package procRTSP

import (
	"errors"
	"fmt"
	"git.insit.tech/sas/rtsp_proxy/protos/gens"
	"github.com/bluenviron/gortsplib/v4"
	"github.com/bluenviron/gortsplib/v4/pkg/base"
	"github.com/bluenviron/gortsplib/v4/pkg/description"
	"github.com/bluenviron/gortsplib/v4/pkg/format"
	"github.com/bluenviron/gortsplib/v4/pkg/format/rtph264"
	"github.com/bluenviron/gortsplib/v4/pkg/format/rtplpcm"
	"github.com/pion/rtp"
	_ "github.com/zaf/g711"
	"log"
	"strings"
	"time"
	"writer/internal/config"
	"writer/internal/media"
	"writer/pkg/converter"
)

var (
	resolutions = []string{"1280x720"}
	h264RTPDec  *rtph264.Decoder
	g711RTPDec  *rtplpcm.Decoder
)

// StartWriter starts the program.
func StartWriter(period int, URI string) error {
	err := procRTSP(period, URI)
	if err != nil {
		// Change domain if a camera was flipped to another domain.
		err = changeDomain(period, URI, err)
		if err != nil {
			return fmt.Errorf("change domain error: %w", err)
		}
	}
	return nil
}

// procRTSP process RTSP protocol and writes H264 and PCM flows into TS container.
func procRTSP(period int, URI string) error {
	// Create FileName structure
	fn := config.CreateFileName(resolutions, period)

	////////////////////////////////////////////////////////////////////////////////////////

	// Create M3U8 playlist.
	go gens.MediaPlaylistGenerator("/home/psa/GoRepository/data", "", fn.Duration, resolutions)

	////////////////////////////////////////////////////////////////////////////////////////

	// Initialise client.
	c := gortsplib.Client{
		UserAgent: "PSA",
	}

	// Parse URL.
	u, err := base.ParseURL(URI)
	if err != nil {
		return fmt.Errorf("parse URL error: %w", err)
	}

	// Connect to the server.
	err = c.Start(u.Scheme, u.Host)
	if err != nil {
		return fmt.Errorf("connect to the server error: %w", err)
	}
	defer c.Close()

	// Find available medias.
	desc, _, err := c.Describe(u)
	if err != nil || desc == nil {
		return fmt.Errorf("medias not found: %w", err)
	}

	////////////////////////////////////////////////////////////////////////////////////////

	// Find the H264 media and format.
	h264Format, h264Media, err := media.CheckH264Format(desc)

	// Find the G711 media and format.
	g711Format, g711Media, err := media.CheckG711Format(desc)

	// Initialising variable for AAC.
	var mpeg4AudioFormat *format.MPEG4Audio

	////////////////////////////////////////////////////////////////////////////////////////

	// Create RTP -> H264 decoder.
	if h264Format != nil {
		h264RTPDec, err = h264Format.CreateDecoder()
		if err != nil {
			return fmt.Errorf("create H264 decoder error: %w", err)
		}
	}

	// Create RTP -> H264 decoder.
	if g711Format != nil {
		g711RTPDec, err = g711Format.CreateDecoder()
		if err != nil {
			return fmt.Errorf("create G711 decoder error: %w", err)
		}
	}

	////////////////////////////////////////////////////////////////////////////////////////

	// Wait for the next period.
	config.Waiter(period)
	log.Println("Start recording")

	////////////////////////////////////////////////////////////////////////////////////////

	// Setup MPEG-TS muxer.
	currentMpegtsMuxer := &converter.MpegtsMuxer{
		FileName:         fn.SetNumNTime(),
		H264Format:       h264Format,
		Mpeg4AudioFormat: mpeg4AudioFormat,
	}
	err = currentMpegtsMuxer.Initialize(resolutions)
	if err != nil {
		panic(err)
	}
	defer currentMpegtsMuxer.Close()

	////////////////////////////////////////////////////////////////////////////////////////

	// Setup all medias.
	err = c.SetupAll(desc.BaseURL, desc.Medias)
	if err != nil {
		panic(err)
	}

	////////////////////////////////////////////////////////////////////////////////////////

	// Called when a H264/RTP or G711/RTP packet arrives.
	c.OnPacketRTPAny(func(medi *description.Media, forma format.Format, pkt *rtp.Packet) {
		switch f := forma.(type) {
		case *format.H264:
			// Process H264 flow and return PTS and AU.
			pts, au, err := media.ProcH264(&c, h264Media, h264RTPDec, pkt)
			if err != nil {
				fmt.Printf("process G711 error: %s\n", err)
			}

			// Encode the access unit into MPEG-TS.
			err = currentMpegtsMuxer.WriteH264(au, pts)
			if err != nil {
				log.Printf("writing H264 packet: %s\n", err)
			}

		case *format.G711:
			// Process G711 flow and returns PTS and AU.
			_, au, err := media.ProcG711(&c, g711Media, g711RTPDec, pkt)
			if err != nil {
				fmt.Printf("process G711 error: %s\n", err)
			}

			// Convert G711 to AAC.
			_, err = converter.ConvertG711ToAAC(au, f.MULaw) // take aacAu
			if err != nil {
				log.Printf("converting G711 to AAC frame: %s\n", err)
			}

			/*
				// Encode the access unit into MPEG-TS.
				err = MpegtsMuxer.writeMPEG4Audio([][]byte{aacAu}, pts)
				if err != nil {
					log.Printf("MPEG-TS write error: %v", err)
					return
				}
			*/
		}
	})

	////////////////////////////////////////////////////////////////////////////////////////

	// Send PLAY request.
	_, err = c.Play(nil)
	if err != nil {
		log.Fatalln("Ошибка запуска воспроизведения:", err)
	}

	// Create ticker for rotation files.
	ticker := time.NewTicker(time.Duration(period) * time.Minute)
	defer ticker.Stop()

	// Rotate files.
	go func() {
		for range ticker.C {
			currentMpegtsMuxer.Close()
			currentMpegtsMuxer.FileName = fn.SetNumNTime()

			err = currentMpegtsMuxer.Initialize(resolutions)
			if err != nil {
				panic(err)
			}

			log.Println("New file for recording created:", currentMpegtsMuxer.FileName)
		}
	}()

	// Restart program if client gets TEARDOWN request.
	c.OnRequest = func(req *base.Request) {
		if req.Method == base.Teardown {
			log.Printf("got TEARDOWN request from server: %v", req)
		}

		go func() {
			err = procRTSP(period, URI)
			if err != nil {
				log.Fatalf("restart RTSP error: %s\n", err)
			}
		}()
	}

	panic(c.Wait())

}

// changeDomain changes domain if a camera was flipped to another domain.
func changeDomain(period int, URI string, err error) error {
	err2 := errors.New("404 (Not found)")
	if errors.As(err, &err2) {
		if strings.Contains(URI, "video-1") {
			err = procRTSP(period, strings.Replace(URI, "video-1", "video-2", 1))
			if err != nil {
				return err
			}
		} else {
			err = procRTSP(period, strings.Replace(URI, "video-2", "video-1", 1))
			if err != nil {
				return err
			}
		}
	} else {
		panic(err)
	}

	return nil
}