<?php

/**
 * @author      Till Glöggler <tgloeggl@uos.de>
 * @author      André Klaßen <klassen@elan-ev.de>
 * @license     GPL 2 or later
 */

namespace Studip\Activity;

abstract class Context
{
    public static $objectTypes = [
        'documents',
        'message',
        'news',
        'participants',
        'schedule',
        'wiki',
        'courseware',
        'forum'
    ];

    public static $contexTypes = [
        'system',
        'course',
        'institute',
        'user'
    ];

    protected
        $provider,
        $observer;


    /**
     * return array, listing all active providers in this context
     *
     * @return array
     */
    abstract protected function getProvider();

    /**
     * get id denoting the context (user_id, course_id, institute_id, ...)
     *
     * @return string
     */
    abstract public function getRangeId();

    /**
     * get type of context (f.e. user, system, course, institute, ...)
     *
     * @return string
     */
    abstract public function getContextType();

    /**
     * get type of context (f.e. user, system, course, institute, ...)
     *
     * @return string
     */
    abstract public function getContextFullname($format = 'default');

    /**
     * Return user for who wants to watch his and related activities
     *
     * @return object  a user object
     */
    public function getObserver()
    {
        return $this->observer;
    }

    /**
     * get list of activities as array for the current context
     *
     * @param \Studip\Activity\Filter $filter
     *
     * @return array
     */
    public function getActivities(Filter $filter)
    {
        $providers = $this->filterProvider($this->getProvider(), $filter);

        $query = 'context = ? AND context_id = ? AND mkdate >= ? AND mkdate <= ? ORDER BY mkdate DESC';
        $params = [$this->getContextType(), $this->getRangeId(), $filter->getStartDate(), $filter->getEndDate()];

        if ($filter->getContext() !== null && $filter->getContextId() !== null) {
            // if a single context is provided and this context does not match, do not return any activites
            if ($this->getRangeId() != $filter->getContextId()) {
                return null;
            }

            $params = [$filter->getContext(), $filter->getContextId(), $filter->getStartDate(), $filter->getEndDate()];
        }

        if(\in_array($filter->getObjectType(), $this::$objectTypes)) {
            $query = 'object_type = ? AND ' . $query;
            \array_unshift($params, $filter->getObjectType());

            //Object ID Filter only available when object type is set
            if($filter->getObjectId() !== null && \strlen($filter->getObjectId()) > 0) {
                $query = 'object_id = ? AND ' . $query;
                \array_unshift($params, $filter->getObjectId());
            }
        }
        $activities = Activity::findAndMapBySQL(
            function ($activity) use ($providers) {
                if (isset($providers[$activity->provider])) {                        // provider is available
                    $activity->setContextObject($this);
                    if ($providers[$activity->provider]->getActivityDetails($activity)) {
                        return $activity;
                    }
                }
            },
            $query,
            $params
        );
        return array_filter($activities);
    }

    /**
     * Add a provider to this context
     *
     * @param string $provider    the name for the provider
     * @param string $class_name  the class that belongs to the provider
     */
    protected function addProvider($class_name)
    {
        $reflectionClass = new \ReflectionClass($class_name);
        $this->provider[$class_name] =  $reflectionClass->newInstanceArgs();
    }

    /**
     * Filter the passed the providers to match the passed filter
     *
     * @param type $providers
     * @param \Studip\Activity\Filter $filter
     * @return type
     */
    protected function filterProvider($providers, Filter $filter)
    {
        $filtered_providers = [];

        if (empty($filter->getType())) {
            $filtered_providers = $providers;
        } else {
            foreach ($providers as $provider) {
                $ctype = $this->getContextType();
                $filtered_classes = $filter->getType()->$ctype ?? null;

                if (is_array($filtered_classes)) {
                    foreach ($filtered_classes as $class) {
                        $iclass = 'Studip\\Activity\\' .ucfirst($class) .'Provider';
                        if ($provider instanceof $iclass) {
                            $filtered_providers[$iclass] =  $provider;
                        }
                    }
                }
            }
        }

        return $filtered_providers;
    }
}