website/pkg/models/photo.go

package models

import (
	"errors"
	"fmt"
	"strings"
	"time"

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

// Photo table.
type Photo struct {
	ID              uint64 `gorm:"primaryKey"`
	UserID          uint64 `gorm:"index"`
	Filename        string
	CroppedFilename string // if cropped, e.g. for profile photo
	Filesize        int64
	Caption         string
	AltText         string
	Flagged         bool            // photo has been reported by the community
	AdminLabel      string          // admin label(s) on this photo (e.g. verified non-explicit)
	Visibility      PhotoVisibility `gorm:"index"`
	Gallery         bool            `gorm:"index"` // photo appears in the public gallery (if public)
	Explicit        bool            `gorm:"index"` // is an explicit photo
	Pinned          bool            `gorm:"index"` // user pins it to the front of their gallery
	LikeCount       int64           `gorm:"index"` // cache of 'likes' count
	CommentCount    int64           `gorm:"index"` // cache of comments count
	Views           uint64          `gorm:"index"` // view count
	CreatedAt       time.Time       `gorm:"index"`
	UpdatedAt       time.Time
}

// PhotoVisibility settings.
type PhotoVisibility string

const (
	PhotoPublic  PhotoVisibility = "public"  // on profile page and/or public gallery
	PhotoFriends PhotoVisibility = "friends" // only friends can see it
	PhotoPrivate PhotoVisibility = "private" // private

	// Special visibility in case, on User Gallery view, user applies a filter
	// for friends-only picture but they are not friends with the user.
	PhotoNotAvailable PhotoVisibility = "not_available"
)

// PhotoVisibility preset settings.
var (
	PhotoVisibilityAll = []PhotoVisibility{
		PhotoPublic,
		PhotoFriends,
		PhotoPrivate,
	}

	// Site Gallery visibility for when your friends show up in the gallery.
	// Or: "Friends + Gallery" photos can appear to your friends in the Site Gallery.
	PhotoVisibilityFriends = []string{
		string(PhotoPublic),
		string(PhotoFriends),
	}
)

// CreatePhoto with most of the settings you want (not ID or timestamps) in the database.
func CreatePhoto(tmpl Photo) (*Photo, error) {
	if tmpl.UserID == 0 {
		return nil, errors.New("UserID required")
	}

	p := &Photo{
		UserID:          tmpl.UserID,
		Filename:        tmpl.Filename,
		CroppedFilename: tmpl.CroppedFilename,
		Filesize:        tmpl.Filesize,
		Caption:         tmpl.Caption,
		AltText:         tmpl.AltText,
		Visibility:      tmpl.Visibility,
		Gallery:         tmpl.Gallery,
		Pinned:          tmpl.Pinned,
		Explicit:        tmpl.Explicit,
	}

	result := DB.Create(p)
	return p, result.Error
}

// GetPhoto by ID.
func GetPhoto(id uint64) (*Photo, error) {
	p := &Photo{}
	result := DB.First(&p, id)
	return p, result.Error
}

// GetPhotos by an array of IDs, mapped to their IDs.
func GetPhotos(IDs []uint64) (map[uint64]*Photo, error) {
	var (
		mp = map[uint64]*Photo{}
		ps = []*Photo{}
	)

	result := DB.Model(&Photo{}).Where("id IN ?", IDs).Find(&ps)
	for _, row := range ps {
		mp[row.ID] = row
	}

	return mp, result.Error
}

// CanBeEditedBy checks whether a photo can be edited by the current user.
//
// Admins with PhotoModerator scope can always edit.
func (p *Photo) CanBeEditedBy(currentUser *User) bool {
	if currentUser.HasAdminScope(config.ScopePhotoModerator) {
		return true
	}

	return p.UserID == currentUser.ID
}

// CanBeSeenBy checks whether a photo can be seen by the current user.
//
// An admin user with omni photo view permission can always see the photo.
//
// Note: this function incurs several DB queries to look up the photo's owner and block lists.
func (p *Photo) CanBeSeenBy(currentUser *User) (bool, error) {
	// Admins with photo moderator ability can always see.
	if currentUser.HasAdminScope(config.ScopePhotoModerator) {
		return true, nil
	}

