<?php
/**
 * AI Image Generator Class
 *
 * Generates featured images using OpenAI (ChatGPT + DALL-E)
 *
 * @package AI_Thumbnails_Maker
 * @since 1.0.0
 */

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

/**
 * AI Image Generator class
 */
class AITM_AI_Image_Generator {

	/**
	 * OpenAI API key
	 *
	 * @var string
	 */
	protected $api_key;

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

	/**
	 * Constructor
	 *
	 * @param array $settings Plugin settings.
	 * @throws Exception If API key is not configured.
	 */
	public function __construct( $settings ) {
		$this->settings = $settings;
		$this->api_key  = $settings['ai_api_key'] ?? '';

	if ( empty( $this->api_key ) && ( ! defined( 'AITM_DEBUG_MODE' ) || ! AITM_DEBUG_MODE ) ) {
		throw new Exception( esc_html__( 'OpenAI API key is not configured', 'ai-thumbnails-maker' ) );
	}
	}

	/**
	 * Generate placeholder image for debug mode
	 *
	 * @param string $size Image size (e.g., '1024x1024').
	 * @return array Image data with path and URL.
	 */
	private function generate_debug_placeholder( $size ) {
		// Parse size
		list($width, $height) = explode( 'x', $size );
		$width  = (int) $width;
		$height = (int) $height;

		// Create image using GD
		$image = imagecreatetruecolor( $width, $height );

		// Set colors
		$bg_color   = imagecolorallocate( $image, 100, 100, 255 );
		$text_color = imagecolorallocate( $image, 255, 255, 255 );

		// Fill background
		imagefill( $image, 0, 0, $bg_color );

		// Add text "AI Debug Mode"
		$text        = 'AI Debug Mode';
		$font_size   = 5;
		$text_width  = imagefontwidth( $font_size ) * strlen( $text );
		$text_height = imagefontheight( $font_size );
		$x           = ( $width - $text_width ) / 2;
		$y           = ( $height - $text_height ) / 2;
		imagestring( $image, $font_size, $x, $y, $text, $text_color );

		// Save to temp file
		$upload_dir = wp_upload_dir();
		$filename   = 'ai-debug-' . time() . '-' . wp_generate_password( 8, false ) . '.png';
		$file_path  = $upload_dir['path'] . '/' . $filename;

		imagepng( $image, $file_path );
		imagedestroy( $image );

		return array(
			'path' => $file_path,
			'url'  => $upload_dir['url'] . '/' . $filename,
			'size' => $size,
		);
	}

	/**
	 * Attach image file to post
	 *
	 * @param string $file_path Path to image file.
	 * @param int    $post_id   Post ID.
	 * @return int|false Attachment ID or false on failure.
	 */
	private function attach_image_to_post( $file_path, $post_id ) {
		$file_type = wp_check_filetype( basename( $file_path ), null );

		$attachment = array(
			'post_mime_type' => $file_type['type'],
			'post_title'     => sanitize_file_name( basename( $file_path ) ),
			'post_content'   => '',
			'post_status'    => 'inherit',
		);

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

		if ( ! is_wp_error( $attachment_id ) ) {
			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;
		}

		return false;
	}

	/**
	 * Get available prompt models
	 *
	 * @return array List of prompt models.
	 */
	public static function get_prompt_models() {
		return array(
			array(
				'model' => 'gpt-4o',
				'name'  => 'GPT-4o',
			),
			array(
				'model' => 'gpt-4o-mini',
				'name'  => 'GPT-4o Mini',
			),
			array(
				'model' => 'gpt-4-turbo',
				'name'  => 'GPT-4 Turbo',
			),
			array(
				'model' => 'gpt-4-turbo-preview',
				'name'  => 'GPT-4 Turbo Preview',
			),
			array(
				'model' => 'gpt-4',
				'name'  => 'GPT-4',
			),
			array(
				'model' => 'gpt-4-32k',
				'name'  => 'GPT-4 32k',
			),
			array(
				'model' => 'gpt-3.5-turbo',
				'name'  => 'GPT-3.5 Turbo',
			),
			array(
				'model' => 'gpt-3.5-turbo-16k',
				'name'  => 'GPT-3.5 Turbo 16k',
			),
		);
	}

	/**
	 * Get available image models
	 *
	 * @return array List of image models.
	 */
	public static function get_image_models() {
		return array(
			array(
				'model' => 'dall-e-3',
				'name'  => 'DALL-E 3',
			),
			array(
				'model' => 'dall-e-2',
				'name'  => 'DALL-E 2',
			),
		);
	}

