Add forum post deletion

src/db/db.go

@@ -54,6 +54,11 @@ func typeIsQueryable(t reflect.Type) bool {
 	return false
 }
 
+// This interface should match both a direct pgx connection or a pgx transaction.
+type ConnOrTx interface {
+	Query(ctx context.Context, sql string, args ...interface{}) (pgx.Rows, error)
+}
+
 var connInfo = pgtype.NewConnInfo()
 
 func NewConn() *pgx.Conn {
@@ -211,7 +216,7 @@ func followPathThroughStructs(structPtrVal reflect.Value, path []int) (reflect.V
 	return val, field
 }
 
-func Query(ctx context.Context, conn *pgxpool.Pool, destExample interface{}, query string, args ...interface{}) (*StructQueryIterator, error) {
+func Query(ctx context.Context, conn ConnOrTx, destExample interface{}, query string, args ...interface{}) (*StructQueryIterator, error) {
 	destType := reflect.TypeOf(destExample)
 	columnNames, fieldPaths, err := getColumnNamesAndPaths(destType, nil, "")
 	if err != nil {
@@ -279,7 +284,7 @@ func getColumnNamesAndPaths(destType reflect.Type, pathSoFar []int, prefix strin
 
 var ErrNoMatchingRows = errors.New("no matching rows")
 
-func QueryOne(ctx context.Context, conn *pgxpool.Pool, destExample interface{}, query string, args ...interface{}) (interface{}, error) {
+func QueryOne(ctx context.Context, conn ConnOrTx, destExample interface{}, query string, args ...interface{}) (interface{}, error) {
 	rows, err := Query(ctx, conn, destExample, query, args...)
 	if err != nil {
 		return nil, err
@@ -294,7 +299,7 @@ func QueryOne(ctx context.Context, conn *pgxpool.Pool, destExample interface{},
 	return result, nil
 }
 
-func QueryScalar(ctx context.Context, conn *pgxpool.Pool, query string, args ...interface{}) (interface{}, error) {
+func QueryScalar(ctx context.Context, conn ConnOrTx, query string, args ...interface{}) (interface{}, error) {
 	rows, err := conn.Query(ctx, query, args...)
 	if err != nil {
 		return nil, err
@@ -317,7 +322,7 @@ func QueryScalar(ctx context.Context, conn *pgxpool.Pool, query string, args ...
 	return nil, ErrNoMatchingRows
 }
 
-func QueryInt(ctx context.Context, conn *pgxpool.Pool, query string, args ...interface{}) (int, error) {
+func QueryInt(ctx context.Context, conn ConnOrTx, query string, args ...interface{}) (int, error) {
 	result, err := QueryScalar(ctx, conn, query, args...)
 	if err != nil {
 		return 0, err
@@ -334,3 +339,17 @@ func QueryInt(ctx context.Context, conn *pgxpool.Pool, query string, args ...int
 		return 0, oops.New(nil, "QueryInt got a non-int result: %v", result)
 	}
 }
+
+func QueryBool(ctx context.Context, conn ConnOrTx, query string, args ...interface{}) (bool, error) {
+	result, err := QueryScalar(ctx, conn, query, args...)
+	if err != nil {
+		return false, err
+	}
+
+	switch r := result.(type) {
+	case bool:
+		return r, nil
+	default:
+		return false, oops.New(nil, "QueryBool got a non-bool result: %v", result)
+	}
+}

