<?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\File;
use Joomla\CMS\Filesystem\Folder;
use Joomla\CMS\Log\Log;

class ImageHelper
{
    /**
     * Target width for OG images (Facebook recommended).
     */
    private const TARGET_WIDTH = 1200;

    /**
     * Target height for OG images (Facebook recommended).
     */
    private const TARGET_HEIGHT = 630;

    /**
     * JPEG quality for generated images.
     */
    private const JPEG_QUALITY = 85;

    /**
     * Output directory relative to JPATH_ROOT.
     */
    private const OUTPUT_DIR = 'images/mokoog/generated';

    /**
     * Resize an image to OG-optimized dimensions if needed.
     *
     * Returns the path to the resized image relative to JPATH_ROOT,
     * or the original path if no resize was needed or possible.
     *
     * @param   string  $imagePath    Image path relative to JPATH_ROOT
     * @param   int     $targetWidth  Target width (default 1200)
     * @param   int     $targetHeight Target height (default 630)
     * @param   int     $quality      JPEG quality 1-100 (default 85)
     *
     * @return  string  Path to the output image (relative to JPATH_ROOT)
     */
    public static function resize(
        string $imagePath,
        int $targetWidth = self::TARGET_WIDTH,
        int $targetHeight = self::TARGET_HEIGHT,
        int $quality = self::JPEG_QUALITY
    ): string {
        // Resolve absolute path
        $absPath = JPATH_ROOT . '/' . ltrim($imagePath, '/');

        if (!is_file($absPath)) {
            return $imagePath;
        }

        $imageInfo = getimagesize($absPath);

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

            return $imagePath;
        }

        [$origWidth, $origHeight, $type] = $imageInfo;

        // Skip if already at or below target size
        if ($origWidth <= $targetWidth && $origHeight <= $targetHeight) {
            return $imagePath;
        }

        // Ensure output directory exists
        $outputDir = JPATH_ROOT . '/' . self::OUTPUT_DIR;

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

            return $imagePath;
        }

        // Generate output filename based on source hash + dimensions
        $hash       = md5($imagePath . $targetWidth . $targetHeight);
        $outputName = $hash . '.jpg';
        $outputPath = $outputDir . '/' . $outputName;
        $outputRel  = self::OUTPUT_DIR . '/' . $outputName;

        // Skip if already generated
        if (is_file($outputPath) && filemtime($outputPath) >= filemtime($absPath)) {
            return $outputRel;
        }

        // Load source image
        $source = self::loadImage($absPath, $type);

        if (!$source) {
            return $imagePath;
        }

        // Calculate crop dimensions (center crop to target aspect ratio)
        $targetRatio = $targetWidth / $targetHeight;
        $sourceRatio = $origWidth / $origHeight;

        if ($sourceRatio > $targetRatio) {
            // Source is wider — crop sides
            $cropHeight = $origHeight;
            $cropWidth  = (int) round($origHeight * $targetRatio);
            $cropX      = (int) round(($origWidth - $cropWidth) / 2);
            $cropY      = 0;
        } else {
            // Source is taller — crop top/bottom
            $cropWidth  = $origWidth;
            $cropHeight = (int) round($origWidth / $targetRatio);
            $cropX      = 0;
            $cropY      = (int) round(($origHeight - $cropHeight) / 2);
        }

        // Create output canvas and resample
        $output = imagecreatetruecolor($targetWidth, $targetHeight);

        imagecopyresampled(
            $output,
            $source,
            0,
            0,
            $cropX,
            $cropY,
            $targetWidth,
            $targetHeight,
            $cropWidth,
            $cropHeight
        );

        // Save as JPEG
        imagejpeg($output, $outputPath, $quality);

        imagedestroy($source);
        imagedestroy($output);

        return $outputRel;
    }

    /**
     * Remove a generated image file.
     *
     * @param   string  $generatedPath  Path relative to JPATH_ROOT
     *
     * @return  void
     */
    public static function cleanup(string $generatedPath): void
    {
        if (empty($generatedPath) || !str_starts_with($generatedPath, self::OUTPUT_DIR)) {
            return;
        }

        $absPath = JPATH_ROOT . '/' . $generatedPath;

        if (is_file($absPath)) {
            File::delete($absPath);
        }
    }

    /**
     * Check if an image meets minimum OG size requirements.
     *
     * @param   string  $imagePath  Image path relative to JPATH_ROOT
     *
     * @return  array{valid: bool, width: int, height: int, message: string}
     */
    public static function validate(string $imagePath): array
    {
        $absPath = JPATH_ROOT . '/' . ltrim($imagePath, '/');

        if (!is_file($absPath)) {
            return ['valid' => false, 'width' => 0, 'height' => 0, 'message' => 'File not found'];
        }

        $imageInfo = getimagesize($absPath);

        if (!$imageInfo) {
            return ['valid' => false, 'width' => 0, 'height' => 0, 'message' => 'Not a valid image'];
        }

        [$width, $height] = $imageInfo;

        // Facebook minimum: 200x200, recommended: 1200x630
        // WhatsApp minimum: 300x200
        if ($width < 200 || $height < 200) {
            return [
                'valid'   => false,
                'width'   => $width,
                'height'  => $height,
                'message' => "Image too small ({$width}x{$height}). Minimum: 200x200px.",
            ];
        }

        return ['valid' => true, 'width' => $width, 'height' => $height, 'message' => 'OK'];
    }

    /**
     * Load an image resource from a file.
     *
     * @param   string  $path  Absolute file path
     * @param   int     $type  IMAGETYPE_* constant
     *
     * @return  \GdImage|false
     */
    private static function loadImage(string $path, int $type)
    {
        $image = match ($type) {
            IMAGETYPE_JPEG => imagecreatefromjpeg($path),
            IMAGETYPE_PNG  => imagecreatefrompng($path),
            IMAGETYPE_GIF  => imagecreatefromgif($path),
            IMAGETYPE_WEBP => function_exists('imagecreatefromwebp') ? imagecreatefromwebp($path) : false,
            default        => false,
        };

        if (!$image) {
            Log::add('MokoOG ImageHelper: Failed to load image: ' . basename($path), Log::WARNING, 'mokoog');
        }

        return $image;
    }
}