package vision

import (
	"fmt"
	"os"
	"os/exec"
	"runtime"
)

// HEICConverter 定义了处理 HEIC/HEIF 转换的工具路径
var heicConverter string

// DetectHEICConverter 探测系统中可用的 HEIC 转换工具。
// 优先级: sips (macOS) > heif-convert (libheif) > magick (ImageMagick)
func DetectHEICConverter() string {
	if heicConverter != "" {
		return heicConverter
	}

	// 1. macOS 专属原生工具
	if runtime.GOOS == "darwin" {
		if p, err := exec.LookPath("sips"); err == nil {
			heicConverter = p
			return p
		}
	}

	// 2. 跨平台开源工具 heif-convert (libheif)
	if p, err := exec.LookPath("heif-convert"); err == nil {
		heicConverter = p
		return p
	}

	// 3. 跨平台全能工具 ImageMagick
	if p, err := exec.LookPath("magick"); err == nil {
		heicConverter = p
		return p
	}

	// 记录警告信息，指导用户安装
	printHEICWarning()
	return ""
}

func printHEICWarning() {
	fmt.Fprintln(os.Stderr, "⚠️  Warning: No HEIC converter found in PATH.")
	switch runtime.GOOS {
	case "darwin":
		fmt.Fprintln(os.Stderr, "   Hint: macOS should have 'sips' pre-installed.")
	case "linux":
		fmt.Fprintln(os.Stderr, "   Hint: Install libheif: 'sudo apt install libheif-examples'")
	case "windows":
		fmt.Fprintln(os.Stderr, "   Hint: Install ImageMagick or libheif for Windows.")
	}
}

// ConvertHEIC 使用探测到的工具将 HEIC 转换为 PNG 临时文件
func ConvertHEIC(src, dst string) error {
	cmdPath := DetectHEICConverter()
	if cmdPath == "" {
		return fmt.Errorf("no HEIC converter available")
	}

	var cmd *exec.Cmd
	base := ""
	if runtime.GOOS == "windows" {
		// 简单处理 Windows 下的路径
		base = cmdPath
	} else {
		// 仅获取文件名判断类型
		// 这里简单处理，直接用 DetectHEICConverter 返回的路径
		base = cmdPath
	}

	// 根据不同工具构造命令
	if contains(base, "sips") {
		// sips -s format png input --out output
		cmd = exec.Command(cmdPath, "-s", "format", "png", src, "--out", dst)
	} else if contains(base, "heif-convert") {
		// heif-convert input output
		cmd = exec.Command(cmdPath, src, dst)
	} else if contains(base, "magick") {
		// magick input output.png
		cmd = exec.Command(cmdPath, src, dst)
	} else {
		return fmt.Errorf("unsupported converter: %s", cmdPath)
	}

	return cmd.Run()
}

func contains(s, substr string) bool {
	// 简单的字符串包含判断
	for i := 0; i <= len(s)-len(substr); i++ {
		if s[i:i+len(substr)] == substr {
			return true
		}
	}
	return false
}