package main

import (
	"context"
	"fmt"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"sync"
	"time"
)

// ---------------------------
// Tasks: Missing Assets erzeugen
// ---------------------------

type AssetsTaskState struct {
	Running           bool       `json:"running"`
	Total             int        `json:"total"`
	Done              int        `json:"done"`
	GeneratedThumbs   int        `json:"generatedThumbs"`
	GeneratedPreviews int        `json:"generatedPreviews"`
	Skipped           int        `json:"skipped"`
	StartedAt         time.Time  `json:"startedAt"`
	FinishedAt        *time.Time `json:"finishedAt,omitempty"`
	Error             string     `json:"error,omitempty"`
}

var assetsTaskMu sync.Mutex
var assetsTaskState AssetsTaskState
var assetsTaskCancel context.CancelFunc

func tasksGenerateAssets(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case http.MethodGet:
		assetsTaskMu.Lock()
		st := assetsTaskState
		assetsTaskMu.Unlock()
		writeJSON(w, http.StatusOK, st)
		return

	case http.MethodPost:
		assetsTaskMu.Lock()
		if assetsTaskState.Running {
			st := assetsTaskState
			assetsTaskMu.Unlock()
			writeJSON(w, http.StatusOK, st)
			return
		}

		// ✅ cancelbaren Context erzeugen
		ctx, cancel := context.WithCancel(context.Background())
		assetsTaskCancel = cancel

		assetsTaskState = AssetsTaskState{
			Running:   true,
			StartedAt: time.Now(),
		}
		st := assetsTaskState
		assetsTaskMu.Unlock()

		go runGenerateMissingAssets(ctx)

		writeJSON(w, http.StatusOK, st)
		return

	case http.MethodDelete:
		assetsTaskMu.Lock()
		cancel := assetsTaskCancel
		running := assetsTaskState.Running
		assetsTaskMu.Unlock()

		if !running || cancel == nil {
			// nichts zu stoppen
			w.WriteHeader(http.StatusNoContent)
			return
		}

		cancel()

		// optional: sofortiges Feedback in state.error
		assetsTaskMu.Lock()
		if assetsTaskState.Running {
			assetsTaskState.Error = "abgebrochen"
		}
		st := assetsTaskState
		assetsTaskMu.Unlock()

		writeJSON(w, http.StatusOK, st)
		return

	default:
		http.Error(w, "Nur GET/POST", http.StatusMethodNotAllowed)
		return
	}
}

func runGenerateMissingAssets(ctx context.Context) {
	finishWithErr := func(err error) {
		now := time.Now()
		assetsTaskMu.Lock()
		assetsTaskState.Running = false
		assetsTaskState.FinishedAt = &now
		if err != nil {
			assetsTaskState.Error = err.Error()
		}
		assetsTaskMu.Unlock()
	}

	defer func() {
		assetsTaskMu.Lock()
		assetsTaskCancel = nil
		assetsTaskMu.Unlock()
	}()

	s := getSettings()
	doneAbs, err := resolvePathRelativeToApp(s.DoneDir)
	if err != nil || strings.TrimSpace(doneAbs) == "" {
		finishWithErr(fmt.Errorf("doneDir auflösung fehlgeschlagen: %v", err))
		return
	}

	type item struct {
		name string
		path string
	}

	// .trash niemals verarbeiten
	isTrashPath := func(full string) bool {
		p := strings.ToLower(strings.ReplaceAll(full, "\\", "/"))
		return strings.Contains(p, "/.trash/") || strings.HasSuffix(p, "/.trash")
	}

	seen := map[string]struct{}{}
	items := make([]item, 0, 512)

	addIfVideo := func(full string) {
		if isTrashPath(full) {
			return
		}

		name := filepath.Base(full)
		low := strings.ToLower(name)
		if strings.Contains(low, ".part") || strings.Contains(low, ".tmp") {
			return
		}
		ext := strings.ToLower(filepath.Ext(name))
		if ext != ".mp4" && ext != ".ts" {
			return
		}

		// Dedupe
		if _, ok := seen[full]; ok {
			return
		}
		seen[full] = struct{}{}
		items = append(items, item{name: name, path: full})
	}

	scanOneLevel := func(dir string) {
		ents, err := os.ReadDir(dir)
		if err != nil {
			return
		}
		for _, e := range ents {
			// .trash-Ordner nie scannen
			if e.IsDir() && strings.EqualFold(e.Name(), ".trash") {
				continue
			}

			full := filepath.Join(dir, e.Name())
			if e.IsDir() {
				sub, err := os.ReadDir(full)
				if err != nil {
					continue
				}
				for _, se := range sub {
					if se.IsDir() {
						continue
					}
					addIfVideo(filepath.Join(full, se.Name()))
				}
				continue
			}
			addIfVideo(full)
		}
	}

