Implements Tags endpoints for Shaarli's REST API

Endpoints:

 * List All Tags [GET]
 * Get a tag [GET]
 * Update a tag [PUT]
 * Delete a tag [DELETE]

Fixes #904
References shaarli/api-documentation#34

4 files changed, 213 insertions, 4 deletions

diff --git a/application/api/ApiUtils.php b/application/api/ApiUtils.php
index f154bb52..fc5ecaf1 100644
--- a/application/api/ApiUtils.php
+++ b/application/api/ApiUtils.php
@@ -134,4 +134,20 @@ class ApiUtils
 
         return $oldLink;
     }
+
+    /**
+     * Format a Tag for the REST API.
+     *
+     * @param string $tag         Tag name
+     * @param int    $occurrences Number of links using this tag
+     *
+     * @return array Link data formatted for the REST API.
+     */
+    public static function formatTag($tag, $occurences)
+    {
+        return [
+            'name'       => $tag,
+            'occurrences' => $occurences,
+        ];
+    }
 }
diff --git a/application/api/controllers/Links.php b/application/api/controllers/Links.php
index 3a9c0355..ffcfd4c7 100644
--- a/application/api/controllers/Links.php
+++ b/application/api/controllers/Links.php
@@ -68,16 +68,16 @@ class Links extends ApiController
         }
 
         // 'environment' is set by Slim and encapsulate $_SERVER.
-        $index = index_url($this->ci['environment']);
+        $indexUrl = index_url($this->ci['environment']);
 
         $out = [];
-        $cpt = 0;
+        $index = 0;
         foreach ($links as $link) {
             if (count($out) >= $limit) {
                 break;
             }
-            if ($cpt++ >= $offset) {
-                $out[] = ApiUtils::formatLink($link, $index);
+            if ($index++ >= $offset) {
+                $out[] = ApiUtils::formatLink($link, $indexUrl);
             }
         }
 
