Add task links (Merge pull-request #610)

5 files changed, 826 insertions, 0 deletions

diff --git a/app/Model/Base.php b/app/Model/Base.php
index 319e53fc..f836231c 100644
--- a/app/Model/Base.php
+++ b/app/Model/Base.php
@@ -25,6 +25,7 @@ use Pimple\Container;
  * @property \Model\File                   $file
  * @property \Model\Helper                 $helper
  * @property \Model\LastLogin              $lastLogin
+ * @property \Model\Link                   $link
  * @property \Model\Notification           $notification
  * @property \Model\Project                $project
  * @property \Model\ProjectDuplication     $projectDuplication
@@ -38,6 +39,7 @@ use Pimple\Container;
  * @property \Model\TaskExport             $taskExport
  * @property \Model\TaskFinder             $taskFinder
  * @property \Model\TaskHistory            $taskHistory
+ * @property \Model\TaskLink               $taskLink
  * @property \Model\TaskPosition           $taskPosition
  * @property \Model\TaskValidator          $taskValidator
  * @property \Model\TimeTracking           $timeTracking
diff --git a/app/Model/Link.php b/app/Model/Link.php
new file mode 100644
index 00000000..eddf1c6c
--- /dev/null
+++ b/app/Model/Link.php
@@ -0,0 +1,437 @@
+<?php
+namespace Model;
+
+use SimpleValidator\Validator;
+use SimpleValidator\Validators;
+use PDO;
+
+/**
+ * Link model
+ * A link is made of one bidirectional (<->), or two sided (<- and ->) link labels.
+ *
+ * @package model
+ * @author Olivier Maridat
+ */
+class Link extends Base
+{
+
+    /**
+     * SQL table name
+     *
+     * @var string
+     */
+    const TABLE = 'link';
+
+    const TABLE_LABEL = 'link_label';
+
+    /**
+     * Direction: left to right ->
+     *
+     * @var integer
+     */
+    const BEHAVIOUR_LEFT2RIGTH = 0;
+
+    /**
+     * Direction: right to left <-
+     *
+     * @var integer
+     */
+    const BEHAVIOUR_RIGHT2LEFT = 1;
+
+    /**
+     * Bidirectional <->
+     *
+     * @var integer
+     */
+    const BEHAVIOUR_BOTH = 2;
+
+    /**
+     * Get a link by the id
+     *
+     * @access public
+     * @param integer $link_id
+     *            Link id
+     * @param integer $project_id
+     *            Specify a project id. Default: -1 to target all projects
+     * @return array
+     */
+    public function getById($link_id, $project_id = -1)
+    {
+        return $this->db->table(self::TABLE)
+            ->eq(self::TABLE . '.link_id', $link_id)
+            ->in('project_id', array(
+            - 1,
+            $project_id
+        ))
+            ->join(self::TABLE_LABEL, 'link_id', 'link_id')
+            ->findAll();
+    }
+
+    /**
+     * Get the id of the inverse link label by a link label id
+     *
+     * @access public
+     * @param integer $link_id
+     *            Link id
+     * @param integer $link_label_id
+     *            Link label id
+     * @return integer
+     */
+    public function getInverseLinkLabelId($link_label_id)
+    {
+        $sql = 'SELECT
+            la2.id
+            FROM ' . self::TABLE_LABEL . ' la1
+            JOIN '.self::TABLE_LABEL.' la2 ON la2.link_id = la1.link_id AND (la2.behaviour=2 OR la2.id != la1.id)
+            WHERE la1.id = ?
