History mechanism

Use case: rest API service

  * saved by default in data/history
  * same format as datastore.php
  * traced events:
     * save/edit/delete link
     * change settings or plugins settings
     * rename tag

1 files changed, 183 insertions, 0 deletions

diff --git a/application/History.php b/application/History.php
new file mode 100644
index 00000000..c06067df
--- /dev/null
+++ b/application/History.php
@@ -0,0 +1,183 @@
+<?php
+
+/**
+ * Class History
+ *
+ * Handle the history file tracing events in Shaarli.
+ * The history is stored as JSON in a file set by 'resource.history' setting.
+ *
+ * Available data:
+ *   - event: event key
+ *   - datetime: event date, in ISO8601 format.
+ *   - id: event item identifier (currently only link IDs).
+ *
+ * Available event keys:
+ *   - CREATED: new link
+ *   - UPDATED: link updated
+ *   - DELETED: link deleted
+ *   - SETTINGS: the settings have been updated through the UI.
+ *
+ * Note: new events are put at the beginning of the file and history array.
+ */
+class History
+{
+    /**
+     * @var string Action key: a new link has been created.
+     */
+    const CREATED = 'CREATED';
+
+    /**
+     * @var string Action key: a link has been updated.
+     */
+    const UPDATED = 'UPDATED';
+
+    /**
+     * @var string Action key: a link has been deleted.
+     */
+    const DELETED = 'DELETED';
+
+    /**
+     * @var string Action key: settings have been updated.
+     */
+    const SETTINGS = 'SETTINGS';
+
+    /**
+     * @var string History file path.
+     */
+    protected $historyFilePath;
+
+    /**
+     * @var array History data.
+     */
+    protected $history;
+
+    /**
+     * @var int History retention time in seconds (1 month).
+     */
+    protected $retentionTime = 2678400;
+
+    /**
+     * History constructor.
+     *
+     * @param string $historyFilePath History file path.
+     * @param int    $retentionTime   History content rentention time in seconds.
+     *
+     * @throws Exception if something goes wrong.
+     */
+    public function __construct($historyFilePath, $retentionTime = null)
+    {
+        $this->historyFilePath = $historyFilePath;
+        if ($retentionTime !== null) {
+            $this->retentionTime = $retentionTime;
+        }
+        $this->check();
+        $this->read();
+    }
+
+    /**
+     * Add Event: new link.
+     *
+     * @param array $link Link data.
+     */
+    public function addLink($link)
+    {
+        $this->addEvent(self::CREATED, $link['id']);
+    }
+
+    /**
+     * Add Event: update existing link.
+     *
+     * @param array $link Link data.
+     */
+    public function updateLink($link)
+    {
+        $this->addEvent(self::UPDATED, $link['id']);
+    }
+
+    /**
+     * Add Event: delete existing link.
+     *
+     * @param array $link Link data.
+     */
+    public function deleteLink($link)
+    {
+        $this->addEvent(self::DELETED, $link['id']);
+    }
+
+    /**
+     * Add Event: settings updated.
+     */
+    public function updateSettings()
+    {
+        $this->addEvent(self::SETTINGS);
+    }
+
+    /**
+     * Save a new event and write it in the history file.
+     *
+     * @param string $status Event key, should be defined as constant.
+     * @param mixed  $id     Event item identifier (e.g. link ID).
+     */
+    protected function addEvent($status, $id = null)
+    {
+        $item = [
+            'event' => $status,
+            'datetime' => (new DateTime())->format(DateTime::ATOM),
+            'id' => $id !== null ? $id : '',
+        ];
+        $this->history = array_merge([$item], $this->history);
+        $this->write();
+    }
+
+    /**
+     * Check that the history file is writable.
+     * Create the file if it doesn't exist.
+     *
+     * @throws Exception if it isn't writable.
+     */
+    protected function check()
+    {
+        if (! is_file($this->historyFilePath)) {
+            FileUtils::writeFlatDB($this->historyFilePath, []);
+        }
+
+        if (! is_writable($this->historyFilePath)) {
+            throw new Exception('History file isn\'t readable or writable');
+        }
+    }
+
+    /**
+     * Read JSON history file.
+     */
+    protected function read()
+    {
+        $this->history = FileUtils::readFlatDB($this->historyFilePath, []);
+        if ($this->history === false) {
+            throw new Exception('Could not parse history file');
+        }
+    }
+
+    /**
+     * Write JSON history file and delete old entries.
+     */
+    protected function write()
+    {
+        $comparaison = new DateTime('-'. $this->retentionTime . ' seconds');
+        foreach ($this->history as $key => $value) {
+            if (DateTime::createFromFormat(DateTime::ATOM, $value['datetime']) < $comparaison) {
+                unset($this->history[$key]);
+            }
+        }
+        FileUtils::writeFlatDB($this->historyFilePath, array_values($this->history));
+    }
+
+    /**
+     * Get the History.
+     *
+     * @return array
+     */
+    public function getHistory()
+    {
+        return $this->history;
+    }
+}