package usbcapture

import (
	"context"
	"errors"
	"fmt"
	"log"
	"mime/multipart"
	"net/http"
	"net/textproto"
	"strings"
	"syscall"

	"github.com/vladimirvivien/go4vl/device"
	"github.com/vladimirvivien/go4vl/v4l2"
)

var (
	camera *device.Device
	frames <-chan []byte
	fps    uint32 = 30
	/*
		1920 x 1080 60fps = 55Mbps //Edge not support
		1920 x 1080 30fps = 50Mbps
		1920 x 1080 25fps = 40Mbps
		1920 x 1080 20fps = 30Mbps
		1920 x 1080 10fps = 15Mbps

		1360 x 768 60fps = 28Mbps
		1360 x 768 30fps = 25Mbps
		1360 x 768 25fps = 20Mbps
		1360 x 768 20fps = 18Mbps
		1360 x 768 10fps = 10Mbps
	*/
	pixfmt     v4l2.FourCCType
	width      = 1920
	height     = 1080
	streamInfo string
)

// start http service
func serveVideoStream(w http.ResponseWriter, req *http.Request) {
	mimeWriter := multipart.NewWriter(w)
	w.Header().Set("Content-Type", fmt.Sprintf("multipart/x-mixed-replace; boundary=%s", mimeWriter.Boundary()))
	partHeader := make(textproto.MIMEHeader)
	partHeader.Add("Content-Type", "image/jpeg")

	var frame []byte
	for frame = range frames {
		if len(frame) == 0 {
			log.Print("skipping empty frame")
			continue
		}

		partWriter, err := mimeWriter.CreatePart(partHeader)
		if err != nil {
			log.Printf("failed to create multi-part writer: %s", err)
			return
		}

		if _, err := partWriter.Write(frame); err != nil {
			if errors.Is(err, syscall.EPIPE) {
				//broken pipe, the client browser has exited
				return
			}
			log.Printf("failed to write image: %s", err)
		}

	}
}

// startVideoServer starts the video server
func startVideoServer() {
	port := ":9090"
	devName := "/dev/video0"
	frameRate := int(fps)
	buffSize := 8
	format := "mjpeg"

	//Check if the video device is a capture device
	isCaptureDev, err := checkVideoCaptureDevice(devName)
	if err != nil {
		panic(err)
	}
	if !isCaptureDev {
		panic("target device is not a capture-able device")
	}
	camera, err := device.Open(devName,
		device.WithIOType(v4l2.IOTypeMMAP),
		device.WithPixFormat(v4l2.PixFormat{PixelFormat: getFormatType(format), Width: uint32(width), Height: uint32(height), Field: v4l2.FieldAny}),
		device.WithFPS(uint32(frameRate)),
		device.WithBufferSize(uint32(buffSize)),
	)

	if err != nil {
		log.Fatalf("failed to open device: %s", err)
	}
	defer camera.Close()

	//Get video supported sizes
	formatInfo, err := getV4L2FormatInfo(devName)
	if err != nil {
		log.Fatal(err)
	}
	for _, format := range formatInfo {
		fmt.Printf("Format: %s\n", format.Format)
		for _, size := range format.Sizes {
			fmt.Printf("  Size: %dx%d\n", size.Width, size.Height)
			fmt.Printf("    FPS: %v\n", size.FPS)
		}
	}

	caps := camera.Capability()
	log.Printf("device [%s] opened\n", devName)
	log.Printf("device info: %s", caps.String())
	//2025/03/16 15:45:25 device info: driver: uvcvideo; card: USB Video: USB Video; bus info: usb-0000:00:14.0-2

	// set device format
	currFmt, err := camera.GetPixFormat()
	if err != nil {
		log.Fatalf("unable to get format: %s", err)
	}
	log.Printf("Current format: %s", currFmt)
	//2025/03/16 15:45:25 Current format: Motion-JPEG [1920x1080]; field=any; bytes per line=0; size image=0; colorspace=Default; YCbCr=Default; Quant=Default; XferFunc=Default
	pixfmt = currFmt.PixelFormat
	streamInfo = fmt.Sprintf("%s - %s [%dx%d] %d fps",
		caps.Card,
		v4l2.PixelFormats[currFmt.PixelFormat],
		currFmt.Width, currFmt.Height, frameRate,
	)

	// start capture
	ctx, cancel := context.WithCancel(context.TODO())
	if err := camera.Start(ctx); err != nil {
		log.Fatalf("stream capture: %s", err)
	}
	defer func() {
		cancel()
		camera.Close()
	}()

	// video stream
	frames = camera.GetOutput()

	log.Printf("device capture started (buffer size set %d)", camera.BufferCount())
	log.Printf("starting server on port %s", port)
	log.Println("use url path /webcam")

	// setup http service
	http.HandleFunc("/stream", serveVideoStream) // returns video feed
	if err := http.ListenAndServe(port, nil); err != nil {
		log.Fatal(err)
	}
}

func getFormatType(fmtStr string) v4l2.FourCCType {
	switch strings.ToLower(fmtStr) {
	case "jpeg":
		return v4l2.PixelFmtJPEG
	case "mpeg":
		return v4l2.PixelFmtMPEG
	case "mjpeg":
		return v4l2.PixelFmtMJPEG
	case "h264", "h.264":
		return v4l2.PixelFmtH264
	case "yuyv":
		return v4l2.PixelFmtYUYV
	case "rgb":
		return v4l2.PixelFmtRGB24
	}
	return v4l2.PixelFmtMPEG
}