add tag filtering

the only currently supported form of tag filtering is by specifying
a single tag, and then only threads with that tag will be displayed.
this meets all of the reasonable use cases i can think of right now.

3 files changed, 75 insertions, 15 deletions

diff --git a/apioforum/forum.py b/apioforum/forum.py
index bf9610d..7f9b0b6 100644
--- a/apioforum/forum.py
+++ b/apioforum/forum.py
@@ -102,7 +102,30 @@ def view_forum(forum,page=1):
         sortby_dir = {'d':'DESC','a':'ASC'}[sortby[1]]
         sortby_by  = {'a':'threads.updated','c':'threads.created'}[sortby[0]]
     except KeyError:
-        return redirect(url_for('forum.view_forum',forum_id=forum_id))
+        return redirect(url_for('forum.view_forum',forum_id=forum['id']))
+
+    avail_tags = get_avail_tags(forum['id'])
+
+    tagfilter = request.args.get("tagfilter",None)
+    tagfilter_clause = ""
+    tagfilter_tag = None
+    if tagfilter is not None:
+        try:
+            tagfilter = int(tagfilter)
+        except ValueError:
+            return redirect(url_for('forum.view_forum',forum_id=forum['id']))
+        else:
+            # there is no risk of sql injection because
+            # we just checked it is an int
+            tagfilter_clause = f"AND thread_tags.tag = {tagfilter}"
+            for the_tag in avail_tags:
+                if the_tag['id'] == tagfilter:
+                    tagfilter_tag = the_tag
+                    break
+            else:
+                flash("that tag doesn't exist or isn't available here")
+                return redirect(url_for('forum.view_forum',forum_id=forum['id']))
+               
 
     threads = db.execute(
         f"""SELECT
@@ -116,7 +139,9 @@ def view_forum(forum,page=1):
         FROM threads
         INNER JOIN most_recent_posts ON most_recent_posts.thread = threads.id
         INNER JOIN number_of_posts ON number_of_posts.thread = threads.id
-        WHERE threads.forum = ?
+        LEFT OUTER JOIN thread_tags ON threads.id = thread_tags.thread
+        WHERE threads.forum = ? {tagfilter_clause}
+        GROUP BY threads.id
         ORDER BY {sortby_by} {sortby_dir}
         LIMIT ? OFFSET ?;
         """,(
@@ -125,14 +150,17 @@ def view_forum(forum,page=1):
             (page-1)*THREADS_PER_PAGE,
         )).fetchall()
 
-    # XXX: update this when thread filtering happens
-    num_threads = db.execute("SELECT count(*) AS count FROM threads WHERE threads.forum = ?",(forum['id'],)).fetchone()['count']
+    num_threads = db.execute(f"""
+        SELECT count(*) AS count FROM threads
+        LEFT OUTER JOIN thread_tags ON threads.id = thread_tags.thread
+        WHERE threads.forum = ? {tagfilter_clause};
+    """,(forum['id'],)).fetchone()['count']
+
     max_pageno = math.ceil(num_threads/THREADS_PER_PAGE)
     
     thread_tags = {}
     thread_polls = {}
 
-    avail_tags = get_avail_tags(forum['id'])
 
     #todo: somehow optimise this
     for thread in threads:
@@ -198,7 +226,8 @@ def view_forum(forum,page=1):
             avail_tags=avail_tags,
             max_pageno=max_pageno,
             page=page,
-            current_sortby=sortby
+            current_sortby=sortby,
+            tagfilter_tag=tagfilter_tag,
             )
 
 @forum_route("create_thread",methods=("GET","POST"))
diff --git a/apioforum/templates/common.html b/apioforum/templates/common.html
index 46402df..fae4b7c 100644
--- a/apioforum/templates/common.html
+++ b/apioforum/templates/common.html
@@ -67,8 +67,20 @@
 <time title="{{dt.isoformat(' ')}}" datetime="{{dt.isoformat(' ')}}">{{dt | fuzzy}}</time>
 {%- endmacro %}
 
-{% macro tag(the_tag) -%}
-<span class="tag" style="color: {{the_tag.text_colour}}; background-color: {{the_tag.bg_colour}}">{{the_tag.name}}</span>
+{% macro tag(the_tag,href=None) -%}
+{% if href is none %}
+{% set el = "span" %}
+{% else %}
+{% set el = "a" %}
+{% endif %}
+<{{el}}
+  class="tag"
+  style="color: {{the_tag.text_colour}}; background-color: {{the_tag.bg_colour}}"
+  {% if href is not none -%}
+  href="{{href}}"
+  {%- endif -%}>
+    {{-the_tag.name-}}
+</{{el}}>
 {%- endmacro %}
 
 {% macro ab(name,href) -%}
diff --git a/apioforum/templates/view_forum.html b/apioforum/templates/view_forum.html
index c1906b6..bac06e4 100644
--- a/apioforum/templates/view_forum.html
+++ b/apioforum/templates/view_forum.html
@@ -26,13 +26,6 @@
 	<p>your role in this forum: {{role}}</p>
 	{% endif %}
 
-	<p>available tags:
-	{% for the_tag in avail_tags %}
-	{{tag(the_tag)}}
-	{% else %}
-	<em>(none available)</em>
-	{% endfor %}
-	</p>
 </div>
 
 <p>
@@ -91,6 +84,12 @@ you do not have permission to create threads in this forum
 {% endif %}
 {% endmacro %}
 
+<details
+{%- if current_sortby != "ad" or tagfilter_tag is not none %}
+ open
+{%- endif -%}>
+	<summary>sorting and filtering options</summary>
+	
 <form class="inline-form small-form" method="get">
 	<label for="sortby">sort threads by</label>
 	<select name="sortby">
@@ -100,7 +99,27 @@ you do not have permission to create threads in this forum
 		{{ sortby_option("ca", "creation time (oldest first)") }}
 	</select>
 	<input type="submit" value="go">
+	{% if tagfilter_tag is not none %}
+	<input type="hidden" name="tagfilter" value="{{tagfilter_tag.id}}">
+	{% endif %}
 </form>
+
+{% if tagfilter_tag is none %}
+<p>filter by tag:
+{% for the_tag in avail_tags %}
+{{tag(the_tag,href=url_for('forum.view_forum',forum_id=forum.id,
+                           sortby=current_sortby,tagfilter=the_tag.id))}}
+
+{% else %}
+<em>(none available)</em>
+{% endfor %}
+</p>
+{% else %}
+<p>only showing posts with the {{tag(tagfilter_tag)}} tag.
+<a href="{{url_for('forum.view_forum',forum_id=forum.id,sortby=current_sortby)}}"> stop filtering</a>
+</p>
+{% endif %}
+</details>
 </p>
 
 {{ pagination_nav(page,max_pageno,'forum.view_forum',forum_id=forum.id) }}