src/templates/src/editor.html

@@ -75,51 +75,7 @@
 
             {{ with .PostReplyingTo }}
                 <h4 class="mt3">The post you're replying to:</h4>
-                <div class="bg--dim pa3 br3">
+                {{ template "forum_post_standalone.html" . }}
-                    <div class="w-100 flex items-center">
-                        {{ if .Author }}
-                            <div class="w-20 mw3 w3">
-                                <!-- Mobile avatar -->
-                                <div class="aspect-ratio--1x1 contain bg-center" style="background-image:url('{{ .Author.AvatarUrl }}');"></div>
-                            </div>
-                            <div class="pl3 flex flex-column">
-                                <div>
-                                    <a class="username" href="{{ .Author.ProfileUrl }}" target="_blank">{{ .Author.Username }}</a> {{/* TODO: Text scale stuff? Seems unnecessary. */}}
-                                    <!-- Mobile badges -->
-                                    <div class="di ph1">
-                                        {{ if .Author.IsStaff }}
-                                            <div class="badge staff"></div>
-                                        {{ end }}
-                                    </div>
-                                </div>
-                                {{ if and .Author.Name (ne .Author.Name .Author.Username) }}
-                                    <div class="c--dim f7"> {{ .Author.Name }} </div>
-                                {{ end }}
-                                <div class="c--dim f7">
-                                    {{ timehtml (relativedate .PostDate) .PostDate }}
-                                    {{ if .Editor }}
-                                        <span class="pl3">
-                                            Edited by
-                                            <a class="name" href="{{ .Editor.ProfileUrl }}" target="_blank">{{ coalesce .Editor.Name .Editor.Username }}</a>
-                                            on {{ timehtml (absolutedate .EditDate) .EditDate }}
-                                            {{ with .EditReason }}
-                                                Reason: {{ . }}
-                                            {{ end }}
-                                        </span>
-                                    {{ end }}
-                                </div>
-                            </div>
-                        {{ else }}
-                            <div class="username">Deleted member</div>
-                            <div class="avatar" style="background-image:url('{{ .Author.AvatarUrl }}');"></div>
-                        {{ end }}
-                    </div>
-                    <div class="w-100 pt3">
-                        <div class="contents overflow-x-auto">
-                            {{ .Content }}
-                        </div>
-                    </div>
-                </div>
             {{ end }}
 
             {{/*

src/templates/src/forum_post_delete.html

@@ -0,0 +1,11 @@
+{{ template "base.html" . }}
+
+{{ define "content" }}
+<div class="mw7 margin-center">
+    <h3 class="mb3">Are you sure you want to delete this post?</h3>
+    {{ template "forum_post_standalone.html" .Post }}
+    <form action="{{ .SubmitUrl }}" method="POST" class="pv3 flex justify-end">
+        <input type="submit" value="Delete Post">
+    </form>
+</div>
+{{ end }}

src/templates/src/include/forum_post_standalone.html

@@ -0,0 +1,40 @@
+<div class="bg--dim pa3 br3 tl">
+    <div class="w-100 flex items-center">
+        <div class="w-20 mw3 w3">
+            <!-- Mobile avatar -->
+            <div class="aspect-ratio--1x1 contain bg-center" style="background-image:url('{{ .Author.AvatarUrl }}');"></div>
+        </div>
+        <div class="pl3 flex flex-column">
+            <div>
+                <a class="username" href="{{ .Author.ProfileUrl }}" target="_blank">{{ .Author.Username }}</a> {{/* TODO: Text scale stuff? Seems unnecessary. */}}
+                <!-- Mobile badges -->
+                <div class="di ph1">
+                    {{ if .Author.IsStaff }}
+                        <div class="badge staff"></div>
+                    {{ end }}
+                </div>
+            </div>
+            {{ if and .Author.Name (ne .Author.Name .Author.Username) }}
+                <div class="c--dim f7"> {{ .Author.Name }} </div>
+            {{ end }}
+            <div class="c--dim f7">
+                {{ timehtml (relativedate .PostDate) .PostDate }}
+                {{ if .Editor }}
+                    <span class="pl3">
+                        Edited by
+                        <a class="name" href="{{ .Editor.ProfileUrl }}" target="_blank">{{ coalesce .Editor.Name .Editor.Username }}</a>
+                        on {{ timehtml (absolutedate .EditDate) .EditDate }}
+                        {{ with .EditReason }}
+                            Reason: {{ . }}
+                        {{ end }}
+                    </span>
+                {{ end }}
+            </div>
+        </div>
+    </div>
+    <div class="w-100 pt3">
+        <div class="contents overflow-x-auto">
+            {{ .Content }}
+        </div>
+    </div>
+</div>

src/website/forums.go

@@ -19,6 +19,7 @@ import (
 	"git.handmade.network/hmn/hmn/src/templates"
 	"git.handmade.network/hmn/hmn/src/utils"
 	"github.com/jackc/pgx/v4"
+	"github.com/jackc/pgx/v4/pgxpool"
 )
 
 type forumCategoryData struct {
@@ -821,8 +822,10 @@ func ForumPostEdit(c *RequestContext) ResponseData {
 	result := postQueryResult.(*postQuery)
 
 	// Ensure that the user is permitted to edit the post
-	isPostAuthor := result.Author != nil && result.Author.ID == c.CurrentUser.ID
+	canEdit, err := canEditPost(c.Context(), c.Conn, requestedPostId, *c.CurrentUser)
-	if !(isPostAuthor || c.CurrentUser.IsStaff) {
+	if err != nil {
+		return ErrorResponse(http.StatusInternalServerError, err)
+	} else if !canEdit {
 		return FourOhFour(c)
 	}
 
