<?php
/**
 * Title Image Generator Class
 *
 * Generates images with post title text on colored background
 *
 * @package AI_Thumbnails_Maker
 * @since 1.0.0
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Title Image Generator class
 */
class AITM_Title_Image_Generator {

	/**
	 * Plugin settings
	 *
	 * @var array
	 */
	private $settings;

	/**
	 * Font path
	 *
	 * @var string
	 */
	private $font_path;

	/**
	 * Constructor
	 *
	 * @param array $settings Plugin settings.
	 */
	public function __construct( $settings = array() ) {
		$this->settings  = $settings;
		$this->font_path = AITM_PLUGIN_DIR . '/fonts/arial.ttf';
	}

	/**
	 * Generate image for post
	 *
	 * @param int $post_id Post ID.
	 * @return int|false Attachment ID or false on failure.
	 */
	public function generate_for_post( $post_id ) {
		$post = get_post( $post_id );
		if ( ! $post ) {
			return false;
		}

		// Get settings with defaults
		$width      = absint( $this->settings['title_image_width'] ?? 1200 );
		$height     = absint( $this->settings['title_image_height'] ?? 630 );
		$bg_color   = $this->settings['title_image_bg_color'] ?? '#2271b1';
		$text_color = $this->settings['title_image_text_color'] ?? '#ffffff';
		$font_size  = absint( $this->settings['title_image_font_size'] ?? 48 );

		// Generate unique filename
		$upload_dir = wp_upload_dir();
		$filename   = 'aitm-title-' . $post_id . '-' . time() . '.jpg';
		$file_path  = $upload_dir['path'] . '/' . $filename;

		// Create image
		$result = $this->create_image_with_text(
			$post->post_title,
			$file_path,
			$width,
			$height,
			$bg_color,
			$text_color,
			$font_size
		);

		if ( ! $result ) {
			return false;
		}

		// Insert into media library
		return $this->insert_attachment( $file_path, $post_id );
	}

	/**
	 * Create image with text using GD Library
	 *
	 * @param string $text Text to render.
	 * @param string $file_path Path to save image.
	 * @param int    $width Image width.
	 * @param int    $height Image height.
	 * @param string $bg_color Background color (hex).
	 * @param string $text_color Text color (hex).
	 * @param int    $font_size Font size.
	 * @return bool Success status.
	 */
	private function create_image_with_text( $text, $file_path, $width, $height, $bg_color, $text_color, $font_size ) {
		// Check if GD is available
		if ( ! function_exists( 'imagecreatetruecolor' ) ) {
			return false;
		}

		// Check if font exists
		if ( ! file_exists( $this->font_path ) ) {
			return false;
		}

		// Create image
		$image = imagecreatetruecolor( $width, $height );
		if ( ! $image ) {
			return false;
		}

		// Set background color
		$bg_rgb = $this->hex_to_rgb( $bg_color );
		$bg     = imagecolorallocate( $image, $bg_rgb['r'], $bg_rgb['g'], $bg_rgb['b'] );
		imagefill( $image, 0, 0, $bg );

		// Set text color
		$text_rgb   = $this->hex_to_rgb( $text_color );
		$text_alloc = imagecolorallocate( $image, $text_rgb['r'], $text_rgb['g'], $text_rgb['b'] );

		// Prepare text (convert encoding)
		$text = mb_convert_encoding( $text, 'UTF-8' );

		// Calculate padding
		$padding_x = (int) ( $width * 0.05 );  // 5% padding
		$padding_y = (int) ( $height * 0.05 ); // 5% padding
		$max_width = $width - ( $padding_x * 2 );

		// Wrap text to fit width
		$lines = $this->wrap_text( $text, $font_size, $max_width );

		// Calculate line height
		$line_height = (int) ( $font_size * 1.3 );

		// Calculate total text height
		$total_height = count( $lines ) * $line_height;

