// NextNVR v0.2.0 — FFmpeg stream recorder
// Launches per-camera FFmpeg processes with stream-copy mode and auto-reconnect.
package main

import (
	"fmt"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"sync"
	"time"
)

// RecorderManager manages FFmpeg recording processes for all cameras.
type RecorderManager struct {
	mu        sync.Mutex
	processes map[string]*recorderProcess
	config    StorageConfig
}

type recorderProcess struct {
	camera CameraConfig
	cmd    *exec.Cmd
	done   chan struct{}
}

// NewRecorderManager creates a new recorder manager.
func NewRecorderManager(cfg StorageConfig) *RecorderManager {
	return &RecorderManager{
		processes: make(map[string]*recorderProcess),
		config:    cfg,
	}
}

// StartAll launches recording goroutines for all enabled cameras.
// Cameras are started with a 500ms stagger to avoid I/O and CPU spikes.
func (rm *RecorderManager) StartAll(cameras []CameraConfig) {
	for _, cam := range cameras {
		if !cam.Enabled || !cam.Record {
			log.Printf("recorder: skipping camera %s (enabled=%v, record=%v)", cam.ID, cam.Enabled, cam.Record)
			continue
		}
		go rm.startRecorder(cam)
		time.Sleep(500 * time.Millisecond) // staggered startup
	}
	log.Printf("recorder: all cameras launched")
}

// StopAll terminates all recording processes.
func (rm *RecorderManager) StopAll() {
	rm.mu.Lock()
	defer rm.mu.Unlock()

	for id, proc := range rm.processes {
		log.Printf("recorder: stopping camera %s", id)
		close(proc.done)
		if proc.cmd != nil && proc.cmd.Process != nil {
			proc.cmd.Process.Signal(os.Interrupt)
		}
	}
	log.Println("recorder: all processes stopped")
}

// startRecorder launches an FFmpeg process for a single camera.
// Uses stream-copy mode (-c copy) for zero transcoding overhead.
// Segments output into 5-minute MP4 files.
// Auto-reconnects on stream failure with a 5-second delay.
func (rm *RecorderManager) startRecorder(cam CameraConfig) {
	rtspURL := cam.RTSPMain
	if rtspURL == "" {
		rtspURL = fmt.Sprintf("rtsp://%s:%s@%s:554/Streaming/Channels/101",
			cam.Username, cam.Password, cam.IP)
	}

	log.Printf("recorder: starting %s → %s", cam.ID, rtspURL)

	rm.mu.Lock()
	proc := &recorderProcess{
		camera: cam,
		done:   make(chan struct{}),
	}
	rm.processes[cam.ID] = proc
	rm.mu.Unlock()

	for {
		select {
		case <-proc.done:
			return
		default:
		}

		// Create output directory: /mnt/recordings/{cam_id}/{YYYY-MM-DD}/
		now := time.Now()
		outDir := filepath.Join(rm.config.RecordingsPath, cam.ID, now.Format("2006-01-02"))
		if err := os.MkdirAll(outDir, 0755); err != nil {
			log.Printf("recorder: %s — mkdir failed: %v", cam.ID, err)
			time.Sleep(5 * time.Second)
			continue
		}

		// Output filename: {HH-MM-SS}.mp4
		outFile := filepath.Join(outDir, now.Format("15-04-05")+".mp4")

		cmd := exec.Command("ffmpeg",
			"-hide_banner", "-loglevel", "error",
			"-rtsp_transport", "tcp", // TCP is more reliable than UDP for RTSP
			"-i", rtspURL,
			"-c", "copy", // stream-copy: zero transcoding
			"-f", "segment",
			"-segment_time", "300", // 5-minute segments
			"-segment_format", "mp4",
			"-reset_timestamps", "1",
			"-strftime", "1",
			outFile,
		)

		cmd.Stdout = os.Stdout
		cmd.Stderr = os.Stderr

		if err := cmd.Start(); err != nil {
			log.Printf("recorder: %s — FFmpeg start failed: %v", cam.ID, err)
			time.Sleep(5 * time.Second)
			continue
		}

		proc.cmd = cmd
		log.Printf("recorder: %s — FFmpeg running (PID %d)", cam.ID, cmd.Process.Pid)

		err := cmd.Wait()
		proc.cmd = nil

		if err != nil {
			log.Printf("recorder: %s — FFmpeg exited: %v — reconnecting in 5s", cam.ID, err)
		} else {
			log.Printf("recorder: %s — FFmpeg exited cleanly — reconnecting in 5s", cam.ID)
		}

		time.Sleep(5 * time.Second)
	}
}