package models

import (
	"strings"
	"time"

	"code.nonshy.com/nonshy/website/pkg/log"
	"gorm.io/gorm"
)

// ForumMembership table.
type ForumMembership struct {
	ID          uint64 `gorm:"primaryKey"`
	UserID      uint64 `gorm:"index"`
	User        User   `gorm:"foreignKey:user_id"`
	ForumID     uint64 `gorm:"index"`
	Forum       Forum  `gorm:"foreignKey:forum_id"`
	Approved    bool   `gorm:"index"`
	IsModerator bool   `gorm:"index"`
	CreatedAt   time.Time
	UpdatedAt   time.Time
}

// Preload related tables for the forum (classmethod).
func (f *ForumMembership) Preload() *gorm.DB {
	return DB.Preload("User").Preload("Forum")
}

// CreateForumMembership subscribes the user to a forum.
func CreateForumMembership(user *User, forum *Forum) (*ForumMembership, error) {
	var (
		f = &ForumMembership{
			User:     *user,
			Forum:    *forum,
			Approved: true,
		}
		result = DB.Create(f)
	)
	return f, result.Error
}

// GetForumMembership looks up a forum membership.
func GetForumMembership(user *User, forum *Forum) (*ForumMembership, error) {
	var (
		f      = &ForumMembership{}
		result = f.Preload().Where(
			"user_id = ? AND forum_id = ?",
			user.ID, forum.ID,
		).First(&f)
	)
	return f, result.Error
}

// IsForumSubscribed checks if the current user subscribes to this forum.
func IsForumSubscribed(user *User, forum *Forum) bool {
	f, _ := GetForumMembership(user, forum)
	return f.UserID == user.ID
}

// Delete a forum membership.
func (f *ForumMembership) Delete() error {
	return DB.Delete(f).Error
}

// PaginateForumMemberships paginates over a user's ForumMemberships.
func PaginateForumMemberships(user *User, pager *Pagination) ([]*ForumMembership, error) {
	var (
		fs           = []*ForumMembership{}
		query        = (&ForumMembership{}).Preload()
		wheres       = []string{}
		placeholders = []interface{}{}
	)

	query = query.Where(
		strings.Join(wheres, " AND "),
		placeholders...,
	).Order(pager.Sort)

	query.Model(&ForumMembership{}).Count(&pager.Total)
	result := query.Offset(pager.GetOffset()).Limit(pager.PerPage).Find(&fs)
	return fs, result.Error
}

// ForumMembershipMap maps table IDs to Likes metadata.
type ForumMembershipMap map[uint64]bool

// Get like stats from the map.
func (fm ForumMembershipMap) Get(id uint64) bool {
	return fm[id]
}

// MapForumMemberships looks up a user's memberships in bulk.
func MapForumMemberships(user *User, forums []*Forum) ForumMembershipMap {
	var (
		result   = ForumMembershipMap{}
		forumIDs = []uint64{}
	)

	// Initialize the result set.
	for _, forum := range forums {
		result[forum.ID] = false
		forumIDs = append(forumIDs, forum.ID)
	}

	// Map the forum IDs the user subscribes to.
	var followIDs = []uint64{}
	if res := DB.Model(&ForumMembership{}).Select(
		"forum_id",
	).Where(
		"user_id = ? AND forum_id IN ?",
		user.ID, forumIDs,
	).Scan(&followIDs); res.Error != nil {
		log.Error("MapForumMemberships: %s", res.Error)
	}

	for _, forumID := range followIDs {
		result[forumID] = true
	}

	return result
}