<?php

/*
Copyright 2011-2016 Chris Jean & iThemes
Licensed under GPLv2 or above
*/

namespace splitbrain\phpico;

class PhpIco
{
    /**
     * Images in the BMP format.
     *
     * @var array
     */
    private $images = array();

    /**
     * Constructor - Create a new ICO generator.
     *
     * If the constructor is not passed a file, a file will need to be supplied using the {@link PHP_ICO::add_image}
     * function in order to generate an ICO file.
     *
     * @param string $file Optional. Path to the source image file.
     * @param array $sizes Optional. An array of sizes (each size is an array with a width and height)
     *                               that the source image should be rendered at in the generated ICO file.
     *                               If sizes are not supplied, the size of the source image will be used.
     */
    public function __construct($file = false, $sizes = array())
    {
        $required_functions = array(
            'getimagesize',
            'imagecreatefromstring',
            'imagecreatetruecolor',
            'imagecolortransparent',
            'imagecolorallocatealpha',
            'imagealphablending',
            'imagesavealpha',
            'imagesx',
            'imagesy',
            'imagecopyresampled',
        );

        foreach ($required_functions as $function) {
            if (!function_exists($function)) {
                throw new \RuntimeException(
                    "The PhpIco class was unable to find the $function function, which is part of the GD library. ".
                    'Ensure that the system has the GD library installed and that PHP has access to it through a PHP '.
                    'interface, such as PHP\'s GD module. Since this function was not found, the library will be '.
                    'unable to create ICO files.'
                );
            }
        }

        if ($file) {
            $this->addImage($file, $sizes);
        }
    }

    /**
     * Add an image to the generator.
     *
     * This function adds a source image to the generator. It serves two main purposes: add a source image if one was
     * not supplied to the constructor and to add additional source images so that different images can be supplied for
     * different sized images in the resulting ICO file. For instance, a small source image can be used for the small
     * resolutions while a larger source image can be used for large resolutions.
     *
     * @param string $file Path to the source image file.
     * @param array $sizes Optional. An array of sizes (each size is an array with a width and height) that the source
     *                     image should be rendered at in the generated ICO file. If sizes are not supplied, the size
     *                     of the source image will be used.
     * @return boolean true on success and false on failure.
     */
    public function addImage($file, $sizes = array())
    {
        if (false === ($im = $this->loadImageFile($file))) {
            return false;
        }


        if (empty($sizes)) {
            $sizes = array(imagesx($im), imagesy($im));
        }

        // If just a single size was passed, put it in array.
        if (!is_array($sizes[0])) {
            $sizes = array($sizes);
        }

        foreach ((array)$sizes as $size) {
            list($width, $height) = $size;

            $new_im = imagecreatetruecolor($width, $height);

            imagecolortransparent($new_im, imagecolorallocatealpha($new_im, 0, 0, 0, 127));
            imagealphablending($new_im, false);
            imagesavealpha($new_im, true);

            $source_width = imagesx($im);
            $source_height = imagesy($im);

            if (false === imagecopyresampled(
                    $new_im,
                    $im,
                    0,
                    0,
                    0,
                    0,
                    $width,
                    $height,
                    $source_width,
                    $source_height)
            ) {
                continue;
            }

            $this->addImageData($new_im);
        }

        return true;
    }

    /**
     * Write the ICO file data to a file path.
     *
     * @param string $file Path to save the ICO file data into.
     * @return boolean true on success and false on failure.
     */
    public function saveIco($file)
    {
        if (false === ($data = $this->getIcoData())) {
            return false;
        }

        if (false === ($fh = fopen($file, 'w'))) {
            return false;
        }

        if (false === (fwrite($fh, $data))) {
            fclose($fh);
            return false;
        }

        fclose($fh);

        return true;
    }

    /**
     * Generate the final ICO data by creating a file header and adding the image data.
     */
    protected function getIcoData()
    {
        if (!is_array($this->images) || empty($this->images)) {
            return false;
        }


        $data = pack('vvv', 0, 1, count($this->images));
        $pixel_data = '';

        $icon_dir_entry_size = 16;

        $offset = 6 + ($icon_dir_entry_size * count($this->images));

        foreach ($this->images as $image) {
            $data .= pack(
                'CCCCvvVV',
                $image['width'],
                $image['height'],
                $image['color_palette_colors'],
                0,
                1,
                $image['bits_per_pixel'],
                $image['size'],
                $offset
            );
            $pixel_data .= $image['data'];

            $offset += $image['size'];
        }

        $data .= $pixel_data;
        unset($pixel_data);


        return $data;
    }

    /**
     * Take a GD image resource and change it into a raw BMP format.
     */
    protected function addImageData($im)
    {
        $width = imagesx($im);
        $height = imagesy($im);


        $pixel_data = array();

        $opacity_data = array();
        $current_opacity_val = 0;

        for ($y = $height - 1; $y >= 0; $y--) {
            for ($x = 0; $x < $width; $x++) {
                $color = imagecolorat($im, $x, $y);

                $alpha = ($color & 0x7F000000) >> 24;
                $alpha = (1 - ($alpha / 127)) * 255;

                $color &= 0xFFFFFF;
                $color |= 0xFF000000 & ($alpha << 24);

                $pixel_data[] = $color;


                $opacity = ($alpha <= 127) ? 1 : 0;

                $current_opacity_val = ($current_opacity_val << 1) | $opacity;

                if ((($x + 1) % 32) == 0) {
                    $opacity_data[] = $current_opacity_val;
                    $current_opacity_val = 0;
                }
            }

            if (($x % 32) > 0) {
                while (($x++ % 32) > 0) {
                    $current_opacity_val = $current_opacity_val << 1;
                }

                $opacity_data[] = $current_opacity_val;
                $current_opacity_val = 0;
            }
        }

        $image_header_size = 40;
        $color_mask_size = $width * $height * 4;
        $opacity_mask_size = (ceil($width / 32) * 4) * $height;


        $data = pack('VVVvvVVVVVV', 40, $width, ($height * 2), 1, 32, 0, 0, 0, 0, 0, 0);

        foreach ($pixel_data as $color) {
            $data .= pack('V', $color);
        }

        foreach ($opacity_data as $opacity) {
            $data .= pack('N', $opacity);
        }


        $image = array(
            'width' => $width,
            'height' => $height,
            'color_palette_colors' => 0,
            'bits_per_pixel' => 32,
            'size' => $image_header_size + $color_mask_size + $opacity_mask_size,
            'data' => $data,
        );

        $this->images[] = $image;
    }

    /**
     * Read in the source image file and convert it into a GD image resource.
     */
    protected function loadImageFile($file)
    {
        if (!is_string($file) || empty($file)) {
            return false;
        }
        // Run a cheap check to verify that it is an image file.
        if (false === ($size = getimagesize($file))) {
            return false;
        }

        if (false === ($file_data = file_get_contents($file))) {
            return false;
        }

        if (false === ($im = imagecreatefromstring($file_data))) {
            return false;
        }

        unset($file_data);


        return $im;
    }
}