	return p.ShouldBeSeenBy(currentUser)
}

// ShouldBeSeenBy checks whether a photo should be seen by the current user.
//
// Even if the current user is an admin with photo moderator ability, this function will return
// whether the admin 'should' be able to see if not for their admin status. Example: a private
// photo may be shown to the admin so they can moderate it, but they shouldn't be able to "like"
// it or mark it as "viewed."
//
// Note: this function incurs several DB queries to look up the photo's owner and block lists.
func (p *Photo) ShouldBeSeenBy(currentUser *User) (bool, error) {
	// Find the photo's owner.
	user, err := GetUser(p.UserID)
	if err != nil {
		return false, err
	}

	var isOwnPhoto = currentUser.ID == user.ID

	// Is either one blocking?
	if IsBlocking(currentUser.ID, user.ID) {
		return false, errors.New("is blocking")
	}

	// Is this user private and we're not friends?
	var (
		areFriends = AreFriends(user.ID, currentUser.ID)
		isPrivate  = user.Visibility == UserVisibilityPrivate && !areFriends
	)
	if isPrivate && !isOwnPhoto {
		return false, errors.New("user is private and we aren't friends")
	}

	// Is this a private photo and are we allowed to see?
	isGranted := IsPrivateUnlocked(user.ID, currentUser.ID)
	if p.Visibility == PhotoPrivate && !isGranted && !isOwnPhoto {
		return false, errors.New("photo is private")
	}

	return true, nil
}

// UserGallery configuration for filtering gallery pages.
type UserGallery struct {
	Explicit   string // "", "true", "false"
	Visibility []PhotoVisibility
}

/*
PaginateUserPhotos gets a page of photos belonging to a user ID.
*/
func PaginateUserPhotos(userID uint64, conf UserGallery, pager *Pagination) ([]*Photo, error) {
	var (
		p            = []*Photo{}
		wheres       = []string{}
		placeholders = []interface{}{}
	)

	var explicit = []bool{}
	switch conf.Explicit {
	case "true":
		explicit = []bool{true}
	case "false":
		explicit = []bool{false}
	}

	wheres = append(wheres, "user_id = ? AND visibility IN ?")
	placeholders = append(placeholders, userID, conf.Visibility)

	if len(explicit) > 0 {
		wheres = append(wheres, "explicit = ?")
		placeholders = append(placeholders, explicit[0])
	}

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

	// Get the total count.
	query.Model(&Photo{}).Count(&pager.Total)

	result := query.Offset(
		pager.GetOffset(),
	).Limit(pager.PerPage).Find(&p)

	return p, result.Error
}

// View a photo, incrementing its Views count but not its UpdatedAt.
// Debounced with a Redis key.
func (p *Photo) View(user *User) error {
	// The owner of the photo does not count views.
	if p.UserID == user.ID {
		return nil
	}

	// Should the viewer be able to see this, regardless of their admin ability?
	if ok, err := p.ShouldBeSeenBy(user); !ok {
		return err
	}

	// Debounce this.
	var redisKey = fmt.Sprintf(config.PhotoViewDebounceRedisKey, user.ID, p.ID)
	if redis.Exists(redisKey) {
		return nil
	}
	redis.Set(redisKey, nil, config.PhotoViewDebounceCooldown)

	return DB.Model(&Photo{}).Where(
		"id = ?",
		p.ID,
	).Updates(map[string]interface{}{
		"views":      p.Views + 1,
		"updated_at": p.UpdatedAt,
	}).Error
}

// CountPhotos returns the total number of photos on a user's account.
func CountPhotos(userID uint64) int64 {
	var count int64
	result := DB.Where(
		"user_id = ?",
		userID,
	).Model(&Photo{}).Count(&count)
	if result.Error != nil {
		log.Error("CountPhotos(%d): %s", userID, result.Error)
	}
	return count
}

