package service

import (
	"archive/zip"
	"fmt"
	"io"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"time"
)

// InstallResult 安装结果
type InstallResult struct {
	Success bool   `json:"success"`
	Message string `json:"message"`
}

// InstallUpdate 安装更新包
func InstallUpdate(installerPath string, autoRestart bool) (*InstallResult, error) {
	return InstallUpdateWithHash(installerPath, autoRestart, "", "")
}

// InstallUpdateWithHash 安装更新包（带哈希验证）
func InstallUpdateWithHash(installerPath string, autoRestart bool, expectedHash string, hashType string) (*InstallResult, error) {
	if _, err := os.Stat(installerPath); os.IsNotExist(err) {
		return nil, fmt.Errorf("安装文件不存在: %s", installerPath)
	}

	// 哈希验证
	if expectedHash != "" && hashType != "" {
		valid, err := VerifyFileHash(installerPath, expectedHash, hashType)
		if err != nil {
			return &InstallResult{Success: false, Message: "文件验证失败: " + err.Error()}, nil
		}
		if !valid {
			return &InstallResult{Success: false, Message: "文件哈希值不匹配，文件可能已损坏或被篡改"}, nil
		}
	}

	// 备份
	backupPath, err := BackupApplication()
	if err != nil {
		return &InstallResult{Success: false, Message: fmt.Sprintf("备份失败: %v", err)}, nil
	}

	// 安装
	ext := filepath.Ext(installerPath)
	switch ext {
	case ".exe":
		if runtime.GOOS != "windows" {
			return &InstallResult{Success: false, Message: "当前系统不是 Windows，无法安装 .exe 文件"}, nil
		}
		err = installExe(installerPath)
	case ".zip":
		err = installZip(installerPath)
	default:
		return nil, fmt.Errorf("不支持的安装包格式: %s", ext)
	}

	// 处理安装结果
	if err != nil {
		// 安装失败，尝试回滚
		if backupPath != "" {
			_ = rollbackFromBackup(backupPath)
		}
		return &InstallResult{Success: false, Message: fmt.Sprintf("安装失败: %v", err)}, nil
	}

	// 自动重启
	if autoRestart {
		go func() {
			time.Sleep(2 * time.Second)
			restartApplication()
		}()
	}

	return &InstallResult{Success: true, Message: "安装成功"}, nil
}

// getExecutablePath 获取当前可执行文件路径
func getExecutablePath() (string, error) {
	execPath, err := os.Executable()
	if err != nil {
		return "", fmt.Errorf("获取可执行文件路径失败: %v", err)
	}
	return execPath, nil
}

// installExe 安装 exe 文件
func installExe(exePath string) error {
	execPath, err := getExecutablePath()
	if err != nil {
		return err
	}
	return replaceExecutableFile(exePath, execPath)
}

// installZip 安装 ZIP 压缩包
func installZip(zipPath string) error {
	zipReader, err := zip.OpenReader(zipPath)
	if err != nil {
		return fmt.Errorf("打开 ZIP 文件失败: %v", err)
	}
	defer zipReader.Close()

	execPath, err := getExecutablePath()
	if err != nil {
		return err
	}
	execDir := filepath.Dir(execPath)
	execName := filepath.Base(execPath)

	// 解压到临时目录
	tempDir := filepath.Join(execDir, ".update-temp")
	if err := os.MkdirAll(tempDir, 0755); err != nil {
		return fmt.Errorf("创建临时目录失败: %v", err)
	}
	defer os.RemoveAll(tempDir)

	// 解压文件
	for _, file := range zipReader.File {
		filePath := filepath.Join(tempDir, file.Name)
		if file.FileInfo().IsDir() {
			os.MkdirAll(filePath, file.FileInfo().Mode())
			continue
		}

		if err := os.MkdirAll(filepath.Dir(filePath), 0755); err != nil {
			return fmt.Errorf("创建目录失败: %v", err)
		}

		rc, err := file.Open()
		if err != nil {
			return fmt.Errorf("打开 ZIP 文件项失败: %v", err)
		}

		targetFile, err := os.OpenFile(filePath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, file.FileInfo().Mode())
		if err != nil {
			rc.Close()
			return fmt.Errorf("创建目标文件失败: %v", err)
		}

		if _, err := io.Copy(targetFile, rc); err != nil {
			targetFile.Close()
			rc.Close()
			return fmt.Errorf("复制文件失败: %v", err)
		}
		targetFile.Close()
		rc.Close()
	}

	// 查找新的可执行文件
	newExecPath := filepath.Join(tempDir, execName)
	if _, err := os.Stat(newExecPath); os.IsNotExist(err) {
		files, _ := os.ReadDir(tempDir)
		for _, f := range files {
			if !f.IsDir() {
				newExecPath = filepath.Join(tempDir, f.Name())
				break
			}
		}
	}

	// 替换文件（使用与 installExe 相同的逻辑）
	return replaceExecutableFile(newExecPath, execPath)
}

