package service

import (
	"archive/tar"
	"compress/gzip"
	"fmt"
	"io"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"time"

	"seeyon-filesystem/config"
	"seeyon-filesystem/dto"
	"seeyon-filesystem/model"
)

// BackupService 备份服务
type BackupService struct{}

func NewBackupService() *BackupService {
	return &BackupService{}
}

// ========== 策略管理 ==========

// CreatePolicy 创建备份策略
func (s *BackupService) CreatePolicy(req *dto.BackupPolicyCreateRequest) error {
	targetConfig := req.TargetConfig
	if targetConfig == "" {
		targetConfig = "{}"
	}

	policy := &model.BackupPolicy{
		Name:         req.Name,
		BackupType:   req.BackupType,
		TargetType:   req.TargetType,
		TargetConfig: targetConfig,
		IncludeDB:    req.IncludeDB,
		IncludeFiles: req.IncludeFiles,
		CronExpr:     req.CronExpr,
		MaxBackups:   req.MaxBackups,
		Status:       1,
	}
	if policy.MaxBackups <= 0 {
		policy.MaxBackups = 7
	}
	return config.DB.Create(policy).Error
}

// ListPolicies 获取所有备份策略
func (s *BackupService) ListPolicies() ([]dto.BackupPolicyVO, error) {
	var policies []model.BackupPolicy
	if err := config.DB.Order("created_at DESC").Find(&policies).Error; err != nil {
		return nil, err
	}

	vos := make([]dto.BackupPolicyVO, 0, len(policies))
	for _, p := range policies {
		vo := dto.BackupPolicyVO{
			ID:           p.ID,
			Name:         p.Name,
			BackupType:   p.BackupType,
			TargetType:   p.TargetType,
			TargetConfig: p.TargetConfig,
			IncludeDB:    p.IncludeDB,
			IncludeFiles: p.IncludeFiles,
			CronExpr:     p.CronExpr,
			MaxBackups:   p.MaxBackups,
			Status:       p.Status,
			CreatedAt:    p.CreatedAt.Format("2006-01-02 15:04:05"),
		}
		if p.LastRunAt != nil {
			t := p.LastRunAt.Format("2006-01-02 15:04:05")
			vo.LastRunAt = &t
		}
		if p.NextRunAt != nil {
			t := p.NextRunAt.Format("2006-01-02 15:04:05")
			vo.NextRunAt = &t
		}
		vos = append(vos, vo)
	}
	return vos, nil
}

// DeletePolicy 删除备份策略
func (s *BackupService) DeletePolicy(id uint64) error {
	return config.DB.Delete(&model.BackupPolicy{}, id).Error
}

// TogglePolicy 启用/禁用备份策略
func (s *BackupService) TogglePolicy(id uint64, status int8) error {
	return config.DB.Model(&model.BackupPolicy{}).Where("id = ?", id).Update("status", status).Error
}

// ========== 执行备份 ==========

// ExecuteBackup 手动执行备份
func (s *BackupService) ExecuteBackup(policyID uint64) (*model.BackupLog, error) {
	var policy model.BackupPolicy
	if err := config.DB.First(&policy, policyID).Error; err != nil {
		return nil, fmt.Errorf("备份策略不存在")
	}

	// 创建备份日志
	log := &model.BackupLog{
		PolicyID:   policyID,
		PolicyName: policy.Name,
		BackupType: policy.BackupType,
		Status:     "running",
		StartedAt:  time.Now(),
	}
	config.DB.Create(log)

	// 异步执行备份
	go s.doBackup(&policy, log)

	return log, nil
}

// doBackup 执行实际备份
func (s *BackupService) doBackup(policy *model.BackupPolicy, log *model.BackupLog) {
	startTime := time.Now()

	// 创建备份目录
	backupDir := filepath.Join(config.AppConfig.Storage.LocalBasePath, ".backups")
	os.MkdirAll(backupDir, 0755)

	timestamp := time.Now().Format("20060102_150405")
	backupFileName := fmt.Sprintf("backup_%s_%s.tar.gz", policy.BackupType, timestamp)
	backupPath := filepath.Join(backupDir, backupFileName)

	// 创建tar.gz文件
	tarFile, err := os.Create(backupPath)
	if err != nil {
		s.finishLog(log, "failed", "", 0, 0, err.Error())
		return
	}
	defer tarFile.Close()

	gzWriter := gzip.NewWriter(tarFile)
	defer gzWriter.Close()

	tarWriter := tar.NewWriter(gzWriter)
	defer tarWriter.Close()

	totalSize := int64(0)
	filesCount := 0

	// 备份数据库
	if policy.IncludeDB == 1 {
		dbSize, err := s.backupDatabase(tarWriter, timestamp)
		if err != nil {
			s.finishLog(log, "failed", "", 0, 0, "数据库备份失败: "+err.Error())
			return
		}
		totalSize += dbSize
	}

