<?php

/**
 * @package tikiwiki
 */

// (c) Copyright by authors of the Tiki Wiki CMS Groupware Project
//
// All Rights Reserved. See copyright.txt for details and a complete list of authors.
// Licensed under the GNU LESSER GENERAL PUBLIC LICENSE. See license.txt for details.
// $Id$

require_once('tiki-setup.php');
require_once('lib/graph-engine/graph.multiline.php');
require_once('lib/graph-engine/gd.php');
require_once('lib/graph-engine/pdflib.php');

// List of valid functions
$valid = [
    'abs',
    'acos',
    'acosh',
    'asin',
    'asinh',
    'atan2',
    'atan',
    'atanh',
    'ceil',
    'cos',
    'cosh',
    'deg2rad',
    'exp',
    'expm1',
    'floor',
    'fmod',
    'hypot',
    'log10',
    'log1p',
    'log',
    'max',
    'min',
    'pi',
    'pow',
    'rad2deg',
    'round',
    'sin',
    'sinh',
    'sqrt',
    'tan',
    'tanh'
];

/**
 * @param $formula
 * @return string
 */
function convert_formula($formula)
{
    global $valid;

    // Stripping all quotes
    $chars = [ '`', "'", '"', '&', '[', ']', '$', '{', '}' ];
    $formula = str_replace($chars, array_fill(0, count($chars), ''), $formula);

    // Make sure only valid functions are used
    preg_match_all('/([a-z0-9_]+)/i', $formula, $out, PREG_PATTERN_ORDER);
    foreach ($out[0] as $match) {
        if (! is_numeric($match) && ! in_array(strtolower($match), $valid) && $match !== 'x') {
            die("Invalid function call {$match}");
        }
    }

    // Replace spaces for commas
    $formula = preg_replace('/\s+/', ', ', $formula);

    $formula = str_replace('x', '$x', $formula);

    return create_function('$x', "return $formula;");
}

$access->check_permission('feature_sheet');

if (
    ! ( is_numeric($_GET['w'])
    && is_numeric($_GET['h'])
    && is_numeric($_GET['s'])
    && $_GET['s'] <= 500 && $_GET['s'] > 0
    && is_numeric($_GET['min'])
    && is_numeric($_GET['max'])
    && is_array($_GET['f'])
    && $_GET['min'] < $_GET['max']
    && $_GET['w'] >= 100
    && $_GET['h'] >= 100 )
) {
    die;
}

switch ($_GET['t']) {
    case 'png':
        $renderer = new GD_GRenderer($_GET['w'], $_GET['h']);
        break;
    case 'pdf':
        $renderer = new PDFLib_GRenderer($_GET['p'], $_GET['o']);
        break;
    default:
        die;
}

$graph = new MultilineGraphic();
$graph->setTitle($_GET['title']);

$size = ($_GET['max'] - $_GET['min']) / $_GET['s'];

$data = [];
foreach (array_values($_GET['f']) as $key => $formula) {
    $formula = convert_formula($formula);

    $data['x'] = [];
    $data['y' . $key] = [];

    for ($x = $_GET['min']; $_GET['max'] > $x; $x += $size) {
        $data['x'][] = $x;
        $data['y' . $key][] = $formula($x);
    }
}

$graph->setData($data);
$graph->draw($renderer);

$renderer->httpOutput("graph.{$_GET['t']}");