Add pruning support (#12)

INSTALLING.md

@@ -43,3 +43,11 @@ Data is stored under the `/src/data` directory, and the default database name is
 ### Date/Time Format
 
 The default format for dates and times look like "May 28, 2023 at 3:15pm". Changing the string there will alter the display on the main page and when reading an item. Any [supported PHP date or time token](https://www.php.net/manual/en/datetime.format.php) is supported.
+
+### Item Purging
+
+Feed Reader Central tries to keep the database tidy by purging items that have been read and are no longer required. There are three variants:
+- `Feed::PURGE_READ` purges non-bookmarked read items for a feed whenever it is refreshed. This is the most aggressive purging strategy, but it is also the only one that will not purge unread items.
+- `Feed::PURGE_BY_DAYS` purges non-bookmarked items that are older than `PURGE_NUMBER` days old. This is the default value, and `PURGE_NUMBER`'s default value is 30; items will be kept for 30 days, read or unread.
+- `Feed::PURGE_BY_COUNT` purges items to preserve at most `PURGE_NUMBER` non-bookmarked items for each feed.
+ 

src/lib/Data.php

@@ -98,4 +98,14 @@ class Data {
             if (is_null($dbConn)) $db->close();
         }
     }
+
+    /**
+     * Return the last SQLite error message as a result array
+     *
+     * @param SQLite3 $db The database connection on which the error has occurred
+     * @return string[] ['error' => message] for last SQLite error message
+     */
+    public static function error(SQLite3 $db): array {
+        return ['error' => 'SQLite error: ' . $db->lastErrorMsg()];
+    }
 }

src/lib/Feed.php

@@ -30,6 +30,15 @@ class Feed {
     private const string USER_AGENT =
         'FeedReaderCentral/' . FRC_VERSION . ' +https://bitbadger.solutions/open-source/feed-reader-central';
 
+    /** @var int Purge all read items (will not purge unread items) */
+    public const int PURGE_READ = 1;
+
+    /** @var int Purge items older than the specified number of days */
+    public const int PURGE_BY_DAYS = 2;
+
+    /** @var int Purge items in number greater than the specified number of items to keep */
+    public const int PURGE_BY_COUNT = 3;
+
     /**
      * When parsing XML into a DOMDocument, errors are presented as warnings; this creates an exception for them
      *
@@ -86,15 +95,16 @@ class Feed {
     private static function fromRSS(DOMDocument $xml, string $url): array {
         $channel = $xml->getElementsByTagName('channel')->item(0);
         if (!($channel instanceof DOMElement)) {
-            return ['error' => "Channel element not found ($channel->nodeType)"];
+            $type = $channel?->nodeType ?? -1;
+            return ['error' => "Channel element not found ($type)"];
         }
 
         // The Atom namespace provides a lastBuildDate, which contains the last time an item in the feed was updated; if
         // that is not present, use the pubDate element instead
-        $updatedOn = self::rssValue($channel, 'lastBuildDate');
+        if (($updatedOn = self::rssValue($channel, 'lastBuildDate')) == 'lastBuildDate not found') {
-        if ($updatedOn == 'lastBuildDate not found') {
+            if (($updatedOn = self::rssValue($channel, 'pubDate')) == 'pubDate not found') {
-            $updatedOn = self::rssValue($channel, 'pubDate');
+                $updatedOn = null;
-            if ($updatedOn == 'pubDate not found') $updatedOn = null;
+            }
         }
 
         $feed            = new Feed();
@@ -149,8 +159,7 @@ class Feed {
      */
     private static function fromAtom(DOMDocument $xml, string $url): array {
         $root = $xml->getElementsByTagNameNS(self::ATOM_NS, 'feed')->item(0);
-        $updatedOn = self::atomValue($root, 'updated');
+        if (($updatedOn = self::atomValue($root, 'updated')) == 'pubDate not found') $updatedOn = null;
-        if ($updatedOn == 'pubDate not found') $updatedOn = null;
 
         $feed            = new Feed();
         $feed->title     = self::atomValue($root, 'title');
@@ -252,8 +261,9 @@ class Feed {
      * @param int $itemId The ID of the item to be updated
      * @param FeedItem $item The item to be updated
      * @param SQLite3 $db A database connection to use for the update
+     * @return bool|SQLite3Result The result if the update is successful, false if it failed
      */
-    private static function updateItem(int $itemId, FeedItem $item, SQLite3 $db): void {
+    private static function updateItem(int $itemId, FeedItem $item, SQLite3 $db): bool|SQLite3Result {
         $query = $db->prepare(<<<'SQL'
             UPDATE item
                SET title        = :title,
@@ -268,7 +278,7 @@ class Feed {
         $query->bindValue(':updated',   $item->updatedOn);
         $query->bindValue(':content',   $item->content);
         $query->bindValue(':id',        $itemId);
-        $query->execute();
+        return $query->execute();
     }
 
