package gstreamer

import (
	"context"
	"fmt"
	"github.com/rs/zerolog"
	"github.com/rs/zerolog/log"
	"github.com/tinyzimmer/go-gst/gst"
	"sync"
)

func (p *Pipeline) Create() (chan PipelineUpdates, error) {
	gstreamerLogger := log.With().Str("Component", "gstreamer").Str("Pipeline", p.Name).Logger()
	p.logger = gstreamerLogger
	pipeline, err := gst.NewPipeline(p.Name)
	if err != nil {
		return nil, err
	}

	elements := map[string]element{}

	err = p.InputElement.create(pipeline, gstreamerLogger)
	if err != nil {
		return nil, err
	}
	for name, e := range p.InputElement.elements {
		elements[name] = e
	}
	lastElement := p.InputElement.getLastElement()

	for _, overlay := range p.Overlays {
		gstreamerLogger.Debug().Str("Overlay", overlay.getName()).Msg("Adding overlay")
		overlayElement, _ := overlay.create(gstreamerLogger)
		e := &element{
			element: overlayElement,
			name:    overlay.getName(),
		}
		lastElement.linkElementWrapper(e, gstreamerLogger)
		lastElement = e
		elements[overlay.getName()] = *lastElement
	}
	err = p.OutputElement.create(pipeline, lastElement, gstreamerLogger)
	if err != nil {
		return nil, err
	}
	for name, e := range p.OutputElement.elements {
		elements[name] = e
	}

	pipeline.GetPipelineBus().AddWatch(func(msg *gst.Message) bool {
		switch msg.Type() {
		case gst.MessageEOS: // When end-of-stream is received flush the pipeline and stop the main loop
			pipeline.BlockSetState(gst.StateNull)
		case gst.MessageError: // Error messages are always fatal
			err := msg.ParseError()
			gstreamerLogger.Error().Msg(err.Error())
			if debug := err.DebugString(); debug != "" {
				gstreamerLogger.Debug().Msg(debug)
			}
		case gst.MessageStreamStart:
			gstreamerLogger.Info().Msgf("STARTING Playout of %s", p.Name)
			clock := pipeline.GetPipelineClock()
			now := clock.GetTime()
			for _, overlay := range p.Overlays {
				if overlay.getBlendInTime() != -1 {
					clock.NewSingleShotID(now + overlay.getBlendInTime()).WaitAsync(overlay.show())
				}
				if overlay.getBlendOutTime() != -1 {
					clock.NewSingleShotID(now + overlay.getBlendOutTime()).WaitAsync(overlay.hide())
				}
			}

		case gst.MessageStateChanged:
			_, newState := msg.ParseStateChanged()
			if newState == gst.StatePlaying && msg.Source() == p.Name {
				gstreamerLogger.Debug().Msgf("Pipeline %s started", p.Name)
				p.resizeAllTextOverlays(gstreamerLogger)
			}
		default:
			// All messages implement a Stringer. However, this is
			// typically an expensive thing to do and should be avoided.
			gstreamerLogger.Debug().Msgf(msg.String())
		}
		return true
	})

	p.ctx, p.ctxCancel = context.WithCancel(gstreamer.ctx)
	updateChannel := make(chan PipelineUpdates)
	go p.overlayUpdater(updateChannel, gstreamerLogger)
	p.PipelineUpdates = updateChannel
	gstreamer.Lock()
	gstreamer.Pipelines[p.ID] = p
	gstreamer.Unlock()

	return updateChannel, nil
}

//TODO check if output is decklink
func (p *Pipeline) Start() error {
	output, err := gstreamer.getDecklinkOutput(p.Name)
	setPropertyWrapper(p.elements[p.OutputElement.Name].element, "device-number", output)
	err = p.pipeline.SetState(gst.StatePlaying)
	if err != nil {
		p.logger.Error().Msgf("Failed to set pipeline %s to playing: %v", p.Name, err)
		return fmt.Errorf("Failed to set pipeline %s to playing: %v", p.Name, err)
	}
	return nil
}

func (p *Pipeline) Stop() error {
	err := p.pipeline.SetState(gst.StateNull)
	if err != nil {
		p.logger.Error().Msgf("Failed to set pipeline %s to null: %v", p.Name, err)
		return fmt.Errorf("Failed to set pipeline %s to null: %v", p.Name, err)
	}
	return nil
}

func (p *Pipeline) resizeAllTextOverlays(log zerolog.Logger) {
	for _, overlay := range p.Overlays {
		if x, ok := overlay.(*TextOverlay); ok {
			go x.resizeTextOverlay(log)
		}
	}
}

func (p *Pipeline) overlayUpdater(updateChannel chan PipelineUpdates, log zerolog.Logger) {
	for {
		select {
		case <-p.ctx.Done():
			return
		case updates := <-updateChannel:
			log.Info().Msgf("Updating overlays with %d text overlays", len(updates.Overlays))

			var wg sync.WaitGroup
			for _, overlay := range updates.Overlays {
				wg.Add(1)
				go func(overlay Overlay) {
					defer wg.Done()
					o, ok := p.Overlays[overlay.getName()]
					if !ok {
						log.Error().Msgf("Could not find overlay %s", overlay.getName())
						return
					}
					overlay.setElement(o.getElement())
					overlay.update(log)

				}(overlay)

			}
			wg.Wait()
			log.Debug().Msg("Overlays updated")
			//TODO channel done
		}
	}

}