.0

// GetTrackReplayGain calculates track ReplayGain 2.0
func GetTrackReplayGain(source audio.Source) (gain, peak float64, err error) {
	state := libebur128.NewState(source.GetChannels(), source.GetSampleRate(), libebur128.LoudnessGlobalMomentary|libebur128.SamplePeak)
	if state == nil {
		err = errors.New("could not initialize state")
		return
	}
	defer state.Close()

	if _, ok := source.(audio.TypedSource[int16]); ok {
		for block := range source.ToInt16().GetBlocks() {
			if err = state.AddShort(block); err != nil {
				return
			}
		}
	} else if int32Source, ok := source.(audio.TypedSource[int32]); ok {
		if source.GetBitDepth() == 16 {
			for block := range source.ToInt16().GetBlocks() {
				if err = state.AddShort(block); err != nil {
					return
				}
			}
		} else {
			for block := range int32Source.ToInt32(32).GetBlocks() {
				if err = state.AddInt(block); err != nil {
					return
				}
			}
		}
	} else {
		for block := range source.ToFloat32().GetBlocks() {
			if err = state.AddFloat(block); err != nil {
				return
			}
		}
	}

	var loudness float64
	var peakSlice []float64

	if loudness, err = state.GetLoudnessGlobal(); err != nil {
		return
	}
	if peakSlice, err = state.GetSamplePeak(); err != nil {
		return
	}

	for _, p := range peakSlice {
		if p > peak {
			peak = p
		}
	}

	gain = referenceLevel - loudness

	return
}

// GetAlbumReplayGain calculates album and tracks ReplayGain 2.0
func GetAlbumReplayGain(sources []audio.Source) (albumGain, albumPeak float64, trackGains []float64, trackPeaks []float64, err error) {
	var states []*libebur128.State
	var wg sync.WaitGroup
	defer func() {
		wg.Wait()
		for _, state := range states {
			state.Close()
		}
	}()

	for _, source := range sources {
		state := libebur128.NewState(source.GetChannels(), source.GetSampleRate(), libebur128.LoudnessGlobalMomentary|libebur128.SamplePeak)
		if state == nil {
			err = errors.New("could not initialize state")
			return
		}
		states = append(states, state)

		wg.Add(1)
		go func(source audio.Source) {
			defer wg.Done()
			var err error

			if _, ok := source.(audio.TypedSource[int16]); ok {
				for block := range source.ToInt16().GetBlocks() {
					if err = state.AddShort(block); err != nil {
						return
					}
				}
			} else if _, ok := source.(audio.TypedSource[int32]); ok {
				if source.GetBitDepth() == 16 {
					for block := range source.ToInt16().GetBlocks() {
						if err = state.AddShort(block); err != nil {
							return
						}
					}
				} else {
					for block := range source.ToInt32(32).GetBlocks() {
						if err = state.AddInt(block); err != nil {
							return
						}
					}
				}
			} else {
				for block := range source.ToFloat32().GetBlocks() {
					if err = state.AddFloat(block); err != nil {
						return
					}
				}
			}

		}(source)
	}

	wg.Wait()

	var albumLoudness float64
	var peakSlice []float64
	var trackLoudness float64

	if albumLoudness, err = libebur128.GetLoudnessGlobalMultiple(states); err != nil {
		return
	}
	for _, state := range states {
		if trackLoudness, err = state.GetLoudnessGlobal(); err != nil {
			return
		}
		if peakSlice, err = state.GetSamplePeak(); err != nil {
			return
		}

		var tPeak float64

		for _, p := range peakSlice {
			if p > albumPeak {
				albumPeak = p
			}
			if p > tPeak {
				tPeak = p
			}
		}

		trackGains = append(trackGains, referenceLevel-trackLoudness)
		trackPeaks = append(trackPeaks, tPeak)
	}

	albumGain = referenceLevel - albumLoudness

	return
}