package repo

import (
  "errors"
  "net/http"
  "slices"

  "github.com/snowykami/neo-blog/internal/dto"
  "github.com/snowykami/neo-blog/internal/model"
  "github.com/snowykami/neo-blog/pkg/constant"
  "github.com/snowykami/neo-blog/pkg/errs"
  "gorm.io/gorm"
)

type postRepo struct{}

var Post = &postRepo{}

func (p *postRepo) CreatePost(post *model.Post) error {
  if err := GetDB().Create(post).Error; err != nil {
    return err
  }
  return nil
}

func (p *postRepo) DeletePost(id string) error {
  if id == "" {
    return errs.New(http.StatusBadRequest, "invalid post ID", nil)
  }
  if err := GetDB().Where("id = ?", id).Delete(&model.Post{}).Error; err != nil {
    return err
  }
  return nil
}

func (p *postRepo) GetPostByID(id string) (*model.Post, error) {
  var post model.Post
  if err := GetDB().Where("id = ?", id).Preload("User").First(&post).Error; err != nil {
    return nil, err
  }
  GetDB().Model(&post).UpdateColumn("view_count", gorm.Expr("view_count + ?", 1))
  GetDB().First(&post, post.ID)
  GetDB().Model(&post).UpdateColumn("heat", post.CalculateHeat())
  // TODO: 对用户进行追踪，实现更真实的访问次数计算，目前粗略地每次访问都+1
  return &post, nil
}

func (p *postRepo) UpdatePost(post *model.Post) error {
  if post.ID == 0 {
    return errs.New(http.StatusBadRequest, "invalid post ID", nil)
  }
  if err := GetDB().Save(post).Error; err != nil {
    return err
  }
  return nil
}

func (p *postRepo) ListPosts(currentUserID uint, keywords []string, labels []dto.LabelDto, labelRule string, page, size uint64, orderBy string, desc bool) ([]model.Post, int64, error) {
  if !slices.Contains(constant.OrderByEnumPost, orderBy) {
    return nil, 0, errs.New(http.StatusBadRequest, "invalid order_by parameter", nil)
  }
  query := GetDB().Model(&model.Post{}).Preload("User")
  if currentUserID > 0 {
    query = query.Where("is_private = ? OR (is_private = ? AND user_id = ?)", false, true, currentUserID)
  } else {
    query = query.Where("is_private = ?", false)
  }

  if len(labels) > 0 {
    var labelIds []uint
    for _, labelDto := range labels {
      label, _ := Label.GetLabelByKeyAndValue(labelDto.Key, labelDto.Value)
      labelIds = append(labelIds, label.ID)
    }
    if labelRule == "intersection" {
      query = query.Joins("JOIN post_labels ON post_labels.post_id = posts.id").
        Where("post_labels.label_id IN ?", labelIds).
        Group("posts.id").
        Having("COUNT(DISTINCT post_labels.label_id) = ?", len(labelIds))
    } else {
      query = query.Joins("JOIN post_labels ON post_labels.post_id = posts.id").
        Where("post_labels.label_id IN ?", labelIds)
    }
  }

  if len(keywords) > 0 {
    for _, keyword := range keywords {
      if keyword != "" {
        query = query.Where("title LIKE ? OR content LIKE ?",
          "%"+keyword+"%", "%"+keyword+"%")
      }
    }
  }

  var total int64
  if err := query.Count(&total).Error; err != nil && !errors.Is(err, gorm.ErrRecordNotFound) {
    return nil, 0, err
  }

  items, _, err := PaginateQuery[model.Post](query, page, size, orderBy, desc)
  if err != nil {
    return nil, 0, err
  }
  return items, total, nil
}

func (p *postRepo) ToggleLikePost(postID uint, userID uint) (bool, error) {
  if postID == 0 || userID == 0 {
    return false, errs.New(http.StatusBadRequest, "invalid post ID or user ID", nil)
  }
  liked, err := Like.ToggleLike(userID, postID, constant.TargetTypePost)
  if err != nil {
    return false, err
  }
  return liked, nil
}