package service

import (
	"bytes"
	"context"
	"encoding/csv"
	"fmt"
	"time"

	"github.com/xuri/excelize/v2"

	"github.com/user-management-system/internal/domain"
	"github.com/user-management-system/internal/repository"
)

// LoginLogService 登录日志服务
type LoginLogService struct {
	loginLogRepo *repository.LoginLogRepository
}

// NewLoginLogService 创建登录日志服务
func NewLoginLogService(loginLogRepo *repository.LoginLogRepository) *LoginLogService {
	return &LoginLogService{loginLogRepo: loginLogRepo}
}

// RecordLogin 记录登录日志
func (s *LoginLogService) RecordLogin(ctx context.Context, req *RecordLoginRequest) error {
	log := &domain.LoginLog{
		LoginType:  req.LoginType,
		DeviceID:   req.DeviceID,
		IP:         req.IP,
		Location:   req.Location,
		Status:     req.Status,
		FailReason: req.FailReason,
	}
	if req.UserID != 0 {
		log.UserID = &req.UserID
	}
	return s.loginLogRepo.Create(ctx, log)
}

// RecordLoginRequest 记录登录请求
type RecordLoginRequest struct {
	UserID     int64  `json:"user_id"`
	LoginType  int    `json:"login_type"` // 1-用户名, 2-邮箱, 3-手机
	DeviceID   string `json:"device_id"`
	IP         string `json:"ip"`
	Location   string `json:"location"`
	Status     int    `json:"status"`     // 0-失败, 1-成功
	FailReason string `json:"fail_reason"`
}

// ListLoginLogRequest 登录日志列表请求
type ListLoginLogRequest struct {
	UserID   int64  `json:"user_id"`
	Status   int    `json:"status"`
	Page     int    `json:"page"`
	PageSize int    `json:"page_size"`
	StartAt  string `json:"start_at"`
	EndAt    string `json:"end_at"`
}

// GetLoginLogs 获取登录日志列表
func (s *LoginLogService) GetLoginLogs(ctx context.Context, req *ListLoginLogRequest) ([]*domain.LoginLog, int64, error) {
	if req.Page <= 0 {
		req.Page = 1
	}
	if req.PageSize <= 0 {
		req.PageSize = 20
	}
	offset := (req.Page - 1) * req.PageSize

	// 按用户 ID 查询
	if req.UserID > 0 {
		return s.loginLogRepo.ListByUserID(ctx, req.UserID, offset, req.PageSize)
	}

	// 按时间范围查询
	if req.StartAt != "" && req.EndAt != "" {
		start, err1 := time.Parse(time.RFC3339, req.StartAt)
		end, err2 := time.Parse(time.RFC3339, req.EndAt)
		if err1 == nil && err2 == nil {
			return s.loginLogRepo.ListByTimeRange(ctx, start, end, offset, req.PageSize)
		}
	}

	// 按状态查询
	if req.Status == 0 || req.Status == 1 {
		return s.loginLogRepo.ListByStatus(ctx, req.Status, offset, req.PageSize)
	}

	return s.loginLogRepo.List(ctx, offset, req.PageSize)
}

// GetMyLoginLogs 获取当前用户的登录日志
func (s *LoginLogService) GetMyLoginLogs(ctx context.Context, userID int64, page, pageSize int) ([]*domain.LoginLog, int64, error) {
	if page <= 0 {
		page = 1
	}
	if pageSize <= 0 {
		pageSize = 20
	}
	offset := (page - 1) * pageSize
	return s.loginLogRepo.ListByUserID(ctx, userID, offset, pageSize)
}

// CleanupOldLogs 清理旧日志（保留最近 N 天）
func (s *LoginLogService) CleanupOldLogs(ctx context.Context, retentionDays int) error {
	return s.loginLogRepo.DeleteOlderThan(ctx, retentionDays)
}

// ExportLoginLogRequest 导出登录日志请求
type ExportLoginLogRequest struct {
	UserID  int64  `form:"user_id"`
	Status  int    `form:"status"`
	Format  string `form:"format"`
	StartAt string `form:"start_at"`
	EndAt   string `form:"end_at"`
}

