<?php

namespace app\common\library\ps;

/**
 * 从原稿图读取页面尺寸和底色，给还原排版用。
 */
class LayoutProbe
{
    /**
     * @param string $path 本地图片路径
     * @return array
     */
    public static function inspect($path)
    {
        $out = [
            'width'      => 0,
            'height'     => 0,
            'background' => '#ffffff',
            'ratio'      => 297 / 210,
        ];
        if (!$path || !is_file($path)) {
            return $out;
        }
        $info = @getimagesize($path);
        if (!$info || empty($info[0]) || empty($info[1])) {
            return $out;
        }
        $out['width'] = (int)$info[0];
        $out['height'] = (int)$info[1];
        $out['ratio'] = $info[1] / $info[0];
        $bg = self::sampleBackground($path, $info);
        if ($bg) {
            $out['background'] = $bg;
        }
        return $out;
    }

    /**
     * 取四角浅色均值，避开油墨。
     * @param string $path
     * @param array  $info
     * @return string
     */
    protected static function sampleBackground($path, array $info)
    {
        if (!function_exists('imagecreatefromstring')) {
            return '#ffffff';
        }
        $bin = @file_get_contents($path);
        if ($bin === false || $bin === '') {
            return '#ffffff';
        }
        $im = @imagecreatefromstring($bin);
        if (!$im) {
            return '#ffffff';
        }
        $w = imagesx($im);
        $h = imagesy($im);
        $points = [
            [4, 4], [$w - 5, 4], [4, $h - 5], [$w - 5, $h - 5],
            [(int)($w / 2), 4], [4, (int)($h / 2)],
        ];
        $rs = $gs = $bs = [];
        foreach ($points as $p) {
            $rgb = imagecolorat($im, max(0, $p[0]), max(0, $p[1]));
            $r = ($rgb >> 16) & 0xFF;
            $g = ($rgb >> 8) & 0xFF;
            $b = $rgb & 0xFF;
            if (($r + $g + $b) < 180) {
                continue;
            }
            $rs[] = $r;
            $gs[] = $g;
            $bs[] = $b;
        }
        imagedestroy($im);
        if (!$rs) {
            return '#ffffff';
        }
        $n = count($rs);
        return sprintf('#%02x%02x%02x', (int)round(array_sum($rs) / $n), (int)round(array_sum($gs) / $n), (int)round(array_sum($bs) / $n));
    }
}