C:/xampp/htdocs/moodle/question/engine/questionusage.php

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<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

defined('MOODLE_INTERNAL') || die();


class question_usage_by_activity {
    protected $id = null;

    protected $preferredbehaviour = null;

    protected $context;

    protected $owningcomponent;

    protected $questionattempts = array();

    protected $observer;

    public function __construct($component, $context) {
        $this->owningcomponent = $component;
        $this->context = $context;
        $this->observer = new question_usage_null_observer();
    }

    public function set_preferred_behaviour($behaviour) {
        $this->preferredbehaviour = $behaviour;
        $this->observer->notify_modified();
    }

    public function get_preferred_behaviour() {
        return $this->preferredbehaviour;
    }

    public function get_owning_context() {
        return $this->context;
    }

    public function get_owning_component() {
        return $this->owningcomponent;
    }

    public function get_id() {
        if (is_null($this->id)) {
            $this->id = random_string(10);
        }
        return $this->id;
    }

    public function set_id_from_database($id) {
        $this->id = $id;
        foreach ($this->questionattempts as $qa) {
            $qa->set_usage_id($id);
        }
    }

    public function get_observer() {
        return $this->observer;
    }

    public function set_observer($observer) {
        $this->observer = $observer;
        foreach ($this->questionattempts as $qa) {
            $qa->set_observer($observer);
        }
    }

    public function add_question(question_definition $question, $maxmark = null) {
        $qa = new question_attempt($question, $this->get_id(), $this->observer, $maxmark);
        if (count($this->questionattempts) == 0) {
            $this->questionattempts[1] = $qa;
        } else {
            $this->questionattempts[] = $qa;
        }
        $qa->set_slot(end(array_keys($this->questionattempts)));
        $this->observer->notify_attempt_added($qa);
        return $qa->get_slot();
    }

    public function get_question($slot) {
        return $this->get_question_attempt($slot)->get_question();
    }

    public function get_slots() {
        return array_keys($this->questionattempts);
    }

    public function get_first_question_number() {
        reset($this->questionattempts);
        return key($this->questionattempts);
    }

    public function question_count() {
        return count($this->questionattempts);
    }

    public function get_attempt_iterator() {
        return new question_attempt_iterator($this);
    }

    protected function check_slot($slot) {
        if (!array_key_exists($slot, $this->questionattempts)) {
            throw new coding_exception('There is no question_attempt number ' . $slot .
                    ' in this attempt.');
        }
    }

    public function get_question_attempt($slot) {
        $this->check_slot($slot);
        return $this->questionattempts[$slot];
    }

    public function get_question_state($slot) {
        return $this->get_question_attempt($slot)->get_state();
    }

    public function get_question_state_string($slot, $showcorrectness) {
        return $this->get_question_attempt($slot)->get_state_string($showcorrectness);
    }

    public function get_question_state_class($slot, $showcorrectness) {
        return $this->get_question_attempt($slot)->get_state_class($showcorrectness);
    }

    public function get_question_action_time($slot) {
        return $this->get_question_attempt($slot)->get_last_action_time();
    }

    public function get_question_fraction($slot) {
        return $this->get_question_attempt($slot)->get_fraction();
    }

    public function get_question_mark($slot) {
        return $this->get_question_attempt($slot)->get_mark();
    }

    public function get_question_max_mark($slot) {
        return $this->get_question_attempt($slot)->get_max_mark();
    }

    public function get_total_mark() {
        $mark = 0;
        foreach ($this->questionattempts as $qa) {
            if ($qa->get_max_mark() > 0 && $qa->get_state() == question_state::$needsgrading) {
                return null;
            }
            $mark += $qa->get_mark();
        }
        return $mark;
    }

    public function get_question_summary($slot) {
        return $this->get_question_attempt($slot)->get_question_summary();
    }

    public function get_response_summary($slot) {
        return $this->get_question_attempt($slot)->get_response_summary();
    }

    public function get_right_answer_summary($slot) {
        return $this->get_question_attempt($slot)->get_right_answer_summary();
    }

    public function render_question($slot, $options, $number = null) {
        $options->context = $this->context;
        return $this->get_question_attempt($slot)->render($options, $number);
    }