	/**
	 * Generate featured image for post
	 *
	 * @param int $post_id Post ID.
	 * @return int Attachment ID of generated image.
	 * @throws Exception If generation fails.
	 */
	public function generate_for_post( $post_id ) {
		$post = get_post( $post_id );

		if ( empty( $post ) ) {
			throw new Exception( sprintf( 'Post %d is not found!', (int) $post_id ) );
		}

		// Debug mode: emulate AI generation without real API calls
		if ( defined( 'AITM_DEBUG_MODE' ) && AITM_DEBUG_MODE ) {
			// Random sleep 15-25 seconds to simulate API call
			sleep( wp_rand( 15, 25 ) );

			// Get size from settings
			$size = $this->settings['ai_resolution'] ?? '1024x1024';

			// Generate placeholder image
			$debug_image = $this->generate_debug_placeholder( $size );

			// Attach to post
			$attachment_id = $this->attach_image_to_post( $debug_image['path'], $post_id );

			if ( $attachment_id ) {
				set_post_thumbnail( $post_id, $attachment_id );
				return $attachment_id;
			}

			throw new Exception( esc_html__( 'Debug mode: Failed to attach image', 'ai-thumbnails-maker' ) );
		}

		// Get post content for prompt generation
		$post_content = $this->get_post_content( $post_id );

	if ( empty( $post_content ) ) {
		throw new Exception( esc_html__( 'Post content is empty', 'ai-thumbnails-maker' ) );
	}

		// Generate prompt using GPT
		$prompt = $this->generate_prompt( $post_content );

		// Generate image using DALL-E
		$image_url = $this->generate_image( $prompt );

		// Add image to media library
		$attachment_id = $this->add_image_from_url( $image_url, $post_id );

		return $attachment_id;
	}

	/**
	 * Extract content from post based on source setting
	 *
	 * @param int $post_id Post ID.
	 * @return string Extracted content.
	 */
	protected function get_post_content( $post_id ) {
		$post           = get_post( $post_id );
		$content        = $post->post_content;
		$title          = $post->post_title;
		$content_source = $this->settings['ai_content_source'] ?? 'title_first_paragraph';

		$blocks     = parse_blocks( $content );
		$paragraphs = array();

		// Extract paragraphs
		if ( count( $blocks ) === 1 && $blocks[0]['blockName'] === null ) {
			// Non-Gutenberg posts
			$html_content = wpautop( $content );
			preg_match_all( '/<p>(.*?)<\/p>/s', $html_content, $matches );
		if ( ! empty( $matches[1] ) ) {
			foreach ( $matches[1] as $paragraph ) {
				$clean = wp_strip_all_tags( $paragraph );
				if ( strlen( trim( $clean ) ) > 50 ) {
					$paragraphs[] = $clean;
					}
				}
			}
		} else {
			// Gutenberg blocks
		foreach ( $blocks as $block ) {
			if ( $block['blockName'] === 'core/paragraph' ) {
				$clean = wp_strip_all_tags( $block['innerHTML'] );
				if ( strlen( trim( $clean ) ) > 50 ) {
					$paragraphs[] = $clean;
					}
				}
			}
		}

		// Build content based on source setting
		$result = '';

		switch ( $content_source ) {
			case 'title_first_paragraph':
				$result = $title;
				if ( ! empty( $paragraphs[0] ) ) {
					$result .= '. ' . $paragraphs[0];
				}
				break;

			case 'title_second_paragraph':
				$result = $title;
				if ( ! empty( $paragraphs[1] ) ) {
					$result .= '. ' . $paragraphs[1];
				} elseif ( ! empty( $paragraphs[0] ) ) {
					$result .= '. ' . $paragraphs[0];
				}
				break;

			case 'title_third_paragraph':
				$result = $title;
				if ( ! empty( $paragraphs[2] ) ) {
					$result .= '. ' . $paragraphs[2];
				} elseif ( ! empty( $paragraphs[0] ) ) {
					$result .= '. ' . $paragraphs[0];
				}
				break;

			case 'random_paragraphs':
				$result = $title;
				if ( count( $paragraphs ) > 0 ) {
					// Take 2-3 random paragraphs
					$count = min( 3, count( $paragraphs ) );
					$random_keys = array_rand( $paragraphs, $count );
					if ( ! is_array( $random_keys ) ) {
						$random_keys = array( $random_keys );
					}
					foreach ( $random_keys as $key ) {
						$result .= '. ' . $paragraphs[ $key ];
					}
				}
				break;