+        ';
+        $rq = $this->db->execute($sql, array(
+            $link_label_id
+        ));
+        return $rq->fetchColumn(0);
+    }
+
+    /**
+     * Return all link labels for a given project
+     *
+     * @access public
+     * @param integer $project_id
+     *            Specify a project id. Default: -1 to target all projects
+     * @return array
+     */
+    public function getLinkLabels($project_id = -1)
+    {
+        return $this->db->table(self::TABLE_LABEL)
+            ->in(self::TABLE . '.project_id', array(
+            - 1,
+            $project_id
+        ))
+            ->join(self::TABLE, 'link_id', 'link_id')
+            ->asc(self::TABLE_LABEL.'.link_id', 'behaviour')
+            ->columns('id', self::TABLE . '.project_id', self::TABLE_LABEL.'.link_id', 'label', 'behaviour')
+            ->findAll();
+    }
+
+    /**
+     * Return the list of all link labels
+     * Used to select a link label
+     *
+     * @access public
+     * @param integer $project_id
+     *            Specify a project id. Default: -1 to target all projects
+     * @return array
+     */
+    public function getLinkLabelList($project_id = -1)
+    {
+        $listing = $this->getLinkLabels($project_id);
+        $mergedListing = array();
+        foreach ($listing as $link) {
+            $suffix = '';
+            $prefix = '';
+            if (self::BEHAVIOUR_BOTH == $link['behaviour'] || self::BEHAVIOUR_LEFT2RIGTH == $link['behaviour']) {
+                $suffix = ' &raquo;';
+            }
+            if (self::BEHAVIOUR_BOTH == $link['behaviour'] || self::BEHAVIOUR_RIGHT2LEFT == $link['behaviour']) {
+                $prefix = '&laquo; ';
+            }
+            $mergedListing[$link['id']] = $prefix . t($link['label']) . $suffix;
+        }
+        $listing = $mergedListing;
+        return $listing;
+    }
+
+    /**
+     * Return the list of all links (label + inverse label)
+     *
+     * @access public
+     * @param integer $project_id
+     *            Specify a project id. Default: -1 to target all projects
+     * @return array
+     */
+    public function getMergedList($project_id = -1)
+    {
+        $listing = $this->getLinkLabels($project_id);
+        $mergedListing = array();
+        $current = null;
+        foreach ($listing as $link) {
+            if (self::BEHAVIOUR_BOTH == $link['behaviour'] || self::BEHAVIOUR_LEFT2RIGTH == $link['behaviour']) {
+                $current = $link;
+            }
+            else {
+                $current['label_inverse'] = $link['label'];
+            }
+            if (self::BEHAVIOUR_BOTH == $link['behaviour'] || self::BEHAVIOUR_RIGHT2LEFT == $link['behaviour']) {
+                $mergedListing[] = $current;
+                $current = null;
+            }
+        }
+        $listing = $mergedListing;
+        return $listing;
+    }
+
+    /**
+     * Prepare data before insert/update
+     *
+     * @access public
+     * @param array $values
+     *            Form values
+     */
+    public function prepare(array &$values)
+    {
+        // Prepare label 1
+        $link = array(
+            'project_id' => $values['project_id']
+        );
+        $label1 = array(
+            'label' => @$values['label'][0],
+            'behaviour' => (isset($values['behaviour'][0]) || !isset($values['label'][1]) || null == $values['label'][1]) ? self::BEHAVIOUR_BOTH : self::BEHAVIOUR_LEFT2RIGTH
+        );
+        $label2 = array(
+            'label' => @$values['label'][1],
+            'behaviour' => self::BEHAVIOUR_RIGHT2LEFT
+        );
+        if (isset($values['link_id'])) {
+            $link['link_id'] = $values['link_id'];
+            $label1['id'] = $values['id'][0];
+            $label2['id'] = @$values['id'][1];
+            $label1['link_id'] = $values['link_id'];
+            $label2['link_id'] = $values['link_id'];
+        }
+        
+        $values = $link;
+        $values[] = $label1;

+        $values[] = $label2;
+        return array(
+            $link,
+            $label1,
+            $label2
+        );
+    }
+
+    /**
+     * Create a link
+     *
+     * @access public
+     * @param array $values
+     *            Form values
+     * @return bool integer
+     */
+    public function create(array $values)
+    {
+        list ($link, $label1, $label2) = $this->prepare($values);
