package services

import (
	"context"
	"time"

	"quyun/v2/app/http/dto"
	"quyun/v2/app/requests"
	"quyun/v2/database"
	"quyun/v2/database/models"

	"github.com/pkg/errors"
	"github.com/samber/lo"
	"go.ipao.vip/gen"
)

// @provider
type posts struct{}

// IncrViewCount
func (m *posts) IncrViewCount(ctx context.Context, postID int64) error {
	tbl, query := models.PostQuery.QueryContext(ctx)

	_, err := query.Where(tbl.ID.Eq(postID)).Inc(tbl.Views, 1)
	if err != nil {
		return errors.Wrapf(err, "failed to increment view count for post %d", postID)
	}
	return nil
}

// List
func (m *posts) List(ctx context.Context, filter *dto.PostListQuery) (*requests.Pager, error) {
	filter.Pagination.Format()

	// conds := []gen.Condition{}

	tbl, query := models.PostQuery.QueryContext(ctx)
	query = query.Order(tbl.ID.Desc())

	if filter.Keyword != nil && *filter.Keyword != "" {
		keyword := database.WrapLike(*filter.Keyword)
		query = query.Where(tbl.Title.Like(keyword))
	}

	// filter status
	if filter.Status != nil {
		query = query.Where(tbl.Status.Eq(*filter.Status))
	}

	items, cnt, err := query.FindByPage(int(filter.Offset()), int(filter.Limit))
	if err != nil {
		return nil, errors.Wrap(err, "list post failed")
	}

	return &requests.Pager{
		Items:      items,
		Total:      cnt,
		Pagination: *filter.Pagination,
	}, nil
}

// SendTo
func (m *posts) SendTo(ctx context.Context, postID, userID int64) error {
	model := &models.UserPost{
		UserID: userID,
		PostID: postID,
		Price:  -1,
	}
	return model.Create(ctx)
}

// PostBoughtStatistics 获取指定文件 ID 的购买次数
func (m *posts) BoughtStatistics(ctx context.Context, postIds []int64) (map[int64]int64, error) {
	tbl, query := models.UserPostQuery.QueryContext(ctx)

	var items []struct {
		Count  int64
		PostID int64
	}
	err := query.Select(
		tbl.UserID.Count().As("count"),
		tbl.PostID,
	).
		Where(tbl.PostID.In(postIds...)).
		Group(tbl.PostID).Scan(&items)
	if err != nil {
		return nil, err
	}
	result := make(map[int64]int64)
	for _, item := range items {
		result[item.PostID] = item.Count
	}
	return result, nil
}

func (m *posts) Bought(ctx context.Context, userId int64, pagination *requests.Pagination) (*requests.Pager, error) {
	pagination.Format()

	tblUserPost, queryUserPost := models.UserPostQuery.QueryContext(ctx)

	cnt, err := queryUserPost.Where(tblUserPost.UserID.Eq(userId)).Count()
	if err != nil {
		return nil, err
	}

	tbl, query := models.PostQuery.QueryContext(ctx)

	var retItems []struct {
		models.Post
		Price    int64     `json:"price"`
		BoughtAt time.Time `json:"bought_at"`
	}

	err = query.
		Select(
			tbl.ALL,
			tblUserPost.Price.As("price"),
			tblUserPost.CreatedAt.As("bought_at"),
		).
		RightJoin(tblUserPost, tbl.ID.EqCol(tblUserPost.PostID)).
		Where(tblUserPost.UserID.Eq(userId)).
		Order(tblUserPost.CreatedAt.Desc()).
		Limit(int(pagination.Limit)).
		Offset(int(pagination.Offset())).
		Scan(&retItems)
	if err != nil {
		return nil, err
	}

	return &requests.Pager{
		Items:      retItems,
		Total:      cnt,
		Pagination: *pagination,
	}, nil
}

// Buyers 获取某个作品的购买人列表（管理端使用）
func (m *posts) Buyers(ctx context.Context, postID int64, pagination *requests.Pagination) (*requests.Pager, error) {
	pagination.Format()

	// 先分页查询购买记录，避免一次性拉取全量 user_posts 造成内存/延迟抖动
	tblUserPost, queryUserPost := models.UserPostQuery.QueryContext(ctx)
	queryUserPost = queryUserPost.
		Where(tblUserPost.PostID.Eq(postID)).
		Order(tblUserPost.CreatedAt.Desc())

	userPosts, cnt, err := queryUserPost.FindByPage(int(pagination.Offset()), int(pagination.Limit))
	if err != nil {
		return nil, err
	}
	if len(userPosts) == 0 {
		return &requests.Pager{
			Items:      []dto.PostBuyerItem{},
			Total:      cnt,
			Pagination: *pagination,
		}, nil
	}

	// 批量回表查询用户信息，避免 N+1
	userIDs := lo.Uniq(lo.Map(userPosts, func(item *models.UserPost, _ int) int64 {
		return item.UserID
	}))
	tblUser, queryUser := models.UserQuery.QueryContext(ctx)
	users, err := queryUser.Where(tblUser.ID.In(userIDs...)).Find()
	if err != nil {
		return nil, err
	}
	userMap := lo.KeyBy(users, func(item *models.User) int64 { return item.ID })

	items := make([]dto.PostBuyerItem, 0, len(userPosts))
	for _, item := range userPosts {
		user, ok := userMap[item.UserID]
		if !ok {
			continue
		}
		items = append(items, dto.PostBuyerItem{
			UserID:   user.ID,
			Username: user.Username,
			Avatar:   user.Avatar,
			Phone:    user.Phone,
			BoughtAt: item.CreatedAt,
			Price:    item.Price,
		})
	}

	return &requests.Pager{
		Items:      items,
		Total:      cnt,
		Pagination: *pagination,
	}, nil
}

// GetPostsMapByIDs
func (m *posts) GetPostsMapByIDs(ctx context.Context, ids []int64) (map[int64]*models.Post, error) {
	tbl, query := models.PostQuery.QueryContext(ctx)
	posts, err := query.Where(tbl.ID.In(ids...)).Find()
	if err != nil {
		return nil, err
	}
	return lo.KeyBy(posts, func(item *models.Post) int64 { return item.ID }), nil
}

// GetMediaByIds
func (m *posts) GetMediasByIds(ctx context.Context, ids []int64) ([]*models.Medium, error) {
	if len(ids) == 0 {
		return nil, nil
	}
	tbl, query := models.MediumQuery.QueryContext(ctx)
	return query.Where(tbl.ID.In(ids...)).Find()
}

// FindByID
func (m *posts) FindByID(ctx context.Context, id int64, conds ...gen.Condition) (*models.Post, error) {
	tbl, query := models.PostQuery.QueryContext(ctx)
	if len(conds) > 0 {
		query = query.Where(conds...)
	}
	return query.Where(tbl.ID.Eq(id)).First()
}

// Count
func (m *posts) Count(ctx context.Context, conds ...gen.Condition) (int64, error) {
	_, query := models.PostQuery.QueryContext(ctx)
	if len(conds) > 0 {
		query = query.Where(conds...)
	}
	return query.Count()
}

// FilterIdsByKeyword filter posts ids by title keywords
func (m *posts) FilterIdsByKeyword(ctx context.Context, keyword string) ([]int64, error) {
	tbl, query := models.PostQuery.QueryContext(ctx)
	return query.Select(tbl.ID).Where(tbl.Title.Like(database.WrapLike(keyword))).PluckIDs()
}