package main

import (
	"bytes"
	"fmt"
	"io/fs"
	"log"
	"os/exec"
	"path/filepath"
	"regexp"
	"sort"
	"strconv"
	"strings"
)

// Movie 电影结构
type Movie struct {
	Name         string `json:"filename"`      // Original filename of the movie, e.g., "video1.mp4"
	Image        string `json:"image"`         // Corresponding image filename, e.g., "video1.png"
	Duration     int    `json:"duration"`      // Duration in minutes
	TimeCategory string `json:"time_category"` // 分类名称, e.g., "15min", "30min"
	VideoPath    string `json:"-"`             // Full path to the video file, used for ffmpeg
}

var movies []Movie // This will store all movies

var IsRemakePNG = false // Set to true to regenerate all PNGs

func getVideoDuration(videoPath string) (float64, error) {
	// 使用ffmpeg获取视频信息
	cmd := exec.Command("ffmpeg", "-i", videoPath)
	var stderr bytes.Buffer
	cmd.Stderr = &stderr
	_ = cmd.Run() // 忽略错误，因为ffmpeg在没有输出文件时会返回错误

	// 解析ffmpeg输出的时长信息
	output := stderr.String()
	re := regexp.MustCompile(`Duration: (\d{2}):(\d{2}):(\d{2}\.\d{2})`)
	matches := re.FindStringSubmatch(output)
	if len(matches) < 4 {
		// Try to find duration even if format is slightly different (e.g. no milliseconds)
		reAlt := regexp.MustCompile(`Duration: (\d{2}):(\d{2}):(\d{2})`)
		matches = reAlt.FindStringSubmatch(output)
		if len(matches) < 4 {
			return 0, fmt.Errorf("duration not found in ffmpeg output for %s. Output: %s", filepath.Base(videoPath), output)
		}
		// Add .00 for consistency if seconds has no decimal part
		matches[3] += ".00"
	}

	// 将时间转换为秒
	hours, errH := strconv.ParseFloat(matches[1], 64)
	minutes, errM := strconv.ParseFloat(matches[2], 64)
	seconds, errS := strconv.ParseFloat(matches[3], 64)

	if errH != nil || errM != nil || errS != nil {
		return 0, fmt.Errorf("error parsing time components from ffmpeg output: %v, %v, %v", errH, errM, errS)
	}

	duration := hours*3600 + minutes*60 + seconds
	return duration, nil
}

func initMovie() {
	// movieDict stores movies for which thumbnails might need to be generated.
	// Key: base filename without extension (e.g., "video1")
	// Value: *Movie object (initially with Name as full path to video, Duration updated later)
	var movieDict map[string]*Movie = make(map[string]*Movie)

	// Glob for all files in "movie/" directory to check for existing PNGs
	allFiles, err := filepath.Glob("movie/*")
	if err != nil {
		log.Printf("Error globbing movie directory: %v", err)
		// Decide if you want to return or continue with an empty list
	}

	// This loop is to determine which videos need thumbnails.
	// If a video `video.mp4` exists but `video.png` also exists,
	// `video.mp4` is removed from `movieDict` unless `IsRemakePNG` is true.
	for _, fullPath := range allFiles {
		baseWithExt := filepath.Base(fullPath)
		ext := filepath.Ext(baseWithExt)
		baseName := strings.TrimSuffix(baseWithExt, ext) // Filename without extension

		if ext == ".png" {
			// If it's a PNG, check if its corresponding video is in the dict
			if movieEntry, ok := movieDict[baseName]; ok {
				if !IsRemakePNG {
					// PNG exists and we are not remaking, so remove video from thumbnail generation list
					log.Printf("Thumbnail %s already exists. Skipping generation for %s.", baseWithExt, movieEntry.VideoPath)
					delete(movieDict, baseName)
				}
			}
		} else if ext != "" && ext != ".db" { // Assume other non-empty extensions are videos
			// If it's a video file (or any non-PNG, non-empty extension file)
			if _, ok := movieDict[baseName]; !ok {
				// If not already processed (e.g. by a .png file check) and not forced remake
				movieDict[baseName] = &Movie{VideoPath: fullPath} // Store full path for ffmpeg
			} else if IsRemakePNG {
				// If it was already there (e.g. from a PNG that we decided to remake), ensure VideoPath is set
				movieDict[baseName].VideoPath = fullPath
			}
		}
	}

