// backend/postwork.go
package main

import (
	"context"
	"strings"
	"sync"
	"time"
)

// Eine Nacharbeit (kann ffmpeg, ffprobe, thumbnails, rename, etc. enthalten)
type PostWorkTask struct {
	Key   string // z.B. Dateiname oder Job-ID, zum Deduplizieren
	Run   func(ctx context.Context) error
	Added time.Time
}

type PostWorkQueue struct {
	q         chan PostWorkTask
	ffmpegSem chan struct{} // "heavy" gate: maxParallelFFmpeg gleichzeitig

	mu       sync.Mutex
	inflight map[string]struct{} // dedupe: queued ODER running

	queued int // Anzahl inflight (queued + running)

	// ✅ für UI: Warteschlange + Running-Keys tracken
	waitingKeys []string            // FIFO der Keys, die noch NICHT gestartet sind
	runningKeys map[string]struct{} // Keys, die gerade wirklich laufen (Semaphor gehalten)
}

func NewPostWorkQueue(queueSize int, maxParallelFFmpeg int) *PostWorkQueue {
	if queueSize <= 0 {
		queueSize = 256
	}
	if maxParallelFFmpeg <= 0 {
		maxParallelFFmpeg = 1 // Default: "nacheinander"
	}

	return &PostWorkQueue{
		q:         make(chan PostWorkTask, queueSize),
		ffmpegSem: make(chan struct{}, maxParallelFFmpeg),

		inflight: make(map[string]struct{}),

		waitingKeys: make([]string, 0, queueSize),
		runningKeys: make(map[string]struct{}),
	}
}

// Enqueue dedupliziert nach Key (damit du nicht durch Events doppelt queue-st)
func (pq *PostWorkQueue) Enqueue(task PostWorkTask) bool {
	if task.Key == "" || task.Run == nil {
		return false
	}

	pq.mu.Lock()
	if _, ok := pq.inflight[task.Key]; ok {
		pq.mu.Unlock()
		return false // schon queued oder läuft
	}
	pq.inflight[task.Key] = struct{}{}
	pq.waitingKeys = append(pq.waitingKeys, task.Key) // ✅ queued für UI
	pq.queued++
	pq.mu.Unlock()

	select {
	case pq.q <- task:
		return true
	default:
		// Queue voll -> inflight zurückrollen
		pq.mu.Lock()
		delete(pq.inflight, task.Key)
		if pq.queued > 0 {
			pq.queued--
		}
		pq.removeWaitingKeyLocked(task.Key)
		pq.mu.Unlock()
		return false
	}
}

func (pq *PostWorkQueue) removeWaitingKeyLocked(key string) {
	for i, k := range pq.waitingKeys {
		if k == key {
			pq.waitingKeys = append(pq.waitingKeys[:i], pq.waitingKeys[i+1:]...)
			return
		}
	}
}

func (pq *PostWorkQueue) RemoveQueued(key string) bool {
	if strings.TrimSpace(key) == "" {
		return false
	}

	pq.mu.Lock()
	defer pq.mu.Unlock()

	// running darf hier NICHT entfernt werden
	if _, running := pq.runningKeys[key]; running {
		return false
	}

	found := false
	for i, k := range pq.waitingKeys {
		if k == key {
			pq.waitingKeys = append(pq.waitingKeys[:i], pq.waitingKeys[i+1:]...)
			found = true
			break
		}
	}
	if !found {
		return false
	}

	delete(pq.inflight, key)
	if pq.queued > 0 {
		pq.queued--
	}

	// Das Task-Element bleibt evtl. noch im Channel liegen.
	// Beim Worker-Start muss es dann erkannt und übersprungen werden.
	return true
}

func (pq *PostWorkQueue) workerLoop(id int) {
	for task := range pq.q {
		pq.mu.Lock()
		_, stillInflight := pq.inflight[task.Key]
		_, alreadyRunning := pq.runningKeys[task.Key]

		waitingFound := false
		for _, k := range pq.waitingKeys {
			if k == task.Key {
				waitingFound = true
				break
			}
		}
		pq.mu.Unlock()

		// queued Job wurde zwischenzeitlich entfernt -> Task aus dem Channel verwerfen
		if !stillInflight || (!waitingFound && !alreadyRunning) {
			continue
		}

		// Task startet jetzt wirklich → waiting -> running
		pq.mu.Lock()
		pq.removeWaitingKeyLocked(task.Key)
		pq.runningKeys[task.Key] = struct{}{}
		pq.mu.Unlock()

		func() {
			defer func() {
				// Panic-Schutz: Worker darf nicht sterben
				if r := recover(); r != nil {
					// optional: hier loggen
					_ = r
				}

				// States immer konsistent aufräumen (auch wenn er nie sauber run() beendet)
				pq.mu.Lock()
				pq.removeWaitingKeyLocked(task.Key) // falls er noch als waiting drin hing
				delete(pq.runningKeys, task.Key)
				delete(pq.inflight, task.Key)
				if pq.queued > 0 {
					pq.queued--
				}
				pq.mu.Unlock()
			}()

