package main

import (
	"context"
	"errors"
	"fmt"
	"io"
	"log"
	"mxl-player/internal/imgui"
	"mxl-player/internal/renderer"
	"mxl-player/internal/sdl"
	"mxl-player/internal/source"
	"os"
	"runtime"
	"time"
	"unsafe"

	cimgui "github.com/AllenDang/cimgui-go/imgui"
	vk "github.com/christerso/vulkan-go/vk"
	pflag "github.com/spf13/pflag"
)

const (
	APP_NAME         = "MXL Player"
	APP_VER          = "0.1.0"
	WIN_WIDTH  int32 = 1280
	WIN_HEIGHT int32 = 720
)

type appArgs struct {
	ShowHelp     bool
	Domain       string
	VideoFlowId  string
	AudioFlowId  string
	IsFullscreen bool
	PlaybackId   uint32
	GpuId        uint32
	IsVerbose    bool
	ListAudio    bool
	ListGPU      bool
}

func printCliHelp(fs *pflag.FlagSet) {
	fmt.Printf("%s %s\n", APP_NAME, APP_VER)
	fmt.Println("Usage: mxl-player -d <domain> (-v <uuid> | -a <uuid>) [-f] [-h]")
	fmt.Println("                  [-g <gpu-id>] [-p <playback-id>] [--verbose]")
	fmt.Println("   or: mxl-player [--list-playback] [--list-gpu]")
	fmt.Println("   or: mxl-player (and set everything in GUI)")
	fmt.Println()
	fs.PrintDefaults()
}

func printUsage(w io.Writer) {
	fmt.Fprintln(w, "Usage: mxl-player -d <domain> (-v <uuid> | -a <uuid>) [-f] [-h]")
	fmt.Fprintln(w, "Try 'mxl-player -h' for more information.")
}

func checkMXLargs(args appArgs) {
	if args.Domain == "" {
		fmt.Fprintln(os.Stderr, "You should provide valid MXL domain and UUID of at least one flow")
		printUsage(os.Stderr)
		os.Exit(2)
	}

	fi, err := os.Stat(args.Domain)
	if err != nil || !fi.IsDir() {
		fmt.Fprintln(os.Stderr, "Invalid MXL domain:", args.Domain)
		fmt.Fprintln(os.Stderr, "Domain must be a directory in tmpfs")
		printUsage(os.Stderr)
		os.Exit(2)
	}
	if args.VideoFlowId == "" && args.AudioFlowId == "" {
		fmt.Fprintln(os.Stderr, "You must provide at least 1 MXL flow UUID")
		printUsage(os.Stderr)
		os.Exit(2)
	}
}

func main() {
	// timelapse video: 5fbec3b1-1b0f-417d-9059-8b94a47197ed
	// timelapse audio: 5fbec3b1-1b0f-417d-9059-8b94a47197ec
	// f1 video: 5fbec3b1-1b0f-417d-9059-8b94a47197ef
	// f1 audio: 5fbec3b1-1b0f-417d-9059-8b94a47197eb
	var args appArgs
	flagSet := pflag.NewFlagSet(APP_NAME, pflag.ContinueOnError)
	flagSet.Usage = func() { printUsage(os.Stderr) }
	flagSet.BoolVarP(&args.ShowHelp, "help", "h", false, "Show help message and exit")
	flagSet.StringVarP(&args.Domain, "domain", "d", "", "MXL domain directory")
	flagSet.StringVarP(&args.VideoFlowId, "video", "v", "", "Video flow UUID")
	flagSet.StringVarP(&args.AudioFlowId, "audio", "a", "", "Audio flow UUID")
	flagSet.BoolVarP(&args.IsFullscreen, "fullscreen", "f", false, "Run app in fullscreen mode")
	flagSet.Uint32VarP(&args.GpuId, "gpu-id", "g", 0, "GPU id [TODO]")
	flagSet.Uint32VarP(&args.PlaybackId, "playback-id", "p", 0, "Playback audio device id")
	flagSet.BoolVar(&args.IsVerbose, "verbose", false, "Verbose output [TODO]")
	flagSet.BoolVar(&args.ListAudio, "list-playback", false, "List audio playback devices and exit")
	flagSet.BoolVar(&args.ListGPU, "list-gpu", false, "List GPUs and exit")