@@ -875,33 +878,10 @@ func ForumPostEditSubmit(c *RequestContext) ResponseData {
 	}
 
 	// Ensure that the user is permitted to edit the post
-	type postResult struct {
+	canEdit, err := canEditPost(c.Context(), c.Conn, postId, *c.CurrentUser)
-		AuthorID *int `db:"author.id"`
+	if err != nil {
-	}
+		return ErrorResponse(http.StatusInternalServerError, err)
-	iresult, err := db.QueryOne(c.Context(), c.Conn, postResult{},
+	} else if !canEdit {
-		`
-		SELECT $columns
-		FROM
-			handmade_post AS post
-			LEFT JOIN auth_user AS author ON post.author_id = author.id
-		WHERE
-			post.category_id = $1
-			AND post.thread_id = $2
-			AND post.id = $3
-			AND NOT post.deleted
-		ORDER BY postdate
-		`,
-		currentCatId,
-		threadId,
-		postId,
-	)
-	if err != nil && !errors.Is(err, db.ErrNoMatchingRows) {
-		return ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to get author of post to delete"))
-	}
-	result := iresult.(*postResult)
-
-	isPostAuthor := result.AuthorID != nil && *result.AuthorID == c.CurrentUser.ID
-	if !(isPostAuthor || c.CurrentUser.IsStaff) {
 		return FourOhFour(c)
 	}
 
@@ -920,6 +900,210 @@ func ForumPostEditSubmit(c *RequestContext) ResponseData {
 	return c.Redirect(postUrl, http.StatusSeeOther)
 }
 