diff --git a/application/api/controllers/Tags.php b/application/api/controllers/Tags.php
new file mode 100644
index 00000000..6dd78750
--- /dev/null
+++ b/application/api/controllers/Tags.php
@@ -0,0 +1,161 @@
+<?php
+
+namespace Shaarli\Api\Controllers;
+
+use Shaarli\Api\ApiUtils;
+use Shaarli\Api\Exceptions\ApiBadParametersException;
+use Shaarli\Api\Exceptions\ApiLinkNotFoundException;
+use Shaarli\Api\Exceptions\ApiTagNotFoundException;
+use Slim\Http\Request;
+use Slim\Http\Response;
+
+/**
+ * Class Tags
+ *
+ * REST API Controller: all services related to tags collection.
+ *
+ * @package Api\Controllers
+ */
+class Tags extends ApiController
+{
+    /**
+     * @var int Number of links returned if no limit is provided.
+     */
+    public static $DEFAULT_LIMIT = 'all';
+
+    /**
+     * Retrieve a list of tags, allowing different filters.
+     *
+     * @param Request  $request  Slim request.
+     * @param Response $response Slim response.
+     *
+     * @return Response response.
+     *
+     * @throws ApiBadParametersException Invalid parameters.
+     */
+    public function getTags($request, $response)
+    {
+        $visibility = $request->getParam('visibility');
+        $tags = $this->linkDb->linksCountPerTag([], $visibility);
+
+        // Return tags from the {offset}th tag, starting from 0.
+        $offset = $request->getParam('offset');
+        if (! empty($offset) && ! ctype_digit($offset)) {
+            throw new ApiBadParametersException('Invalid offset');
+        }
+        $offset = ! empty($offset) ? intval($offset) : 0;
+        if ($offset > count($tags)) {
+            return $response->withJson([], 200, $this->jsonStyle);
+        }
+
+        // limit parameter is either a number of links or 'all' for everything.
+        $limit = $request->getParam('limit');
+        if (empty($limit)) {
+            $limit = self::$DEFAULT_LIMIT;
+        }
+        if (ctype_digit($limit)) {
+            $limit = intval($limit);
+        } elseif ($limit === 'all') {
+            $limit = count($tags);
+        } else {
+            throw new ApiBadParametersException('Invalid limit');
+        }
+
+        $out = [];
+        $index = 0;
+        foreach ($tags as $tag => $occurrences) {
+            if (count($out) >= $limit) {
+                break;
+            }
+            if ($index++ >= $offset) {
+                $out[] = ApiUtils::formatTag($tag, $occurrences);
+            }
+        }
+
+        return $response->withJson($out, 200, $this->jsonStyle);
+    }
+
+    /**
+     * Return a single formatted tag by its name.
+     *
+     * @param Request  $request  Slim request.
+     * @param Response $response Slim response.
+     * @param array    $args     Path parameters. including the tag name.
+     *
+     * @return Response containing the link array.
+     *
+     * @throws ApiTagNotFoundException generating a 404 error.
+     */
+    public function getTag($request, $response, $args)
+    {
+        $tags = $this->linkDb->linksCountPerTag();
+        if (!isset($tags[$args['tagName']])) {
+            throw new ApiTagNotFoundException();
+        }
+        $out = ApiUtils::formatTag($args['tagName'], $tags[$args['tagName']]);
+
+        return $response->withJson($out, 200, $this->jsonStyle);
+    }
+
+    /**
+     * Rename a tag from the given name.
+     * If the new name provided matches an existing tag, they will be merged.
+     *
+     * @param Request  $request  Slim request.
+     * @param Response $response Slim response.
+     * @param array    $args     Path parameters. including the tag name.
+     *
+     * @return Response response.
+     *
+     * @throws ApiTagNotFoundException generating a 404 error.
+     * @throws ApiBadParametersException new tag name not provided
+     */
+    public function putTag($request, $response, $args)
+    {
+        $tags = $this->linkDb->linksCountPerTag();
+        if (! isset($tags[$args['tagName']])) {
+            throw new ApiTagNotFoundException();
+        }
+
+        $data = $request->getParsedBody();
+        if (empty($data['name'])) {
+            throw new ApiBadParametersException('New tag name is required in the request body');
+        }
+
+        $updated = $this->linkDb->renameTag($args['tagName'], $data['name']);
+        $this->linkDb->save($this->conf->get('resource.page_cache'));
+        foreach ($updated as $link) {
+            $this->history->updateLink($link);
+        }
+
+        $tags = $this->linkDb->linksCountPerTag();
+        $out = ApiUtils::formatTag($data['name'], $tags[$data['name']]);
+        return $response->withJson($out, 200, $this->jsonStyle);
+    }
+
+    /**
+     * Delete an existing tag by its name.
+     *
+     * @param Request  $request  Slim request.
+     * @param Response $response Slim response.
+     * @param array    $args     Path parameters. including the tag name.
+     *
+     * @return Response response.
+     *
+     * @throws ApiTagNotFoundException generating a 404 error.
+     */
+    public function deleteTag($request, $response, $args)
+    {
+        $tags = $this->linkDb->linksCountPerTag();
+        if (! isset($tags[$args['tagName']])) {
+            throw new ApiTagNotFoundException();
+        }
+        $updated = $this->linkDb->renameTag($args['tagName'], null);
+        $this->linkDb->save($this->conf->get('resource.page_cache'));
+        foreach ($updated as $link) {
+            $this->history->updateLink($link);
+        }
+
+        return $response->withStatus(204);
+    }
+}
diff --git a/application/api/exceptions/ApiTagNotFoundException.php b/application/api/exceptions/ApiTagNotFoundException.php
new file mode 100644
index 00000000..eed5afa5
--- /dev/null
+++ b/application/api/exceptions/ApiTagNotFoundException.php
@@ -0,0 +1,32 @@
+<?php
+
+namespace Shaarli\Api\Exceptions;
+
+
+use Slim\Http\Response;
+
+/**
+ * Class ApiTagNotFoundException
+ *
+ * Tag selected by name couldn't be found in the datastore, results in a 404 error.
+ *
+ * @package Shaarli\Api\Exceptions
+ */
+class ApiTagNotFoundException extends ApiException
+{
+    /**
+     * ApiLinkNotFoundException constructor.
+     */
+    public function __construct()
+    {
+        $this->message = 'Tag not found';
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getApiResponse()
+    {
+        return $this->buildApiResponse(404);
+    }
+}