    public function render_question_head_html($slot) {
        //$options->context = $this->context;
        return $this->get_question_attempt($slot)->render_head_html();
    }

    public function render_question_at_step($slot, $seq, $options, $number = null) {
        $options->context = $this->context;
        return $this->get_question_attempt($slot)->render_at_step(
                $seq, $options, $number, $this->preferredbehaviour);
    }

    public function check_file_access($slot, $options, $component, $filearea,
            $args, $forcedownload) {
        return $this->get_question_attempt($slot)->check_file_access(
                $options, $component, $filearea, $args, $forcedownload);
    }

    public function replace_loaded_question_attempt_info($slot, $qa) {
        $this->check_slot($slot);
        $this->questionattempts[$slot] = $qa;
    }

    public function get_field_prefix($slot) {
        return $this->get_question_attempt($slot)->get_field_prefix();
    }

    public function get_num_variants($slot) {
        return $this->get_question_attempt($slot)->get_question()->get_num_variants();
    }

    public function get_variant($slot) {
        return $this->get_question_attempt($slot)->get_variant();
    }

    public function start_question($slot, $variant = null) {
        if (is_null($variant)) {
            $variant = rand(1, $this->get_num_variants($slot));
        }

        $qa = $this->get_question_attempt($slot);
        $qa->start($this->preferredbehaviour, $variant);
        $this->observer->notify_attempt_modified($qa);
    }

    public function start_all_questions(question_variant_selection_strategy $variantstrategy = null,
            $timestamp = null, $userid = null) {
        if (is_null($variantstrategy)) {
            $variantstrategy = new question_variant_random_strategy();
        }

        foreach ($this->questionattempts as $qa) {
            $qa->start($this->preferredbehaviour, $qa->select_variant($variantstrategy));
            $this->observer->notify_attempt_modified($qa);
        }
    }

    public function start_question_based_on($slot, question_attempt $oldqa) {
        $qa = $this->get_question_attempt($slot);
        $qa->start_based_on($oldqa);
        $this->observer->notify_attempt_modified($qa);
    }

    public function process_all_actions($timestamp = null, $postdata = null) {
        $slots = question_attempt::get_submitted_var('slots', PARAM_SEQUENCE, $postdata);
        if (is_null($slots)) {
            $slots = $this->get_slots();
        } else if (!$slots) {
            $slots = array();
        } else {
            $slots = explode(',', $slots);
        }
        foreach ($slots as $slot) {
            if (!$this->validate_sequence_number($slot, $postdata)) {
                continue;
            }
            $submitteddata = $this->extract_responses($slot, $postdata);
            $this->process_action($slot, $submitteddata, $timestamp);
        }
        $this->update_question_flags($postdata);
    }

    public function extract_responses($slot, $postdata = null) {
        return $this->get_question_attempt($slot)->get_submitted_data($postdata);
    }

    public function process_action($slot, $submitteddata, $timestamp = null) {
        $qa = $this->get_question_attempt($slot);
        $qa->process_action($submitteddata, $timestamp);
        $this->observer->notify_attempt_modified($qa);
    }

    public function validate_sequence_number($slot, $postdata = null) {
        $qa = $this->get_question_attempt($slot);
        $sequencecheck = $qa->get_submitted_var(
                $qa->get_control_field_name('sequencecheck'), PARAM_INT, $postdata);
        if (is_null($sequencecheck)) {
            return false;
        } else if ($sequencecheck != $qa->get_num_steps()) {
            throw new question_out_of_sequence_exception($this->id, $slot, $postdata);
        } else {
            return true;
        }
    }
    public function update_question_flags($postdata = null) {
        foreach ($this->questionattempts as $qa) {
            $flagged = $qa->get_submitted_var(
                    $qa->get_flag_field_name(), PARAM_BOOL, $postdata);
            if (!is_null($flagged) && $flagged != $qa->is_flagged()) {
                $qa->set_flagged($flagged);
            }
        }
    }

    public function get_correct_response($slot) {
        return $this->get_question_attempt($slot)->get_correct_response();
    }

    public function finish_question($slot, $timestamp = null) {
        $qa = $this->get_question_attempt($slot);
        $qa->finish($timestamp);
        $this->observer->notify_attempt_modified($qa);
    }

    public function finish_all_questions($timestamp = null) {
        foreach ($this->questionattempts as $qa) {
            $qa->finish($timestamp);
            $this->observer->notify_attempt_modified($qa);
        }
    }

    public function manual_grade($slot, $comment, $mark) {
        $qa = $this->get_question_attempt($slot);
        $qa->manual_grade($comment, $mark);
        $this->observer->notify_attempt_modified($qa);
    }

    public function regrade_question($slot, $finished = false, $newmaxmark = null) {
        $oldqa = $this->get_question_attempt($slot);
        if (is_null($newmaxmark)) {
            $newmaxmark = $oldqa->get_max_mark();
        }