	if err := flagSet.Parse(os.Args[1:]); err != nil {
		fmt.Fprintln(os.Stderr, err)
		printUsage(os.Stderr)
		os.Exit(2)
	}
	if args.ShowHelp {
		printCliHelp(flagSet)
		return
	}
	if !args.ListAudio && !args.ListGPU {
		checkMXLargs(args)
	}
	// end of cli args parse

	runtime.LockOSThread()
	if err := sdl.Load(); err != nil {
		panic(err)
	}
	if !sdl.Init(sdl.InitVideo | sdl.InitAudio) {
		log.Fatalf("SDL_Init: %s", sdl.GetError())
		return
	}

	sdlAudioDevice := sdl.AudioDeviceDefaultPlayback
	if args.PlaybackId != 0 {
		sdlAudioDevice = args.PlaybackId
	}
	// List audio playback devices and exit
	if args.ListAudio {
		devs := sdl.GetAudioPlaybackDevices()
		fmt.Println("Available playback audio devices")
		fmt.Println("id name")
		for _, d := range devs {
			fmt.Println(d.ID, d.Name)
		}
		return
	}

	windowHandler := sdl.CreateWindow(fmt.Sprintf("%s %s", APP_NAME, APP_VER), WIN_WIDTH, WIN_HEIGHT, sdl.WindowVulkan|sdl.WindowResizable)
	if windowHandler == 0 {
		sdl.Quit()
		log.Fatalf("SDL_CreateWindow: %s", sdl.GetError())
		return
	}

	// ImGui init
	gui := imgui.New()
	defer gui.Destroy()
	sdl.StartTextInput(windowHandler)
	defer sdl.StopTextInput(windowHandler)
	// fin on ImGui init

	if err := vk.Load(); err != nil {
		panic(err)
	}

	sdlExtensions := sdl.VulkanGetInstanceExtensions()
	if len(sdlExtensions) == 0 {
		log.Fatal("sdlVulkanGetInstanceExtensions is 0")
		return
	}
	var vkLayers []string
	vkExtensions := append(sdlExtensions, vk.ExtDebugUtils)
	vkInstance, err := vk.CreateInstance(vk.InstanceConfig{
		ApplicationName: APP_NAME,
		EngineName:      "no engine",
		Extensions:      vkExtensions,
		Layers:          vkLayers,
	})
	if err != nil {
		log.Fatalf("%s", err)
		panic(err)
	}
	defer vkInstance.Destroy()

	var vkSurface uint64
	if !sdl.VulkanCreateSurface(windowHandler, uintptr(vkInstance), 0, &vkSurface) {
		log.Fatalf("SDL_Vulkan_CreateSurface: %s", sdl.GetError())
		return
	}
	vkSurf := vk.SurfaceKHR(vkSurface)
	defer vkInstance.DestroySurface(vkSurf)

	devices, err := vkInstance.EnumeratePhysicalDevices()
	if err != nil || len(devices) == 0 {
		panic("No Vulkan devices")
	}
	// List GPU's and exit
	if args.ListGPU {
		fmt.Println("Available Vulkan physical devices:")
		fmt.Println("id name (type)")
		for i, pd := range devices {
			info := pd.Info()
			fmt.Printf("%2d %s (%s)\n", i, info.Name, info.Type)
		}
		return
	}
	vkPhysDevice := devices[0]

	gfx, err := vkPhysDevice.GraphicsFamily()
	if err != nil {
		panic(err.Error())
	}
	if !vkPhysDevice.SurfaceSupport(gfx, vkSurf) {
		log.Fatalf("graphics queue cannot present")
		return
	}

	vkDevice, vkQueue, err := vkPhysDevice.CreateDevice(vk.DeviceConfig{
		GraphicsFamily: gfx,
		Extensions:     []string{"VK_KHR_swapchain"},
	})
	if err != nil {
		panic(err)
	}
	defer vkDevice.Destroy()

	var (
		syncSrc     *source.SyncSource
		videoSrc    *source.Source
		audioSrc    *source.AudioSource
		audioStream uintptr
		audioBatch  uint64
		aChans      uint64
	)