	// 备份文件
	if policy.IncludeFiles == 1 {
		fileSize, count, err := s.backupFiles(tarWriter)
		if err != nil {
			s.finishLog(log, "failed", "", 0, 0, "文件备份失败: "+err.Error())
			return
		}
		totalSize += fileSize
		filesCount = count
	}

	tarWriter.Close()
	gzWriter.Close()
	tarFile.Close()

	// 获取备份文件大小
	backupInfo, _ := os.Stat(backupPath)
	backupSize := int64(0)
	if backupInfo != nil {
		backupSize = backupInfo.Size()
	}

	duration := int(time.Since(startTime).Seconds())

	// 更新策略最后执行时间
	now := time.Now()
	config.DB.Model(policy).Updates(map[string]interface{}{
		"last_run_at": now,
	})

	s.finishLog(log, "success", backupPath, backupSize, filesCount, "")
	log.DBSize = totalSize
	log.Duration = duration
	config.DB.Save(log)

	// 清理旧备份
	s.cleanOldBackups(policy)
}

// backupDatabase 备份数据库
func (s *BackupService) backupDatabase(tarWriter *tar.Writer, timestamp string) (int64, error) {
	dbCfg := config.AppConfig.Database
	dumpFile := filepath.Join(os.TempDir(), fmt.Sprintf("db_dump_%s.sql", timestamp))

	mysqldumpPath := s.findTool("mysqldump", config.AppConfig.Backup.MysqlDumpPath)

	cmd := exec.Command(mysqldumpPath,
		"-h", dbCfg.Host,
		"-P", fmt.Sprintf("%d", dbCfg.Port),
		"-u", dbCfg.Username,
		"-p"+dbCfg.Password,
		"--single-transaction",
		"--routines",
		"--triggers",
		dbCfg.DBName,
	)

	outFile, err := os.Create(dumpFile)
	if err != nil {
		return 0, err
	}
	cmd.Stdout = outFile
	cmd.Stderr = os.Stderr

	if err := cmd.Run(); err != nil {
		outFile.Close()
		os.Remove(dumpFile)
		return 0, fmt.Errorf("mysqldump执行失败: %w", err)
	}
	outFile.Close()

	// 获取文件大小
	info, _ := os.Stat(dumpFile)
	dbSize := int64(0)
	if info != nil {
		dbSize = info.Size()
	}

	// 写入tar
	file, err := os.Open(dumpFile)
	if err != nil {
		os.Remove(dumpFile)
		return 0, err
	}
	defer file.Close()

	header := &tar.Header{
		Name:    "database/" + dbCfg.DBName + ".sql",
		Size:    dbSize,
		Mode:    0644,
		ModTime: time.Now(),
	}
	if err := tarWriter.WriteHeader(header); err != nil {
		os.Remove(dumpFile)
		return 0, err
	}

	if _, err := io.Copy(tarWriter, file); err != nil {
		os.Remove(dumpFile)
		return 0, err
	}

	os.Remove(dumpFile)
	return dbSize, nil
}

// backupFiles 备份文件
func (s *BackupService) backupFiles(tarWriter *tar.Writer) (int64, int, error) {
	basePath := config.AppConfig.Storage.LocalBasePath
	totalSize := int64(0)
	count := 0

	err := filepath.Walk(basePath, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return nil // 跳过错误
		}
		// 跳过备份目录和临时目录
		if info.IsDir() && (info.Name() == ".backups" || info.Name() == ".tmp") {
			return filepath.SkipDir
		}
		if info.IsDir() {
			return nil
		}

		relPath, _ := filepath.Rel(basePath, path)

		file, err := os.Open(path)
		if err != nil {
			return nil
		}
		defer file.Close()

		header := &tar.Header{
			Name:    "files/" + relPath,
			Size:    info.Size(),
			Mode:    int64(info.Mode()),
			ModTime: info.ModTime(),
		}
		if err := tarWriter.WriteHeader(header); err != nil {
			return nil
		}

		if _, err := io.Copy(tarWriter, file); err != nil {
			return nil
		}

		totalSize += info.Size()
		count++
		return nil
	})

	return totalSize, count, err
}

// finishLog 更新备份日志状态
func (s *BackupService) finishLog(log *model.BackupLog, status, filePath string, fileSize int64, filesCount int, errMsg string) {
	now := time.Now()
	log.Status = status
	log.FilePath = filePath
	log.FileSize = fileSize
	log.FilesCount = filesCount
	log.FinishedAt = &now
	log.ErrorMsg = errMsg
	if !now.IsZero() && !log.StartedAt.IsZero() {
		log.Duration = int(now.Sub(log.StartedAt).Seconds())
	}
	config.DB.Save(log)
}