+        // Create link
+        $this->db->startTransaction();
+        $res = $this->db->table(self::TABLE)->save($link);
+        if (! $res) {
+            $this->db->cancelTransaction();
+            return false;
+        }
+        
+        // Create label 1
+        $label1['link_id'] = $this->db->getConnection()->lastInsertId(self::TABLE);
+        $res = $this->db->table(self::TABLE_LABEL)->save($label1);
+        if (! $res) {
+            $this->db->cancelTransaction();
+            return false;
+        }
+        
+        // Create label 2 if any
+        if (null != $label2 && self::BEHAVIOUR_BOTH != $label1['behaviour']) {
+            $label2['link_id'] = $label1['link_id'];
+            $res = $this->db->table(self::TABLE_LABEL)->save($label2);
+            if (! $res) {
+                $this->db->cancelTransaction();
+                return false;
+            }
+        }
+        $this->db->closeTransaction();
+        return $res;
+    }
+
+    /**
+     * Update a link
+     *
+     * @access public
+     * @param array $values
+     *            Form values
+     * @return bool
+     */
+    public function update(array $values)
+    {
+        list($link, $label1, $label2) = $this->prepare($values);
+        // Update link
+        $this->db->startTransaction();
+        $res = $this->db->table(self::TABLE)
+            ->eq('link_id', $link['link_id'])
+            ->save($link);
+        if (! $res) {
+            $this->db->cancelTransaction();
+            return false;
+        }
+        
+        // Update label 1
+        $this->db->startTransaction();
+        $res = $this->db->table(self::TABLE_LABEL)
+            ->eq('id', $label1['id'])
+            ->save($label1);
+        if (! $res) {
+            $this->db->cancelTransaction();
+            return false;
+        }
+        
+        // Update label 2 (if label 1 not bidirectional)
+        if (null != $label2 && self::BEHAVIOUR_BOTH != $label1['behaviour']) {
+            // Create
+            if (! isset($label2['id']) || null == $label2['id']) {
+                unset($label2['id']);
+                $res = $this->db->table(self::TABLE_LABEL)->save($label2);
+                if (! $res) {
+                    $this->db->cancelTransaction();
+                    return false;
+                }
+                $label2['id'] = $this->db->getConnection()->lastInsertId(self::TABLE_LABEL);
+                $this->taskLink->changeLinkLabel($link['link_id'], $label2['id'], true);
+            }
+            // Update
+            else {
+                $res = $this->db->table(self::TABLE_LABEL)
+                    ->eq('id', $label2['id'])
+                    ->save($label2);
+                if (! $res) {
+                    $this->db->cancelTransaction();
+                    return false;
+                }
+            }
+        }
+        // Remove label 2 (if label 1 bidirectional)
+        else {
+            $this->taskLink->changeLinkLabel($link['link_id'], $label1['id']);
+            $this->db->table(self::TABLE_LABEL)
+                ->eq('link_id', $link['link_id'])
+                ->neq('id', $label1['id'])
+                ->remove();
+        }
+        $this->db->closeTransaction();
+        return $res;
+    }
+
+    /**
+     * Remove a link
+     *
+     * @access public
+     * @param integer $link_id
+     *            Link id
+     * @return bool
+     */
+    public function remove($link_id)
+    {
+        $this->db->startTransaction();
+        if (! $this->db->table(self::TABLE)
+            ->eq('link_id', $link_id)
+            ->remove()) {
+            $this->db->cancelTransaction();
+            return false;
+        }
+        $this->db->closeTransaction();
+        return true;
+    }
+
+    /**
+     * Duplicate links from a project to another one, must be executed inside a transaction
+     *
+     * @param integer $src_project_id
+     *            Source project id
+     * @return integer $dst_project_id Destination project id
+     * @return boolean
+     */
+    public function duplicate($src_project_id, $dst_project_id)
+    {
+        $labels = $this->db->table(self::TABLE_LABEL)
+            ->columns(self::TABLE_LABEL.'.link_id', 'label', 'behaviour')
+            ->eq('project_id', $src_project_id)
+            ->join(self::TABLE, 'link_id', 'link_id')