// GetOrphanedPhotos gets all photos having no user ID associated.
func GetOrphanedPhotos() ([]*Photo, int64, error) {
	var (
		count int64
		ps    = []*Photo{}
	)

	query := DB.Model(&Photo{}).Where(`
		NOT EXISTS (
			SELECT 1 FROM users WHERE users.id = photos.user_id
		)
		OR photos.user_id = 0
	`)
	query.Count(&count)
	res := query.Find(&ps)
	if res.Error != nil {
		return nil, 0, res.Error
	}

	return ps, count, res.Error
}

// HasAdminLabelNonExplicit checks if the non-explicit admin label is applied to this photo.
func (p *Photo) HasAdminLabelNonExplicit() bool {
	return config.HasAdminLabel(config.AdminLabelPhotoNonExplicit, p.AdminLabel)
}

// HasAdminLabelForceExplicit checks if the force-explicit admin label is applied to this photo.
func (p *Photo) HasAdminLabelForceExplicit() bool {
	return config.HasAdminLabel(config.AdminLabelPhotoForceExplicit, p.AdminLabel)
}

// HasAdminLabel checks if the photo has an admin label (for convenient front-end access on the Edit page).
func (p *Photo) HasAdminLabel(label string) bool {
	return config.HasAdminLabel(label, p.AdminLabel)
}

// PhotoMap helps map a set of users to look up by ID.
type PhotoMap map[uint64]*Photo

// MapPhotos looks up a set of photos IDs in bulk and returns a PhotoMap suitable for templates.
func MapPhotos(photoIDs []uint64) (PhotoMap, error) {
	var (
		photoMap = PhotoMap{}
		set      = map[uint64]interface{}{}
		distinct = []uint64{}
	)

	// Uniqueify the IDs.
	for _, uid := range photoIDs {
		if _, ok := set[uid]; ok {
			continue
		}
		set[uid] = nil
		distinct = append(distinct, uid)
	}

	var (
		photos = []*Photo{}
		result = DB.Model(&Photo{}).Where("id IN ?", distinct).Find(&photos)
	)

	if result.Error == nil {
		for _, row := range photos {
			photoMap[row.ID] = row
		}
	}

	return photoMap, result.Error
}

// Has a photo ID in the map?
func (pm PhotoMap) Has(id uint64) bool {
	_, ok := pm[id]
	return ok
}

// Get a photo from the PhotoMap.
func (pm PhotoMap) Get(id uint64) *Photo {
	if photo, ok := pm[id]; ok {
		return photo
	}
	return nil
}

/*
IsSiteGalleryThrottled returns whether the user is throttled from marking additional pictures for the Site Gallery.

The thresholds are in pkg/config but the idea is a user can only upload (say) 5 Site Gallery photos within a
24 hour time span, so that new users who sign up and immediately max out their full gallery don't end up
spamming the Site Gallery for pages and pages.

If the user has too many recent Site Gallery pictures:

  - Newly uploaded photos can NOT check the Gallery box.
  - Editing any existing photo which is NOT in the Gallery: you can not mark the box either.
  - Existing Gallery photos CAN be un-marked for the gallery, which (if it is one of the 5 recent
    photos) may put the user below the threshold again.

If the user is on the Edit page for an existing photo, provide the Photo; otherwise leave it nil
if the user is uploading a new photo for the first time.
*/
func IsSiteGalleryThrottled(user *User, editPhoto *Photo) bool {
	// If the editing photo is already in the gallery, allow the user to keep or remove it.
	if editPhoto != nil && editPhoto.Gallery {
		return false
	}

	var count = CountRecentGalleryPhotos(user, config.SiteGalleryRateLimitInterval)
	log.Debug("IsSiteGalleryThrottled(%s): they have %d recent Gallery photos", user.Username, count)
	return count >= config.SiteGalleryRateLimitMax
}

