package capture

import (
	"errors"
	"sync"
	"regexp"
	"strconv"

	"github.com/rs/zerolog"
	"github.com/rs/zerolog/log"

	"m1k1o/neko/internal/capture/gst"
	"m1k1o/neko/internal/types"
	"m1k1o/neko/internal/types/codec"
)

type StreamSinkManagerCtx struct {
	logger zerolog.Logger
	mu     sync.Mutex
	wg     sync.WaitGroup

	codec             codec.RTPCodec
	pipeline          *gst.Pipeline
	pipelineMu        sync.Mutex
	pipelineFn        func() (string, error)
	adaptiveFramerate bool

	listeners   int
	listenersMu sync.Mutex

	changeFramerate int16
	sampleChannel  chan types.Sample
}

func streamSinkNew(codec codec.RTPCodec, pipelineFn func() (string, error), video_id string) *StreamSinkManagerCtx {
	logger := log.With().
		Str("module", "capture").
		Str("submodule", "stream-sink").
		Str("video_id", video_id).Logger()

	manager := &StreamSinkManagerCtx{
		logger:            logger,
		codec:             codec,
		pipelineFn:        pipelineFn,
		changeFramerate:   0,
		adaptiveFramerate: false,
		sampleChannel:     make(chan types.Sample, 100),
	}

	return manager
}

func (manager *StreamSinkManagerCtx) shutdown() {
	manager.logger.Info().Msgf("shutdown")

	manager.destroyPipeline()
	manager.wg.Wait()
}

func (manager *StreamSinkManagerCtx) Codec() codec.RTPCodec {
	return manager.codec
}

func (manager *StreamSinkManagerCtx) start() error {
	if manager.listeners == 0 {
		err := manager.createPipeline()
		if err != nil && !errors.Is(err, types.ErrCapturePipelineAlreadyExists) {
			return err
		}

		manager.logger.Info().Msgf("first listener, starting")
	}

	return nil
}

func (manager *StreamSinkManagerCtx) stop() {
	if manager.listeners == 0 {
		manager.destroyPipeline()
		manager.logger.Info().Msgf("last listener, stopping")
	}
}

func (manager *StreamSinkManagerCtx) addListener() {
	manager.listenersMu.Lock()
	manager.listeners++
	manager.listenersMu.Unlock()
}

func (manager *StreamSinkManagerCtx) removeListener() {
	manager.listenersMu.Lock()
	manager.listeners--
	manager.listenersMu.Unlock()
}

func (manager *StreamSinkManagerCtx) AddListener() error {
	manager.mu.Lock()
	defer manager.mu.Unlock()

	// start if stopped
	if err := manager.start(); err != nil {
		return err
	}

	// add listener
	manager.addListener()

	return nil
}

func (manager *StreamSinkManagerCtx) RemoveListener() error {
	manager.mu.Lock()
	defer manager.mu.Unlock()

	// remove listener
	manager.removeListener()

	// stop if started
	manager.stop()

	return nil
}

func (manager *StreamSinkManagerCtx) ListenersCount() int {
	manager.listenersMu.Lock()
	defer manager.listenersMu.Unlock()

	return manager.listeners
}

func (manager *StreamSinkManagerCtx) Started() bool {
	return manager.ListenersCount() > 0
}

func (manager *StreamSinkManagerCtx) createPipeline() error {
	manager.pipelineMu.Lock()
	defer manager.pipelineMu.Unlock()

	if manager.pipeline != nil {
		return types.ErrCapturePipelineAlreadyExists
	}

	pipelineStr, err := manager.pipelineFn()
	if err != nil {
		return err
	}

	if manager.changeFramerate > 0 && manager.adaptiveFramerate {
		m1 := regexp.MustCompile(`framerate=\d+/1`)
		pipelineStr = m1.ReplaceAllString(pipelineStr, "framerate=" + strconv.FormatInt(int64(manager.changeFramerate), 10) + "/1")
	}

	manager.logger.Info().
		Str("codec", manager.codec.Name).
		Str("src", pipelineStr).
		Msgf("creating pipeline")

	manager.pipeline, err = gst.CreatePipeline(pipelineStr)
	if err != nil {
		return err
	}

	appsinkSubfix := "audio"
	if codec.IsVideo(manager.codec.Type) {
		appsinkSubfix = "video"
	}

	manager.pipeline.AttachAppsink("appsink" + appsinkSubfix)
	manager.pipeline.Play()

	manager.wg.Add(1)
	pipeline := manager.pipeline

	go func() {
		manager.logger.Debug().Msg("started emitting samples")
		defer manager.wg.Done()

		for {
			sample, ok := <-pipeline.Sample
			if !ok {
				manager.logger.Debug().Msg("stopped emitting samples")
				return
			}

			manager.sampleChannel <- sample
		}
	}()

	return nil
}

func (manager *StreamSinkManagerCtx) destroyPipeline() {
	manager.pipelineMu.Lock()
	defer manager.pipelineMu.Unlock()

	if manager.pipeline == nil {
		return
	}

	manager.pipeline.Destroy()
	manager.logger.Info().Msgf("destroying pipeline")
	manager.pipeline = nil
}

func (manager *StreamSinkManagerCtx) GetSampleChannel() (chan types.Sample) {
	return manager.sampleChannel
}

func (manager *StreamSinkManagerCtx) SetChangeFramerate(rate int16) {
	manager.changeFramerate = rate
}

func (manager *StreamSinkManagerCtx) SetAdaptiveFramerate(allow bool) {
	manager.adaptiveFramerate = allow
}