+            ->asc(self::TABLE_LABEL.'.link_id', 'behaviour')
+            ->findAll();
+        
+        $this->db->startTransaction();
+        $link = array('project_id' => $dst_project_id);

+        if (! $this->db->table(self::TABLE)->save($link)) {
+        	$this->db->cancelTransaction();

+        	return false;

+        }
+        $link['id'] = $this->db->getConnection()->lastInsertId(self::TABLE);
+        
+        foreach ($labels as $label) {
+            $label['link_id'] = $link['id'];
+            if (! $this->db->table(self::TABLE_LABEL)->save($label)) {
+            	$this->db->cancelTransaction();
+                return false;
+            }
+        }
+        $this->db->closeTransaction();
+        return true;
+    }
+
+    /**
+     * Validate link creation
+     *
+     * @access public
+     * @param array $values
+     *            Form values
+     * @return array $valid, $errors [0] = Success or not, [1] = List of errors
+     */
+    public function validateCreation(array $values)
+    {
+        $v = new Validator($values, $this->commonValidationRules());
+        
+        return array(
+            $v->execute(),
+            $v->getErrors()
+        );
+    }
+
+    /**
+     * Validate link modification
+     *
+     * @access public
+     * @param array $values
+     *            Form values
+     * @return array $valid, $errors [0] = Success or not, [1] = List of errors
+     */
+    public function validateModification(array $values)
+    {
+        $rules = array(
+            new Validators\Required('link_id', t('The id is required')),
+//             new Validators\Required('id[0]', t('The label id is required'))
+        );
+        $v = new Validator($values, array_merge($rules, $this->commonValidationRules()));
+        
+        return array(
+            $v->execute(),
+            $v->getErrors()
+        );
+    }
+
+    /**
+     * Common validation rules
+     *
+     * @access private
+     * @return array
+     */
+    private function commonValidationRules()
+    {
+        // TODO Update simple-validator to support array in forms
+        return array(
+            new Validators\Required('project_id', t('The project id required')),
+            // new Validators\Required('label[0]', t('The link label is required')),
+            new Validators\Integer('project_id', t('The project id must be an integer')),
+            new Validators\Integer('link_id', t('The link id must be an integer')),
+//             new Validators\Integer('id[0]', t('The link label id must be an integer')),
+//             new Validators\Integer('id[1]', t('The link label id must be an integer')),
+//             new Validators\Integer('behaviour[0]', t('The link label id must be an integer')),
+//             new Validators\Integer('behaviour[1]', t('The link label id must be an integer')),
+//             new Validators\MaxLength('label[0]', t('The maximum length is %d characters', 200), 200),
+//             new Validators\MaxLength('label[1]', t('The maximum length is %d characters', 200), 200)
+        );
+    }
+}
diff --git a/app/Model/TaskDuplication.php b/app/Model/TaskDuplication.php
index bd593dc1..faa5467f 100644
--- a/app/Model/TaskDuplication.php
+++ b/app/Model/TaskDuplication.php
@@ -159,6 +159,7 @@ class TaskDuplication extends Base
 
         if ($new_task_id) {
             $this->subtask->duplicate($task_id, $new_task_id);
+            $this->taskLink->duplicate($task_id, $new_task_id);
         }
 
         return $new_task_id;
diff --git a/app/Model/TaskFinder.php b/app/Model/TaskFinder.php
index 27fa8150..cf756cd8 100644
--- a/app/Model/TaskFinder.php
+++ b/app/Model/TaskFinder.php
@@ -3,6 +3,7 @@
 namespace Model;
 
 use PDO;
+use Model\TaskLink;
 
 /**
  * Task Finder model
@@ -84,6 +85,7 @@ class TaskFinder extends Base
                 '(SELECT count(*) FROM task_has_files WHERE task_id=tasks.id) AS nb_files',
                 '(SELECT count(*) FROM task_has_subtasks WHERE task_id=tasks.id) AS nb_subtasks',
                 '(SELECT count(*) FROM task_has_subtasks WHERE task_id=tasks.id AND status=2) AS nb_completed_subtasks',
+                '(SELECT count(*) FROM ' . TaskLink::TABLE . ' WHERE ' . TaskLink::TABLE . '.task_id = tasks.id) AS nb_links',
                 'tasks.id',
                 'tasks.reference',
