package service

import (
	"time"

	"github.com/freefire/jiang13-bbs/model"
	"gorm.io/gorm"
)

// BoardService 板块服务
type BoardService struct {
	db *gorm.DB
}

func NewBoardService(db *gorm.DB) *BoardService {
	return &BoardService{db: db}
}

// BoardWithCount 板块及其已发布帖子计数（Board 字段被 encoding/json 展平）
type BoardWithCount struct {
	model.Board
	PostCount int64 `json:"post_count"`
}

// BoardModerator 板块管理员公开资料
type BoardModerator struct {
	ID       uint   `json:"id"`
	Username string `json:"username"`
	Nickname string `json:"nickname"`
	Avatar   string `json:"avatar"`
}

// BoardSidebarStats 板级统计（不含在线）
type BoardSidebarStats struct {
	PostCount     int64 `json:"post_count"`
	TodayPosts    int64 `json:"today_posts"`
	CommentCount  int64 `json:"comment_count"`
	TodayComments int64 `json:"today_comments"`
}

// BoardSidebarData 首页选中板块后的右栏聚合
type BoardSidebarData struct {
	Board       BoardWithCount    `json:"board"`
	Moderators  []BoardModerator  `json:"moderators"`
	Stats       BoardSidebarStats `json:"stats"`
	Hot         []PostListItem    `json:"hot"`
	ActiveUsers []ActiveUser      `json:"active_users"`
	Checkin     *CheckinStatus    `json:"checkin,omitempty"`
}

// List 获取所有板块（按 sort_order 排序），附带各板块已发布帖子数（板块目录页展示用）
func (s *BoardService) List() ([]BoardWithCount, error) {
	var boards []model.Board
	if err := s.db.Order("sort_order ASC, id ASC").Find(&boards).Error; err != nil {
		return nil, err
	}
	type countRow struct {
		BoardID uint
		Cnt     int64
	}
	var counts []countRow
	if err := s.db.Model(&model.Post{}).
		Select("board_id, COUNT(*) AS cnt").
		Where("status = ?", model.ContentStatusPublished).
		Group("board_id").Scan(&counts).Error; err != nil {
		return nil, err
	}
	countMap := make(map[uint]int64, len(counts))
	for _, c := range counts {
		countMap[c.BoardID] = c.Cnt
	}
	items := make([]BoardWithCount, 0, len(boards))
	for _, b := range boards {
		items = append(items, BoardWithCount{Board: b, PostCount: countMap[b.ID]})
	}
	return items, nil
}

// Get 根据 ID 获取板块
func (s *BoardService) Get(id uint) (*model.Board, error) {
	var board model.Board
	if err := s.db.First(&board, id).Error; err != nil {
		return nil, err
	}
	return &board, nil
}

// Sidebar 首页板块右栏：管理员 + 概况统计 + 本板热门/活跃
func (s *BoardService) Sidebar(boardID uint) (*BoardSidebarData, error) {
	board, err := s.Get(boardID)
	if err != nil {
		return nil, err // 含 gorm.ErrRecordNotFound
	}

	data := &BoardSidebarData{
		Board:       BoardWithCount{Board: *board},
		Moderators:  []BoardModerator{},
		Hot:         []PostListItem{},
		ActiveUsers: []ActiveUser{},
	}

	now := time.Now()
	dayStart := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, now.Location())
	weekStart := startOfWeek(now)

	// 帖子总数 / 今日新帖
	if err := s.db.Model(&model.Post{}).
		Where("board_id = ? AND status = ?", boardID, model.ContentStatusPublished).
		Count(&data.Stats.PostCount).Error; err != nil {
		return nil, err
	}
	data.Board.PostCount = data.Stats.PostCount
	if err := s.db.Model(&model.Post{}).
		Where("board_id = ? AND status = ? AND created_at >= ?", boardID, model.ContentStatusPublished, dayStart).
		Count(&data.Stats.TodayPosts).Error; err != nil {
		return nil, err
	}

