package video_server

import (
	"fmt"
	"io"
	"os"
	"os/exec"
	"path/filepath"
	"sort"
	"strconv"
	"strings"
	"time"

	"FireLeave_tool/logger"
)

// MergeVideo 合并视频文件 - 完全适配 mp4_merge --out 模式
func MergeVideo(deviceUUID string, alarmTime int64) (string, error) {
	videoDir := fmt.Sprintf("/usr/data/camera/%s", deviceUUID)
	if _, err := os.Stat(videoDir); os.IsNotExist(err) {
		return "", fmt.Errorf("video directory not exist: %s", videoDir)
	}

	// === 1. 时间对齐到 10 秒 ===
	alarmTimeAligned := alignTo10Seconds(alarmTime)
	alarmTimeStr := time.Unix(alarmTimeAligned, 0).Format("20060102150405")

	beforeTime := alarmTimeAligned - 10
	afterTime := alarmTimeAligned + 10

	beforeStr := time.Unix(beforeTime, 0).Format("20060102150405")
	afterStr := time.Unix(afterTime, 0).Format("20060102150405")

	paths := map[string]string{
		beforeStr:    filepath.Join(videoDir, beforeStr+".mp4"),
		alarmTimeStr: filepath.Join(videoDir, alarmTimeStr+".mp4"),
		afterStr:     filepath.Join(videoDir, afterStr+".mp4"),
	}

	videoFiles := []string{}
	for name, path := range paths {
		if _, err := os.Stat(path); err == nil {
			videoFiles = append(videoFiles, path)
			logger.Logger.Printf("Found video: %s", name+".mp4")
		} else {
			logger.Logger.Printf("Missing video: %s", name+".mp4")
		}
	}

	// === 2. 补充替代文件 ===
	if len(videoFiles) < 3 {
		allFiles, _ := os.ReadDir(videoDir)
		var candidates []struct {
			path string
			ts   int64
		}
		for _, f := range allFiles {
			if !f.IsDir() && strings.HasSuffix(f.Name(), ".mp4") && !strings.Contains(f.Name(), "_joined") {
				if ts, err := parseSimpleTimestamp(f.Name()); err == nil {
					candidates = append(candidates, struct {
						path string
						ts   int64
					}{filepath.Join(videoDir, f.Name()), ts})
				}
			}
		}
		targets := []int64{beforeTime, alarmTimeAligned, afterTime}
		for _, target := range targets {
			if containsTimestamp(videoFiles, target) {
				continue
			}
			closest := findClosest(candidates, target)
			if closest != "" && !contains(videoFiles, closest) {
				videoFiles = append(videoFiles, closest)
				logger.Logger.Printf("Using fallback: %s", filepath.Base(closest))
			}
		}
	}

	if len(videoFiles) < 2 {
		return "", fmt.Errorf("insufficient video files: %d", len(videoFiles))
	}

	// === 3. 排序 ===
	sort.Slice(videoFiles, func(i, j int) bool {
		return getTimestampFromPath(videoFiles[i]) < getTimestampFromPath(videoFiles[j])
	})

	logger.Logger.Printf("Merging %d videos:", len(videoFiles))
	for i, f := range videoFiles {
		logger.Logger.Printf("  [%d] %s", i, filepath.Base(f))
	}

	// === 4. 显式指定输出文件（100% 可控）===
	outputFile := fmt.Sprintf("%s.mp4_joined.mp4", alarmTimeStr)
	joinedPath := filepath.Join(videoDir, outputFile)

	// 清理旧文件（防止冲突）
	if err := os.Remove(joinedPath); err != nil && !os.IsNotExist(err) {
		logger.Logger.Printf("Failed to remove old output file %s: %v", joinedPath, err)
	}

	// === 5. 调用 mp4_merge，显式 --out ===
	args := append(videoFiles, "--out", joinedPath)
	cmd := exec.Command("mp4_merge", args...)
	cmd.Stdout = logger.Logger.Writer()
	cmd.Stderr = logger.Logger.Writer()

	if err := cmd.Run(); err != nil {
		return "", fmt.Errorf("mp4_merge failed: %v", err)
	}

	// === 6. 验证输出文件存在 ===
	if _, err := os.Stat(joinedPath); err != nil {
		return "", fmt.Errorf("output file not created: %s, error: %v", joinedPath, err)
	}

	info, err := os.Stat(joinedPath)
	if err != nil {
		return "", fmt.Errorf("stat output file failed: %v", err)
	}
	logger.Logger.Printf("Merged file created: %s (size: %d bytes)", outputFile, info.Size())

	// === 7. 移动到 /data/upload/ ===
	t := time.Unix(alarmTimeAligned, 0)
	year, month, day := t.Date()
	timestampPart := fmt.Sprintf("%d-%d-%d-%d", year, int(month), day, alarmTimeAligned)
	finalName := fmt.Sprintf("%s-%s.MP4", deviceUUID, timestampPart)
	finalPath := filepath.Join("/data/upload", finalName)

	if err := os.MkdirAll("/data/upload", 0755); err != nil {
		return "", fmt.Errorf("create /data/upload failed: %v", err)
	}

