package filter

import (
	"git.gammaspectra.live/S.O.N.G/Kirika/audio"
	"git.gammaspectra.live/S.O.N.G/Kirika/vector"
	"log"
	"time"
)

type Filter interface {
	Process(source audio.Source) audio.Source
}

func NewFilterChain(source audio.Source, filters ...Filter) audio.Source {
	for _, filter := range filters {
		source = filter.Process(source)
	}
	return source
}

type SourceFormatFilter struct {
	Format audio.SourceFormat
}

func (f SourceFormatFilter) Process(source audio.Source) audio.Source {
	switch f.Format {
	case audio.SourceFloat32:
		return source.ToFloat32()
	case audio.SourceInt16:
		return source.ToInt16()
	case audio.SourceInt32:
		if int16Source, ok := source.(audio.TypedSource[int16]); ok {
			return source.ToInt32(int16Source.GetBitDepth())
		} else if int32Source, ok := source.(audio.TypedSource[int32]); ok {
			return int32Source
		} else {
			return source.ToInt32(source.GetBitDepth())
		}
	}

	//TODO: panic?
	return source
}

type BufferFilter struct {
	blockBufferSize int
}

func NewBufferFilter(blockBufferSize int) BufferFilter {
	return BufferFilter{
		blockBufferSize: blockBufferSize,
	}
}

func bufferFilterHelper[T audio.AllowedSourceTypes](source audio.TypedSource[T], blockBufferSize int) audio.TypedSource[T] {
	outBlocks := make(chan []T, blockBufferSize)
	go func() {
		defer close(outBlocks)
		for block := range source.GetBlocks() {
			outBlocks <- block
		}
	}()

	newSource := audio.NewSource[T](source.GetBitDepth(), source.GetSampleRate(), source.GetChannels())
	close(newSource.SwapBlocks(outBlocks))
	return newSource
}

func (f BufferFilter) Process(source audio.Source) audio.Source {
	if floatSource, ok := source.(audio.TypedSource[float32]); ok {
		return bufferFilterHelper(floatSource, f.blockBufferSize)
	} else if int16Source, ok := source.(audio.TypedSource[int16]); ok {
		return bufferFilterHelper(int16Source, f.blockBufferSize)
	} else if int32Source, ok := source.(audio.TypedSource[int32]); ok {
		return bufferFilterHelper(int32Source, f.blockBufferSize)
	}

	return source
}

type BlockSizeFilter struct {
	blockSize int
}

func NewBlockSizeFilter(blockSize int) BlockSizeFilter {
	return BlockSizeFilter{
		blockSize: blockSize,
	}
}

func blockSizeFilterHelper[T audio.AllowedSourceTypes](source audio.TypedSource[T], blockSize int) audio.TypedSource[T] {

	bs := blockSize * source.GetChannels()

	outSource := audio.NewSource[T](source.GetBitDepth(), source.GetSampleRate(), source.GetChannels())
	go func() {
		defer outSource.Close()
		var buffer []T
		buf := buffer
		for block := range source.GetBlocks() {
			buf = append(buf, block...)
			for len(buf) >= bs {
				outSource.IngestNative(buf[:bs], source.GetBitDepth())
				buf = buf[bs:]
			}

			if len(buf) == 0 {
				//reuse resources
				buf = buffer[:0]
			}
		}

		if len(buf) > 0 {
			outSource.IngestNative(buf, source.GetBitDepth())
		}
	}()

	return outSource
}

func (f BlockSizeFilter) Process(source audio.Source) audio.Source {
	if floatSource, ok := source.(audio.TypedSource[float32]); ok {
		return blockSizeFilterHelper(floatSource, f.blockSize)
	} else if int16Source, ok := source.(audio.TypedSource[int16]); ok {
		return blockSizeFilterHelper(int16Source, f.blockSize)
	} else if int32Source, ok := source.(audio.TypedSource[int32]); ok {
		return blockSizeFilterHelper(int32Source, f.blockSize)
	}

	return nil
}

type RealTimeFilter struct {
	blocksPerSecond int
}

func NewRealTimeFilter(blocksPerSecond int) RealTimeFilter {
	return RealTimeFilter{
		blocksPerSecond: blocksPerSecond,
	}
}

func realTimeFilterHelper[T audio.AllowedSourceTypes](source audio.TypedSource[T], blocksPerSecond int) audio.TypedSource[T] {
	blockSize := source.GetSampleRate() / blocksPerSecond
	throttler := time.Tick(time.Second / time.Duration(blocksPerSecond))

	outSource := audio.NewSource[T](source.GetBitDepth(), source.GetSampleRate(), source.GetChannels())
	go func() {
		defer outSource.Close()
		for block := range NewBlockSizeFilter(blockSize).Process(source).(audio.TypedSource[T]).GetBlocks() {
			outSource.IngestNative(block, source.GetBitDepth())
			<-throttler
		}
	}()

	return outSource
}

func (f RealTimeFilter) Process(source audio.Source) audio.Source {
	if source.GetSampleRate()%f.blocksPerSecond != 0 {
		log.Panicf("%d %% %d != 0", source.GetSampleRate(), f.blocksPerSecond)
	}

