<?php
/**
 * AI alt text: prepares the image, asks the chosen provider for a
 * description, and keeps the answer as a suggestion for the owner to review.
 *
 * Nothing is sent anywhere unless the owner turns this on in Settings and,
 * for Fixlight's free service, ticks the consent box.
 *
 * @package Fixlight
 */

namespace Fixlight;

defined( 'ABSPATH' ) || exit;

/**
 * AI orchestration.
 */
class Ai {

	const SUGGESTION_META = '_fixlight_ai_suggestion';
	const MAX_SIDE        = 768;

	/**
	 * Providers: the AI connected to WordPress (when this WordPress has it) and
	 * Fixlight's free service.
	 *
	 * @return array<string,array{label:string,class:string}>
	 */
	public static function providers() {
		$providers = array();
		if ( Ai_WordPress::available() ) {
			$providers['connectors'] = array(
				'label' => __( 'The AI connected to WordPress (Settings → Connectors)', 'fixlight' ),
				'class' => Ai_WordPress::class,
			);
		}
		return $providers + array(
			'hosted' => array(
				'label' => __( 'Fixlight free service (50 images a month)', 'fixlight' ),
				'class' => Ai_Hosted::class,
			),
		);
	}

	/**
	 * The active provider id, or '' when AI is off or not set up.
	 *
	 * @return string
	 */
	public static function active_provider() {
		$provider = (string) Settings::get( 'ai_provider' );
		if ( 'hosted' === $provider ) {
			return Settings::get( 'ai_hosted_consent' ) ? 'hosted' : '';
		}
		if ( 'connectors' === $provider ) {
			return Ai_WordPress::available() ? 'connectors' : '';
		}
		return '';
	}

	/**
	 * The instructions every provider gets.
	 *
	 * @return string
	 */
	public static function system_prompt() {
		return implode(
			"\n",
			array(
				'You write alt text for images on websites, for people who use screen readers.',
				'',
				'Rules:',
				'- One sentence, at most 125 characters.',
				'- Describe what the image shows that matters to a visitor of this page. Use the page context if it is given.',
				'- Do not start with "Image of", "Picture of", "Photo of" or similar.',
				'- If the image contains text that matters (a sign, a banner, a menu, a chart title), include that text exactly as written, without translating it.',
				'- For a chart or graph, state its main takeaway in one short sentence.',
				'- For a logo, write the name shown in the logo followed by the word "logo" (in the requested language).',
				'- If the image is purely decorative (a pattern, a divider, a texture, a spacer, an abstract background), set "decorative" to true and "alt" to "".',
				'- Never guess who a person is. Describe people only by what is visible and relevant.',
				'- Write in the requested language.',
				'',
				'Answer only with JSON: {"alt": "...", "decorative": false}',
			)
		);
	}

	/**
	 * JSON schema of the answer.
	 *
	 * @return array
	 */
	public static function schema() {
		return array(
			'type'                 => 'object',
			'properties'           => array(
				'alt'        => array( 'type' => 'string' ),
				'decorative' => array( 'type' => 'boolean' ),
			),
			'required'             => array( 'alt', 'decorative' ),
			'additionalProperties' => false,
		);
	}

	/**
	 * Writes a suggestion for one image and stores it for review.
	 *
	 * @param int $attachment_id Attachment id.
	 * @return array|\WP_Error Suggestion: alt, decorative, provider, model, applied.
	 */
	public static function suggest( $attachment_id ) {
		$provider = self::active_provider();
		if ( '' === $provider ) {
			return new \WP_Error( 'fixlight_ai_off', __( 'AI alt text is not set up. Turn it on in Fixlight → Settings.', 'fixlight' ), array( 'status' => 400 ) );
		}
		if ( ! wp_attachment_is_image( $attachment_id ) ) {
			return new \WP_Error( 'fixlight_not_image', __( 'That is not an image in the media library.', 'fixlight' ), array( 'status' => 404 ) );
		}