                 'tasks.title',
@@ -128,6 +130,29 @@ class TaskFinder extends Base
                     ->asc('tasks.position')
                     ->findAll();
     }
+    
+    /**
+     * Get ids and names of all (limited by $limit) tasks for a given project and status
+     *
+     * @access public
+     * @param  integer   $project_id      Project id
+     * @param  integer   $status_id       Status id
+     * @param  integer   $exclude_id      Exclude this task id in the result
+     * @param  integer   $limit           Number of tasks to list
+     * @return array
+     */
+    public function getList($project_id, $status_id = Task::STATUS_OPEN, $exclude_id=null, $limit=50)
+    {
+        $sql = $this->db
+                    ->hashtable(Task::TABLE)
+                    ->eq('project_id', $project_id)
+                    ->eq('is_active', $status_id)
+                    ->limit($limit);
+        if (null != $exclude_id) {
+            $sql->neq('id', $exclude_id);
+        }
+        return $sql->getAll('id', 'title');
+    }
 
     /**
      * Get all tasks for a given project and status
diff --git a/app/Model/TaskLink.php b/app/Model/TaskLink.php
new file mode 100644
index 00000000..09f37d2e
--- /dev/null
+++ b/app/Model/TaskLink.php
@@ -0,0 +1,361 @@
+<?php
+namespace Model;
+
+use Core\Helper;
+use SimpleValidator\Validator;
+use SimpleValidator\Validators;
+use PDO;
+
+/**
+ * TaskLink model
+ *
+ * @package model
+ * @author Olivier Maridat
+ */
+class TaskLink extends Base
+{
+
+    /**
+     * SQL table name
+     *
+     * @var string
+     */
+    const TABLE = 'task_has_links';
+
+    /**
+     * Get a link by the task link id
+     *
+     * @access public
+     * @param integer $task_link_id
+     *            Task link id
+     * @return array
+     */
+    public function getById($task_link_id)
+    {
+        $sql = 'SELECT
+            tl1.id AS id,
+            tl1.link_label_id AS link_label_id,
+            tl1.task_id AS task_id,
+            tl1.task_inverse_id AS task_inverse_id,
+            tl2.id AS task_link_inverse_id
+            FROM ' . self::TABLE . ' tl1
+            LEFT JOIN ' . Link::TABLE_LABEL . ' l1 ON l1.id = tl1.link_label_id
+            LEFT JOIN ' . Link::TABLE_LABEL . ' l2 ON l2.link_id = l1.link_id
+            LEFT JOIN ' . self::TABLE . ' tl2 ON tl2.task_id = tl1.task_inverse_id
+            		AND ( (l1.behaviour = 2 AND tl2.link_label_id = l1.id) OR (tl2.link_label_id = l2.id) )
+            WHERE tl1.id = ?
+        ';
+        $rq = $this->db->execute($sql, array(
+            $task_link_id
+        ));
+        return $rq->fetch();
+    }
+
+    /**
+     * Get the id of the inverse task link by a task link id
+     *
+     * @access public
+     * @param integer $link_id
+     *            Task link id
+     * @return integer
+     */
+    public function getInverseTaskLinkId($task_link_id)
+    {
+        $sql = 'SELECT
+            tl2.id
+            FROM ' . self::TABLE . ' tl1
+            LEFT JOIN ' . Link::TABLE_LABEL . ' l1 ON l1.id = tl1.link_label_id
+            LEFT JOIN ' . Link::TABLE_LABEL . ' l2 ON l2.link_id = l1.link_id
+            LEFT JOIN ' . self::TABLE . ' tl2 ON tl2.task_id = tl1.task_inverse_id
+            		AND ( (l1.behaviour = 2 AND tl2.link_label_id = l1.id) OR (tl2.link_label_id = l2.id) )
+            WHERE tl1.id = ?
+        ';
+        $rq = $this->db->execute($sql, array(
+            $task_link_id
+        ));
+        return $rq->fetchColumn(0);
+    }
+
+    /**
+     * Return all links for a given task
+     *
+     * @access public
+     * @param integer $task_id
+     *            Task id
+     * @return array
+     */
+    public function getAll($task_id)
+    {
+        $sql = 'SELECT
+            tl1.id,
+            l.label AS label,
+            t2.id AS task_inverse_id,
+            t2.project_id AS task_inverse_project_id,
+            t2.title AS task_inverse_title,
+            t2.is_active AS task_inverse_is_active,
+            t2cat.name AS task_inverse_category
+            FROM ' . self::TABLE . ' tl1
+            LEFT JOIN ' . Link::TABLE_LABEL . ' l ON l.id = tl1.link_label_id
+            LEFT JOIN ' . Task::TABLE . ' t2 ON t2.id = tl1.task_inverse_id
+            LEFT JOIN ' . Category::TABLE . ' t2cat ON t2cat.id = t2.category_id
+            WHERE tl1.task_id = ?
