From 4f7396d059aa6a143b1166abf695fcfbdc800bdd Mon Sep 17 00:00:00 2001
From: Miguel <leu-gim@moy-server.ru>
Date: Tue, 11 Nov 2014 08:22:11 +0300
Subject: [PATCH] Forum search added and some modifications done.

---
 fts.sql                | 74 ++++++++++++++++++++++++++++++++++++++++++
 static/search-help.rst | 35 ++++++++++++++++++++
 2 files changed, 109 insertions(+)
 create mode 100644 fts.sql
 create mode 100644 static/search-help.rst

diff --git a/fts.sql b/fts.sql
new file mode 100644
index 0000000..ab49d31
--- /dev/null
+++ b/fts.sql
@@ -0,0 +1,74 @@
+-- selects just threads,
+-- those where title doesn't coinside with some of its posts' titles
+-- by now selects only the threads title (no post snippet)
+SELECT
+        thread_id,
+        snippet(thread_fts, '<b>', '</b>', '<b>...</b>') AS thread,
+        0 AS post_id,
+        '' AS header,
+        '' AS content,
+        person.name AS author,
+        cdate,
+        author_id,
+        person.email AS email,
+        0 AS what
+    FROM (
+        SELECT
+                thread_fts.id AS thread_id,
+                post.id AS post_id,
+                post.creation AS cdate,
+                MIN(post.creation) AS cdate,
+                post.author AS author_id
+            FROM thread_fts
+            JOIN post ON post.thread=thread_id
+            WHERE thread_fts MATCH ?
+            GROUP BY thread_id, post_id
+            HAVING thread_id NOT IN (
+                SELECT thread
+                    FROM post_fts JOIN post USING(id)
+                    WHERE post_fts MATCH ?
+            )
+            LIMIT ? OFFSET (? - 1) * ?
+    )
+        JOIN thread_fts ON thread_fts.id=thread_id
+        JOIN person ON person.id=author_id
+    WHERE thread_fts MATCH ?
+UNION
+-- the main query, selects posts
+SELECT
+        thread.id AS thread_id,
+        thread.name AS thread,
+        post.id AS post_id,
+        CASE what WHEN 1
+            THEN snippet(post_fts, '<b>', '</b>', '...', what)
+            ELSE post_fts.header END AS header,
+        CASE what WHEN 2
+            THEN snippet(post_fts, '<b>', '</b>', '...', what, -45)
+            ELSE SUBSTR(post_fts.content, 1, 200) END AS content,
+        person.name AS author,
+        cdate,
+        post.author AS author_id,
+        person.email AS email,
+        what
+    FROM post_fts JOIN (
+    -- inner query, selects ids of matching posts, orders and limits them,
+    -- so snippets only for limited count of posts are created (in outer query)
+        SELECT id, post.creation AS cdate, thread, 1 AS what, post.author AS author
+            FROM post_fts JOIN post USING(id)
+            WHERE post_fts.header MATCH ?
+            GROUP BY post.header
+            HAVING SUBSTR(post.header,1,3)<>'Re:'
+        UNION
+        SELECT id, post.creation AS cdate, thread, 2 AS what, post.author AS author
+            FROM post_fts JOIN post USING(id)
+            WHERE post_fts.content MATCH ?
+        ORDER BY what, cdate DESC
+        LIMIT ? OFFSET (? - 1) * ?
+    ) AS post USING(id)
+        JOIN thread ON thread.id=thread
+        JOIN person ON person.id=author
+    WHERE post_fts MATCH ?
+ORDER BY what ASC, cdate DESC
+LIMIT 300 -- hardcoded limit just in case
+;
+
diff --git a/static/search-help.rst b/static/search-help.rst
new file mode 100644
index 0000000..8e7fc80
--- /dev/null
+++ b/static/search-help.rst
@@ -0,0 +1,35 @@
+Full-text search for Nim forum
+==============================
+
+Syntax (using *SQLite* dll compiled without *Enhanced Query Syntax* support):
+-----------------------------------------------------------------------------
+
+- Only alphanumeric characters are searched.
+- Only full words and words beginnings (e.g. ``Nim*`` for both ``Nimrod`` and ``Nim``) are searched
+- All words are joined with implicit **AND** operator; there's no explicit one
+- There's explicit **OR** operator (upper-case) and it has higher priority
+- Words can be prepended with **-** to be excluded from search
+- No parentheses support
+- Quotes for phrases search, e.g. ``"programming language"``
+- Distances between words/phrases can be specified putting ``NEAR`` or ``NEAR/some_number`` between them
+
+Syntax - differences in *Enhanced Query Syntax* (should be enabled in *SQLite* dll):
+------------------------------------------------------------------------------------
+
+- **AND** and **NOT** logical operators available
+- Precedence of operators is, from highest to lowest: **NOT**, **AND**, **OR**
+- Parentheses for grouping are supported
+
+Where search is performed:
+--------------------------
+
+- **Threads' titles** - these results are outputed first
+- **Posts' titles** - middle precedence
+- **Posts' contents** - the latest
+
+How results are shown:
+----------------------
+
+- All results are ordered by date (posts' edits don't affect)
+- Matched tokens in text are marked (bold or dotted underline)
+- Threads title is the link to the thread and posts title is the link to the post