		$image = self::image_payload( $attachment_id );
		if ( is_wp_error( $image ) ) {
			return $image;
		}
		$context = self::context( $attachment_id );
		$class   = self::providers()[ $provider ]['class'];
		$answer  = call_user_func( array( $class, 'describe' ), $image, $context );
		if ( is_wp_error( $answer ) ) {
			return $answer;
		}

		$suggestion = array(
			'alt'        => self::clean_alt( isset( $answer['alt'] ) ? (string) $answer['alt'] : '' ),
			'decorative' => ! empty( $answer['decorative'] ),
			'provider'   => $provider,
			'model'      => isset( $answer['model'] ) ? sanitize_text_field( (string) $answer['model'] ) : '',
			'time'       => time(),
			'applied'    => false,
		);
		if ( ! $suggestion['decorative'] && '' === $suggestion['alt'] ) {
			return new \WP_Error( 'fixlight_ai_empty', __( 'The AI did not return a description. Try again, or write one yourself.', 'fixlight' ), array( 'status' => 502 ) );
		}

		if ( Settings::get( 'ai_auto_apply' ) ) {
			$saved = Images::save( $attachment_id, $suggestion['alt'], $suggestion['decorative'] );
			if ( ! is_wp_error( $saved ) ) {
				$suggestion['applied'] = true;
			}
		}
		update_post_meta( $attachment_id, self::SUGGESTION_META, $suggestion );
		if ( isset( $answer['quota'] ) ) {
			$suggestion['quota'] = $answer['quota'];
		}
		return $suggestion;
	}

	/**
	 * The stored suggestion for an image, if any.
	 *
	 * @param int $attachment_id Attachment id.
	 * @return array|null
	 */
	public static function stored_suggestion( $attachment_id ) {
		$suggestion = get_post_meta( $attachment_id, self::SUGGESTION_META, true );
		return is_array( $suggestion ) && isset( $suggestion['alt'] ) ? $suggestion : null;
	}

	/**
	 * Tidies model output into alt text.
	 *
	 * @param string $alt Raw alt text.
	 * @return string
	 */
	public static function clean_alt( $alt ) {
		$alt = trim( wp_strip_all_tags( $alt ) );
		$alt = preg_replace( '/^(an?\s+)?(image|picture|photo|photograph)\s+(of|showing)\s+/i', '', $alt );
		$alt = preg_replace( '/^(una?\s+)?(imagen|foto|fotografía)\s+(de|que muestra)\s+/iu', '', $alt );
		$alt = trim( (string) $alt, " \t\n\r\0\x0B\"'" );
		if ( function_exists( 'mb_substr' ) && mb_strlen( $alt ) > 250 ) {
			$alt = rtrim( mb_substr( $alt, 0, 249 ) ) . '…';
		}
		if ( '' !== $alt && function_exists( 'mb_strtoupper' ) ) {
			$alt = mb_strtoupper( mb_substr( $alt, 0, 1 ) ) . mb_substr( $alt, 1 );
		}
		return $alt;
	}

	/**
	 * A JPEG of the image, at most 768 pixels on its longest side, base64 encoded.
	 *
	 * @param int $attachment_id Attachment id.
	 * @return array|\WP_Error mime, data (base64), bytes.
	 */
	public static function image_payload( $attachment_id ) {
		$source = get_attached_file( $attachment_id );
		$sized  = image_get_intermediate_size( $attachment_id, 'medium_large' );
		if ( $sized && ! empty( $sized['path'] ) ) {
			$uploads   = wp_get_upload_dir();
			$candidate = trailingslashit( $uploads['basedir'] ) . $sized['path'];
			if ( is_readable( $candidate ) ) {
				$source = $candidate;
			}
		}
		if ( ! $source || ! is_readable( $source ) ) {
			return new \WP_Error( 'fixlight_no_file', __( 'The image file could not be read.', 'fixlight' ), array( 'status' => 404 ) );
		}