// ExportLoginLogs 导出登录日志
func (s *LoginLogService) ExportLoginLogs(ctx context.Context, req *ExportLoginLogRequest) ([]byte, string, string, error) {
	format := "csv"
	if req.Format == "xlsx" {
		format = "xlsx"
	}

	var startAt, endAt *time.Time
	if req.StartAt != "" {
		if t, err := time.Parse(time.RFC3339, req.StartAt); err == nil {
			startAt = &t
		}
	}
	if req.EndAt != "" {
		if t, err := time.Parse(time.RFC3339, req.EndAt); err == nil {
			endAt = &t
		}
	}

	logs, err := s.loginLogRepo.ListAllForExport(ctx, req.UserID, req.Status, startAt, endAt)
	if err != nil {
		return nil, "", "", fmt.Errorf("查询登录日志失败: %w", err)
	}

	filename := fmt.Sprintf("login_logs_%s.%s", time.Now().Format("20060102_150405"), format)

	if format == "xlsx" {
		data, err := buildLoginLogXLSXExport(logs)
		if err != nil {
			return nil, "", "", err
		}
		return data, filename, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", nil
	}

	data, err := buildLoginLogCSVExport(logs)
	if err != nil {
		return nil, "", "", err
	}
	return data, filename, "text/csv; charset=utf-8", nil
}

func buildLoginLogCSVExport(logs []*domain.LoginLog) ([]byte, error) {
	headers := []string{"ID", "用户ID", "登录方式", "设备ID", "IP地址", "位置", "状态", "失败原因", "时间"}
	rows := make([][]string, 0, len(logs)+1)
	rows = append(rows, headers)

	for _, log := range logs {
		rows = append(rows, []string{
			fmt.Sprintf("%d", log.ID),
			fmt.Sprintf("%d", derefInt64(log.UserID)),
			loginTypeLabel(log.LoginType),
			log.DeviceID,
			log.IP,
			log.Location,
			loginStatusLabel(log.Status),
			log.FailReason,
			log.CreatedAt.Format("2006-01-02 15:04:05"),
		})
	}

	var buf bytes.Buffer
	buf.Write([]byte{0xEF, 0xBB, 0xBF})
	writer := csv.NewWriter(&buf)
	if err := writer.WriteAll(rows); err != nil {
		return nil, fmt.Errorf("写CSV失败: %w", err)
	}
	return buf.Bytes(), nil
}

func buildLoginLogXLSXExport(logs []*domain.LoginLog) ([]byte, error) {
	file := excelize.NewFile()
	defer file.Close()

	sheet := file.GetSheetName(file.GetActiveSheetIndex())
	if sheet == "" {
		sheet = "Sheet1"
	}

	headers := []string{"ID", "用户ID", "登录方式", "设备ID", "IP地址", "位置", "状态", "失败原因", "时间"}
	for idx, header := range headers {
		cell, _ := excelize.CoordinatesToCellName(idx+1, 1)
		_ = file.SetCellValue(sheet, cell, header)
	}

	for rowIdx, log := range logs {
		row := []string{
			fmt.Sprintf("%d", log.ID),
			fmt.Sprintf("%d", derefInt64(log.UserID)),
			loginTypeLabel(log.LoginType),
			log.DeviceID,
			log.IP,
			log.Location,
			loginStatusLabel(log.Status),
			log.FailReason,
			log.CreatedAt.Format("2006-01-02 15:04:05"),
		}
		for colIdx, value := range row {
			cell, _ := excelize.CoordinatesToCellName(colIdx+1, rowIdx+2)
			_ = file.SetCellValue(sheet, cell, value)
		}
	}

	var buf bytes.Buffer
	if _, err := file.WriteTo(&buf); err != nil {
		return nil, fmt.Errorf("生成Excel失败: %w", err)
	}
	return buf.Bytes(), nil
}

func loginTypeLabel(t int) string {
	switch t {
	case 1:
		return "密码登录"
	case 2:
		return "邮箱验证码"
	case 3:
		return "手机验证码"
	case 4:
		return "OAuth"
	default:
		return "未知"
	}
}

func loginStatusLabel(s int) string {
	if s == 1 {
		return "成功"
	}
	return "失败"
}

func derefInt64(v *int64) int64 {
	if v == nil {
		return 0
	}
	return *v
}