// replaceExecutableFile 替换可执行文件（Windows 和 Unix 通用逻辑）
func replaceExecutableFile(newFilePath, execPath string) error {
	if runtime.GOOS == "windows" {
		return replaceExecutableFileWindows(newFilePath, execPath)
	}

	// Unix-like: 直接替换
	if err := copyFile(newFilePath, execPath); err != nil {
		return fmt.Errorf("复制文件失败: %v", err)
	}
	return os.Chmod(execPath, 0755)
}

// replaceExecutableFileWindows Windows 平台替换可执行文件
func replaceExecutableFileWindows(newFilePath, execPath string) error {
	oldExecPath := execPath + ".old"
	newExecPathTemp := execPath + ".new"

	// 清理旧文件
	os.Remove(oldExecPath)
	os.Remove(newExecPathTemp)

	// 复制新文件到临时位置
	if err := copyFile(newFilePath, newExecPathTemp); err != nil {
		return fmt.Errorf("复制新文件失败: %v", err)
	}

	// 尝试重命名当前文件（如果失败，说明文件正在使用）
	if err := os.Rename(execPath, oldExecPath); err != nil {
		return nil
	}

	// 替换文件
	if err := os.Rename(newExecPathTemp, execPath); err != nil {
		os.Rename(oldExecPath, execPath) // 恢复
		return fmt.Errorf("替换文件失败: %v", err)
	}

	// 延迟删除旧文件
	go func() {
		time.Sleep(10 * time.Second)
		os.Remove(oldExecPath)
	}()
	return nil
}

// restartApplication 重启应用
func restartApplication() {
	execPath, err := getExecutablePath()
	if err != nil {
		return
	}

	currentPID := os.Getpid()
	if runtime.GOOS != "windows" {
		return
	}

	replacePendingFile(execPath)

	// 创建并执行重启脚本
	tempDir := os.TempDir()
	batFile := filepath.Join(tempDir, fmt.Sprintf("restart_%d.bat", currentPID))
	execDir := filepath.Dir(execPath)

	batContent := fmt.Sprintf(`@echo off
cd /d "%s"
start "" "%s"
timeout /t 3 /nobreak >nul
taskkill /PID %d /F >nul 2>&1
del "%%~f0"
`, execDir, execPath, currentPID)

	if err := os.WriteFile(batFile, []byte(batContent), 0644); err != nil {
		fallbackRestart(execPath)
		return
	}

	cmd := exec.Command("cmd", "/C", batFile)
	cmd.Stdout = nil
	cmd.Stderr = nil
	if err := cmd.Start(); err != nil {
		fallbackRestart(execPath)
		return
	}

	os.Exit(0)
}

// fallbackRestart 降级重启方案
func fallbackRestart(execPath string) {
	exec.Command("cmd", "/C", "start", "", execPath).Start()
	time.Sleep(2 * time.Second)
	os.Exit(0)
}

// replacePendingFile 替换待替换的文件（.new -> 可执行文件）
func replacePendingFile(execPath string) error {
	newExecPathTemp := execPath + ".new"
	if _, err := os.Stat(newExecPathTemp); os.IsNotExist(err) {
		return nil // 没有待替换文件
	}

	oldExecPath := execPath + ".old"
	os.Remove(oldExecPath)
	if err := os.Rename(newExecPathTemp, execPath); err != nil {
		return fmt.Errorf("文件替换失败: %v", err)
	}
	return nil
}

// rollbackFromBackup 从备份恢复
func rollbackFromBackup(backupPath string) error {
	execPath, err := getExecutablePath()
	if err != nil {
		return err
	}
	return copyFile(backupPath, execPath)
}

// BackupApplication 备份当前应用
func BackupApplication() (string, error) {
	execPath, err := getExecutablePath()
	if err != nil {
		return "", err
	}

	homeDir, err := os.UserHomeDir()
	if err != nil {
		return "", fmt.Errorf("获取用户目录失败: %v", err)
	}

	backupDir := filepath.Join(homeDir, ".ssq-desk", "backups")
	if err := os.MkdirAll(backupDir, 0755); err != nil {
		return "", fmt.Errorf("创建备份目录失败: %v", err)
	}

	timestamp := time.Now().Format("20060102-150405")
	backupFileName := fmt.Sprintf("ssq-desk-backup-%s%s", timestamp, filepath.Ext(execPath))
	backupPath := filepath.Join(backupDir, backupFileName)

	sourceFile, err := os.Open(execPath)
	if err != nil {
		return "", fmt.Errorf("打开源文件失败: %v", err)
	}
	defer sourceFile.Close()

	backupFile, err := os.Create(backupPath)
	if err != nil {
		return "", fmt.Errorf("创建备份文件失败: %v", err)
	}
	defer backupFile.Close()

	if _, err := backupFile.ReadFrom(sourceFile); err != nil {
		return "", fmt.Errorf("复制文件失败: %v", err)
	}

	return backupPath, nil
}