// cleanOldBackups 清理旧备份
func (s *BackupService) cleanOldBackups(policy *model.BackupPolicy) {
	var logs []model.BackupLog
	config.DB.Where("policy_id = ? AND status = 'success'", policy.ID).
		Order("started_at DESC").Offset(policy.MaxBackups).Find(&logs)

	for _, log := range logs {
		// 删除备份文件
		if log.FilePath != "" {
			os.Remove(log.FilePath)
		}
		config.DB.Delete(&log)
	}
}

// ========== 查询 ==========

// ListLogs 查询备份日志
func (s *BackupService) ListLogs(policyID uint64, page, size int) ([]dto.BackupLogVO, int64, error) {
	query := config.DB.Model(&model.BackupLog{})
	if policyID > 0 {
		query = query.Where("policy_id = ?", policyID)
	}

	var total int64
	query.Count(&total)

	var logs []model.BackupLog
	query.Order("started_at DESC").Offset((page - 1) * size).Limit(size).Find(&logs)

	vos := make([]dto.BackupLogVO, 0, len(logs))
	for _, l := range logs {
		vo := dto.BackupLogVO{
			ID:         l.ID,
			PolicyID:   l.PolicyID,
			PolicyName: l.PolicyName,
			BackupType: l.BackupType,
			Status:     l.Status,
			FilePath:   l.FilePath,
			FileSize:   l.FileSize,
			DBSize:     l.DBSize,
			FilesCount: l.FilesCount,
			Duration:   l.Duration,
			ErrorMsg:   l.ErrorMsg,
			StartedAt:  l.StartedAt.Format("2006-01-02 15:04:05"),
		}
		if l.FinishedAt != nil {
			t := l.FinishedAt.Format("2006-01-02 15:04:05")
			vo.FinishedAt = &t
		}
		vos = append(vos, vo)
	}
	return vos, total, nil
}

// ========== 恢复 ==========

// RestoreResult 恢复结果
type RestoreResult struct {
	Success     bool   `json:"success"`
	Message     string `json:"message"`
	DBRestored  bool   `json:"db_restored"`
	FilesCount  int    `json:"files_count"`
	Duration    int    `json:"duration_ms"`
}

// RestoreFromBackup 从备份文件恢复
// logID: 备份日志ID
// restoreDB: 是否恢复数据库
// restoreFiles: 是否恢复文件
func (s *BackupService) RestoreFromBackup(logID uint64, restoreDB, restoreFiles bool) (*RestoreResult, error) {
	// 获取备份日志
	var log model.BackupLog
	if err := config.DB.First(&log, logID).Error; err != nil {
		return nil, fmt.Errorf("备份记录不存在")
	}
	if log.Status != "success" {
		return nil, fmt.Errorf("只能恢复成功的备份")
	}
	if log.FilePath == "" {
		return nil, fmt.Errorf("备份文件路径为空")
	}

	// 检查备份文件是否存在
	if _, err := os.Stat(log.FilePath); os.IsNotExist(err) {
		return nil, fmt.Errorf("备份文件不存在: %s", log.FilePath)
	}

	startTime := time.Now()
	result := &RestoreResult{}

	// 解压备份文件
	tempDir := filepath.Join(os.TempDir(), "restore_"+fmt.Sprintf("%d", logID))
	os.MkdirAll(tempDir, 0755)
	defer os.RemoveAll(tempDir)

	if err := s.extractTarGz(log.FilePath, tempDir); err != nil {
		return nil, fmt.Errorf("解压备份文件失败: %w", err)
	}

	// 恢复数据库
	if restoreDB {
		dbFile := filepath.Join(tempDir, "database")
		if _, err := os.Stat(dbFile); err == nil {
			// 找到SQL文件
			entries, _ := os.ReadDir(dbFile)
			for _, entry := range entries {
				if !entry.IsDir() && filepath.Ext(entry.Name()) == ".sql" {
					sqlPath := filepath.Join(dbFile, entry.Name())
					if err := s.restoreDatabase(sqlPath); err != nil {
						result.Message = "数据库恢复失败: " + err.Error()
						result.Duration = int(time.Since(startTime).Milliseconds())
						return result, nil
					}
					result.DBRestored = true
					break
				}
			}
		}
	}