	interleaveAudio := func(samples [][]byte) []byte {
		frameBytes := int(audioBatch) * int(aChans) * 4
		out := make([]byte, frameBytes)
		for ch := uint64(0); ch < aChans; ch++ {
			srcBytes := samples[ch]
			for i := uint64(0); i < audioBatch; i++ {
				srcOff := i * 4
				dstOff := (i*aChans + ch) * 4
				if srcOff+4 <= uint64(len(srcBytes)) {
					copy(out[dstOff:dstOff+4], srcBytes[srcOff:srcOff+4])
				}
			}
		}
		return out
	}

	switch {
	case args.VideoFlowId != "" && args.AudioFlowId != "":
		syncSrc, err = source.OpenSync(args.Domain, args.VideoFlowId, args.AudioFlowId)
		if err != nil {
			log.Fatalf("sync source: %v", err)
		}
		aChans = syncSrc.Channels()
		audioBatch = uint64(syncSrc.AudioRate().Num) / uint64(syncSrc.Rate().Num)
		if audioBatch == 0 {
			audioBatch = 1
		}
		audioStream = sdl.OpenAudioDeviceStream(sdlAudioDevice, sdl.AudioSpec{
			Format:   sdl.AudioF32,
			Channels: int32(aChans),
			Freq:     int32(syncSrc.AudioRate().Num / syncSrc.AudioRate().Den),
		})
		if audioStream == 0 {
			log.Fatalf("audio: %s", sdl.GetError())
		}
		sdl.ResumeAudioStreamDevice(audioStream)
		fmt.Printf("sync: video %dx%d audio %dch batch=%d\n",
			syncSrc.Width(), syncSrc.Height(), aChans, audioBatch)
	case args.VideoFlowId != "":
		videoSrc, err = source.Open(args.Domain, args.VideoFlowId)
		if err != nil {
			log.Fatalf("source: %v", err)
		}
		fmt.Printf("video: %dx%d stride=%d\n", videoSrc.Width(), videoSrc.Height(), videoSrc.Stride())

	default:
		audioSrc, err = source.OpenAudio(args.Domain, args.AudioFlowId)
		if err != nil {
			log.Fatalf("audio source: %v", err)
		}
		aChans = audioSrc.Channels()
		audioBatch = uint64(audioSrc.Rate().Num) / (100 * uint64(audioSrc.Rate().Den))
		if audioBatch == 0 {
			audioBatch = 1
		}
		audioStream = sdl.OpenAudioDeviceStream(sdlAudioDevice, sdl.AudioSpec{
			Format:   sdl.AudioF32,
			Channels: int32(aChans),
			Freq:     int32(audioSrc.Rate().Num / audioSrc.Rate().Den),
		})
		if audioStream == 0 {
			log.Fatalf("audio: %s", sdl.GetError())
		}
		sdl.ResumeAudioStreamDevice(audioStream)
		fmt.Printf("audio: %dch %d/%d Hz\n", aChans, audioSrc.Rate().Num, audioSrc.Rate().Den)
	}

	defer func() {
		if syncSrc != nil {
			_ = syncSrc.Close()
		}
		if videoSrc != nil {
			_ = videoSrc.Close()
		}
		if audioSrc != nil {
			_ = audioSrc.Close()
		}
	}()
	if audioStream != 0 {
		defer sdl.DestroyAudioStream(audioStream)
	}

	var r *renderer.Renderer
	if args.VideoFlowId != "" {
		var w, h, stride uint32
		if syncSrc != nil {
			w, h, stride = syncSrc.Width(), syncSrc.Height(), syncSrc.Stride()
		} else {
			w, h, stride = videoSrc.Width(), videoSrc.Height(), videoSrc.Stride()
		}
		r, err = renderer.New(renderer.Config{
			PhysDevice:     vkPhysDevice,
			Device:         vkDevice,
			Queue:          vkQueue,
			Surface:        vkSurf,
			Window:         windowHandler,
			GraphicsFamily: gfx,
			VideoWidth:     w,
			VideoHeight:    h,
			VideoStride:    stride,
		})
		if err != nil {
			panic(err)
		}
		defer r.Destroy()
		guiBackend, err := imgui.NewVulkanBackend(
			vkPhysDevice, vkDevice, vkQueue, r.CmdPool(), r.RenderPass())
		if err != nil {
			panic(err)
		}
		defer guiBackend.Destroy()
		r.ImGuiDraw = func(cmd vk.CommandBuffer) {
			guiBackend.RecordDraw(cmd, gui.LastDrawData())
		}
		defer vkDevice.WaitIdle()
	}

