package frp

import (
	"embed"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"sync"
)

//go:embed bin/*
var embeddedFrpc embed.FS

var (
	cachedFrpcPath string
	frpcPathMutex  sync.Mutex
)

// GetFrpcPath 获取 frpc 二进制路径
// 优先级: 本地缓存 > 内嵌二进制 > 系统 PATH
func GetFrpcPath() (string, error) {
	frpcPathMutex.Lock()
	defer frpcPathMutex.Unlock()

	if cachedFrpcPath != "" {
		if _, err := os.Stat(cachedFrpcPath); err == nil {
			return cachedFrpcPath, nil
		}
		cachedFrpcPath = ""
	}

	var fileName string
	switch {
	case runtime.GOOS == "windows" && runtime.GOARCH == "amd64":
		fileName = "frpc_windows_amd64.exe"
	case runtime.GOOS == "linux" && runtime.GOARCH == "amd64":
		fileName = "frpc_linux_amd64"
	case runtime.GOOS == "linux" && runtime.GOARCH == "arm64":
		fileName = "frpc_linux_arm64"
	case runtime.GOOS == "linux" && runtime.GOARCH == "arm":
		fileName = "frpc_linux_arm_hf"
	default:
		path, err := exec.LookPath("frpc")
		if err == nil {
			cachedFrpcPath = path
			return path, nil
		}
		return "", fmt.Errorf("不支持的平台: %s/%s", runtime.GOOS, runtime.GOARCH)
	}

	// 尝试从本地 bin 目录加载
	localPath := filepath.Join(".", "bin", fileName)
	if _, err := os.Stat(localPath); err == nil {
		cachedFrpcPath = localPath
		return localPath, nil
	}

	// 从 embed 提取到 data 目录（Windows 和 Linux 统一）
	dataDir := "./data"
	if err := os.MkdirAll(dataDir, 0755); err != nil {
		return "", fmt.Errorf("创建 data 目录失败: %w", err)
	}

	tmpPath := filepath.Join(dataDir, "frpc")
	if runtime.GOOS == "windows" {
		tmpPath += ".exe"
	}

	data, err := embeddedFrpc.ReadFile("bin/" + fileName)
	if err == nil {
		if err := os.WriteFile(tmpPath, data, 0755); err == nil {
			cachedFrpcPath = tmpPath
			return tmpPath, nil
		}
		// 如果写入失败，检查文件是否已存在
		if _, statErr := os.Stat(tmpPath); statErr == nil {
			cachedFrpcPath = tmpPath
			return tmpPath, nil
		}
	}

	// 最后尝试从系统 PATH 查找
	path, err := exec.LookPath("frpc")
	if err == nil {
		cachedFrpcPath = path
		return path, nil
	}

	return "", fmt.Errorf("未找到 frpc 文件")
}