package frameserver

import (
	"git.gammaspectra.live/S.O.N.G/Ignite/decoder/y4m"
	"git.gammaspectra.live/S.O.N.G/Ignite/frame"
	"io"
	"sync"
)

type FrameServer struct {
	readerLock sync.Mutex
	decoder    *y4m.Decoder
}

func New(reader io.ReadSeeker, cachedFrameSeekTable []int64) *FrameServer {
	s := &FrameServer{}

	var err error
	settings := make(map[string]any)
	settings["seek_table"] = cachedFrameSeekTable
	if s.decoder, err = y4m.NewDecoder(reader, settings); err != nil {
		return nil
	}

	return s
}

func NewXZCompressed(reader io.ReadSeeker, cachedFrameSeekTable []int64) *FrameServer {
	s := &FrameServer{}

	var err error
	settings := make(map[string]any)
	settings["seek_table"] = cachedFrameSeekTable
	if s.decoder, err = y4m.NewXZCompressedDecoder(reader, settings); err != nil {
		return nil
	}

	return s
}

func (s *FrameServer) GetFrameSeekTable() []int64 {
	s.readerLock.Lock()
	defer s.readerLock.Unlock()
	return s.decoder.GetFrameSeekTable()
}

// GetAllFrames gets all frames from start to end. Locks on every iteration. See GetAllFramesLock
func (s *FrameServer) GetAllFrames() *frame.Stream {
	frameNumber := 0

	stream, channel := frame.NewStream(s.decoder.Properties())
	go func() {
		defer close(channel)
		for {
			if f, err := s.GetFrame(frameNumber); err != nil {
				return
			} else {
				channel <- f
			}
			frameNumber++
		}
	}()
	return stream
}

// GetAllFramesLock gets all frames from start to end. Locks on every iteration. See GetAllFramesLock
func (s *FrameServer) GetAllFramesLock() *frame.Stream {
	s.readerLock.Lock()
	defer s.readerLock.Unlock()

	frameNumber := 0

	if err := s.decoder.SeekToFrame(frameNumber); err != nil {
		return nil
	} else {
		stream, channel := frame.NewStream(s.decoder.Properties())
		go func() {
			defer close(channel)
			for {
				if f, err := s.decoder.Decode(); err != nil {
					return
				} else {
					channel <- f
				}
				frameNumber++
			}
		}()
		return stream
	}
}

// GetFrames gets a range of frames, like a slice [0, 1] will return just one frame.Frame. Locks on every iteration. See GetFramesLock
func (s *FrameServer) GetFrames(startFrameNumber, endFrameNumber int) *frame.Stream {
	if endFrameNumber < startFrameNumber {
		return nil
	}
	frameNumber := startFrameNumber

	stream, channel := frame.NewStream(s.decoder.Properties())
	go func() {
		defer close(channel)
		for frameNumber < endFrameNumber {
			if f, err := s.GetFrame(frameNumber); err != nil {
				return
			} else {
				channel <- f
			}
			frameNumber++
		}
	}()
	return stream
}

// GetFramesLock gets a range of frames, but locks during all of them. See GetFrames
func (s *FrameServer) GetFramesLock(startFrameNumber, endFrameNumber int) *frame.Stream {
	if endFrameNumber < startFrameNumber {
		return nil
	}
	s.readerLock.Lock()
	defer s.readerLock.Unlock()

	frameNumber := startFrameNumber

	//todo: spawn new frame.Stream or just use GetFrame()?

	if err := s.decoder.SeekToFrame(frameNumber); err != nil {
		return nil
	} else {
		stream, channel := frame.NewStream(s.decoder.Properties())
		go func() {
			defer close(channel)
			for frameNumber < endFrameNumber {
				if f, err := s.decoder.Decode(); err != nil {
					return
				} else {
					channel <- f
				}
				frameNumber++
			}
		}()
		return stream
	}
}

func (s *FrameServer) GetFrame(frameNumber int) (f frame.Frame, err error) {
	s.readerLock.Lock()
	defer s.readerLock.Unlock()
	if err = s.decoder.SeekToFrame(frameNumber); err != nil {
		return nil, err
	} else {
		return s.decoder.Decode()
	}
}