// MXL pattern generator feed rendered on the GPU via wgpu (WebGPU/Vulkan).
// Run from the repo root: make wgpu-gen
// (mixing libmxl cgo with wgpu/goffi needs the internal linker)
package main

import (
	"context"
	"fmt"
	"io"
	"log"
	"os"
	"os/signal"
	"sort"
	"strings"
	"syscall"

	"github.com/google/uuid"
	"github.com/qvest-digital/go-mxl/mxl"
	"github.com/spf13/pflag"

	"mxl-pattern-generator/internal/app"
	"mxl-pattern-generator/internal/audio"
	"mxl-pattern-generator/internal/flowdef"
	"mxl-pattern-generator/internal/video"
)

const (
	APP_NAME = app.Name
	APP_VER  = app.Version
)

type appArgs struct {
	showHelp bool

	domain           string
	videoFlowDefFile string
	audioFlowDefFile string
	pattern          string
	listPatterns     bool

	textOverlay string
	overlayX    int
	overlayY    int
	overlayPos  string

	videoWidth  uint
	videoHeight uint
	videoFPS    string
	videoUUID   string
	noVideo     bool

	audioChannels     uint8
	audioSamplingFreq string
	audioLevel        string
	audioUUID         string
}

type parseResult struct {
	args      appArgs
	shouldRun bool
}

var frameRates = map[string]mxl.Rational{
	"23.97": {Num: 24000, Den: 1001},
	"24":    {Num: 24, Den: 1},
	"25":    {Num: 25, Den: 1},
	"29.97": {Num: 30000, Den: 1001},
	"30":    {Num: 30, Den: 1},
	"50":    {Num: 50, Den: 1},
	"59.94": {Num: 60000, Den: 1001},
	"60":    {Num: 60, Den: 1},
	"120":   {Num: 120, Den: 1},
	"240":   {Num: 240, Den: 1},
}

var samplingRates = map[string]mxl.Rational{
	"44.1": {Num: 44100, Den: 1},
	"48":   {Num: 48000, Den: 1},
	"96":   {Num: 96000, Den: 1},
	"192":  {Num: 192000, Den: 1},
}

func printHelp(w io.Writer, fs *pflag.FlagSet) {
	fmt.Fprintf(w, "%s %s\n", APP_NAME, APP_VER)
	fmt.Fprintln(w, "Usage: mxl-gen -d <domain> [-v <flowDef.json>] [-a <flowDef.json>] [options]")
	fmt.Fprintln(w, "   or: mxl-gen -d <domain> [--width <width px>] [--height <height px>] [--fps <framerate>] \\")
	fmt.Fprintln(w, "   [-c <channels amount>] [-f <sample rate>]")
	fmt.Fprintln(w, "   or: mxl-gen -d <domain> --no-video (-c <channels amount> | -a <flowDef.json>)")
	fmt.Fprintln(w, "   or: mxl-gen -d <domain> with default params")
	fmt.Fprintln(w, "Video and audio feed parameters are ignored when a flow definition file is provided.")
	fmt.Fprintln(w)
	fs.SetOutput(w)
	fs.PrintDefaults()
}

func printUsage(w io.Writer) {
	fmt.Fprintln(w, "Usage: mxl-gen -d <domain> [--no-video] [-v <flowDef.json>] [-a <flowDef.json>] [options]")
	fmt.Fprintln(w, "Try 'mxl-gen -h' for more information.")
}

func validateDomain(domain string) error {
	if domain == "" {
		return fmt.Errorf("domain is required")
	}
	fi, err := os.Stat(domain)
	if err != nil {
		return fmt.Errorf("invalid MXL domain %q: %w", domain, err)
	}
	if !fi.IsDir() {
		return fmt.Errorf("invalid MXL domain %q: not a directory", domain)
	}
	if ok, err := mxl.IsTmpFs(domain); err != nil || !ok {
		if err != nil {
			return fmt.Errorf("check MXL domain %q: %w", domain, err)
		}
		return fmt.Errorf("invalid MXL domain %q: directory must be on tmpfs", domain)
	}
	return nil
}