	// 跨分区复制 + 删除
	if err := copyFile(joinedPath, finalPath); err != nil {
		return "", fmt.Errorf("copy failed: %v", err)
	}
	if err := os.Remove(joinedPath); err != nil {
		logger.Logger.Printf("Failed to delete temp file %s: %v", joinedPath, err)
	}

	logger.Logger.Printf("Video merged and moved successfully: %s", finalPath)
	return finalPath, nil
}

// containsTimestamp 检查是否已有该时间戳
func containsTimestamp(files []string, ts int64) bool {
	for _, f := range files {
		if getTimestampFromPath(f) == ts {
			return true
		}
	}
	return false
}

// findClosest 查找最接近的时间戳文件
func findClosest(candidates []struct {
	path string
	ts   int64
}, target int64) string {
	var best string
	var minDiff int64 = 1<<63 - 1
	for _, c := range candidates {
		diff := abs(c.ts - target)
		if diff < minDiff {
			minDiff = diff
			best = c.path
		}
	}
	if minDiff <= 30 {
		return best
	}
	return ""
}

func abs(x int64) int64 {
	if x < 0 {
		return -x
	}
	return x
}

// copyFile 支持跨分区复制
func copyFile(src, dst string) error {
	in, err := os.Open(src)
	if err != nil {
		return err
	}
	defer in.Close()

	out, err := os.Create(dst)
	if err != nil {
		return err
	}
	defer out.Close()

	if _, err = io.Copy(out, in); err != nil {
		return err
	}
	return out.Sync()
}

// alignTo10Seconds 将时间对齐到最近的10秒间隔
func alignTo10Seconds(timestamp int64) int64 {
	t := time.Unix(timestamp, 0)
	// 获取秒数并对齐到10秒
	seconds := t.Second()
	alignedSeconds := (seconds / 10) * 10
	// 创建新的时间
	alignedTime := time.Date(t.Year(), t.Month(), t.Day(), t.Hour(), t.Minute(), alignedSeconds, 0, t.Location())
	return alignedTime.Unix()
}

// parseSimpleTimestamp 解析简单的时间戳文件名 (如: 20251029181740.mp4)
func parseSimpleTimestamp(filename string) (int64, error) {
	// 移除文件扩展名
	nameWithoutExt := strings.TrimSuffix(filename, filepath.Ext(filename))

	// 文件名应该就是14位时间戳
	if len(nameWithoutExt) != 14 {
		//return 0, fmt.Errorf("无效的时间戳格式: %s (期望14位数字)", nameWithoutExt)
	}

	// 解析时间戳
	year, _ := strconv.Atoi(nameWithoutExt[0:4])
	month, _ := strconv.Atoi(nameWithoutExt[4:6])
	day, _ := strconv.Atoi(nameWithoutExt[6:8])
	hour, _ := strconv.Atoi(nameWithoutExt[8:10])
	minute, _ := strconv.Atoi(nameWithoutExt[10:12])
	second, _ := strconv.Atoi(nameWithoutExt[12:14])

	t := time.Date(year, time.Month(month), day, hour, minute, second, 0, time.Local)
	return t.Unix(), nil
}

// getTimestampFromPath 从文件路径中提取时间戳
func getTimestampFromPath(filePath string) int64 {
	filename := filepath.Base(filePath)
	timestamp, err := parseSimpleTimestamp(filename)
	if err != nil {
		return 0
	}
	return timestamp
}

// contains 检查切片是否包含某个元素
func contains(slice []string, item string) bool {
	for _, s := range slice {
		if s == item {
			return true
		}
	}
	return false
}

// CleanupOldVideos 清理旧的合并视频文件，保留最近的 10 个
func CleanupOldVideos(deviceUUID string) {
	const maxFiles = 10
	videoDir := "/data/upload"
	prefix := fmt.Sprintf("%s_", deviceUUID)

	files, err := os.ReadDir(videoDir)
	if err != nil {
		logger.Logger.Printf("read the signals %s Error: %v", videoDir, err)
		return
	}

	var videoFiles []os.DirEntry
	for _, file := range files {
		if strings.HasPrefix(file.Name(), prefix) && strings.HasSuffix(file.Name(), "_merged.mp4") {
			videoFiles = append(videoFiles, file)
		}
	}

	if len(videoFiles) <= maxFiles {
		return
	}

	sort.Slice(videoFiles, func(i, j int) bool {
		infoI, _ := videoFiles[i].Info()
		infoJ, _ := videoFiles[j].Info()
		return infoI.ModTime().Before(infoJ.ModTime())
	})

	for i := 0; i < len(videoFiles)-maxFiles; i++ {
		filePath := filepath.Join(videoDir, videoFiles[i].Name())
		if err := os.Remove(filePath); err != nil {
			logger.Logger.Printf("Clean up old videos %s Error: %v", filePath, err)
		} else {
			logger.Logger.Printf("Clean up old videos: %s", filePath)
		}
	}
}