API: Get History endpoint

See http://shaarli.github.io/api-documentation/#links-history-get

application/api/controllers/History.php

@@ -0,0 +1,71 @@
+<?php
+
+
+namespace Shaarli\Api\Controllers;
+
+use Shaarli\Api\Exceptions\ApiBadParametersException;
+use Slim\Http\Request;
+use Slim\Http\Response;
+
+/**
+ * Class History
+ *
+ * REST API Controller: /history
+ *
+ * @package Shaarli\Api\Controllers
+ */
+class History extends ApiController
+{
+    /**
+     * Service providing operation regarding Shaarli datastore and settings.
+     *
+     * @param Request  $request  Slim request.
+     * @param Response $response Slim response.
+     *
+     * @return Response response.
+     *
+     * @throws ApiBadParametersException Invalid parameters.
+     */
+    public function getHistory($request, $response)
+    {
+        $history = (new \History($this->conf->get('resource.history')))->getHistory();
+        $history = array_reverse($history);
+
+        // Return history operations from the {offset}th, starting from {since}.
+        $since = \DateTime::createFromFormat(\DateTime::ATOM, $request->getParam('since'));
+        $offset = $request->getParam('offset');
+        if (empty($offset)) {
+            $offset = 0;
+        }
+        else if (ctype_digit($offset)) {
+            $offset = (int) $offset;
+        } else {
+            throw new ApiBadParametersException('Invalid offset');
+        }
+
+        // limit parameter is either a number of links or 'all' for everything.
+        $limit = $request->getParam('limit');
+        if (empty($limit)) {
+            $limit = count($history);
+        } else if (ctype_digit($limit)) {
+            $limit = (int) $limit;
+        } else {
+            throw new ApiBadParametersException('Invalid limit');
+        }
+
+        $out = [];
+        $i = 0;
+        foreach ($history as $entry) {
+            if ((! empty($since) && $entry['datetime'] <= $since) || count($out) >= $limit) {
+                break;
+            }
+            if (++$i > $offset) {
+                $out[$i] = $entry;
+                $out[$i]['datetime'] = $out[$i]['datetime']->format(\DateTime::ATOM);
+            }
+        }
+        $out = array_values($out);
+
+        return $response->withJson($out, 200, $this->jsonStyle);
+    }
+}