+            ORDER BY l.label, t2cat.name, t2.id
+        ';
+        $rq = $this->db->execute($sql, array(
+            $task_id
+        ));
+        $res = $rq->fetchAll(PDO::FETCH_ASSOC);
+        return $res;
+    }
+
+    /**
+     * Prepare data before insert/update
+     *
+     * @access public
+     * @param array $values
+     *            Form values
+     */
+    public function prepare(array &$values)
+    {
+        $this->removeFields($values, array(
+            'another_link'
+        ));
+        $taskLink1 = array(
+            'link_label_id' => $values['link_label_id'],
+            'task_id' => $values['task_id'],
+            'task_inverse_id' => $values['task_inverse_id']
+        );
+        $taskLink2 = array(
+            'link_label_id' => $this->link->getInverseLinkLabelId($taskLink1['link_label_id']),
+            'task_id' => $values['task_inverse_id'],
+            'task_inverse_id' => $values['task_id']
+        );
+        if (isset($values['id']) && isset($values['task_link_inverse_id'])) {
+            $taskLink1['id'] = $values['id'];
+            $taskLink2['id'] = $values['task_link_inverse_id'];
+        }
+        return array(
+            $taskLink1,
+            $taskLink2
+        );
+    }
+
+    /**
+     * Create a link
+     *
+     * @access public
+     * @param array $values
+     *            Form values
+     * @return bool integer
+     */
+    public function create(array $values)
+    {
+        list($taskLink1, $taskLink2) = $this->prepare($values);
+        $this->db->startTransaction();
+        if (! $this->db->table(self::TABLE)->save($taskLink1)) {
+            $this->db->cancelTransaction();
+            return false;
+        }
+        if (! $this->db->table(self::TABLE)->save($taskLink2)) {
+            $this->db->cancelTransaction();
+            return false;
+        }
+        $this->db->closeTransaction();
+        return true;
+    }
+
+    /**
+     * Update a link
+     *
+     * @access public
+     * @param array $values
+     *            Form values
+     * @return bool
+     */
+    public function update(array $values)
+    {
+        list($taskLink1, $taskLink2) = $this->prepare($values);
+        $this->db->startTransaction();
+        if (! $this->db->table(self::TABLE)
+            ->eq('id', $taskLink1['id'])
+            ->save($taskLink1)) {
+            $this->db->cancelTransaction();
+            return false;
+        }
+        if (! $this->db->table(self::TABLE)
+            ->eq('id', $taskLink2['id'])
+            ->save($taskLink2)) {
+            $this->db->cancelTransaction();
+            return false;
+        }
+        $this->db->closeTransaction();
+        return true;
+    }
+
+    /**
+     * Remove a link
+     *
+     * @access public
+     * @param integer $task_link_id
+     *            Task Link id
+     * @return bool
+     */
+    public function remove($task_link_id)
+    {
+        $task_link_inverse_id = $this->getInverseTaskLinkId($task_link_id);
+        $this->db->startTransaction();
+        if (! $this->db->table(self::TABLE)
+            ->eq('id', $task_link_id)
+            ->remove()) {
+            $this->db->cancelTransaction();
+            return false;
+        }
+        if (! $this->db->table(self::TABLE)
+            ->eq('id', $task_link_inverse_id)
+            ->remove()) {
+            $this->db->cancelTransaction();
+            return false;
+        }
+        $this->db->closeTransaction();
+        return true;
+    }
+
+    /**
+     * Duplicate all links to another task
+     *
+     * @access public
+     * @param integer $src_task_id
+     *            Source task id
+     * @param integer $dst_task_id
+     *            Destination task id
+     * @return bool
+     */
+    public function duplicate($src_task_id, $dst_task_id)
+    {
+        return $this->db->transaction(function ($db) use($src_task_id, $dst_task_id)
+        {
+            $links = $db->table(TaskLink::TABLE)
+                ->columns('link_label_id', 'task_id', 'task_inverse_id')
+                ->eq('task_id', $src_task_id)
+                ->asc('id')
+                ->findAll();
+            foreach ($links as &$link) {
+                $link['task_id'] = $dst_task_id;