+func ForumPostDelete(c *RequestContext) ResponseData {
+	// TODO(compression): This logic for fetching posts by thread id / post id is gonna
+	// show up in a lot of places. It's used multiple times for forums, and also for blogs.
+	// Consider compressing this later.
+	c.Perf.StartBlock("SQL", "Fetch category tree")
+	categoryTree := models.GetFullCategoryTree(c.Context(), c.Conn)
+	lineageBuilder := models.MakeCategoryLineageBuilder(categoryTree)
+	c.Perf.EndBlock()
+
+	currentCatId, valid := validateSubforums(lineageBuilder, c.CurrentProject, c.PathParams["cats"])
+	if !valid {
+		return FourOhFour(c)
+	}
+
+	requestedThreadId, err := strconv.Atoi(c.PathParams["threadid"])
+	if err != nil {
+		return FourOhFour(c)
+	}
+
+	requestedPostId, err := strconv.Atoi(c.PathParams["postid"])
+	if err != nil {
+		return FourOhFour(c)
+	}
+
+	// Ensure that the user is allowed to delete this post
+	canEdit, err := canEditPost(c.Context(), c.Conn, requestedPostId, *c.CurrentUser)
+	if err != nil {
+		return ErrorResponse(http.StatusInternalServerError, err)
+	} else if !canEdit {
+		return FourOhFour(c)
+	}
+
+	c.Perf.StartBlock("SQL", "Fetch post to delete")
+	type postQuery struct {
+		Thread         models.Thread      `db:"thread"`
+		Post           models.Post        `db:"post"`
+		CurrentVersion models.PostVersion `db:"ver"`
+		Author         *models.User       `db:"author"`
+		Editor         *models.User       `db:"editor"`
+	}
+	postQueryResult, err := db.QueryOne(c.Context(), c.Conn, postQuery{},
+		`
+		SELECT $columns
+		FROM
+			handmade_thread AS thread
+			JOIN handmade_post AS post ON post.thread_id = thread.id
+			JOIN handmade_postversion AS ver ON post.current_id = ver.id
+			LEFT JOIN auth_user AS author ON post.author_id = author.id
+			LEFT JOIN auth_user AS editor ON ver.editor_id = editor.id
+		WHERE
+			post.category_id = $1
+			AND post.thread_id = $2
+			AND post.id = $3
+			AND NOT post.deleted
+		ORDER BY postdate
+		`,
+		currentCatId,
+		requestedThreadId,
+		requestedPostId,
+	)
+	if err != nil {
+		if errors.Is(err, db.ErrNoMatchingRows) {
+			return FourOhFour(c)
+		} else {
+			return ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to fetch post to delete"))
+		}
+	}
+	result := postQueryResult.(*postQuery)
+
+	baseData := getBaseData(c)
+	baseData.Title = fmt.Sprintf("Deleting post in \"%s\" | %s", result.Thread.Title, *categoryTree[currentCatId].Name)
+	baseData.MathjaxEnabled = true
+	// TODO(ben): Set breadcrumbs
+
+	templatePost := templates.PostToTemplate(&result.Post, result.Author, c.Theme)
+	templatePost.AddContentVersion(result.CurrentVersion, result.Editor)
+
+	type forumPostDeleteData struct {
+		templates.BaseData
+		Post      templates.Post
+		SubmitUrl string
+	}
+
+	var res ResponseData
+	res.MustWriteTemplate("forum_post_delete.html", forumPostDeleteData{
+		BaseData:  baseData,
+		SubmitUrl: hmnurl.BuildForumPostDelete(c.CurrentProject.Slug, lineageBuilder.GetSubforumLineageSlugs(currentCatId), requestedThreadId, requestedPostId),
+		Post:      templatePost,
+	}, c.Perf)
+	return res
+}
+
+func ForumPostDeleteSubmit(c *RequestContext) ResponseData {
+	// TODO(compression): This logic for fetching posts by thread id / post id is gonna
+	// show up in a lot of places. It's used multiple times for forums, and also for blogs.
+	// Consider compressing this later.
+	c.Perf.StartBlock("SQL", "Fetch category tree")
+	categoryTree := models.GetFullCategoryTree(c.Context(), c.Conn)
+	lineageBuilder := models.MakeCategoryLineageBuilder(categoryTree)
+	c.Perf.EndBlock()
+
+	currentCatId, valid := validateSubforums(lineageBuilder, c.CurrentProject, c.PathParams["cats"])
+	if !valid {
+		return FourOhFour(c)
+	}
+
+	threadId, err := strconv.Atoi(c.PathParams["threadid"])
+	if err != nil {
+		return FourOhFour(c)
+	}
+
+	postId, err := strconv.Atoi(c.PathParams["postid"])
+	if err != nil {
+		return FourOhFour(c)
+	}
+
+	// Ensure that the user is allowed to delete this post
+	canEdit, err := canEditPost(c.Context(), c.Conn, postId, *c.CurrentUser)
+	if err != nil {
+		return ErrorResponse(http.StatusInternalServerError, err)
+	} else if !canEdit {
+		return FourOhFour(c)
+	}
+
+	tx, err := c.Conn.Begin(c.Context())
+	if err != nil {
+		panic(err)
+	}
+	defer tx.Rollback(c.Context())
+
+	isFirstPost, err := db.QueryBool(c.Context(), tx,
+		`
+		SELECT thread.first_id = $1
+		FROM
+			handmade_thread AS thread
+		WHERE
+			thread.id = $2
+		`,
+		postId,
+		threadId,
+	)
+	if err != nil {
+		return ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to check if post was the first post in the thread"))
+	}
+
+	if isFirstPost {
+		// Just delete the whole thread and all its posts.
+		_, err = tx.Exec(c.Context(),
+			`
+			UPDATE handmade_thread
+			SET deleted = TRUE
