<?php

/**
 * @package     MokoSuiteOpenGraph
 * @subpackage  plg_system_mokoog
 * @author      Moko Consulting <hello@mokoconsulting.tech>
 * @copyright   Copyright (C) 2026 Moko Consulting. All rights reserved.
 * @license     GNU General Public License version 3 or later; see LICENSE
 */

namespace Joomla\Plugin\System\MokoOG\Helper;

defined('_JEXEC') or die;

use Joomla\CMS\Filesystem\Folder;
use Joomla\CMS\Log\Log;

class ImageGenerator
{
    private const WIDTH = 1200;
    private const HEIGHT = 630;
    private const OUTPUT_DIR = 'images/mokoog/generated';

    /**
     * Generate an OG image with title text overlaid on a template background.
     *
     * @param   string  $title           Article title to overlay
     * @param   string  $templateImage   Path to template/background image relative to JPATH_ROOT
     * @param   string  $fontFile        Absolute path to TTF font file
     * @param   int     $fontSize        Font size in points (default 42)
     * @param   array   $fontColor       RGB array [r, g, b] (default white)
     * @param   int     $quality         JPEG quality (default 90)
     *
     * @return  string  Path to generated image relative to JPATH_ROOT, or empty on failure
     */
    public static function generate(
        string $title,
        string $templateImage,
        string $fontFile = '',
        int $fontSize = 42,
        array $fontColor = [255, 255, 255],
        int $quality = 90
    ): string {
        if (!\extension_loaded('gd')) {
            Log::add('MokoOG ImageGenerator: GD extension is not loaded. Image generation disabled.', Log::WARNING, 'mokoog');

            return '';
        }

        $templateAbs = JPATH_ROOT . '/' . ltrim($templateImage, '/');

        if (!is_file($templateAbs)) {
            Log::add('MokoOG ImageGenerator: Template image not found: ' . $templateImage, Log::WARNING, 'mokoog');

            return '';
        }

        if (!$fontFile || !is_file($fontFile)) {
            Log::add('MokoOG ImageGenerator: TTF font file not found: ' . ($fontFile ?: '(not configured)'), Log::WARNING, 'mokoog');

            return '';
        }

        $outputDir = JPATH_ROOT . '/' . self::OUTPUT_DIR;

        if (!is_dir($outputDir) && !Folder::create($outputDir)) {
            Log::add('MokoOG ImageGenerator: Cannot create output directory: ' . self::OUTPUT_DIR, Log::WARNING, 'mokoog');

            return '';
        }

        $hash       = md5($title . $templateImage . $fontSize);
        $outputName = 'overlay_' . $hash . '.jpg';
        $outputPath = $outputDir . '/' . $outputName;
        $outputRel  = self::OUTPUT_DIR . '/' . $outputName;

        // Skip if already generated
        if (is_file($outputPath)) {
            return $outputRel;
        }

        // Load template image
        $imageInfo = getimagesize($templateAbs);

        if (!$imageInfo) {
            Log::add('MokoOG ImageGenerator: Cannot read image dimensions: ' . $templateImage, Log::WARNING, 'mokoog');

            return '';
        }

        $source = match ($imageInfo[2]) {
            IMAGETYPE_JPEG => imagecreatefromjpeg($templateAbs),
            IMAGETYPE_PNG  => imagecreatefrompng($templateAbs),
            IMAGETYPE_WEBP => function_exists('imagecreatefromwebp') ? imagecreatefromwebp($templateAbs) : false,
            default        => false,
        };

        if (!$source) {
            Log::add('MokoOG ImageGenerator: Failed to load image (unsupported type or corrupt): ' . $templateImage, Log::WARNING, 'mokoog');

            return '';
        }

        // Create output canvas at target dimensions
        $canvas = imagecreatetruecolor(self::WIDTH, self::HEIGHT);

        imagecopyresampled(
            $canvas,
            $source,
            0, 0, 0, 0,
            self::WIDTH, self::HEIGHT,
            $imageInfo[0], $imageInfo[1]
        );

        imagedestroy($source);

        // Semi-transparent overlay for text readability
        $overlay = imagecolorallocatealpha($canvas, 0, 0, 0, 64);
        imagefilledrectangle($canvas, 0, (int) (self::HEIGHT * 0.55), self::WIDTH, self::HEIGHT, $overlay);

        // Render title text with word wrapping
        $textColor = imagecolorallocate($canvas, $fontColor[0], $fontColor[1], $fontColor[2]);
        $wrappedTitle = self::wrapText($title, $fontFile, $fontSize, (int) (self::WIDTH * 0.85));
        $textX = (int) (self::WIDTH * 0.075);
        $textY = (int) (self::HEIGHT * 0.72);

        imagettftext($canvas, $fontSize, 0, $textX, $textY, $textColor, $fontFile, $wrappedTitle);

        // Save
        imagejpeg($canvas, $outputPath, $quality);
        imagedestroy($canvas);

        return $outputRel;
    }

    /**
     * Wrap text to fit within a maximum pixel width.
     *
     * @param   string  $text      Text to wrap
     * @param   string  $fontFile  Path to TTF font
     * @param   int     $fontSize  Font size in points
     * @param   int     $maxWidth  Maximum width in pixels
     *
     * @return  string  Wrapped text with newlines
     */
    private static function wrapText(string $text, string $fontFile, int $fontSize, int $maxWidth): string
    {
        $words  = explode(' ', $text);
        $lines  = [];
        $line   = '';

        foreach ($words as $word) {
            $testLine = $line ? $line . ' ' . $word : $word;
            $bbox     = imagettfbbox($fontSize, 0, $fontFile, $testLine);
            $lineWidth = abs($bbox[4] - $bbox[0]);

            if ($lineWidth > $maxWidth && $line !== '') {
                $lines[] = $line;
                $line    = $word;
            } else {
                $line = $testLine;
            }
        }

        if ($line !== '') {
            $lines[] = $line;
        }

        // Limit to 3 lines, truncate last line if needed
        if (\count($lines) > 3) {
            $lines = \array_slice($lines, 0, 3);

            if (mb_strlen($lines[2]) > 3) {
                $lines[2] = mb_substr($lines[2], 0, -3) . '...';
            } else {
                $lines[2] .= '...';
            }
        }

        return implode("\n", $lines);
    }
}