	if floatSource, ok := source.(audio.TypedSource[float32]); ok {
		return realTimeFilterHelper(floatSource, f.blocksPerSecond)
	} else if int16Source, ok := source.(audio.TypedSource[int16]); ok {
		return realTimeFilterHelper(int16Source, f.blocksPerSecond)
	} else if int32Source, ok := source.(audio.TypedSource[int32]); ok {
		return realTimeFilterHelper(int32Source, f.blocksPerSecond)
	}

	return nil
}

type VolumeFilter struct {
	adjustment float64
}

func NewVolumeFilter(adjustment float64) VolumeFilter {
	return VolumeFilter{
		adjustment: adjustment,
	}
}

func (f VolumeFilter) Process(source audio.Source) audio.Source {
	if f.adjustment == 1. {
		return source
	}

	if int32Source, ok := source.(audio.TypedSource[int32]); ok {
		bpsMultiplier := int64((1 << (source.GetBitDepth() - 1)) - 1)
		adjustment := int64(f.adjustment * float64(bpsMultiplier))
		outSource := audio.NewSource[int32](source.GetBitDepth(), source.GetSampleRate(), source.GetChannels())
		go func() {
			defer outSource.Close()
			for block := range int32Source.GetBlocks() {
				out := make([]int32, len(block))
				for i := range block {
					out[i] = int32((int64(block[i]) * adjustment) / bpsMultiplier)
				}
				outSource.IngestNative(out, source.GetBitDepth())
			}
		}()
		return outSource
	} else if int16Source, ok := source.(audio.TypedSource[int16]); ok {
		bpsMultiplier := int32((1 << (source.GetBitDepth() - 1)) - 1)
		adjustment := int32(f.adjustment * float64(bpsMultiplier))
		outSource := audio.NewSource[int16](source.GetBitDepth(), source.GetSampleRate(), source.GetChannels())
		go func() {
			defer outSource.Close()
			for block := range int16Source.GetBlocks() {
				out := make([]int16, len(block))
				for i := range block {
					out[i] = int16((int32(block[i]) * adjustment) / bpsMultiplier)
				}
				outSource.IngestNative(out, source.GetBitDepth())
			}
		}()
		return outSource
	} else {
		adjustment := float32(f.adjustment)
		outSource := audio.NewSource[float32](source.GetBitDepth(), source.GetSampleRate(), source.GetChannels())
		go func() {
			defer outSource.Close()

			for block := range source.ToFloat32().GetBlocks() {
				out := make([]float32, len(block))
				for i := range block {
					out[i] = block[i] * adjustment
				}
				outSource.IngestNative(out, source.GetBitDepth())
			}

		}()

		return outSource
	}
}

type StereoFilter struct {
}

func (f StereoFilter) Process(source audio.Source) audio.Source {
	if source.GetChannels() == 2 { //no change
		return source
	}

	outSource := audio.NewTypedInterface(source, source.GetBitDepth(), source.GetSampleRate(), 2)

	go func() {
		defer outSource.Close()
		if _, ok := source.(audio.TypedSource[int32]); ok {
			for block := range source.ToInt32(source.GetBitDepth()).GetBlocks() {
				outSource.IngestInt32(vector.MultipleChannelsToStereoInt32(block, source.GetChannels()), source.GetBitDepth())
			}
		} else if _, ok = source.(audio.TypedSource[int16]); ok {
			for block := range source.ToInt32(source.GetBitDepth()).GetBlocks() {
				outSource.IngestInt32(vector.MultipleChannelsToStereoInt32(block, source.GetChannels()), source.GetBitDepth())
			}
		} else {
			for block := range source.ToFloat32().GetBlocks() {
				outSource.IngestFloat32(vector.MultipleChannelsToStereoFloat32(block, source.GetChannels()))
			}
		}

	}()

	return outSource
}

type MonoFilter struct {
}

func (f MonoFilter) Process(source audio.Source) audio.Source {
	if source.GetChannels() == 1 { //no change
		return source
	}

	outSource := audio.NewTypedInterface(source, source.GetBitDepth(), source.GetSampleRate(), 1)

	go func() {
		defer outSource.Close()
		if _, ok := source.(audio.TypedSource[int32]); ok {
			for block := range source.ToInt32(source.GetBitDepth()).GetBlocks() {
				outSource.IngestInt32(vector.MultipleChannelsToMonoInt32(block, source.GetChannels()), source.GetBitDepth())
			}
		} else if _, ok = source.(audio.TypedSource[int16]); ok {
			for block := range source.ToInt32(source.GetBitDepth()).GetBlocks() {
				outSource.IngestInt32(vector.MultipleChannelsToMonoInt32(block, source.GetChannels()), source.GetBitDepth())
			}
		} else {
			for block := range source.ToFloat32().GetBlocks() {
				outSource.IngestFloat32(vector.MultipleChannelsToMonoFloat32(block, source.GetChannels()))
			}
		}

	}()

	return outSource
}