        $newqa = new question_attempt($oldqa->get_question(), $oldqa->get_usage_id(),
                $this->observer, $newmaxmark);
        $newqa->set_database_id($oldqa->get_database_id());
        $newqa->set_slot($oldqa->get_slot());
        $newqa->regrade($oldqa, $finished);

        $this->questionattempts[$slot] = $newqa;
        $this->observer->notify_attempt_modified($newqa);
    }

    public function regrade_all_questions($finished = false) {
        foreach ($this->questionattempts as $slot => $notused) {
            $this->regrade_question($slot, $finished);
        }
    }

    public static function load_from_records($records, $qubaid) {
        $record = $records->current();
        while ($record->qubaid != $qubaid) {
            $records->next();
            if (!$records->valid()) {
                throw new coding_exception("Question usage $qubaid not found in the database.");
            }
            $record = $records->current();
        }

        $quba = new question_usage_by_activity($record->component,
            get_context_instance_by_id($record->contextid));
        $quba->set_id_from_database($record->qubaid);
        $quba->set_preferred_behaviour($record->preferredbehaviour);

        $quba->observer = new question_engine_unit_of_work($quba);

        while ($record && $record->qubaid == $qubaid && !is_null($record->slot)) {
            $quba->questionattempts[$record->slot] =
                    question_attempt::load_from_records($records,
                    $record->questionattemptid, $quba->observer,
                    $quba->get_preferred_behaviour());
            if ($records->valid()) {
                $record = $records->current();
            } else {
                $record = false;
            }
        }

        return $quba;
    }
}


class question_attempt_iterator implements Iterator, ArrayAccess {
    protected $quba;
    protected $slots;

    public function __construct(question_usage_by_activity $quba) {
        $this->quba = $quba;
        $this->slots = $quba->get_slots();
        $this->rewind();
    }

    public function current() {
        return $this->offsetGet(current($this->slots));
    }
    public function key() {
        return current($this->slots);
    }
    public function next() {
        next($this->slots);
    }
    public function rewind() {
        reset($this->slots);
    }
    public function valid() {
        return current($this->slots) !== false;
    }

    public function offsetExists($slot) {
        return in_array($slot, $this->slots);
    }
    public function offsetGet($slot) {
        return $this->quba->get_question_attempt($slot);
    }
    public function offsetSet($slot, $value) {
        throw new coding_exception('You are only allowed read-only access to ' .
                'question_attempt::states through a question_attempt_step_iterator. Cannot set.');
    }
    public function offsetUnset($slot) {
        throw new coding_exception('You are only allowed read-only access to ' .
                'question_attempt::states through a question_attempt_step_iterator. Cannot unset.');
    }
}


interface question_usage_observer {
    public function notify_modified();

    public function notify_attempt_modified(question_attempt $qa);

    public function notify_attempt_added(question_attempt $qa);

    public function notify_step_added(question_attempt_step $step, question_attempt $qa, $seq);

    public function notify_step_modified(question_attempt_step $step, question_attempt $qa, $seq);

    public function notify_step_deleted(question_attempt_step $step, question_attempt $qa);

}


class question_usage_null_observer implements question_usage_observer {
    public function notify_modified() {
    }
    public function notify_attempt_modified(question_attempt $qa) {
    }
    public function notify_attempt_added(question_attempt $qa) {
    }
    public function notify_step_added(question_attempt_step $step, question_attempt $qa, $seq) {
    }
    public function notify_step_modified(question_attempt_step $step, question_attempt $qa, $seq) {
    }
    public function notify_step_deleted(question_attempt_step $step, question_attempt $qa) {
    }
}