// CountRecentGalleryPhotos returns the count of recently uploaded Site Gallery photos for a user,
// within the past 24 hours, to rate limit spammy bulk uploads that will flood the gallery.
func CountRecentGalleryPhotos(user *User, duration time.Duration) (count int64) {
	result := DB.Where(
		"user_id = ? AND created_at >= ? AND gallery IS TRUE",
		user.ID,
		time.Now().Add(-duration),
	).Model(&Photo{}).Count(&count)
	if result.Error != nil {
		log.Error("CountRecentGalleryPhotos(%d): %s", user.ID, result.Error)
	}
	return
}

// AllFriendsOnlyPhotoIDs returns the listing of all friends-only photo IDs belonging to the user(s) given.
func AllFriendsOnlyPhotoIDs(users ...*User) ([]uint64, error) {
	var userIDs = []uint64{}
	for _, user := range users {
		userIDs = append(userIDs, user.ID)
	}

	if len(userIDs) == 0 {
		return nil, errors.New("no user IDs given")
	}

	var photoIDs = []uint64{}
	err := DB.Table(
		"photos",
	).Select(
		"photos.id AS id",
	).Where(
		"user_id IN ? AND visibility = ?",
		userIDs, PhotoFriends,
	).Scan(&photoIDs)

	if err.Error != nil {
		return photoIDs, fmt.Errorf("AllFriendsOnlyPhotoIDs(%+v): %s", userIDs, err.Error)
	}

	return photoIDs, nil
}

// CountPhotosICanSee returns the number of photos on an account which can be seen by the given viewer.
func CountPhotosICanSee(user *User, viewer *User) int64 {
	// Visibility filters to query by.
	var visibilities = []PhotoVisibility{
		PhotoPublic,
	}

	// Is the viewer friends with the target?
	if AreFriends(user.ID, viewer.ID) {
		visibilities = append(visibilities, PhotoFriends)
	}

	// Is the viewer granted private access?
	if IsPrivateUnlocked(user.ID, viewer.ID) {
		visibilities = append(visibilities, PhotoPrivate)
	}

	// Get the photo count now.
	var count int64
	result := DB.Where(
		"user_id = ? AND visibility IN ?",
		user.ID, visibilities,
	).Model(&Photo{}).Count(&count)
	if result.Error != nil {
		log.Error("CountPhotosICanSee(%d, %d): %s", user.ID, viewer.ID, result.Error)
	}
	return count
}

// MapPhotoCounts returns a mapping of user ID to the CountPhotos()-equivalent result for each.
// It's used on the member directory to show photo counts on each user card.
func MapPhotoCounts(users []*User) PhotoCountMap {
	return MapPhotoCountsByVisibility(users, PhotoPublic)
}

// MapPhotoCountsByVisibility returns a mapping of user ID to the CountPhotos()-equivalent result for each.
func MapPhotoCountsByVisibility(users []*User, visibility PhotoVisibility) PhotoCountMap {
	var (
		userIDs = []uint64{}
		result  = PhotoCountMap{}
	)

	for _, user := range users {
		userIDs = append(userIDs, user.ID)
	}

	type group struct {
		UserID     uint64
		PhotoCount int64
	}
	var groups = []group{}

	if res := DB.Table(
		"photos",
	).Select(
		"user_id, count(id) AS photo_count",
	).Where(
		"user_id IN ? AND visibility = ?", userIDs, visibility,
	).Group("user_id").Scan(&groups); res.Error != nil {
		log.Error("CountPhotosForUsers: %s", res.Error)
	}

	// Map the results in.
	for _, row := range groups {
		result[row.UserID] = row.PhotoCount
	}

	return result
}

// MapPhotoCounts returns a mapping of user ID to the CountPhotosICanSee()-equivalent result for each.
// It's used on the member directory to show photo counts on each user card.
/* TODO: under construction..
func MapPhotoCounts(users []*User, viewer *User) PhotoCountMap {
	var (
		userIDs = []uint64{}
		result  = PhotoCountMap{}

		wheres       = []string{}
		placeholders = []interface{}{}

		// User ID filters for the viewer's context.
		myFriendIDs         = FriendIDs(viewer.ID)
		myPrivateGrantedIDs = PrivateGrantedUserIDs(viewer.ID)
	)