		case 'full_content':
			$result = $title . '. ' . wp_strip_all_tags( $content );
			// Limit to 3000 characters to avoid too high costs
			$result = substr( $result, 0, 3000 );
				break;

			default:
				$result = $title;
				if ( ! empty( $paragraphs[0] ) ) {
					$result .= '. ' . $paragraphs[0];
				}
		}

		return $result;
	}

	/**
	 * Generate prompt using GPT
	 *
	 * @param string $post_content Post content.
	 * @return string Generated prompt.
	 * @throws Exception If prompt generation fails.
	 */
	protected function generate_prompt( $post_content ) {
		$model          = $this->settings['ai_prompt_model'] ?? 'gpt-4o-mini';
		$lang           = $this->settings['ai_language'] ?? 'en_US';
		$content_source = $this->settings['ai_content_source'] ?? 'title_first_paragraph';

		// Build system prompt based on content source
		$system_instructions = 'You are an expert AI assistant specialized in creating detailed, vivid image generation prompts for DALL-E.';

		// Build user prompt based on content source
		$user_prompt = sprintf(
			'Based on the following %s text, create a detailed and descriptive prompt for DALL-E to generate a featured image. The image should be visually appealing, relevant to the content, and suitable as a blog post thumbnail. Focus on creating a professional, eye-catching illustration.',
			$this->get_language_name( $lang )
		);

		// Add context about content source
		switch ( $content_source ) {
			case 'full_content':
				$user_prompt .= ' The full article content is provided, so create a comprehensive image that captures the main theme.';
				break;
			case 'random_paragraphs':
				$user_prompt .= ' Key excerpts from the article are provided to give you context.';
				break;
			default:
				$user_prompt .= ' The title and introduction are provided.';
		}

		$user_prompt .= "\n\nContent:\n" . $post_content;
		$user_prompt .= "\n\nRespond ONLY with the DALL-E prompt, no additional text.";

		$response = $this->request(
			'chat/completions',
			array(
				'model'    => $model,
				'messages' => array(
					array(
						'role'    => 'system',
						'content' => $system_instructions,
					),
					array(
						'role'    => 'user',
						'content' => $user_prompt,
					),
				),
			)
		);

	if ( ! isset( $response['choices'][0]['message']['content'] ) ) {
		throw new Exception( esc_html__( 'Invalid response from GPT', 'ai-thumbnails-maker' ) );
	}

		$prompt = trim( $response['choices'][0]['message']['content'] );
		$prompt = str_replace( array( 'Prompt for DALL-E: ', 'DALL-E Prompt: ', 'Prompt: ' ), '', $prompt );

		return $prompt;
	}

	/**
	 * Get language name from code
	 *
	 * @param string $lang_code Language code.
	 * @return string Language name.
	 */
	protected function get_language_name( $lang_code ) {
		$languages = array(
			'en_US' => 'English',
			'ru_RU' => 'Russian',
			'es_ES' => 'Spanish',
			'fr_FR' => 'French',
			'de_DE' => 'German',
			'zh_CN' => 'Chinese',
			'ja_JP' => 'Japanese',
			'it_IT' => 'Italian',
			'ko_KR' => 'Korean',
			'pt_PT' => 'Portuguese',
			'ar_SA' => 'Arabic',
			'hi_IN' => 'Hindi',
		);

		return $languages[ $lang_code ] ?? 'English';
	}

	/**
	 * Generate image using DALL-E
	 *
	 * @param string $prompt Image prompt.
	 * @return string Image URL.
	 * @throws Exception If image generation fails.
	 */
	protected function generate_image( $prompt ) {
		$model      = $this->settings['ai_image_model'] ?? 'dall-e-3';
		$resolution = $this->settings['ai_image_resolution'] ?? '1024x1024';
		$style      = $this->settings['ai_image_style'] ?? 'natural';

		$body = array(
			'model'  => $model,
			'prompt' => $prompt,
			'n'      => 1,
			'size'   => $resolution,
		);

		// Add style only if not 'none' and model supports it
		if ( $style !== 'none' && $model === 'dall-e-3' ) {
			$body['style'] = $style;
		}

