package video

import (
	"context"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"time"

	dto "media/model/dto/video"

	"github.com/gogf/gf/v2/frame/g"
)

type transcodeService struct{}

var Transcode = new(transcodeService)

// TranscodeToMP4 将视频转码为 H.264 + AAC + MP4 + faststart
// inputPath: 输入文件路径
// outputDir: 输出目录（可选），为空则使用 resource/temp
// 返回输出文件完整路径、文件信息
func (s *transcodeService) TranscodeToMP4(ctx context.Context, inputPath string, outputDir string) (*dto.TranscodeRes, error) {
	ffmpegPath, err := lookupFFmpegPath()
	if err != nil {
		return nil, fmt.Errorf("ffmpeg 未找到: %v", err)
	}

	// 输出目录
	if outputDir == "" {
		outputDir = g.Cfg().MustGet(ctx, "ffmpeg.temp_dir", "resource/temp").String()
		if outputDir == "" {
			outputDir = "resource/temp"
		}
		if !filepath.IsAbs(outputDir) {
			absDir, _ := filepath.Abs(outputDir)
			outputDir = absDir
		}
	}
	os.MkdirAll(outputDir, 0755)

	// 输出文件名：原文件名_转码_时间戳.mp4
	base := filepath.Base(inputPath)
	ext := filepath.Ext(base)
	name := base[:len(base)-len(ext)]
	outputName := fmt.Sprintf("%s_transcoded_%d.mp4", name, time.Now().UnixMilli())
	outputPath := filepath.Join(outputDir, outputName)

	g.Log().Infof(ctx, "[转码] 开始: %s → %s", inputPath, outputPath)

	// FFmpeg 转码命令
	// -c:v libx264    H.264 视频编码
	// -preset fast    编码速度/质量平衡
	// -crf 22         画质(0-51,越小越好,18-28常用)
	// -c:a aac        AAC 音频编码
	// -b:a 128k       音频码率 128k
	// -movflags +faststart  MOOV 前置（关键！seed-lite 必需）
	args := []string{
		"-i", inputPath,
		"-c:v", "libx264",
		"-preset", "fast",
		"-crf", "22",
		"-c:a", "aac",
		"-b:a", "128k",
		"-movflags", "+faststart",
		"-y", outputPath,
	}

	cmd := exec.CommandContext(ctx, ffmpegPath, args...)
	output, err := cmd.CombinedOutput()
	if err != nil {
		return nil, fmt.Errorf("FFmpeg 转码失败: %v\n%s", err, string(output))
	}

	// 检查输出文件
	stat, statErr := os.Stat(outputPath)
	if statErr != nil {
		return nil, fmt.Errorf("转码输出文件不存在: %v", statErr)
	}

	// 获取时长
	durationStr := getVideoDurationStr(ctx, outputPath)

	g.Log().Infof(ctx, "[转码] 完成: %s, 大小=%d, 时长=%s", outputPath, stat.Size(), durationStr)

	return &dto.TranscodeRes{
		OutputPath:  outputPath,
		FileSize:    stat.Size(),
		FileName:    outputName,
		DurationStr: durationStr,
	}, nil
}