     /**
@@ -277,8 +287,9 @@ class Feed {
      * @param int $feedId The ID of the feed to which the item should be added
      * @param FeedItem $item The item to be added
      * @param SQLite3 $db A database connection to use for the addition
+     * @return bool|SQLite3Result The result if the update is successful, false if it failed
      */
-    private static function addItem(int $feedId, FeedItem $item, SQLite3 $db): void {
+    private static function addItem(int $feedId, FeedItem $item, SQLite3 $db): bool|SQLite3Result {
         $query = $db->prepare(<<<'SQL'
             INSERT INTO item (
                 feed_id, item_guid, item_link, title, published_on, updated_on, content
@@ -293,7 +304,7 @@ class Feed {
         $query->bindValue(':published', $item->publishedOn);
         $query->bindValue(':updated',   $item->updatedOn);
         $query->bindValue(':content',   $item->content);
-        $query->execute();
+        return $query->execute();
     }
 
     /**
@@ -304,31 +315,71 @@ class Feed {
      * @return array ['ok' => true] if successful, ['error' => message] if not
      */
     public static function updateItems(int $feedId, Feed $feed, SQLite3 $db): array {
-        try {
+
+        // Do not add items that are older than the oldest we currently have; this keeps us from re-adding items that
+        // have been purged already
+        $oldestQuery = $db->prepare(
+            'SELECT MIN(coalesce(updated_on, published_on)) FROM item where feed_id = :feed AND is_bookmarked = 0');
+        $oldestQuery->bindValue(':feed', $feedId);
+        if (!($oldest = $oldestQuery->execute())) return Data::error($db);
+        $minDate = date_create_immutable($oldest->fetchArray(SQLITE3_NUM)[0] ?? '1993-04-30T00:00:00+00:00');
+
         foreach ($feed->items as $item) {
+            if (date_create_immutable($item->updatedOn ?? $item->publishedOn) < $minDate) continue;
             $existsQuery = $db->prepare(
                 'SELECT id, published_on, updated_on FROM item WHERE feed_id = :feed AND item_guid = :guid');
             $existsQuery->bindValue(':feed', $feedId);
             $existsQuery->bindValue(':guid', $item->guid);
-                $exists = $existsQuery->execute();
+            if ($exists = $existsQuery->execute()) {
-                if ($exists) {
+                if ($existing = $exists->fetchArray(SQLITE3_ASSOC)) {
-                    $existing = $exists->fetchArray(SQLITE3_ASSOC);
-                    if ($existing) {
                     if (   $existing['published_on']       != $item->publishedOn
                         || ($existing['updated_on'] ?? '') != ($item->updatedOn ?? '')) {
-                            self::updateItem($existing['id'], $item, $db);
+                        if (!self::updateItem($existing['id'], $item, $db)) return Data::error($db);
                     }
                 } else {
-                        self::addItem($feedId, $item, $db);
+                    if (!self::addItem($feedId, $item, $db)) return Data::error($db);
                 }
             } else {
-                    throw new Exception($db->lastErrorMsg());
+                return Data::error($db);
             }
         }
+        return ['ok', true];
+    }
+
+    /**
+     * Purge items for a feed
+     *
+     * @param int $feedId The ID of the feed to be purged
+     * @param SQLite3 $db The database connection on which items should be purged
+     * @return array|string[]|true[] ['ok' => true] if purging was successful, ['error' => message] if not
+     */
+    private static function purgeItems(int $feedId, SQLite3 $db): array {
+
+        if (!array_search(PURGE_TYPE, [self::PURGE_READ, self::PURGE_BY_DAYS, self::PURGE_BY_COUNT])) {
+            return ['error' => 'Unrecognized purge type ' . PURGE_TYPE];
+        }
+
+        try {
+            $sql = match (PURGE_TYPE) {
+                self::PURGE_READ     => 'AND is_read = 1',
+                self::PURGE_BY_DAYS  => 'AND date(coalesce(updated_on, published_on)) < date(:oldest)',
+                self::PURGE_BY_COUNT => 'AND id IN (SELECT id FROM item WHERE feed_id = :feed
+                                         ORDER BY date(coalesce(updated_on, published_on)) DESC
+                                         LIMIT -1 OFFSET :keep)',
+                default              => 'AND 1 = 0'
+            };
+
+            $purge = $db->prepare("DELETE FROM item WHERE feed_id = :feed AND is_bookmarked = 0 $sql");
+            $purge->bindValue(':feed', $feedId);
+            if (PURGE_TYPE == self::PURGE_BY_DAYS) {
+                $purge->bindValue(':oldest', Data::formatDate('-' . PURGE_NUMBER . ' day'));
+            } elseif (PURGE_TYPE == self::PURGE_BY_COUNT) {
+                $purge->bindValue(':keep', PURGE_NUMBER);
+            }
+            return $purge->execute() ? ['ok' => true] : Data::error($db);
         } catch (Exception $ex) {
             return ['error' => $ex->getMessage()];
         }
-        return ['ok', true];
     }
 