func validateFlowDefPath(label, path string) error {
	if path == "" {
		return nil
	}
	fi, err := os.Stat(path)
	if err != nil {
		return fmt.Errorf("%s flow definition %q is not accessible: %w", label, path, err)
	}
	if fi.IsDir() {
		return fmt.Errorf("%s flow definition %q is a directory", label, path)
	}
	return nil
}

func validateVideoArgs(args *appArgs) error {
	if args.noVideo {
		return nil
	}
	if !video.HasPattern(args.pattern) {
		return fmt.Errorf("unknown video pattern %q (use --list-patterns to see available patterns)", args.pattern)
	}
	if args.videoFlowDefFile != "" {
		return nil
	}
	if args.videoWidth == 0 || args.videoWidth%6 != 0 {
		// v210 stores 6 pixels in each 16-byte block.
		return fmt.Errorf("video width must be greater than zero and divisible by 6")
	}
	if args.videoHeight == 0 {
		return fmt.Errorf("video height must be greater than zero")
	}
	if _, exists := frameRates[args.videoFPS]; !exists {
		return fmt.Errorf("unsupported video FPS %q (supported: %s); use a flow definition for other rates",
			args.videoFPS, sortedMapKeys(frameRates))
	}
	if args.videoUUID == "" {
		args.videoUUID = uuid.NewString()
		return nil
	}
	if _, err := uuid.Parse(args.videoUUID); err != nil {
		return fmt.Errorf("invalid video UUID %q: %w", args.videoUUID, err)
	}
	return nil
}

func validateMediaSelection(args appArgs) error {
	if args.noVideo && args.videoFlowDefFile != "" {
		return fmt.Errorf("--no-video cannot be used with --video")
	}
	if args.noVideo && args.audioFlowDefFile == "" && args.audioChannels == 0 {
		return fmt.Errorf("--no-video requires audio enabled with --channel or --audio")
	}
	return nil
}

func validateAudioArgs(args *appArgs) error {
	if args.audioFlowDefFile == "" && args.audioChannels == 0 {
		return nil
	}
	if _, ok := audioLevels[args.audioLevel]; !ok {
		return fmt.Errorf(
			"unsupported audio level %q (supported: %s)",
			args.audioLevel,
			sortedMapKeys(audioLevels),
		)
	}
	if args.audioFlowDefFile != "" {
		return nil
	}
	if _, exists := samplingRates[args.audioSamplingFreq]; !exists {
		return fmt.Errorf("unsupported audio sample rate %q (supported: %s); use a flow definition for other rates",
			args.audioSamplingFreq, sortedMapKeys(samplingRates))
	}
	if args.audioUUID == "" {
		args.audioUUID = uuid.NewString()
		return nil
	}
	if err := uuid.Validate(args.audioUUID); err != nil {
		return fmt.Errorf("invalid audio UUID %q: %w", args.audioUUID, err)
	}
	return nil
}

func validateArgs(args *appArgs) error {
	checks := []func() error{
		func() error { return validateDomain(args.domain) },
		func() error { return validateMediaSelection(*args) },
		func() error { return validateFlowDefPath("video", args.videoFlowDefFile) },
		func() error { return validateFlowDefPath("audio", args.audioFlowDefFile) },
		func() error { return validateVideoArgs(args) },
		func() error { return validateAudioArgs(args) },
	}
	for _, check := range checks {
		if err := check(); err != nil {
			return err
		}
	}
	return nil
}

func sortedMapKeys[V any](values map[string]V) string {
	keys := make([]string, 0, len(values))
	for key := range values {
		keys = append(keys, key)
	}
	sort.Strings(keys)
	return strings.Join(keys, ", ")
}

var audioLevels = map[string]float64{
	"ebu":   audio.LevelEBUDBFS,
	"smpte": audio.LevelSMPTEDBFS,
}