			// 3) Optional: Task timeout (gegen hängende ffmpeg)
			ctx, cancel := context.WithTimeout(context.Background(), 60*time.Minute)
			defer cancel()

			// 4) Run
			if task.Run != nil {
				_ = task.Run(ctx) // optional: loggen
			}
		}()
	}
}

func (pq *PostWorkQueue) StartWorkers(n int) {
	if n <= 0 {
		n = 1
	}
	for i := 0; i < n; i++ {
		go pq.workerLoop(i + 1)
	}
}

// Stats bleibt kompatibel zu deinem bisherigen Code
func (pq *PostWorkQueue) Stats() (queued int, inflight int, maxParallel int) {
	pq.mu.Lock()
	defer pq.mu.Unlock()
	return pq.queued, len(pq.inflight), cap(pq.ffmpegSem)
}

// Optional für UI/Debug (praktisch für "Warte… Position X/Y")
type PostWorkKeyStatus struct {
	State       string `json:"state"`       // "queued" | "running" | "missing"
	Position    int    `json:"position"`    // 1..n (nur queued), 0 sonst
	Waiting     int    `json:"waiting"`     // Anzahl wartend
	Running     int    `json:"running"`     // Anzahl running
	MaxParallel int    `json:"maxParallel"` // cap(ffmpegSem)
}

func (pq *PostWorkQueue) StatusForKey(key string) PostWorkKeyStatus {
	pq.mu.Lock()
	defer pq.mu.Unlock()

	waiting := len(pq.waitingKeys)
	running := len(pq.runningKeys)
	maxPar := cap(pq.ffmpegSem)

	if _, ok := pq.runningKeys[key]; ok {
		return PostWorkKeyStatus{
			State:       "running",
			Position:    0,
			Waiting:     waiting,
			Running:     running,
			MaxParallel: maxPar,
		}
	}

	for i, k := range pq.waitingKeys {
		if k == key {
			return PostWorkKeyStatus{
				State:       "queued",
				Position:    i + 1, // 1-basiert
				Waiting:     waiting,
				Running:     running,
				MaxParallel: maxPar,
			}
		}
	}

	// Key ist weder queued noch running (wahrscheinlich schon fertig oder nie queued)
	return PostWorkKeyStatus{
		State:       "missing",
		Position:    0,
		Waiting:     waiting,
		Running:     running,
		MaxParallel: maxPar,
	}
}

// global (oder in deinem app struct halten)
var postWorkQ = NewPostWorkQueue(512, 6) // maxParallelFFmpeg = 6

// --- Status Refresher (ehemals postwork_refresh.go) ---

func startPostWorkStatusRefresher() {
	t := time.NewTicker(1 * time.Second)
	go func() {
		defer t.Stop()

		for range t.C {
			changedJobs := make([]*RecordJob, 0, 16)

			jobsMu.Lock()
			for _, job := range jobs {
				key := strings.TrimSpace(job.PostWorkKey)
				if key == "" {
					continue
				}

				st := postWorkQ.StatusForKey(key)

				changed := false

				// PostWork-Daten aktualisieren
				if job.PostWork == nil ||
					job.PostWork.State != st.State ||
					job.PostWork.Position != st.Position ||
					job.PostWork.Waiting != st.Waiting ||
					job.PostWork.Running != st.Running ||
					job.PostWork.MaxParallel != st.MaxParallel {
					tmp := st
					job.PostWork = &tmp
					changed = true
				}

				// Status / Phase für UI vereinheitlichen
				switch st.State {
				case "queued":
					if job.Status != JobPostwork {
						job.Status = JobPostwork
						changed = true
					}

					phaseLower := strings.TrimSpace(strings.ToLower(job.Phase))
					if phaseLower == "" || phaseLower == "recording" {
						job.Phase = "postwork"
						changed = true
					}

					if job.Progress < 0 || job.Progress > 100 {
						job.Progress = 0
						changed = true
					}

				case "running":
					if job.Status != JobPostwork {
						job.Status = JobPostwork
						changed = true
					}

					phaseLower := strings.TrimSpace(strings.ToLower(job.Phase))

					// Konkrete Unterphasen NICHT überschreiben
					switch phaseLower {
					case "probe", "remuxing", "moving", "assets":
						// ok, so lassen
					default:
						if phaseLower == "" || phaseLower == "recording" || phaseLower == "postwork" {
							if phaseLower != "postwork" {
								job.Phase = "postwork"
								changed = true
							}
						}
					}
				}
				if changed {
					changedJobs = append(changedJobs, job)
				}
			}
			jobsMu.Unlock()

			for _, job := range changedJobs {
				publishJobUpsert(job)
			}
		}
	}()
}