	// Define "all photos visibilities"
	var (
		photosPublic = []PhotoVisibility{
			PhotoPublic,
		}
		photosFriends = []PhotoVisibility{
			PhotoPublic,
			PhotoFriends,
		}
		photosPrivate = []PhotoVisibility{
			PhotoPublic,
			PhotoPrivate,
		}
	)

	// Flatten the userIDs of all passed in users.
	for _, user := range users {
		userIDs = append(userIDs, user.ID)
	}

	// Build the where clause.
	wheres = append(wheres, "user_id IN ?")
	placeholders = append(placeholders, userIDs)

	log.Error("FRIEND IDS: %+v", myFriendIDs)

	// Filter by which photos are visible to us.
	wheres = append(wheres,
		"((user_id IN ? AND visibility IN ?) OR "+
			"(user_id IN ? AND visibility IN ?) OR "+
			"(user_id NOT IN ? AND visibility IN ?))",
	)
	placeholders = append(placeholders,
		myFriendIDs, photosFriends,
		myPrivateGrantedIDs, photosPrivate,
		myFriendIDs, photosPublic,
	)

	type group struct {
		UserID     uint64
		PhotoCount int64
	}
	var groups = []group{}

	if res := DB.Table(
		"photos",
	).Select(
		"user_id, count(id) AS photo_count",
	).Where(
		strings.Join(wheres, " AND "),
		placeholders...,
	).Group("user_id").Scan(&groups); res.Error != nil {
		log.Error("CountPhotosForUsers: %s", res.Error)
	}

	// Map the results in.
	for _, row := range groups {
		result[row.UserID] = row.PhotoCount
	}

	return result
}
*/

type PhotoCountMap map[uint64]int64

// Get a photo count for the given user ID from the map.
func (pc PhotoCountMap) Get(id uint64) int64 {
	if value, ok := pc[id]; ok {
		return value
	}
	return 0
}

// CountExplicitPhotos returns the number of explicit photos a user has (so non-explicit viewers can see some do exist)
func CountExplicitPhotos(userID uint64, visibility []PhotoVisibility) (int64, error) {
	query := DB.Where(
		"user_id = ? AND visibility IN ? AND explicit = ?",
		userID,
		visibility,
		true,
	)

	var count int64
	result := query.Model(&Photo{}).Count(&count)
	return count, result.Error
}

// CountPublicPhotos returns the number of public photos on a user's page.
func CountPublicPhotos(userID uint64) int64 {
	return CountUserPhotosByVisibility(userID, PhotoPublic)
}

// CountUserPhotosByVisibility returns the number of a user's photos by visibility.
func CountUserPhotosByVisibility(userID uint64, visibility PhotoVisibility) int64 {
	query := DB.Where(
		"user_id = ? AND visibility = ?",
		userID,
		visibility,
	)

	var count int64
	result := query.Model(&Photo{}).Count(&count)
	if result.Error != nil {
		log.Error("CountUserPhotosByVisibility(%d, %s): %s", userID, visibility, result.Error)
	}
	return count
}

// DistinctPhotoTypes returns types of photos the user has: a set of public, friends, or private.
//
// The result is cached on the User the first time it's queried.
func (u *User) DistinctPhotoTypes() (result map[PhotoVisibility]struct{}) {
	if u.cachePhotoTypes != nil {
		return u.cachePhotoTypes
	}

	result = map[PhotoVisibility]struct{}{}

	var results = []*Photo{}
	query := DB.Model(&Photo{}).
		Select("DISTINCT photos.visibility").
		Where("user_id = ?", u.ID).
		Group("photos.visibility").
		Find(&results)
	if query.Error != nil {
		log.Error("User.DistinctPhotoTypes(%s): %s", u.Username, query.Error)
		return
	}

	for _, row := range results {
		log.Warn("DistinctPhotoTypes(%s): got %+v", u.Username, row)
		result[row.Visibility] = struct{}{}
	}

	u.cachePhotoTypes = result
	return
}

// FlushCaches clears any cached attributes (such as distinct photo types) for the user.
func (u *User) FlushCaches() {
	u.cachePhotoTypes = nil
	u.cacheBlockedUserIDs = nil
	u.cachePhotoIDs = nil
}