func listPatterns(w io.Writer) {
	fmt.Fprintln(w, "List of available video patterns:")
	patterns := video.Patterns()
	maxNameWidth := 0
	for _, pattern := range patterns {
		l := len(pattern.Name)
		if l > maxNameWidth {
			maxNameWidth = l
		}
	}
	for _, pattern := range patterns {
		fmt.Fprintf(w, "  %-*s - %s\n", maxNameWidth, pattern.Name, pattern.Description)
	}
}

func addFlags(fs *pflag.FlagSet, args *appArgs) {
	// common flags
	fs.BoolVarP(&args.showHelp, "help", "h", false, "Show help message and exit")
	// MXL flags
	fs.StringVarP(&args.domain, "domain", "d", "", "MXL domain")
	fs.StringVarP(&args.videoFlowDefFile, "video", "v", "", "Video flow definition JSON file path")
	fs.StringVarP(&args.audioFlowDefFile, "audio", "a", "", "Audio flow definition JSON file path")
	// Video pattern flags
	fs.StringVarP(&args.pattern, "pattern", "p", "ebu75", "Video pattern type")
	fs.BoolVar(&args.listPatterns, "list-patterns", false, "List video available video patterns and exit")

	fs.StringVarP(&args.textOverlay, "text", "t", "", "Text overlay above video pattern. Ignored if text-pos set")
	fs.IntVar(&args.overlayX, "text-x", 0, "Text overlay X position in px. Ignored if text-pos set")
	fs.IntVar(
		&args.overlayY,
		"text-y",
		0,
		"Text overlay Y position in px")
	fs.StringVar(
		&args.overlayPos,
		"text-pos",
		"",
		"Text overlay position with pre-defined values:\n"+
			"tl - top-left corner\n"+
			"tc - top-center\n"+
			"tr - top-right corner\n"+
			"cc - center of the frame\n"+
			"bl - bottom-left corner\n"+
			"bc - bottom-center\n"+
			"br - bottom-right corner",
	)

	fs.UintVar(&args.videoWidth, "width", 1920, "Video pattern width")
	fs.UintVar(&args.videoHeight, "height", 1080, "Video pattern height")
	fs.StringVar(&args.videoFPS, "fps", "25", "Video pattern FPS")
	fs.StringVar(&args.videoUUID, "video-id", "", "Video UUID. Will be created, if not provided")
	fs.BoolVar(&args.noVideo, "no-video", false, "Disable video generation; audio must be enabled")
	// Audio pattern flags
	fs.Uint8VarP(&args.audioChannels, "channel", "c", 0, "Amount of audio channels. Each channel: num * 1kHz")
	fs.StringVarP(&args.audioSamplingFreq, "freq", "f", "48", "Sampling frequency of test audio feed in kHz")
	fs.StringVar(&args.audioLevel, "audio-level", "ebu", "Audio alignment level: ebu (-18 dBFS) or smpte (-20 dBFS)")
	fs.StringVar(&args.audioUUID, "audio-id", "", "Audio UUID. Will be created, if not provided")
}

func parseArgs(argv []string, stdout, stderr io.Writer) (parseResult, error) {
	var args appArgs
	flagSet := pflag.NewFlagSet("args", pflag.ContinueOnError)
	flagSet.SortFlags = false
	flagSet.SetOutput(stderr)
	flagSet.Usage = func() { printUsage(stderr) }
	addFlags(flagSet, &args)

	if err := flagSet.Parse(argv); err != nil {
		return parseResult{}, err
	}
	if args.showHelp {
		printHelp(stdout, flagSet)
		return parseResult{args: args}, nil
	}
	if args.listPatterns {
		listPatterns(stdout)
		return parseResult{args: args}, nil
	}
	if flagSet.NArg() != 0 {
		return parseResult{}, fmt.Errorf("unexpected positional arguments: %v", flagSet.Args())
	}
	if err := validateArgs(&args); err != nil {
		return parseResult{}, err
	}
	return parseResult{args: args, shouldRun: true}, nil
}

func buildVideoConfig(args appArgs) (*video.Config, error) {
	if args.noVideo {
		return nil, nil
	}

