package vision

import (
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"

	"apigo.cc/go/file"
)

// Video 代表一个视频操作封装
type Video struct {
	FFmpegPath string
}

// NewVideo 创建一个视频处理器，自动查找或下载 ffmpeg
func NewVideo() (*Video, error) {
	p, err := EnsureFFmpeg()
	if err != nil {
		return nil, err
	}
	return &Video{FFmpegPath: p}, nil
}

// ExtractFrame 从视频中提取指定时间的帧
func (v *Video) ExtractFrame(videoPath string, offsetSeconds float64) (*Canvas, error) {
	tmpFile := filepath.Join(os.TempDir(), fmt.Sprintf("frame_%d.png", os.Getpid()))
	defer os.Remove(tmpFile)

	cmd := exec.Command(v.FFmpegPath, "-ss", fmt.Sprintf("%f", offsetSeconds), "-i", videoPath, "-frames:v", "1", tmpFile)
	if err := cmd.Run(); err != nil {
		return nil, fmt.Errorf("ffmpeg extract failed: %w", err)
	}

	return Load(tmpFile)
}

// WatermarkVideo 给视频添加水印
// videoPath: 输入视频
// markPath: 水印图片路径
// outPath: 输出视频路径
// pos: 水印位置 (使用 FFmpeg 语法, 如 '10:10', 'main_w-overlay_w-10:10')
func (v *Video) WatermarkVideo(videoPath, markPath, outPath, pos string) error {
	if pos == "" {
		pos = "main_w-overlay_w-10:main_h-overlay_h-10" // 默认右下角
	}
	
	filter := fmt.Sprintf("overlay=%s", pos)
	cmd := exec.Command(v.FFmpegPath, "-i", videoPath, "-i", markPath, "-filter_complex", filter, "-codec:a", "copy", outPath)
	return cmd.Run()
}

// CreateVideoFromImages 从一系列图片创建视频
func (v *Video) CreateVideoFromImages(imagePattern string, frameRate int, outPath string) error {
	cmd := exec.Command(v.FFmpegPath, "-framerate", fmt.Sprintf("%d", frameRate), "-i", imagePattern, "-c:v", "libx264", "-pix_fmt", "yuv420p", outPath)
	return cmd.Run()
}

// EnsureFFmpeg 确保 ffmpeg 命令可用
func EnsureFFmpeg() (string, error) {
	// 1. 检查 PATH
	if p, err := exec.LookPath("ffmpeg"); err == nil {
		return p, nil
	}

	// 2. 检查本地目录
	localDir := filepath.Join(os.Getenv("HOME"), ".vision", "bin")
	localFF := filepath.Join(localDir, "ffmpeg")
	if runtime.GOOS == "windows" {
		localFF += ".exe"
	}

	if file.Exists(localFF) {
		return localFF, nil
	}

	// 3. 自动下载
	return DownloadFFmpeg(localDir)
}

// DownloadFFmpeg 下载对应系统的 FFmpeg 二进制文件
func DownloadFFmpeg(targetDir string) (string, error) {
	if err := os.MkdirAll(targetDir, 0755); err != nil {
		return "", err
	}

	var url string
	switch runtime.GOOS {
	case "darwin":
		// 使用针对 macOS 的精简版二进制 (示例 URL，实际应指向可靠镜像)
		url = "https://evermeet.cx/ffmpeg/get/zip" 
	case "linux":
		url = "https://johnvansickle.com/ffmpeg/releases/ffmpeg-release-amd64-static.tar.xz"
	case "windows":
		url = "https://www.gyan.dev/ffmpeg/builds/ffmpeg-release-essentials.zip"
	default:
		return "", fmt.Errorf("unsupported OS: %s", runtime.GOOS)
	}

	// 注意：实际下载逻辑需要处理解压、权限等。
	// 为了精简，这里我们只提供语义。在真实场景中可以使用 go/http 下载并解压。
	fmt.Printf("FFmpeg not found. Please install it or download from: %s\n", url)
	return "", fmt.Errorf("ffmpeg not found, please install manually or check %s", url)
}