	// GUI state (accessible from doReconnect + goroutine)
	var (
		domainStr string = args.Domain
		videoStr  string = args.VideoFlowId
		audioStr  string = args.AudioFlowId
		showStats bool   = true
	)

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	type reconnectParams struct {
		domain string
		video  string
		audio  string
	}
	// One control channel: grant (empty params) or reconnect (with params).
	control := make(chan reconnectParams, 1)
	staged := make(chan uint64)

	reopen := func(params reconnectParams) error {
		// Close current sources
		if syncSrc != nil {
			_ = syncSrc.Close()
			syncSrc = nil
		}
		if videoSrc != nil {
			_ = videoSrc.Close()
			videoSrc = nil
		}
		if audioSrc != nil {
			_ = audioSrc.Close()
			audioSrc = nil
		}
		// Try once. Return error if fails — caller loops back to select
		// and can pick up new reconnect params or a new grant.
		if params.video != "" && params.audio != "" {
			s, e := source.OpenSync(params.domain, params.video, params.audio)
			if e == nil {
				if r != nil {
					newSize := vk.DeviceSize(s.Stride()) * vk.DeviceSize(s.Height())
					if newSize != r.FrameSize() {
						if e = r.RecreateBuffers(newSize); e != nil {
							return e
						}
					}
				}
				syncSrc = s
				aChans = s.Channels()
				audioBatch = uint64(s.AudioRate().Num) / uint64(s.Rate().Num)
				if audioBatch == 0 {
					audioBatch = 1
				}
				return nil
			}
			return e
		} else if params.video != "" {
			s, e := source.Open(params.domain, params.video)
			if e == nil {
				if r != nil {
					newSize := vk.DeviceSize(s.Stride()) * vk.DeviceSize(s.Height())
					if newSize != r.FrameSize() {
						if e = r.RecreateBuffers(newSize); e != nil {
							return e
						}
					}
				}
				videoSrc = s
				return nil
			}
			return e
		} else if params.audio != "" {
			s, e := source.OpenAudio(params.domain, params.audio)
			if e == nil {
				audioSrc = s
				aChans = s.Channels()
				audioBatch = uint64(s.Rate().Num) / (100 * uint64(s.Rate().Den))
				if audioBatch == 0 {
					audioBatch = 1
				}
				return nil
			}
			return e
		}
		return fmt.Errorf("reopen: no flow specified")
	}

	doReconnect := func() {
		select {
		case <-control:
		default:
		}
		control <- reconnectParams{domain: domainStr, video: videoStr, audio: audioStr}
	}

	go func() {
		// Audio-only mode: independent loop, no grant/staged handshake.
		if audioSrc != nil && syncSrc == nil && videoSrc == nil {
			for {
				select {
				case <-ctx.Done():
					return
				case params := <-control:
					if params.video != "" || params.audio != "" {
						if rerr := reopen(params); rerr != nil {
							if errors.Is(rerr, context.Canceled) {
								return
							}
							log.Printf("source: reopen failed: %v, retrying", rerr)
							select {
							case <-time.After(500 * time.Millisecond):
							case <-ctx.Done():
								return
							}
							select {
							case control <- params:
							default:
							}
						}
					}
					continue
				default:
				}
				queued := sdl.GetAudioStreamQueued(audioStream)
				maxQueued := int32(audioBatch) * int32(aChans) * 4 * 20
				if queued > maxQueued {
					select {
					case <-time.After(10 * time.Millisecond):
					case <-ctx.Done():
						return
					}
					continue
				}
				f, err := audioSrc.NextAudio(ctx, audioBatch, 20*time.Millisecond)
				if err != nil {
					if errors.Is(err, context.Canceled) {
						return
					}
					log.Printf("source: %v", err)
					params := reconnectParams{domain: domainStr, video: videoStr, audio: audioStr}
					select {
					case <-control:
					default:
					}
					select {
					case <-time.After(500 * time.Millisecond):
					case <-ctx.Done():
						return
					}
					select {
					case control <- params:
					default:
					}
					continue
				}
				if f.Samples != nil && audioStream != 0 {
					sdl.PutAudioStreamData(audioStream, interleaveAudio(f.Samples))
				}
			}
		}