+                if (! $db->table(TaskLink::TABLE)
+                    ->save($link)) {
+                    return false;
+                }
+            }
+            
+            $links = $db->table(TaskLink::TABLE)
+                ->columns('link_label_id', 'task_id', 'task_inverse_id')
+                ->eq('task_inverse_id', $src_task_id)
+                ->asc('id')
+                ->findAll();
+            foreach ($links as &$link) {
+                $link['task_inverse_id'] = $dst_task_id;
+                if (! $db->table(TaskLink::TABLE)
+                    ->save($link)) {
+                    return false;
+                }
+            }
+        });
+    }
+
+    /**
+     * Move a task link from a link label to an other
+     *
+     * @access public
+     * @param integer $link_id
+     *            Link id
+     * @param integer $dst_link_label_id
+     *            Destination link label id
+     * @return bool
+     */
+    public function changeLinkLabel($link_id, $dst_link_label_id, $alternate=false)
+    {
+        $taskLinks = $this->db->table(Link::TABLE_LABEL)
+            ->eq('link_id', $link_id)
+            ->neq(Link::TABLE_LABEL.'.id', $dst_link_label_id)
+            ->join(self::TABLE, 'link_label_id', 'id')
+            ->asc(self::TABLE.'.id')
+            ->findAllByColumn(self::TABLE.'.id');
+        foreach ($taskLinks as $i => $taskLinkId) {
+            if (null == $taskLinkId || ($alternate && 0 != $i % 2)) {
+                continue;
+            }
+            if (! $this->db->table(self::TABLE)
+                ->eq('id', $taskLinkId)
+                ->save(array('link_label_id' => $dst_link_label_id))) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    /**
+     * Validate link creation
+     *
+     * @access public
+     * @param array $values
+     *            Form values
+     * @return array $valid, $errors [0] = Success or not, [1] = List of errors
+     */
+    public function validateCreation(array $values)
+    {
+        $v = new Validator($values, $this->commonValidationRules());
+        $res = array(
+            $v->execute(),
+            $v->getErrors()
+        );
+        return $res;
+    }
+
+    /**
+     * Validate link modification
+     *
+     * @access public
+     * @param array $values
+     *            Form values
+     * @return array $valid, $errors [0] = Success or not, [1] = List of errors
+     */
+    public function validateModification(array $values)
+    {
+        $rules = array(
+            new Validators\Required('id', t('The id is required'))
+        );
+        $v = new Validator($values, array_merge($rules, $this->commonValidationRules()));
+        $res = array(
+            $v->execute(),
+            $v->getErrors()
+        );
+        return $res;
+    }
+
+    /**
+     * Common validation rules
+     *
+     * @access private
+     * @return array
+     */
+    private function commonValidationRules()
+    {
+        return array(
+            new Validators\Required('link_label_id', t('The link type is required')),
+            new Validators\Required('task_id', t('The task id is required')),
+            new Validators\Required('task_inverse_id', t('The linked task id is required')),
+            new Validators\Integer('id', t('The id must be an integer')),
+            new Validators\Integer('link_label_id', t('The link id must be an integer')),
+            new Validators\Integer('task_id', t('The task id must be an integer')),
+            new Validators\Integer('task_inverse_id', t('The related task id must be an integer')),
+            new Validators\Integer('task_link_inverse_id', t('The related task link id must be an integer')),
+            new Validators\NotEquals('task_inverse_id', 'task_id', t('A task can not be linked to itself')),
+            new Validators\Exists('task_inverse_id', t('This linked task id doesn\'t exist'), $this->db->getConnection(), Task::TABLE, 'id'),
+            new Validators\Unique(array(
+                'task_inverse_id',
+                'link_label_id',
+                'task_id'
+            ), t('The exact same link already exists'), $this->db->getConnection(), self::TABLE)
+        );
+    }
+}