+			WHERE id = $1
+			`,
+			threadId,
+		)
+		_, err = tx.Exec(c.Context(),
+			`
+			UPDATE handmade_post
+			SET deleted = TRUE
+			WHERE thread_id = $1
+			`,
+			threadId,
+		)
+
+		err = tx.Commit(c.Context())
+		if err != nil {
+			return ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to delete thread and posts when deleting the first post"))
+		}
+
+		forumUrl := hmnurl.BuildForumCategory(c.CurrentProject.Slug, lineageBuilder.GetSubforumLineageSlugs(currentCatId), 1)
+		return c.Redirect(forumUrl, http.StatusSeeOther)
+	}
+
+	_, err = tx.Exec(c.Context(),
+		`
+		UPDATE handmade_post
+		SET deleted = TRUE
+		WHERE
+			id = $1
+		`,
+		postId,
+	)
+	if err != nil {
+		return ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to mark forum post as deleted"))
+	}
+
+	err = fixThreadPostIds(c.Context(), tx, threadId)
+	if err != nil {
+		if errors.Is(err, errThreadEmpty) {
+			panic("it shouldn't be possible to delete the last remaining post in a thread, without it also being the first post in the thread and thus resulting in the whole thread getting deleted earlier")
+		} else {
+			return ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to fix up thread post ids"))
+		}
+	}
+
+	err = tx.Commit(c.Context())
+	if err != nil {
+		return ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to delete post"))
+	}
+
+	threadUrl := hmnurl.BuildForumThread(c.CurrentProject.Slug, lineageBuilder.GetSubforumLineageSlugs(currentCatId), threadId, "", 1) // TODO: Go to the last page of the thread? Or the post before the post we just deleted?
+	return c.Redirect(threadUrl, http.StatusSeeOther)
+}
+
 func createNewForumPostAndVersion(ctx context.Context, tx pgx.Tx, catId, threadId, userId, projectId int, unparsedContent string, ipString string, replyId *int) (postId, versionId int) {
 	// Create post
 	err := tx.QueryRow(ctx,
@@ -1028,3 +1212,92 @@ func validateSubforums(lineageBuilder *models.CategoryLineageBuilder, project *m
 	}
 	return subforumCatId, valid
 }
+
+func canEditPost(ctx context.Context, conn *pgxpool.Pool, postId int, currentUser models.User) (bool, error) {
+	if currentUser.IsStaff {
+		return true, nil
+	}
+
+	type postResult struct {
+		AuthorID *int `db:"author.id"`
+	}
+	iresult, err := db.QueryOne(ctx, conn, postResult{},
+		`
+		SELECT $columns
+		FROM
+			handmade_post AS post
+			LEFT JOIN auth_user AS author ON post.author_id = author.id
+		WHERE
+			post.id = $1
+			AND NOT post.deleted
+		ORDER BY postdate
+		`,
+		postId,
+	)
+	if err != nil {
+		if errors.Is(err, db.ErrNoMatchingRows) {
+			return false, nil
+		} else {
+			return false, oops.New(err, "failed to get author of post when checking permissions")
+		}
+	}
+	result := iresult.(*postResult)
+
+	return result.AuthorID != nil && *result.AuthorID == currentUser.ID, nil
+}
+
+var errThreadEmpty = errors.New("thread contained no non-deleted posts")
+
+/*
+Ensures that the first_id and last_id on the thread are still good.
+
+Returns errThreadEmpty if the thread contains no visible posts any more.
+You should probably mark the thread as deleted in this case.
+*/
+func fixThreadPostIds(ctx context.Context, tx pgx.Tx, threadId int) error {
+	postsIter, err := db.Query(ctx, tx, models.Post{},
+		`
+		SELECT $columns
+		FROM handmade_post
+		WHERE
+			thread_id = $1
+			AND NOT deleted
+		`,
+		threadId,
+	)
+	if err != nil {
+		return oops.New(err, "failed to fetch posts when fixing up thread")
+	}
+
+	var firstPost, lastPost *models.Post
+	for _, ipost := range postsIter.ToSlice() {
+		post := ipost.(*models.Post)
+
+		if firstPost == nil || post.PostDate.Before(firstPost.PostDate) {
+			firstPost = post
+		}
+		if lastPost == nil || post.PostDate.After(lastPost.PostDate) {
+			lastPost = post
+		}
+	}
+
+	if firstPost == nil || lastPost == nil {
+		return errThreadEmpty
+	}
+
+	_, err = tx.Exec(ctx,
+		`
+		UPDATE handmade_thread
+		SET first_id = $1, last_id = $2
+		WHERE id = $3
+		`,
+		firstPost.ID,
+		lastPost.ID,
+		threadId,
+	)
+	if err != nil {
+		return oops.New(err, "failed to update thread first/last ids")
+	}
+
+	return nil
+}

src/website/routes.go

@@ -162,7 +162,8 @@ func NewWebsiteRoutes(conn *pgxpool.Pool, perfCollector *perf.PerfCollector) htt
 	mainRoutes.POST(hmnurl.RegexForumPostReply, authMiddleware(ForumPostReplySubmit))
 	mainRoutes.GET(hmnurl.RegexForumPostEdit, authMiddleware(ForumPostEdit))
 	mainRoutes.POST(hmnurl.RegexForumPostEdit, authMiddleware(ForumPostEditSubmit))
-	// mainRoutes.GET(hmnurl.RegexForumPostDelete, authMiddleware(ForumPostDelete))
+	mainRoutes.GET(hmnurl.RegexForumPostDelete, authMiddleware(ForumPostDelete))
+	mainRoutes.POST(hmnurl.RegexForumPostDelete, authMiddleware(ForumPostDeleteSubmit))
 
 	mainRoutes.GET(hmnurl.RegexProjectCSS, ProjectCSS)