<?php
// scorechart.php -- HotCRP chart generator
// Copyright (c) 2006-2018 Eddie Kohler; see LICENSE.

// Generates a PNG image of a bar chat.
// Arguments are passed in as v; s is graph style.
// Don't forget to change the width and height calculations in
// ReviewField::unparse_graph if you change the width and height here.

if (!isset($_GET["v"])) {
    header("HTTP/1.0 400 Bad Request");
    exit;
}

// fail if no GD support so the browser displays alt text
if (!function_exists("imagecreate")) {
    require_once("src/init.php");
    Dbl::q("insert into Settings set name='__gd_required', value=1 on duplicate key update value=1");
    header("HTTP/1.0 503 Service Unavailable");
    exit;
}

// parse values
$s = (isset($_GET["s"]) ? $_GET["s"] : 0);
if ($s != 0 && $s != 1 && $s != 2)
    $s = 2;
$valMax = 1;
$values = array();
$maxY = $sum = 0;
foreach (explode(",", $_GET["v"]) as $value) {
    $value = (ctype_digit($value) && $value > 0 ? intval($value) : 0);
    $values[$valMax++] = $value;
    $maxY = max($value, $maxY);
    $sum += $value;
}
if (isset($_GET["h"]) && is_numeric($_GET["h"]))
    $valLight = intval($_GET["h"]);
else
    $valLight = 0;
if ($valLight < 1 || $valLight >= $valMax)
    $valLight = 0;
$levelChar = (isset($_GET["c"]) && ord($_GET["c"]) >= 65
              ? ord($_GET["c"]) : 0);


// set shape constants
if ($s == 0) {
    list($blockHeight, $blockWidth, $blockSkip, $blockPad, $textWidth)
        = array(8, 8, 2, 4, 12);
} else if ($s == 1) {
    list($blockHeight, $blockWidth, $blockSkip, $blockPad, $textWidth)
        = array(3, 3, 2, 2, 0);
}

if ($s == 0 || $s == 1) {
    $maxY = max($maxY, 3);
    $picWidth = ($blockWidth + $blockPad) * ($valMax - 1)
        + $blockPad
        + 2 * $textWidth;
    $picHeight = $blockHeight * $maxY + $blockSkip * ($maxY + 1);
    $pic = @imagecreate($picWidth + 1, $picHeight + 1);
} else if ($s == 2) {
    $picWidth = 64;
    $picHeight = 8;
    $pic = @imagecreate($picWidth, $picHeight);
}

$cWhite = imagecolorallocate($pic, 255, 255, 255);
$cBlack = imagecolorallocate($pic, 0, 0, 0);
$cgray = imagecolorallocate($pic, 190, 190, 255);

if ($s == 0) {
    imagefilledrectangle($pic, 0, 0, $picWidth + 1, $picHeight + 1, $cBlack);
    imagefilledrectangle($pic, 1, 1, $picWidth - 1, $picHeight - 1, $cWhite);
} else if ($s == 1) {
    imagecolortransparent($pic, $cWhite);
    imagefilledrectangle($pic, 0, $picHeight, $picWidth + 1, $picHeight + 1, $cgray);
    imagefilledrectangle($pic, 0, $picHeight - $blockHeight - $blockPad, 0, $picHeight + 1, $cgray);
    imagefilledrectangle($pic, $picWidth, $picHeight - $blockHeight - $blockPad, $picWidth + 1, $picHeight + 1, $cgray);
}

$cv_black = array(0, 0, 0);
$cv_bad = array(200, 128, 128);
$cv_good = array(0, 232, 0);
function quality_color($c1, $c2, $f) {
    return array($c2[0] * $f + $c1[0] * (1 - $f),
                 $c2[1] * $f + $c1[1] * (1 - $f),
                 $c2[2] * $f + $c1[2] * (1 - $f));
}

$pos = 0;

for ($value = 1; $value < $valMax; $value++) {
    $vpos = ($levelChar ? $valMax - $value : $value);
    $height = $values[$vpos];
    $frac = ($vpos - 1) / ($valMax - 1);
    $cv_cur = quality_color($cv_bad, $cv_good, $frac);
    $cFill = imagecolorallocate($pic, $cv_cur[0], $cv_cur[1], $cv_cur[2]);

    if ($s == 0 || $s == 1) {
        $curX = $blockWidth * ($value - 1)
            + $blockPad * $value + $textWidth;
        $curY = $picHeight - ($blockHeight + $blockSkip) * $height + $blockHeight;

        for ($h = 1; $h <= $height; $h++) {
            if ($h == $height && $vpos == $valLight) {
                $cv_cur = quality_color($cv_black, $cv_cur, 0.5);
                $cFill = imagecolorallocate($pic, $cv_cur[0], $cv_cur[1], $cv_cur[2]);
            }
            imagefilledrectangle($pic, $curX, $curY - $blockHeight,
                                 $curX + $blockWidth, $curY, $cFill);
            $curY += ($blockHeight + $blockSkip);
        }
    } else {
        if ($height > 0)
            imagefilledrectangle($pic, ($picWidth + 1) * $pos / $sum, 0,
                                 ($picWidth + 1) * ($pos + $height) / $sum - 2, $picHeight,
                                 $cFill);
        $pos += $height;
    }
}

if ($s == 0) {
    imagestringup($pic, 2, 0, 30, "Bad", $cBlack);
    imagestringup($pic, 2, $picWidth-$textWidth, 30, "Good", $cBlack);
 } else if ($s == 1) {
    $lx = $textWidth + $blockPad;
    $rx = $picWidth - $blockWidth - $textWidth - $blockPad;
    $y = $picHeight - $blockHeight - $blockSkip - 3;
    if (isset($_GET["c"]) && ord($_GET["c"]) >= 65) {
        if ($values[1] == 0)
            imagestring($pic, 1, $rx, $y, $_GET["c"], $cgray);
        if ($values[$valMax - 1] == 0)
            imagestring($pic, 1, $lx, $y, chr(ord($_GET["c"]) - $valMax + 2), $cgray);
    } else {
        if ($values[1] == 0)
            imagestring($pic, 1, $lx, $y, 1, $cgray);
        if ($values[$valMax - 1] == 0)
            imagestring($pic, 1, $rx, $y, $valMax - 1, $cgray);
    }
}

session_cache_limiter("");
header("Cache-Control: max-age=31557600, public");
header("Expires: " . gmdate("D, d M Y H:i:s", time() + 31557600) . " GMT");
header("Content-Type: image/png");
imagepng($pic);
exit();