		$response = $this->request( 'images/generations', $body );

	if ( ! isset( $response['data'][0]['url'] ) ) {
		throw new Exception( esc_html__( 'Invalid response from DALL-E', 'ai-thumbnails-maker' ) );
	}

		return $response['data'][0]['url'];
	}

	/**
	 * Send request to OpenAI API
	 *
	 * @param string $endpoint API endpoint.
	 * @param array  $body Request body.
	 * @return array Response data.
	 * @throws Exception If request fails.
	 */
	protected function request( $endpoint, $body ) {
		$request = wp_remote_post(
			'https://api.openai.com/v1/' . $endpoint,
			array(
				'timeout' => 60,
				'headers' => array(
					'Content-Type'  => 'application/json; charset=utf-8',
					'Authorization' => sprintf( 'Bearer %s', $this->api_key ),
				),
				'body'    => wp_json_encode( $body ),
			)
		);

	if ( is_wp_error( $request ) ) {
		throw new Exception( esc_html( $request->get_error_message() ) );
	}

		$response = json_decode( wp_remote_retrieve_body( $request ), true );

	if ( ! is_object( $response ) && ! is_array( $response ) ) {
		throw new Exception( esc_html__( 'Request returned an empty result!', 'ai-thumbnails-maker' ) );
	}

	if ( isset( $response['error'] ) ) {
		throw new Exception( esc_html( $response['error']['message'] ) );
	}

		return $response;
	}

	/**
	 * Add image from URL to media library
	 *
	 * @param string $url Image URL.
	 * @param int    $post_id Post ID.
	 * @return int Attachment ID.
	 * @throws Exception If image download or upload fails.
	 */
	protected function add_image_from_url( $url, $post_id ) {
		$parsed_url = wp_parse_url( $url );
		if ( empty( $parsed_url['path'] ) ) {
			throw new Exception( 'Invalid image URL.' );
		}

		$path_parts   = pathinfo( $parsed_url['path'] );
		$url_filename = $path_parts['basename'];
		$file_type    = wp_check_filetype( $url_filename, null );
		$allowed_types = get_allowed_mime_types();

		if ( ! $file_type || ! in_array( $file_type['type'], $allowed_types, true ) ) {
			throw new Exception( 'Invalid file type from URL.' );
		}

		$extension = $file_type['ext'];

		// Download image
		$image_data = $this->download_image( $url );

		if ( ! $image_data ) {
			throw new Exception( 'Could not download the image.' );
		}

		// Generate filename
		$filename = $this->get_random_id( 16 ) . '.' . $extension;

		// Store the file through WordPress upload APIs so paths and permissions follow site settings.
		$upload = wp_upload_bits( $filename, null, $image_data );
		if ( ! empty( $upload['error'] ) ) {
			throw new Exception( esc_html( $upload['error'] ) );
		}

		$file = $upload['file'];

		// Create attachment
		$attachment = array(
			'post_mime_type' => $file_type['type'],
			'post_title'     => '',
			'post_content'   => '',
			'post_status'    => 'inherit',
		);

		$attachment_id = wp_insert_attachment( $attachment, $file, $post_id );

		require_once ABSPATH . 'wp-admin/includes/image.php';
		$attachment_data = wp_generate_attachment_metadata( $attachment_id, $file );
		wp_update_attachment_metadata( $attachment_id, $attachment_data );

		return $attachment_id;
	}

	/**
	 * Download image from URL
	 *
	 * @param string $url Image URL.
	 * @return string Image content.
	 * @throws Exception If download fails.
	 */
	protected function download_image( $url ) {
	$args     = array( 'timeout' => 60 );
	$response = wp_safe_remote_get( $url, $args );

	if ( is_wp_error( $response ) ) {
		throw new Exception( esc_html( $response->get_error_message() ) );
	}

	$output = wp_remote_retrieve_body( $response );

	if ( is_wp_error( $output ) ) {
		throw new Exception( esc_html( $output->get_error_message() ) );
	}

		return $output;
	}

	/**
	 * Generate random alphanumeric ID
	 *
	 * @param int $length ID length.
	 * @return string Random ID.
	 */
	protected function get_random_id( $length = 8 ) {
		$characters        = '0123456789abcdefghijklmnopqrstuvwxyz';
		$characters_length = strlen( $characters );
		$random_id         = '';

		for ( $i = 0; $i < $length; $i++ ) {
			$random_id .= $characters[ wp_rand( 0, $characters_length - 1 ) ];
		}

		return $random_id;
	}
}