// Gallery config for the main Gallery paginator.
type Gallery struct {
	Explicit    string // Explicit filter
	Visibility  string // Visibility filter
	AdminView   bool   // Show all images
	IsShy       bool   // Current user is like a Shy Account (or: show self/friends and private photo grants only)
	FriendsOnly bool   // Only show self/friends instead of everybody's pics
	MyLikes     bool   // Filter to photos I have liked
	Uncertified bool   // Filter for non-certified members only
}

/*
PaginateGalleryPhotos gets a page of all public user photos for the site gallery.

Admin view returns ALL photos regardless of Gallery status.
*/
func PaginateGalleryPhotos(user *User, conf Gallery, pager *Pagination) ([]*Photo, error) {
	var (
		filterExplicit   = conf.Explicit
		filterVisibility = conf.Visibility
		adminView        = conf.AdminView
		friendsOnly      = conf.FriendsOnly // Show only self and friends pictures
		isShy            = conf.IsShy       // Self, friends, and private photo grants only
		p                = []*Photo{}
		query            *gorm.DB

		// Get the user ID and their preferences.
		userID     = user.ID
		explicitOK = user.Explicit // User opted-in for explicit content

		blocklist                = BlockedUserIDs(user)
		privateUserIDs           = PrivateGrantedUserIDs(userID)
		privateUserIDsAreFriends = PrivateGrantedUserIDsAreFriends(user)
		wheres                   = []string{}
		placeholders             = []interface{}{}
	)

	// Define "all photos visibilities"
	var (
		photosPublic = []PhotoVisibility{
			PhotoPublic,
		}
		photosFriends = []PhotoVisibility{
			PhotoPublic,
			PhotoFriends,
		}
		photosPrivate = []PhotoVisibility{
			PhotoPrivate,
		}
	)

	// Admins see everything on the site (only an admin user can get an admin view).
	adminView = user.HasAdminScope(config.ScopePhotoModerator) && adminView

	// Friend IDs subquery, used in a "WHERE user_id IN ?" clause.
	friendsQuery := fmt.Sprintf(`(
		SELECT target_user_id
		FROM friends
		WHERE source_user_id = %d
		AND approved IS TRUE
	)`, userID)

	// What sets of User ID * Visibility filters to query under?
	var (
		visOrs          = []string{}
		visPlaceholders = []interface{}{}
	)

	// Whose photos can you see on the Site Gallery?
	if isShy {
		// Shy users can only see their Friends photos (public or friends visibility)
		// and any Private photos to whom they were granted access.
		visOrs = append(visOrs,
			fmt.Sprintf("(photos.user_id IN %s AND photos.visibility IN ?)", friendsQuery),
			"(photos.user_id IN ? AND photos.visibility IN ?)",
			"photos.user_id = ?",
		)
		visPlaceholders = append(visPlaceholders,
			photosFriends,
			privateUserIDs, photosPrivate,
			userID,
		)
	} else if friendsOnly {
		// User wants to see only self and friends photos.
		visOrs = append(visOrs,
			fmt.Sprintf("(photos.user_id IN %s AND photos.visibility IN ?)", friendsQuery),
			"photos.user_id = ?",
		)
		visPlaceholders = append(visPlaceholders, photosFriends, userID)

		// If their friends granted private photos, include those too.
		if len(privateUserIDsAreFriends) > 0 {
			visOrs = append(visOrs, "(photos.user_id IN ? AND photos.visibility IN ?)")
			visPlaceholders = append(visPlaceholders, privateUserIDsAreFriends, photosPrivate)
		}
	} else {
		// You can see friends' Friend photos but only public for non-friends.
		visOrs = append(visOrs,
			fmt.Sprintf("(photos.user_id IN %s AND photos.visibility IN ?)", friendsQuery),
			"(photos.user_id IN ? AND photos.visibility IN ?)",
			fmt.Sprintf("(photos.user_id NOT IN %s AND photos.visibility IN ?)", friendsQuery),
			"photos.user_id = ?",
		)
		visPlaceholders = append(placeholders,
			photosFriends,
			privateUserIDs, photosPrivate,
			photosPublic,
			userID,
		)
	}

	// Join the User ID * Visibility filters into a nested "OR"
	wheres = append(wheres, fmt.Sprintf("(%s)", strings.Join(visOrs, " OR ")))
	placeholders = append(placeholders, visPlaceholders...)

