package unpacker

import (
	"bytes"
	"encoding/binary"
	"fmt"
	"git.insit.tech/psa/rtsp_reader-writer/writer/pkg/storage"
	"git.insit.tech/sas/rtsp_proxy/core/gen"
	"git.insit.tech/sas/rtsp_proxy/proto/common"
	"github.com/bluenviron/gortsplib/v4/pkg/format"
	"go.uber.org/zap"
	"io"
	"log"
	"os"
	"reader/internal/processor"
	"strconv"
	"strings"
	"time"
)

// CreateFlow generate TS files and M3U8 playlists.
func CreateFlow(dir string, cutURI string, fn *common.FileName, resolutions []string, Log *zap.Logger) {
	fmt.Println("Reader started")

	// Establish starting period.
	per := 60
	period := time.Duration(per)

	// Create M3U8 playlist.
	go gen.MediaPlaylistGenerator(dir+"/data", cutURI, fn.Duration, resolutions, Log)

	for {
		time.Sleep(period * time.Second)
		for _, resolution := range resolutions {
			filenames := gen.StringDirEntryList(dir+"/data/"+cutURI+"/"+resolution, "insit", Log)

			for i := len(filenames) - 2; i < len(filenames)-1; i++ {

				segment := storage.Segment{}

				// Open file for reading.
				f, err := os.Open(dir + "/data/" + cutURI + "/" + resolution + "/" + filenames[i])
				if err != nil {
					fmt.Println("opening file error: ", err)
					return
				}
				defer f.Close()

				// Read StreamID.
				var streamIDLen int32
				if err := binary.Read(f, binary.LittleEndian, &streamIDLen); err != nil {
					fmt.Println("reading StreamID length error: ", err)
					return
				}
				streamIDBytes := make([]byte, streamIDLen)
				if _, err := io.ReadFull(f, streamIDBytes); err != nil {
					fmt.Println("reading StreamID error: ", err)
					return
				}
				streamID := string(streamIDBytes)
				fmt.Println("Stream ID:", streamID)

				// Read header of the file.
				var segLen int32
				if err := binary.Read(f, binary.LittleEndian, &segLen); err != nil {
					fmt.Println("reading header length error: ", err)
					return
				}
				segData := make([]byte, segLen)
				if _, err := io.ReadFull(f, segData); err != nil {
					fmt.Println("reading header error: ", err)
					return
				}
				headerReader := bytes.NewReader(segData)
				headerSeg, err := readHeaderSegment(headerReader)
				if err != nil {
					fmt.Println("func readHeaderSegment error: ", err)
					return
				}

				// Parse duration of a segment.
				per, err = strconv.Atoi(headerSeg.Duration)
				if err != nil {
					fmt.Println("parsing duration error: ", err)
				}

				// Setup MPEG-TS muxer.
				var h264Format format.H264
				var aacFormat format.MPEG4Audio

				filename, _ := strings.CutSuffix(filenames[i], ".insit")

				currentMpegtsMuxer := processor.MpegtsMuxer{
					FileName:         dir + "/data/" + cutURI + "/" + resolution + "/" + filename + ".ts",
					H264Format:       &h264Format,
					Mpeg4AudioFormat: &aacFormat,
				}

				err = currentMpegtsMuxer.Initialize()
				if err != nil {
					fmt.Printf("init muxer error: %w\n", err)
				}

				// Read segments.
				for {
					// Read segments length.
					var segLen int32
					err := binary.Read(f, binary.LittleEndian, &segLen)
					if err != nil {
						if err == io.EOF {
							break
						}
						fmt.Println("read segments length error: ", err)
						return
					}
					// Read segments data.
					segData = make([]byte, segLen)
					if _, err := io.ReadFull(f, segData); err != nil {
						fmt.Println("read segments error: ", err)
						return
					}
					packetReader := bytes.NewReader(segData)
					packets, err := readPacketSegment(packetReader)
					if err != nil {
						fmt.Println("func readPacketSegment error: ", err)
						return
					}

					segment.Packets = append(segment.Packets, packets...)

					for _, pkt := range packets {
						switch pkt.Type {
						case storage.PacketTypeH264:
							// Encode the access unit into MPEG-TS.
							err = currentMpegtsMuxer.WriteH264(pkt.Pts, pkt.H264AUs)
							if err != nil {
								log.Printf("write H264 packet error: %v\n", err)
							}
						case storage.PacketTypeLPCM:
							// Convert G711 to AAC.
							au, err := processor.ConvertLPCMToAAC(pkt.LPCMSamples)
							if err != nil {
								log.Printf("converting to AAC frame error: %v\n", err)
							}

							// Encode the access unit into MPEG-TS.
							err = currentMpegtsMuxer.WriteAAC([][]byte{au}, pkt.Pts)
							if err != nil {
								log.Printf("write G711 packet error: %v\n", err)
							}
						}
					}
				}
				currentMpegtsMuxer.Close()
			}
		}
	}
}