		// Adjust font size if text is too tall
		while ( $total_height > ( $height - ( $padding_y * 2 ) ) && $font_size > 20 ) {
			$font_size --;
			$line_height   = (int) ( $font_size * 1.3 );
			$lines         = $this->wrap_text( $text, $font_size, $max_width );
			$total_height  = count( $lines ) * $line_height;
		}

		// Calculate starting Y position (center vertically)
		$y = (int) ( ( $height - $total_height ) / 2 + $font_size );

		// Draw each line centered
		foreach ( $lines as $line ) {
			$line = trim( $line );
			
			// Get text bounding box
			$bbox = imagettfbbox( $font_size, 0, $this->font_path, $line );
			$text_width = $bbox[2] - $bbox[0];
			
			// Center horizontally
			$x = (int) ( ( $width - $text_width ) / 2 );
			
			// Draw text
			imagettftext( $image, $font_size, 0, $x, $y, $text_alloc, $this->font_path, $line );
			
			// Move to next line
			$y += $line_height;
		}

		// Save image as JPEG
		$result = imagejpeg( $image, $file_path, 90 );
		
		// Free memory
		imagedestroy( $image );

		return $result;
	}

	/**
	 * Wrap text to multiple lines
	 *
	 * @param string $text Text to wrap.
	 * @param int    $font_size Font size.
	 * @param int    $max_width Maximum width in pixels.
	 * @return array Array of text lines.
	 */
	private function wrap_text( $text, $font_size, $max_width ) {
		$words = explode( ' ', $text );
		$lines = array();
		$line  = '';

		foreach ( $words as $word ) {
			$test_line = empty( $line ) ? $word : $line . ' ' . $word;
			$bbox      = imagettfbbox( $font_size, 0, $this->font_path, $test_line );
			$width     = $bbox[2] - $bbox[0];

			if ( $width > $max_width && ! empty( $line ) ) {
				// Line is too long, save current line and start new one
				$lines[] = $line;
				$line    = $word;
			} else {
				$line = $test_line;
			}
		}

		// Add last line
		if ( ! empty( $line ) ) {
			$lines[] = $line;
		}

		return $lines;
	}

	/**
	 * Convert hex color to RGB
	 *
	 * @param string $hex Hex color code.
	 * @return array RGB values.
	 */
	private function hex_to_rgb( $hex ) {
		$hex = ltrim( $hex, '#' );
		
		if ( strlen( $hex ) === 3 ) {
			$hex = $hex[0] . $hex[0] . $hex[1] . $hex[1] . $hex[2] . $hex[2];
		}
		
		list( $r, $g, $b ) = sscanf( $hex, '%02x%02x%02x' );
		
		return array(
			'r' => $r,
			'g' => $g,
			'b' => $b,
		);
	}

	/**
	 * Insert image into media library
	 *
	 * @param string $file_path Path to image file.
	 * @param int    $post_id Post ID to attach to.
	 * @return int|false Attachment ID or false on failure.
	 */
	private function insert_attachment( $file_path, $post_id ) {
		// Check if file exists
		if ( ! file_exists( $file_path ) ) {
			return false;
		}

		// Get file type
		$file_type = wp_check_filetype( basename( $file_path ), null );

		// Prepare attachment data
		$attachment = array(
			'guid'           => wp_upload_dir()['url'] . '/' . basename( $file_path ),
			'post_mime_type' => $file_type['type'],
			'post_title'     => get_the_title( $post_id ),
			'post_content'   => '',
			'post_status'    => 'inherit',
		);

		// Insert attachment
		$attachment_id = wp_insert_attachment( $attachment, $file_path, $post_id );

		if ( is_wp_error( $attachment_id ) ) {
			return false;
		}

		// Generate attachment metadata
		require_once ABSPATH . 'wp-admin/includes/image.php';
		$attach_data = wp_generate_attachment_metadata( $attachment_id, $file_path );
		wp_update_attachment_metadata( $attachment_id, $attach_data );

		return $attachment_id;
	}
}