		if ( ! function_exists( 'wp_tempnam' ) ) {
			require_once ABSPATH . 'wp-admin/includes/file.php'; // Not loaded on REST requests.
		}
		$editor = wp_get_image_editor( $source );
		if ( ! is_wp_error( $editor ) ) {
			$editor->resize( self::MAX_SIDE, self::MAX_SIDE, false );
			$editor->set_quality( 82 );
			$base  = wp_tempnam( 'fixlight-ai' ); // Creates an empty file; deleted below with the JPEG.
			$temp  = $base . '.jpg';
			$saved = $editor->save( $temp, 'image/jpeg' );
			if ( ! is_wp_error( $saved ) && ! empty( $saved['path'] ) && is_readable( $saved['path'] ) ) {
				$bytes = file_get_contents( $saved['path'] ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents -- Local temporary file.
				wp_delete_file( $saved['path'] );
				wp_delete_file( $temp );
				wp_delete_file( $base );
				if ( false !== $bytes && '' !== $bytes ) {
					return array(
						'mime'  => 'image/jpeg',
						'data'  => base64_encode( $bytes ), // phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.obfuscation_base64_encode -- Image bytes for the API request.
						'bytes' => strlen( $bytes ),
					);
				}
			}
			wp_delete_file( $temp );
			wp_delete_file( $base );
		}

		// No image editor on this server: send the file as it is if it is small and in a common format.
		$type = wp_check_filetype( $source );
		if ( in_array( $type['type'], array( 'image/jpeg', 'image/png', 'image/webp', 'image/gif' ), true ) && filesize( $source ) <= 1500000 ) {
			$bytes = file_get_contents( $source ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents -- Local media file.
			if ( false !== $bytes ) {
				return array(
					'mime'  => $type['type'],
					'data'  => base64_encode( $bytes ), // phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.obfuscation_base64_encode -- Image bytes for the API request.
					'bytes' => strlen( $bytes ),
				);
			}
		}
		return new \WP_Error( 'fixlight_image_format', __( 'This image could not be prepared for the AI. Write its alt text yourself.', 'fixlight' ), array( 'status' => 415 ) );
	}

	/**
	 * Page context sent with the image.
	 *
	 * @param int $attachment_id Attachment id.
	 * @return array{language:string,text:string}
	 */
	public static function context( $attachment_id ) {
		$lines = array();
		$file  = wp_basename( (string) get_attached_file( $attachment_id ) );
		if ( '' !== $file ) {
			$lines[] = 'File name: ' . $file;
		}
		$title = get_the_title( $attachment_id );
		// Camera names (IMG_2041, DSC0034) say nothing about the picture.
		if ( '' !== $title && ! preg_match( '/^(img|dsc|dscn|pxl|photo|image|screenshot|whatsapp)[\s_\-]?\d/i', $title ) && ! preg_match( '/^\d+$/', $title ) ) {
			$lines[] = 'Image title: ' . $title;
		}
		$caption = wp_get_attachment_caption( $attachment_id );
		if ( $caption ) {
			$lines[] = 'Caption: ' . wp_strip_all_tags( $caption );
		}
		$parent = (int) wp_get_post_parent_id( $attachment_id );
		if ( $parent ) {
			$lines[] = 'Used on the page: ' . wp_strip_all_tags( get_the_title( $parent ) );
			if ( 'product' === get_post_type( $parent ) ) {
				$lines[] = 'This is a product photo in an online shop.';
			}
		}
		$lines[] = 'Website: ' . wp_strip_all_tags( get_bloginfo( 'name' ) );
		// The site's language, not the language of the admin's own profile.
		$language = self::language_name( get_locale() );
		$lines[]  = 'Write the alt text in: ' . $language;
		return array(
			'language' => $language,
			'text'     => implode( "\n", $lines ),
		);
	}

