website/pkg/models/forum_recent.go

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package models
import (
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"sort"
"strings"
"time"
"code.nonshy.com/nonshy/website/pkg/config"
"code.nonshy.com/nonshy/website/pkg/log"
)
// RecentPost drives the "Forums / Newest" page - carrying all forum comments
// on all threads sorted by date.
type RecentPost struct {
CommentID uint64
ThreadID uint64
ForumID uint64
UpdatedAt time.Time
Thread *Thread
Comment *Comment
Forum *Forum
}
// PaginateRecentPosts returns all of the comments on a forum paginated.
func PaginateRecentPosts(user *User, categories []string, allComments bool, pager *Pagination) ([]*RecentPost, error) {
var (
result = []*RecentPost{}
blockedUserIDs = BlockedUserIDs(user)
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// Separate the WHERE clauses that involve forums/threads from the ones
// that involve comments. Rationale: if the user is getting a de-duplicated
// thread view, we'll end up running two queries - one to get all threads and
// another to get the latest comments, and the WHERE clauses need to be separate.
wheres = []string{}
placeholders = []interface{}{}
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comment_wheres = []string{"table_name = 'threads'"}
comment_ph = []interface{}{}
)
if len(categories) > 0 {
wheres = append(wheres, "forums.category IN ?")
placeholders = append(placeholders, categories)
}
// Hide explicit forum if user hasn't opted into it.
if !user.Explicit && !user.IsAdmin {
wheres = append(wheres, "forums.explicit = false")
}
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// Circle membership.
if !user.IsInnerCircle() {
wheres = append(wheres, "forums.inner_circle is not true")
}
// Blocked users?
if len(blockedUserIDs) > 0 {
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comment_wheres = append(comment_wheres, "comments.user_id NOT IN ?")
comment_ph = append(comment_ph, blockedUserIDs)
}
// Don't show comments from banned or disabled accounts.
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comment_wheres = append(comment_wheres, `
EXISTS (
SELECT 1
FROM users
WHERE users.id = comments.user_id
AND users.status = 'active'
)
`)
// Get the page of recent forum comment IDs of all time.
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var scan NewestForumPostsScanner
// Deduplicate forum threads: if one thread is BLOWING UP with replies, we should only
// mention the thread once and show the newest comment so it doesn't spam the whole page.
if config.Current.Database.IsPostgres && !allComments {
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// Note: only Postgres supports this function (SELECT DISTINCT ON).
if res, err := ScanLatestForumCommentsPerThread(wheres, comment_wheres, placeholders, comment_ph, pager); err != nil {
return nil, err
} else {
scan = res
}
} else {
// SQLite/non-Postgres doesn't support DISTINCT ON, this is the old query which
// shows objectively all comments and a popular thread may dominate the page.
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if res, err := ScanLatestForumCommentsAll(wheres, comment_wheres, placeholders, comment_ph, pager); err != nil {
return nil, err
} else {
scan = res
}
}
// Ingest the results.
var (
commentIDs = []uint64{} // collect distinct IDs
threadIDs = []uint64{}
forumIDs = []uint64{}
seenComments = map[uint64]interface{}{} // deduplication
seenThreads = map[uint64]interface{}{}
seenForums = map[uint64]interface{}{}
mapCommentRC = map[uint64]*RecentPost{} // map commentID to result
)
for _, row := range scan {
// Upsert the result set.
var rp *RecentPost
if existing, ok := mapCommentRC[row.CommentID]; ok {
rp = existing
} else {
rp = &RecentPost{
CommentID: row.CommentID,
}
mapCommentRC[row.CommentID] = rp
result = append(result, rp)
}
// Got a thread ID?
if row.ThreadID != nil {
rp.ThreadID = *row.ThreadID
if _, ok := seenThreads[rp.ThreadID]; !ok {
seenThreads[rp.ThreadID] = nil
threadIDs = append(threadIDs, rp.ThreadID)
}
}
// Got a forum ID?
if row.ForumID != nil {
rp.ForumID = *row.ForumID
if _, ok := seenForums[rp.ForumID]; !ok {
seenForums[rp.ForumID] = nil
forumIDs = append(forumIDs, rp.ForumID)
}
}
// Collect distinct comment IDs.
if _, ok := seenComments[rp.CommentID]; !ok {
seenComments[rp.CommentID] = nil
commentIDs = append(commentIDs, rp.CommentID)
}
}
// Load all of the distinct comments, threads and forums.
var (
comments = map[uint64]*Comment{}
threads = map[uint64]*Thread{}
forums = map[uint64]*Forum{}
)
if len(commentIDs) > 0 {
comments, _ = GetComments(commentIDs)
}
if len(threadIDs) > 0 {
threads, _ = GetThreadsAsUser(user, threadIDs)
}
if len(forumIDs) > 0 {
forums, _ = GetForums(forumIDs)
}
// Collect comments so we can inject UserRelationships in efficiently.
var (
coms = []*Comment{}
thrs = []*Thread{}
)
// Merge all the objects back in.
for _, rc := range result {
if com, ok := comments[rc.CommentID]; ok {
rc.Comment = com
coms = append(coms, com)
}
if thr, ok := threads[rc.ThreadID]; ok {
rc.Thread = thr
thrs = append(thrs, thr)
} else {
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log.Error("RecentPosts: didn't find thread ID %d in map!", rc.ThreadID)
// Create a dummy placeholder Thread (e.g.: the thread originator has been
// banned or disabled, but the thread summary is shown on the new comment view)
rc.Thread = &Thread{
Comment: Comment{
Message: "[unavailable]",
},
}
}
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// Is the new comment unavailable? (e.g. blocked, banned, disabled)
if rc.Comment == nil {
rc.Comment = &Comment{
Message: "[unavailable]",
}
}
if f, ok := forums[rc.ForumID]; ok {
rc.Forum = f
}
}
// Inject user relationships into all comment users now.