	// 恢复文件
	if restoreFiles {
		filesDir := filepath.Join(tempDir, "files")
		if _, err := os.Stat(filesDir); err == nil {
			basePath := config.AppConfig.Storage.LocalBasePath
			count, err := s.restoreFiles(filesDir, basePath)
			if err != nil {
				result.Message = "文件恢复失败: " + err.Error()
				result.Duration = int(time.Since(startTime).Milliseconds())
				return result, nil
			}
			result.FilesCount = count
		}
	}

	result.Success = true
	result.Duration = int(time.Since(startTime).Milliseconds())

	parts := []string{}
	if result.DBRestored {
		parts = append(parts, "数据库已恢复")
	}
	if result.FilesCount > 0 {
		parts = append(parts, fmt.Sprintf("%d个文件已恢复", result.FilesCount))
	}
	if len(parts) == 0 {
		result.Message = "没有可恢复的内容"
	} else {
		result.Message = "恢复成功: " + strings.Join(parts, ", ")
	}

	return result, nil
}

// extractTarGz 解压tar.gz文件
func (s *BackupService) extractTarGz(tarGzPath, destDir string) error {
	file, err := os.Open(tarGzPath)
	if err != nil {
		return err
	}
	defer file.Close()

	gzReader, err := gzip.NewReader(file)
	if err != nil {
		return err
	}
	defer gzReader.Close()

	tarReader := tar.NewReader(gzReader)
	for {
		header, err := tarReader.Next()
		if err == io.EOF {
			break
		}
		if err != nil {
			return err
		}

		targetPath := filepath.Join(destDir, header.Name)

		switch header.Typeflag {
		case tar.TypeDir:
			os.MkdirAll(targetPath, 0755)
		case tar.TypeReg:
			os.MkdirAll(filepath.Dir(targetPath), 0755)
			outFile, err := os.Create(targetPath)
			if err != nil {
				return err
			}
			io.Copy(outFile, tarReader)
			outFile.Close()
			os.Chmod(targetPath, os.FileMode(header.Mode))
		}
	}
	return nil
}

// restoreDatabase 从SQL文件恢复数据库
func (s *BackupService) restoreDatabase(sqlFilePath string) error {
	dbCfg := config.AppConfig.Database

	mysqlPath := s.findTool("mysql", config.AppConfig.Backup.MysqlPath)

	cmd := exec.Command(mysqlPath,
		"-h", dbCfg.Host,
		"-P", fmt.Sprintf("%d", dbCfg.Port),
		"-u", dbCfg.Username,
		"-p"+dbCfg.Password,
		dbCfg.DBName,
	)

	sqlFile, err := os.Open(sqlFilePath)
	if err != nil {
		return err
	}
	defer sqlFile.Close()

	cmd.Stdin = sqlFile
	cmd.Stderr = os.Stderr

	return cmd.Run()
}

// restoreFiles 恢复文件到目标目录
func (s *BackupService) restoreFiles(srcDir, destDir string) (int, error) {
	count := 0
	err := filepath.Walk(srcDir, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return nil
		}

		relPath, _ := filepath.Rel(srcDir, path)
		targetPath := filepath.Join(destDir, relPath)

		if info.IsDir() {
			os.MkdirAll(targetPath, 0755)
			return nil
		}

		// 复制文件
		srcFile, err := os.Open(path)
		if err != nil {
			return nil
		}
		defer srcFile.Close()

		os.MkdirAll(filepath.Dir(targetPath), 0755)
		dstFile, err := os.Create(targetPath)
		if err != nil {
			return nil
		}
		defer dstFile.Close()

		io.Copy(dstFile, srcFile)
		count++
		return nil
	})

	return count, err
}

// ListBackups 列出所有可恢复的备份文件
func (s *BackupService) ListBackups() ([]dto.BackupLogVO, error) {
	var logs []model.BackupLog
	config.DB.Where("status = 'success' AND file_path != ''").
		Order("started_at DESC").Find(&logs)

	vos := make([]dto.BackupLogVO, 0, len(logs))
	for _, l := range logs {
		vo := dto.BackupLogVO{
			ID:         l.ID,
			PolicyName: l.PolicyName,
			BackupType: l.BackupType,
			FileSize:   l.FileSize,
			FilesCount: l.FilesCount,
			StartedAt:  l.StartedAt.Format("2006-01-02 15:04:05"),
		}
		vos = append(vos, vo)
	}
	return vos, nil
}

// findTool 查找可执行工具路径
// 优先使用配置路径, 否则搜索常见路径
func (s *BackupService) findTool(name, configPath string) string {
	if configPath != "" {
		if _, err := os.Stat(configPath); err == nil {
			return configPath
		}
	}
	if _, err := exec.LookPath(name); err == nil {
		return name
	}
	commonPaths := []string{
		fmt.Sprintf(`C:\Program Files\MySQL\MySQL Server 8.0\bin\%s.exe`, name),
		fmt.Sprintf(`/usr/bin/%s`, name),
	}
	for _, p := range commonPaths {
		if _, err := os.Stat(p); err == nil {
			return p
		}
	}
	return name
}