	// Gallery photos only.
	wheres = append(wheres, "photos.gallery = ?")
	placeholders = append(placeholders, true)

	// Filter by photos the user has liked.
	if conf.MyLikes {
		wheres = append(wheres, `
			EXISTS (
				SELECT 1
				FROM likes
				WHERE likes.user_id = ?
				AND likes.table_name = 'photos'
				AND likes.table_id = photos.id
			)
		`)
		placeholders = append(placeholders, user.ID)
	}

	// Filter blocked users.
	if len(blocklist) > 0 {
		wheres = append(wheres, "photos.user_id NOT IN ?")
		placeholders = append(placeholders, blocklist)
	}

	// Non-explicit pics unless the user opted in. Allow explicit filter setting to override.
	if filterExplicit != "" {
		wheres = append(wheres, "photos.explicit = ?")
		placeholders = append(placeholders, filterExplicit == "true")
	} else if !explicitOK {
		wheres = append(wheres, "photos.explicit = ?")
		placeholders = append(placeholders, false)
	}

	// Is the user furthermore clamping the visibility filter?
	if filterVisibility != "" {
		wheres = append(wheres, "photos.visibility = ?")
		placeholders = append(placeholders, filterVisibility)
	}

	// Only certified (and not banned) user photos.
	if conf.Uncertified {
		wheres = append(wheres,
			"EXISTS (SELECT 1 FROM users WHERE id = photos.user_id AND users.certified IS NOT true AND users.status='active')",
		)
	} else {
		wheres = append(wheres,
			"EXISTS (SELECT 1 FROM users WHERE id = photos.user_id AND users.certified = true AND users.status='active')",
		)
	}

	// Exclude private users' photos.
	wheres = append(wheres,
		"NOT EXISTS (SELECT 1 FROM users WHERE id = photos.user_id AND photos.visibility = 'private')",
	)

	// Admin view: get ALL PHOTOS on the site, period.
	if adminView {
		query = DB

		// Admin may filter too.
		if filterVisibility != "" {
			query = query.Where("photos.visibility = ?", filterVisibility)
		}
		if filterExplicit != "" {
			query = query.Where("photos.explicit = ?", filterExplicit == "true")
		}
		if conf.Uncertified {
			query = query.Where(
				"EXISTS (SELECT 1 FROM users WHERE id = photos.user_id AND users.certified IS NOT true AND users.status='active')",
			)
		}
	} else {
		query = DB.Where(
			strings.Join(wheres, " AND "),
			placeholders...,
		)
	}

	query = query.Order(pager.Sort)
	query.Model(&Photo{}).Count(&pager.Total)
	result := query.Offset(pager.GetOffset()).Limit(pager.PerPage).Find(&p)
	return p, result.Error
}

// UpdatePhotoCachedCounts will refresh the cached like/comment count on the photos table.
func UpdatePhotoCachedCounts(photoID uint64) error {
	res := DB.Exec(`
		UPDATE photos
		SET like_count = (
			SELECT count(id)
			FROM likes
			WHERE table_name='photos'
			AND table_id=photos.id
		),
		comment_count = (
			SELECT count(id)
			FROM comments
			WHERE table_name='photos'
			AND table_id=photos.id
		)
		WHERE photos.id = ?;
	`, photoID)
	return res.Error
}

// Save photo.
func (p *Photo) Save() error {
	result := DB.Save(p)
	return result.Error
}

// Delete photo.
func (p *Photo) Delete() error {
	result := DB.Delete(p)
	return result.Error
}