	// ✅ done + done/<model>/ + done/keep + done/keep/<model>/
	scanOneLevel(doneAbs)
	scanOneLevel(filepath.Join(doneAbs, "keep"))

	assetsTaskMu.Lock()
	assetsTaskState.Total = len(items)
	assetsTaskState.Done = 0
	assetsTaskState.GeneratedThumbs = 0
	assetsTaskState.GeneratedPreviews = 0
	assetsTaskState.Skipped = 0
	assetsTaskState.Error = ""
	assetsTaskMu.Unlock()

	for i, it := range items {
		if err := ctx.Err(); err != nil {
			finishWithErr(err)
			return
		}

		base := strings.TrimSuffix(it.name, filepath.Ext(it.name))
		id := stripHotPrefix(base)
		if strings.TrimSpace(id) == "" {
			assetsTaskMu.Lock()
			assetsTaskState.Done = i + 1
			assetsTaskMu.Unlock()
			continue
		}

		assetDir, derr := ensureGeneratedDir(id)
		if derr != nil {
			assetsTaskMu.Lock()
			assetsTaskState.Error = "mindestens ein Eintrag konnte nicht verarbeitet werden (siehe Logs)"
			assetsTaskState.Done = i + 1
			assetsTaskMu.Unlock()
			fmt.Println("⚠️ ensureGeneratedDir:", derr)
			continue
		}

		thumbPath := filepath.Join(assetDir, "thumbs.jpg")
		previewPath := filepath.Join(assetDir, "preview.mp4")
		metaPath := filepath.Join(assetDir, "meta.json")

		thumbOK := func() bool {
			fi, err := os.Stat(thumbPath)
			return err == nil && !fi.IsDir() && fi.Size() > 0
		}()
		previewOK := func() bool {
			fi, err := os.Stat(previewPath)
			return err == nil && !fi.IsDir() && fi.Size() > 0
		}()

		// Datei-Info (für Meta-Validierung)
		vfi, verr := os.Stat(it.path)
		if verr != nil || vfi.IsDir() || vfi.Size() <= 0 {
			assetsTaskMu.Lock()
			assetsTaskState.Done = i + 1
			assetsTaskMu.Unlock()
			continue
		}

		// ✅ SourceURL best-effort: aus bestehender meta.json, wenn vorhanden/valide
		sourceURL := ""
		if u, ok := readVideoMetaSourceURL(metaPath, vfi); ok {
			sourceURL = u
		}

		// ✅ Dauer zuerst aus meta.json, sonst 1× ffprobe & meta.json schreiben
		durSec := 0.0
		metaOK := false

		if d, ok := readVideoMetaDuration(metaPath, vfi); ok {
			durSec = d
			metaOK = true

			// meta ist valide (Duration ok), aber falls wir (irgendwoher) eine SourceURL hätten
			// und sie in meta noch fehlt -> meta anreichern ohne ffprobe.
			if strings.TrimSpace(sourceURL) != "" {
				if u, ok := readVideoMetaSourceURL(metaPath, vfi); !ok || strings.TrimSpace(u) == "" {
					_ = writeVideoMetaDuration(metaPath, vfi, durSec, sourceURL)
				}
			}
		} else {
			dctx, cancel := context.WithTimeout(ctx, 6*time.Second)
			d, derr := durationSecondsCached(dctx, it.path)
			cancel()

			if derr == nil && d > 0 {
				durSec = d
				// ✅ HIER: nicht writeVideoMeta(metaPath, fi, dur, sourceURL) !!
				// sondern Duration-only writer nutzen
				_ = writeVideoMetaDuration(metaPath, vfi, durSec, sourceURL)
				metaOK = true
			}
		}

		if thumbOK && previewOK && metaOK {
			assetsTaskMu.Lock()
			assetsTaskState.Skipped++
			assetsTaskState.Done = i + 1
			assetsTaskMu.Unlock()
			continue
		}

		// ----------------
		// Thumbs
		// ----------------
		if !thumbOK {
			genCtx, cancel := context.WithTimeout(ctx, 45*time.Second)
			if err := thumbSem.Acquire(genCtx); err != nil {
				cancel()
				finishWithErr(err)
				return
			}
			cancel() // Timeout-Context freigeben, Semaphore bleibt gehalten
			defer thumbSem.Release()

			t := 0.0
			if durSec > 0 {
				t = durSec * 0.5
			}

			img, e1 := extractFrameAtTimeJPEG(it.path, t)
			if e1 != nil || len(img) == 0 {
				img, e1 = extractLastFrameJPEG(it.path)
				if e1 != nil || len(img) == 0 {
					img, e1 = extractFirstFrameJPEG(it.path)
				}
			}

			// Release wurde defer’t, aber wir wollen pro Iteration releasen:
			thumbSem.Release()

			if e1 == nil && len(img) > 0 {
				if err := atomicWriteFile(thumbPath, img); err == nil {
					assetsTaskMu.Lock()
					assetsTaskState.GeneratedThumbs++
					assetsTaskMu.Unlock()
				} else {
					fmt.Println("⚠️ thumb write:", err)
				}
			}
		}

		// ----------------
		// Preview
		// ----------------
		if !previewOK {
			genCtx, cancel := context.WithTimeout(ctx, 3*time.Minute)
			if err := genSem.Acquire(genCtx); err != nil {
				cancel()
				finishWithErr(err)
				return
			}

			err := generateTeaserClipsMP4(genCtx, it.path, previewPath, 1.0, 18)

			genSem.Release()
			cancel()

			if err == nil {
				assetsTaskMu.Lock()
				assetsTaskState.GeneratedPreviews++
				assetsTaskMu.Unlock()
			} else {
				fmt.Println("⚠️ preview clips:", err)
			}
		}

		assetsTaskMu.Lock()
		assetsTaskState.Done = i + 1
		assetsTaskMu.Unlock()
	}

	finishWithErr(nil)
}