     /**
@@ -362,9 +413,9 @@ class Feed {
         $feedUpdate->bindValue(':checked', Data::formatDate('now'));
         $feedUpdate->bindValue(':id',      $feedId);
         if ($urlUpdate != '') $feedUpdate->bindValue(':url', $feed->url);
-        $feedUpdate->execute();
+        if (!$feedUpdate->execute()) return Data::error($db);
 
-        return ['ok' => true];
+        return self::purgeItems($feedId, $db);
     }
 
     /**
@@ -382,26 +433,24 @@ class Feed {
         $existsQuery = $db->prepare('SELECT COUNT(*) FROM feed WHERE user_id = :user AND url = :url');
         $existsQuery->bindValue(':user', $_SESSION[Key::USER_ID]);
         $existsQuery->bindValue(':url',  $feed->url);
-        $existsResult = $existsQuery->execute();
+        if (!($exists = $existsQuery->execute()))    return Data::error($db);
-        if (!$existsResult) return ['error' => 'SQLite error: ' . $db->lastErrorMsg()];
+        if ($exists->fetchArray(SQLITE3_NUM)[0] > 0) return ['error' => "Already subscribed to feed $feed->url"];
-
-        $exists = $existsResult->fetchArray(SQLITE3_NUM);
-        if ($exists[0] != 0) return ['error' => "Already subscribed to feed $feed->url"];
 
         $query = $db->prepare(<<<'SQL'
-            INSERT INTO feed (user_id, url, title, updated_on, checked_on)
+            INSERT INTO feed (
-            VALUES (:user, :url, :title, :updated, :checked)
+                user_id, url, title, updated_on, checked_on
+            ) VALUES (
+                :user, :url, :title, :updated, :checked
+            )
             SQL);
         $query->bindValue(':user',    $_SESSION[Key::USER_ID]);
         $query->bindValue(':url',     $feed->url);
         $query->bindValue(':title',   $feed->title);
         $query->bindValue(':updated', $feed->updatedOn);
         $query->bindValue(':checked', Data::formatDate('now'));
-        $result = $query->execute();
+        if (!$query->execute()) return Data::error($db);
-
-        $feedId = $result ? $db->lastInsertRowID() : -1;
-        if ($feedId < 0) return ['error' => $db->lastErrorMsg()];
 
+        $feedId = $db->lastInsertRowID();
         $result = self::updateItems($feedId, $feed, $db);
         if (array_key_exists('error', $result)) return $result;
 
@@ -421,7 +470,7 @@ class Feed {
         $query->bindValue(':url',  $url);
         $query->bindValue(':id',   $existing['id']);
         $query->bindValue(':user', $_SESSION[Key::USER_ID]);
-        $query->execute();
+        if (!$query->execute()) return Data::error($db);
 
         return self::refreshFeed($existing['id'], $url, $db);
     }
@@ -438,8 +487,7 @@ class Feed {
         $query = $db->prepare(
             "SELECT f.id, f.url, u.email FROM feed f INNER JOIN frc_user u ON u.id = f.user_id$extraSQL");
         if ($user > 0) $query->bindValue(':user', $user);
-        $result = $query->execute();
+        if (!($result = $query->execute())) return Data::error($db);
-        if (!$result) return ['error', $db->lastErrorMsg()];
         $feeds = [];
         while ($feed = $result->fetchArray(SQLITE3_ASSOC)) $feeds[] = $feed;
         return $feeds;

src/user-config.dist.php

@@ -25,3 +25,16 @@ const DATABASE_NAME = 'frc.db';
  * The default, 'F j, Y \a\t g:ia', equates to "August 17, 2023 at 4:45pm"
  */
 const DATE_TIME_FORMAT = 'F j, Y \a\t g:ia';
+
+/**
+ * How should item purging be done? (Purging never applies to bookmarked items.) Options are:
+ * - Feed::PURGE_READ - Purge all read items whenever purging is run (will not purge unread items)
+ * - Feed::PURGE_BY_DAYS - Purge read and unread items older than a number of days (PURGE_NUMBER below)
+ * - Feed::PURGE_BY_COUNT - Purge read and unread items beyond the number to keep (PURGE_NUMBER below)
+ */
+const PURGE_TYPE = Feed::PURGE_BY_DAYS;
+
+/**
+ * For purge-by-days, how many days of items should be kept; for purge-by-count, how many items should be kept
+ */
+const PURGE_NUMBER = 30;