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 > 程序同目录 > 当前工作目录 > embed 提取到当前目录 > 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)
	}

	// 方法1: 尝试从程序同目录加载
	execPath, err := os.Executable()
	if err == nil {
		execDir := filepath.Dir(execPath)
		localPath := filepath.Join(execDir, "frpc")
		if runtime.GOOS == "windows" {
			localPath += ".exe"
		}
		if _, err := os.Stat(localPath); err == nil {
			cachedFrpcPath = localPath
			return localPath, nil
		}
	}

	// 方法2: 尝试从当前工作目录加载
	cwdPath := "./frpc"
	if runtime.GOOS == "windows" {
		cwdPath += ".exe"
	}
	if _, err := os.Stat(cwdPath); err == nil {
		cachedFrpcPath = cwdPath
		return cwdPath, nil
	}

	// 方法3: 从 embed 提取到当前工作目录
	data, err := embeddedFrpc.ReadFile("bin/" + fileName)
	if err == nil {
		extractPath := "./frpc"
		if runtime.GOOS == "windows" {
			extractPath += ".exe"
		}
		if err := os.WriteFile(extractPath, data, 0755); err == nil {
			cachedFrpcPath = extractPath
			return extractPath, nil
		}
	}

	// 方法4: 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")
}