SetUserRelationshipsInComments(user, coms)
SetUserRelationshipsInThreads(user, thrs)
return result, nil
}
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// NewestForumPosts collects the IDs of the latest forum posts.
type NewestForumPosts struct {
CommentID uint64
ThreadID *uint64
ForumID *uint64
UpdatedAt time.Time
}
type NewestForumPostsScanner []NewestForumPosts
// ScanLatestForumCommentsAll returns a scan of Newest forum posts containing ALL comments, which may
// include runs of 'duplicate' forum threads if a given thread was commented on rapidly. This is the classic
// 'Newest' tab behavior, showing just ALL forum comments by newest.
func ScanLatestForumCommentsAll(wheres, comment_wheres []string, placeholders, comment_ph []interface{}, pager *Pagination) (NewestForumPostsScanner, error) {
var scan NewestForumPostsScanner
// This one is all one joined query so join the wheres/placeholders.
wheres = append(wheres, comment_wheres...)
placeholders = append(placeholders, comment_ph...)
// SQLite/non-Postgres doesn't support DISTINCT ON, this is the old query which
// shows objectively all comments and a popular thread may dominate the page.
query := DB.Table("comments").Select(
`comments.id AS comment_id,
threads.id AS thread_id,
forums.id AS forum_id,
comments.updated_at AS updated_at`,
).Joins(
"LEFT OUTER JOIN threads ON (table_name = 'threads' AND table_id = threads.id)",
).Joins(
"LEFT OUTER JOIN forums ON (threads.forum_id = forums.id)",
).Where(
strings.Join(wheres, " AND "),
placeholders...,
).Order("comments.updated_at desc")
query.Model(&Comment{}).Count(&pager.Total)
// Execute the query.
query = query.Offset(pager.GetOffset()).Limit(pager.PerPage).Find(&scan)
return scan, query.Error
}
// ScanLatestForumCommentsPerThread returns a scan of Newest forum posts, deduplicated by thread.
// Each thread ID will only appear once in the result, paired with the newest comment in that
// thread.
func ScanLatestForumCommentsPerThread(wheres, comment_wheres []string, placeholders, comment_ph []interface{}, pager *Pagination) (NewestForumPostsScanner, error) {
var (
result NewestForumPostsScanner
threadIDs = []uint64{}
// Query for ALL thread IDs (in forums the user can see).
query = DB.Table(
"threads",
).Select(`
DISTINCT ON (threads.id)
threads.forum_id,
threads.id AS thread_id,
threads.updated_at AS updated_at
`).Joins(
"JOIN forums ON (threads.forum_id = forums.id)",
).Where(
strings.Join(wheres, " AND "),
placeholders...,
).Order(
"threads.id",
)
)
query = query.Find(&result)
if query.Error != nil {
return result, query.Error
}
pager.Total = int64(len(result))
// Reorder the result by timestamp.
sort.Slice(result, func(i, j int) bool {
return result[i].UpdatedAt.After(result[j].UpdatedAt)
})
// Subslice the result per the user's pagination setting.
var (
start = pager.GetOffset()
stop = start + pager.PerPage
)
if start > len(result) {
return NewestForumPostsScanner{}, nil
} else if stop > len(result) {
stop = len(result)
}
result = result[start:stop]
// Map the thread IDs to their result row.
var threadMap = map[uint64]int{}
for i, row := range result {
threadIDs = append(threadIDs, *row.ThreadID)
threadMap[*row.ThreadID] = i
}
// With these thread IDs, select the newest comments.
type scanner struct {
ThreadID uint64
CommentID uint64
}
var scan []scanner
err := DB.Table(
"comments",
).Select(
"table_id AS thread_id, id AS comment_id",
).Where(
`table_name='threads' AND table_id IN ?
AND updated_at = (SELECT MAX(updated_at)
FROM comments c2
WHERE c2.table_name=comments.table_name
AND c2.table_id=comments.table_id
)`,
threadIDs,
).Where(
strings.Join(comment_wheres, " AND "),
comment_ph...,
).Order(
"updated_at desc",
).Scan(&scan)
if err.Error != nil {
log.Error("Getting most recent post IDs: %s", err.Error)
return result, err.Error
}
// Populate the comment IDs back in.
for _, row := range scan {
if idx, ok := threadMap[row.ThreadID]; ok {
result[idx].CommentID = row.CommentID
}
}
return result, query.Error
}