	/**
	 * English name of the site's language, for the prompt.
	 *
	 * @param string $locale Locale such as es_MX.
	 * @return string
	 */
	public static function language_name( $locale ) {
		$names   = array(
			'en' => 'English',
			'es' => 'Spanish',
			'pt' => 'Portuguese',
			'fr' => 'French',
			'de' => 'German',
			'it' => 'Italian',
			'nl' => 'Dutch',
			'pl' => 'Polish',
			'sv' => 'Swedish',
			'da' => 'Danish',
			'nb' => 'Norwegian',
			'fi' => 'Finnish',
			'cs' => 'Czech',
			'ro' => 'Romanian',
			'hu' => 'Hungarian',
			'el' => 'Greek',
			'tr' => 'Turkish',
			'ru' => 'Russian',
			'uk' => 'Ukrainian',
			'ja' => 'Japanese',
			'ko' => 'Korean',
			'zh' => 'Chinese',
			'ar' => 'Arabic',
			'he' => 'Hebrew',
			'hi' => 'Hindi',
			'id' => 'Indonesian',
			'vi' => 'Vietnamese',
			'th' => 'Thai',
			'ca' => 'Catalan',
		);
		$regions = array(
			'MX' => 'Mexico',
			'ES' => 'Spain',
			'AR' => 'Argentina',
			'CO' => 'Colombia',
			'CL' => 'Chile',
			'BR' => 'Brazil',
			'PT' => 'Portugal',
			'GB' => 'United Kingdom',
			'US' => 'United States',
			'CA' => 'Canada',
			'AU' => 'Australia',
			'TW' => 'Taiwan',
			'CN' => 'China',
		);
		$parts   = explode( '_', (string) $locale );
		$name    = isset( $names[ $parts[0] ] ) ? $names[ $parts[0] ] : 'the language with code ' . $parts[0];
		if ( isset( $parts[1], $regions[ $parts[1] ] ) && in_array( $parts[0], array( 'es', 'pt', 'zh' ), true ) ) {
			$name .= ' (' . $regions[ $parts[1] ] . ')';
		}
		return $name;
	}

	/**
	 * Parses a JSON answer, tolerating code fences around it.
	 *
	 * @param string $text Model output.
	 * @return array|null
	 */
	public static function parse_answer( $text ) {
		$text = trim( (string) $text );
		$text = preg_replace( '/^```(?:json)?\s*|\s*```$/', '', $text );
		$data = json_decode( $text, true );
		if ( ! is_array( $data ) && preg_match( '/\{.*\}/s', $text, $matches ) ) {
			$data = json_decode( $matches[0], true );
		}
		return is_array( $data ) && array_key_exists( 'alt', $data ) ? $data : null;
	}

	/**
	 * Turns a failed HTTP response into a readable error.
	 *
	 * @param array|\WP_Error $response Response.
	 * @param string          $service  Service name for the message.
	 * @return \WP_Error|null Null when the response is a success.
	 */
	public static function http_error( $response, $service ) {
		if ( is_wp_error( $response ) ) {
			/* translators: 1: service name, 2: error message. */
			return new \WP_Error( 'fixlight_ai_http', sprintf( __( 'Could not reach %1$s: %2$s', 'fixlight' ), $service, $response->get_error_message() ), array( 'status' => 502 ) );
		}
		$code = (int) wp_remote_retrieve_response_code( $response );
		if ( $code >= 200 && $code < 300 ) {
			return null;
		}
		$body    = json_decode( wp_remote_retrieve_body( $response ), true );
		$message = '';
		if ( is_array( $body ) ) {
			if ( isset( $body['error']['message'] ) ) {
				$message = (string) $body['error']['message'];
			} elseif ( isset( $body['message'] ) ) {
				$message = (string) $body['message'];
			}
		}
		if ( 401 === $code || 403 === $code ) {
			/* translators: %s: service name. */
			$message = sprintf( __( '%s refused the request. Try again later.', 'fixlight' ), $service );
		} elseif ( 429 === $code && '' === $message ) {
			/* translators: %s: service name. */
			$message = sprintf( __( '%s says there were too many requests. Wait a minute and try again.', 'fixlight' ), $service );
		}
		/* translators: 1: service name, 2: HTTP status code, 3: error message. */
		return new \WP_Error( 'fixlight_ai_http', sprintf( __( '%1$s answered with an error (%2$d). %3$s', 'fixlight' ), $service, $code, wp_strip_all_tags( substr( $message, 0, 300 ) ) ), array( 'status' => 502 ) );
	}
}