<?php
    /**
     * @author Gasper Kozak
     * @copyright 2007-2011

     **/

    /**
     * AutoCrop operation.
     */
    class WideImage_Operation_AutoCrop
    {
        /**
         * Executes the auto-crop operation on the $img.
         *
         * @param WideImage_Image $img
         * @param int             $rgb_threshold The difference in RGB from $base_color
         * @param int             $pixel_cutoff  The number of pixels on each border that must be over $rgb_threshold
         * @param int             $base_color    The color that will get cropped
         *
         * @return WideImage_Image resulting auto-cropped image
         */
        public function execute($img, $margin, $rgb_threshold, $pixel_cutoff, $base_color)
        {
            $margin = intval($margin);

            $rgb_threshold = intval($rgb_threshold);
            if ($rgb_threshold < 0) {
                $rgb_threshold = 0;
            }

            $pixel_cutoff = intval($pixel_cutoff);
            if ($pixel_cutoff <= 1) {
                $pixel_cutoff = 1;
            }

            if ($base_color === null) {
                $rgb_base = $img->getRGBAt(0, 0);
            } else {
                if ($base_color < 0) {
                    return $img->copy();
                }

                $rgb_base = $img->getColorRGB($base_color);
            }

            $cut_rect = ['left' => 0, 'top' => 0, 'right' => $img->getWidth() - 1, 'bottom' => $img->getHeight() - 1];

            for ($y = 0; $y <= $cut_rect['bottom']; ++$y) {
                $count = 0;
                for ($x = 0; $x <= $cut_rect['right']; ++$x) {
                    $rgb  = $img->getRGBAt($x, $y);
                    $diff = abs($rgb['red'] - $rgb_base['red']) + abs($rgb['green'] - $rgb_base['green']) + abs($rgb['blue'] - $rgb_base['blue']);
                    if ($diff > $rgb_threshold) {
                        ++$count;
                        if ($count >= $pixel_cutoff) {
                            $cut_rect['top'] = $y;
                            break 2;
                        }
                    }
                }
            }

            for ($y = $img->getHeight() - 1; $y >= $cut_rect['top']; --$y) {
                $count = 0;
                for ($x = 0; $x <= $cut_rect['right']; ++$x) {
                    $rgb  = $img->getRGBAt($x, $y);
                    $diff = abs($rgb['red'] - $rgb_base['red']) + abs($rgb['green'] - $rgb_base['green']) + abs($rgb['blue'] - $rgb_base['blue']);
                    if ($diff > $rgb_threshold) {
                        ++$count;
                        if ($count >= $pixel_cutoff) {
                            $cut_rect['bottom'] = $y;
                            break 2;
                        }
                    }
                }
            }

            for ($x = 0; $x <= $cut_rect['right']; ++$x) {
                $count = 0;
                for ($y = $cut_rect['top']; $y <= $cut_rect['bottom']; ++$y) {
                    $rgb  = $img->getRGBAt($x, $y);
                    $diff = abs($rgb['red'] - $rgb_base['red']) + abs($rgb['green'] - $rgb_base['green']) + abs($rgb['blue'] - $rgb_base['blue']);
                    if ($diff > $rgb_threshold) {
                        ++$count;
                        if ($count >= $pixel_cutoff) {
                            $cut_rect['left'] = $x;
                            break 2;
                        }
                    }
                }
            }

            for ($x = $cut_rect['right']; $x >= $cut_rect['left']; --$x) {
                $count = 0;
                for ($y = $cut_rect['top']; $y <= $cut_rect['bottom']; ++$y) {
                    $rgb  = $img->getRGBAt($x, $y);
                    $diff = abs($rgb['red'] - $rgb_base['red']) + abs($rgb['green'] - $rgb_base['green']) + abs($rgb['blue'] - $rgb_base['blue']);
                    if ($diff > $rgb_threshold) {
                        ++$count;
                        if ($count >= $pixel_cutoff) {
                            $cut_rect['right'] = $x;
                            break 2;
                        }
                    }
                }
            }

            $cut_rect = [
                    'left'   => $cut_rect['left'] - $margin,
                    'top'    => $cut_rect['top'] - $margin,
                    'right'  => $cut_rect['right'] + $margin,
                    'bottom' => $cut_rect['bottom'] + $margin,
                ];

            if ($cut_rect['left'] < 0) {
                $cut_rect['left'] = 0;
            }

            if ($cut_rect['top'] < 0) {
                $cut_rect['top'] = 0;
            }

            if ($cut_rect['right'] >= $img->getWidth()) {
                $cut_rect['right'] = $img->getWidth() - 1;
            }

            if ($cut_rect['bottom'] >= $img->getHeight()) {
                $cut_rect['bottom'] = $img->getHeight() - 1;
            }

            return $img->crop($cut_rect['left'], $cut_rect['top'], $cut_rect['right'] - $cut_rect['left'] + 1, $cut_rect['bottom'] - $cut_rect['top'] + 1);
        }
    }