	var definition flowdef.Video
	if args.videoFlowDefFile != "" {
		data, err := os.ReadFile(args.videoFlowDefFile)
		if err != nil {
			return nil, fmt.Errorf(
				"read video flow definition %q: %w",
				args.videoFlowDefFile,
				err,
			)
		}

		definition, err = flowdef.ParseV210Video(data)
		if err != nil {
			return nil, fmt.Errorf(
				"parse video flow definition %q: %w",
				args.videoFlowDefFile,
				err,
			)
		}
	} else {
		rate, ok := frameRates[args.videoFPS]
		if !ok {
			return nil, fmt.Errorf("unsupported video FPS %q", args.videoFPS)
		}

		var err error
		definition, err = flowdef.NewV210Video(
			args.videoUUID,
			args.videoWidth,
			args.videoHeight,
			flowdef.Rational{
				Numerator:   uint(rate.Num),
				Denominator: uint(rate.Den),
			},
		)
		if err != nil {
			return nil, fmt.Errorf(
				"build video flow definition: %w",
				err,
			)
		}
	}
	if !video.HasPattern(args.pattern) {
		return nil, fmt.Errorf("unknown video pattern %q", args.pattern)
	}

	return &video.Config{
		Definition: definition,
		Pattern:    args.pattern,
		Overlay: video.OverlayConfig{
			Text:     args.textOverlay,
			X:        args.overlayX,
			Y:        args.overlayY,
			Position: args.overlayPos,
		},
	}, nil
}

// buildAudioConfig returns nil when audio is disabled. An explicit audio flow
// definition enables audio even when --channel is zero.
func buildAudioConfig(args appArgs) (*audio.Config, error) {
	if args.audioFlowDefFile == "" && args.audioChannels == 0 {
		return nil, nil
	}
	levelDBFS, ok := audioLevels[args.audioLevel]
	if !ok {
		return nil, fmt.Errorf("unsupported audio level %q", args.audioLevel)
	}

	var definition flowdef.Audio
	if args.audioFlowDefFile != "" {
		data, err := os.ReadFile(args.audioFlowDefFile)
		if err != nil {
			return nil, fmt.Errorf("read audio flow definition %q: %w", args.audioFlowDefFile, err)
		}
		definition, err = flowdef.ParseFloat32Audio(data)
		if err != nil {
			return nil, fmt.Errorf("parse audio flow definition %q: %w", args.audioFlowDefFile, err)
		}
	} else {
		rate, ok := samplingRates[args.audioSamplingFreq]
		if !ok {
			return nil, fmt.Errorf("unsupported audio sample rate %q", args.audioSamplingFreq)
		}
		var err error
		definition, err = flowdef.NewFloat32Audio(
			args.audioUUID,
			uint(args.audioChannels),
			flowdef.Rational{Numerator: uint(rate.Num), Denominator: uint(rate.Den)},
		)
		if err != nil {
			return nil, fmt.Errorf("build audio flow definition: %w", err)
		}
	}

	return &audio.Config{
		Definition: definition,
		LevelDBFS:  levelDBFS,
	}, nil
}

func main() {
	parsed, err := parseArgs(os.Args[1:], os.Stdout, os.Stderr)
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		printUsage(os.Stderr)
		os.Exit(2)
	}
	if !parsed.shouldRun {
		return
	}

	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
	defer stop()
	if err := run(ctx, parsed.args); err != nil {
		log.Printf("%s: %v", APP_NAME, err)
		os.Exit(1)
	}
}

func run(ctx context.Context, args appArgs) error {
	videoCfg, err := buildVideoConfig(args)
	if err != nil {
		return fmt.Errorf("video configuration: %w", err)
	}
	audioCfg, err := buildAudioConfig(args)
	if err != nil {
		return fmt.Errorf("audio configuration: %w", err)
	}

	return app.Run(ctx, app.Config{
		Domain: args.domain,
		Video:  videoCfg,
		Audio:  audioCfg,
	})
}