	// Reset the global movies slice
	movies = []Movie{}

	// Walk through the movie directory to process video files
	err = filepath.WalkDir("./movie", func(path string, d fs.DirEntry, err error) error {
		if err != nil {
			log.Printf("Error accessing path %q: %v\n", path, err)
			return err
		}
		if d.IsDir() || filepath.Ext(d.Name()) == ".png" || filepath.Ext(d.Name()) == ".db" { // Skip directories, PNGs, and DB files
			return nil
		}

		videoFileName := d.Name() // e.g., "video1.mp4"
		baseNameWithoutExt := strings.TrimSuffix(videoFileName, filepath.Ext(videoFileName))

		durationSec, err := getVideoDuration(path)
		if err != nil {
			// log.Printf("Error getting duration for %s: %v. Skipping this file.", videoFileName, err)
			// Remove from movieDict if it was there, as we can't process it
			delete(movieDict, baseNameWithoutExt)
			return nil // Continue with next file
		}

		durationMin := int(durationSec / 60.0)

		var timeCat string
		if durationMin <= 15 {
			timeCat = "15min"
		} else if durationMin <= 30 {
			timeCat = "30min"
		} else if durationMin <= 60 {
			timeCat = "60min"
		} else {
			timeCat = "大于60min"
		}

		movie := Movie{
			Name:         videoFileName,
			Image:        baseNameWithoutExt + ".png",
			Duration:     durationMin,
			TimeCategory: timeCat,
			VideoPath:    path, // Store full path
		}
		movies = append(movies, movie)

		// If this movie base name is in movieDict (meaning it needs/might need a thumbnail),
		// update its duration.
		if mEntry, ok := movieDict[baseNameWithoutExt]; ok {
			mEntry.Duration = movie.Duration // Update duration for thumbnail filter logic
			// Ensure VideoPath in movieDict is the one we just processed (it should be)
			mEntry.VideoPath = path
			mEntry.Name = movie.Name // Also update Name for logging in thumbnail part
		}
		return nil
	})

	if err != nil {
		log.Printf("Error walking the path ./movie: %v\n", err)
	}

	// Sort the global movies list.
	// First by custom time category order, then by duration within that category.
	categoryOrderMap := map[string]int{
		"15min":   0,
		"30min":   1,
		"60min":   2,
		"大于60min": 3,
	}

	sort.Slice(movies, func(i, j int) bool {
		catOrderI := categoryOrderMap[movies[i].TimeCategory]
		catOrderJ := categoryOrderMap[movies[j].TimeCategory]

		if catOrderI != catOrderJ {
			return catOrderI < catOrderJ
		}
		return movies[i].Duration < movies[j].Duration
	})

	// Generate thumbnails for movies in movieDict
	// These are the movies for which PNGs didn't exist or IsRemakePNG is true
	for key, movieToProcess := range movieDict {
		if movieToProcess.VideoPath == "" {
			// log.Printf("Skipping thumbnail for %s, VideoPath is empty (likely only PNG found and no corresponding video processed).", key)
			continue
		}
		// movieToProcess.Duration should have been updated by the WalkDir logic.
		// If a video was in movieDict but not found/processed by WalkDir, its Duration might be 0.
		if movieToProcess.Duration == 0 && movieToProcess.Name != "" { // Name check to avoid new entries
			// Try to get duration again if it's missing, might happen if it was added to dict but WalkDir failed for it
			// Or if the logic for updating movieDict was missed for some edge case.
			// For simplicity, we assume duration is now correctly populated from WalkDir pass.
			log.Printf("Warning: Duration for %s (path: %s) is 0, thumbnail filter might be suboptimal.", movieToProcess.Name, movieToProcess.VideoPath)
		}

		log.Printf("Generating thumbnail for: %s (Duration: %d min, Path: %s)", movieToProcess.Name, movieToProcess.Duration, movieToProcess.VideoPath)

		var filter string
		// Use movieToProcess.Duration for filter logic
		if movieToProcess.Duration <= 2 {
			filter = "select='isnan(prev_selected_t)+gte(t-prev_selected_t\\,5)',scale=320:180,tile=3x3"
		} else if movieToProcess.Duration <= 5 {
			filter = "select='isnan(prev_selected_t)+gte(t-prev_selected_t\\,10)',scale=320:180,tile=3x3"
		} else if movieToProcess.Duration <= 30 {
			filter = "select='isnan(prev_selected_t)+gte(t-prev_selected_t\\,20)',scale=320:180,tile=3x3"
		} else if movieToProcess.Duration <= 60 {
			filter = "select='isnan(prev_selected_t)+gte(t-prev_selected_t\\,35)',scale=320:180,tile=3x3"
		} else { // duration > 60
			filter = "select='isnan(prev_selected_t)+gte(t-prev_selected_t\\,60)',scale=320:180,tile=3x3"
		}

		outputImagePath := filepath.Join("movie", key+".png")

		cmd := exec.Command("ffmpeg",
			"-i", movieToProcess.VideoPath, // Use full path to video
			"-vf", filter,
			"-frames:v", "1",
			"-q:v", "3", // Quality for JPEG/PNG, usually 2-5 is good for -qscale:v
			"-y", // Overwrite output files without asking
			outputImagePath,
		)

		var stderr bytes.Buffer
		cmd.Stderr = &stderr
		if err := cmd.Run(); err != nil {
			log.Printf("Error generating thumbnail for %s (Duration: %d min): %v\nStderr: %s",
				movieToProcess.VideoPath, movieToProcess.Duration, err, stderr.String())
			// Consider whether to panic or just log
			// panic(fmt.Errorf("could not generate frame %s %d. Error: %v. Stderr: %s", movieToProcess.VideoPath, movieToProcess.Duration, err, stderr.String()))
		} else {
			log.Printf("Successfully generated thumbnail: %s", outputImagePath)
		}
	}
}