	// 评论总数 / 今日评论（经 posts.board_id）
	if err := s.db.Model(&model.Comment{}).
		Joins("JOIN posts ON posts.id = comments.post_id AND posts.deleted_at IS NULL").
		Where("posts.board_id = ? AND posts.status = ? AND comments.status = ?",
			boardID, model.ContentStatusPublished, model.ContentStatusPublished).
		Count(&data.Stats.CommentCount).Error; err != nil {
		return nil, err
	}
	if err := s.db.Model(&model.Comment{}).
		Joins("JOIN posts ON posts.id = comments.post_id AND posts.deleted_at IS NULL").
		Where("posts.board_id = ? AND posts.status = ? AND comments.status = ? AND comments.created_at >= ?",
			boardID, model.ContentStatusPublished, model.ContentStatusPublished, dayStart).
		Count(&data.Stats.TodayComments).Error; err != nil {
		return nil, err
	}

	// 板块管理员：仅 board_admin 且授权本板、未封禁
	var mods []model.User
	if err := s.db.Table("users").
		Select("users.id, users.username, users.nickname, users.avatar").
		Joins("JOIN user_boards ON user_boards.user_id = users.id AND user_boards.board_id = ?", boardID).
		Where("users.role = ? AND users.banned = ? AND users.deleted_at IS NULL", model.RoleBoardAdmin, false).
		Order("users.id ASC").
		Find(&mods).Error; err != nil {
		return nil, err
	}
	for _, u := range mods {
		data.Moderators = append(data.Moderators, BoardModerator{
			ID:       u.ID,
			Username: u.Username,
			Nickname: u.Nickname,
			Avatar:   u.Avatar,
		})
	}

	// 本板热门
	var hotPosts []model.Post
	if err := s.db.Where("board_id = ? AND status = ? AND pinned = 0", boardID, model.ContentStatusPublished).
		Order("(like_count + comment_count * 2) DESC, created_at DESC").
		Limit(5).Preload("Board").Preload("User").Find(&hotPosts).Error; err != nil {
		return nil, err
	}
	data.Hot = toPostListItems(hotPosts)

	// 本板本周活跃
	type activityRow struct {
		UserID       uint
		PostCount    int64
		CommentCount int64
	}
	var rows []activityRow
	activitySQL := `
SELECT a.user_id AS user_id,
       SUM(a.is_post) AS post_count,
       SUM(1 - a.is_post) AS comment_count
FROM (
	SELECT user_id, 1 AS is_post FROM posts
	WHERE status = ? AND board_id = ? AND created_at >= ? AND deleted_at IS NULL
	UNION ALL
	SELECT c.user_id, 0 AS is_post FROM comments c
	JOIN posts p ON p.id = c.post_id AND p.deleted_at IS NULL
	WHERE c.status = ? AND c.created_at >= ? AND c.deleted_at IS NULL
	  AND p.board_id = ? AND p.status = ?
) AS a
JOIN users AS u ON u.id = a.user_id
WHERE u.banned = ? AND u.deleted_at IS NULL
GROUP BY a.user_id
ORDER BY COUNT(*) DESC, a.user_id ASC
LIMIT 5`
	if err := s.db.Raw(activitySQL,
		model.ContentStatusPublished, boardID, weekStart,
		model.ContentStatusPublished, weekStart, boardID, model.ContentStatusPublished,
		false).Scan(&rows).Error; err != nil {
		return nil, err
	}
	if len(rows) > 0 {
		ids := make([]uint, 0, len(rows))
		for _, r := range rows {
			ids = append(ids, r.UserID)
		}
		var users []model.User
		if err := s.db.Where("id IN ?", ids).Find(&users).Error; err != nil {
			return nil, err
		}
		userMap := make(map[uint]model.User, len(users))
		for _, u := range users {
			userMap[u.ID] = u
		}
		for _, r := range rows {
			u, ok := userMap[r.UserID]
			if !ok {
				continue
			}
			data.ActiveUsers = append(data.ActiveUsers, ActiveUser{
				ID:           u.ID,
				Username:     u.Username,
				Nickname:     u.Nickname,
				Avatar:       u.Avatar,
				PostCount:    r.PostCount,
				CommentCount: r.CommentCount,
			})
		}
	}

	return data, nil
}