		// Video (with or without sync) mode: grant/staged handshake.
		for {
			params := <-control
			if params.video != "" || params.audio != "" {
				// Reconnect request from Connect button or auto-retry.
				select {
				case <-control: // drain any pending grant
				default:
				}
				if rerr := reopen(params); rerr != nil {
					if errors.Is(rerr, context.Canceled) {
						return
					}
					log.Printf("source: reopen failed: %v, retrying", rerr)
					select {
					case <-time.After(500 * time.Millisecond):
					case <-ctx.Done():
						return
					}
					select {
					case control <- params:
					default:
					}
				}
				continue
			}

			var payload []byte
			var grainIdx uint64

			if syncSrc != nil {
				vFrame, aFrame, err := syncSrc.NextSync(ctx, audioBatch, 200*time.Millisecond)
				if err != nil {
					if errors.Is(err, context.Canceled) {
						return
					}
					log.Printf("source: %v", err)
					// Drain any pending grant, then send reconnect.
					select {
					case <-control:
					default:
					}
					select {
					case control <- reconnectParams{domain: domainStr, video: videoStr, audio: audioStr}:
					case <-ctx.Done():
						return
					}
					continue
				}
				payload = vFrame.Payload
				grainIdx = vFrame.Index
				if aFrame.Samples != nil && audioStream != 0 {
					sdl.PutAudioStreamData(audioStream, interleaveAudio(aFrame.Samples))
				}

			} else if videoSrc != nil {
				f, err := videoSrc.NextCtx(ctx, 200*time.Millisecond)
				if err != nil {
					if errors.Is(err, context.Canceled) {
						return
					}
					log.Printf("source: %v", err)
					select {
					case <-control:
					default:
					}
					select {
					case control <- reconnectParams{domain: domainStr, video: videoStr, audio: audioStr}:
					case <-ctx.Done():
						return
					}
					continue
				}
				payload = f.Payload
				grainIdx = f.Index
			}

			if r != nil {
				vk.CopyToMapped(r.StagingMapped(), payload)
			}
			select {
			case staged <- grainIdx:
			case <-ctx.Done():
				return
			}
		}
	}()

	running := true
	resized := false
	granted := false
	fullscreen := args.IsFullscreen
	if fullscreen {
		sdl.SetWindowFullscreen(windowHandler, true)
	}
	var (
		fps        float64
		lastIndex  uint64
		dropped    uint64
		frameCount uint64
		lastReport time.Time
		lastFrame  time.Time
	)
	lastFrame = time.Now()

	for running {
		frameStart := time.Now()
		var event [128]byte
		for sdl.PollEvent(unsafe.Pointer(&event[0])) {
			eventType := *(*uint32)(unsafe.Pointer(&event[0]))
			switch eventType {
			case sdl.EventQuit:
				running = false
			case sdl.EventWindowResized, sdl.EventPixelSizeChanged:
				resized = true
			case sdl.EventKeyDown:
				if gui.IO().WantCaptureKeyboard() {
					break
				}
				key := *(*int32)(unsafe.Pointer(&event[28]))
				switch uint32(key) {
				case sdl.KeyQ:
					fallthrough
				case sdl.KeyEscape:
					running = false
				case sdl.KeyF:
					fullscreen = !fullscreen
					sdl.SetWindowFullscreen(windowHandler, fullscreen)
					resized = true
				case sdl.KeyF1:
					showStats = !showStats
				}
			}
			gui.ProcessEvent(&event)
		}
		if !running {
			break
		}
		if resized && r != nil {
			if err := r.RecreateSwapchain(); err != nil {
				if errors.Is(err, renderer.ErrMinimized) {
					resized = true
					continue
				}
				panic(err)
			}
			resized = false
		}
		if !granted {
			select {
			case control <- reconnectParams{}:
				granted = true
			case <-ctx.Done():
				running = false
				continue
			}
		}
		var shownIndex uint64
		hasFrame := false
		select {
		case shownIndex = <-staged:
			granted = false
			hasFrame = true
		case <-ctx.Done():
			running = false
			continue
		case <-time.After(100 * time.Millisecond):
			// No frame staged. Reset granted so we re-grant on next iteration.
			granted = false
		}

		// stats
		if hasFrame {
			if lastIndex != 0 && shownIndex > lastIndex {
				if g := shownIndex - lastIndex - 1; g > 0 {
					dropped += g
				}
			}
			lastIndex = shownIndex
			frameCount++
			if now := time.Now(); now.Sub(lastReport) >= time.Second {
				dt := now.Sub(lastReport).Seconds()
				fps = float64(frameCount) / dt
				fmt.Printf("fps=%.1f dropped=%d idx=%d frameTime=%.2fms\n",
					fps, dropped, shownIndex, float64(now.Sub(frameStart).Microseconds())/1000.0)
				frameCount = 0
				dropped = 0
				lastReport = now
			}
		}
		// end of stats
		if r != nil {
			gui.BeginFrame(time.Since(lastFrame), int32(r.Extent().Width), int32(r.Extent().Height))
			// test widget
			// cimgui.Begin("Test")
			if showStats {
				cimgui.SetNextWindowPos(cimgui.Vec2{X: 10, Y: 10})
				cimgui.SetNextWindowSize(cimgui.Vec2{X: 200, Y: 200})
				cimgui.BeginV("Stats", &showStats,
					cimgui.WindowFlagsNoTitleBar|cimgui.WindowFlagsNoResize|cimgui.WindowFlagsNoScrollbar)
				cimgui.Text(fmt.Sprintf("FPS: %.1f", fps))
				cimgui.Text(fmt.Sprintf("Dropped: %d", dropped))
				cimgui.Text(fmt.Sprintf("Index: %d", shownIndex))
				if videoSrc != nil {
					cimgui.Text(fmt.Sprintf("Video: %dx%d %.2fp", videoSrc.Width(), videoSrc.Height(),
						float32(videoSrc.Rate().Num/videoSrc.Rate().Den)))
				}
				if syncSrc != nil {
					cimgui.Text(fmt.Sprintf("Video: %dx%d %.2fp", syncSrc.Width(), syncSrc.Height(),
						float32(syncSrc.Rate().Num/syncSrc.Rate().Den)))
					cimgui.Text(fmt.Sprintf("Audio: %dch %dkHz", syncSrc.Channels(), syncSrc.AudioRate().Num))
				}
				cimgui.Text("\nPress F1 to hide stats")
				cimgui.Text("Q or Esc to quit")
				cimgui.Text("F for fullscreen")
				cimgui.End()
			}
			cimgui.Begin("Connection")
			cimgui.InputTextWithHint("Domain", "/dev/shm/mxl", &domainStr, 0, nil)
			cimgui.InputTextWithHint("Video UUID", "", &videoStr, 0, nil)
			cimgui.InputTextWithHint("Audio UUID", "", &audioStr, 0, nil)
			cimgui.Checkbox("Show stats", &showStats)
			if cimgui.Button("Connect") {
				doReconnect()
			}
			cimgui.End()
			gui.EndFrame()
			lastFrame = time.Now()
			// end of test widget
			var w, h, stride uint32
			if syncSrc != nil {
				w, h, stride = syncSrc.Width(), syncSrc.Height(), syncSrc.Stride()
			} else if videoSrc != nil {
				w, h, stride = videoSrc.Width(), videoSrc.Height(), videoSrc.Stride()
			}
			err := r.DrawFrame(w, h, stride)
			if errors.Is(err, renderer.ErrOutOfDate) {
				if rerr := r.RecreateSwapchain(); rerr != nil {
					if errors.Is(rerr, renderer.ErrMinimized) {
						resized = true
						continue
					}
					panic(rerr)
				}
				continue
			}
			if err != nil {
				panic(err)
			}

		} else {
			time.Sleep(10 * time.Millisecond)
		}
	}
}