<?php

namespace Automattic\WooCommerce\Blocks\Images;

use Automattic\WooCommerce\Blocks\AI\Connection;
use Automattic\WooCommerce\Blocks\AIContent\ContentProcessor;
use Automattic\WooCommerce\Blocks\AIContent\UpdatePatterns;

/**
 * Pexels API client.
 *
 * @internal
 */
class Pexels {

	/**
	 * The Pexels API endpoint.
	 */
	const EXTERNAL_MEDIA_PEXELS_ENDPOINT = '/wpcom/v2/external-media/list/pexels';

	/**
	 * Returns the list of images for the given search criteria.
	 *
	 * @param Connection $ai_connection The AI connection.
	 * @param string     $token The JWT token.
	 * @param string     $business_description The business description.
	 *
	 * @return array|\WP_Error Array of images, or WP_Error if the request failed.
	 */
	public function get_images( $ai_connection, $token, $business_description ) {
		$business_description = ContentProcessor::summarize_business_description( $business_description, $ai_connection, $token );

		if ( str_word_count( $business_description ) === 1 ) {
			$search_term = $business_description;
		} else {
			$search_term = $this->define_search_term( $ai_connection, $token, $business_description );
		}

		if ( is_wp_error( $search_term ) ) {
			return $search_term;
		}

		$required_images = $this->total_number_required_images();

		if ( is_wp_error( $required_images ) ) {
			return $required_images;
		}

		$returned_images = $this->request( $search_term );

		if ( is_wp_error( $returned_images ) ) {
			return $returned_images;
		}

		$refined_images = $this->refine_returned_images_results( $ai_connection, $token, $business_description, $returned_images );

		if ( is_wp_error( $refined_images ) ) {
			return $returned_images;
		}

		$refined_images_count = count( $refined_images );

		$i      = 0;
		$errors = array();
		while ( $refined_images_count < $required_images && $i < 5 ) {
			$i ++;
			$search_term = $this->define_search_term( $ai_connection, $token, $business_description );

			if ( is_wp_error( $search_term ) ) {
				$errors[] = $search_term;
				continue;
			}

			$images_to_add = $this->request( $search_term );

			if ( is_wp_error( $images_to_add ) ) {
				$errors[] = $images_to_add;
				continue;
			}

			$images_to_add = $this->refine_returned_images_results( $ai_connection, $token, $business_description, $images_to_add );

			if ( is_wp_error( $images_to_add ) ) {
				$errors[] = $images_to_add;
				continue;
			}

			$refined_images = array_merge( $refined_images, $images_to_add );
		}

		if ( $refined_images_count < $required_images && ! empty( $errors ) ) {
			return new \WP_Error( 'ai_service_unavailable', __( 'AI Service is unavailable, try again later.', 'woocommerce' ), $errors );
		}

		if ( empty( $refined_images ) ) {
			return new \WP_Error( 'woocommerce_no_images_found', __( 'No images found.', 'woocommerce' ) );
		}

		return array(
			'images'      => $refined_images,
			'search_term' => $search_term,
		);
	}

	/**
	 * Define the search term to be used on Pexels using the AI endpoint.
	 *
	 * The search term is a shorter description of the business.
	 *
	 * @param Connection $ai_connection The AI connection.
	 * @param string     $token The JWT token.
	 * @param string     $business_description The business description.
	 *
	 * @return mixed|\WP_Error
	 */
	private function define_search_term( $ai_connection, $token, $business_description ) {

		$prompt = sprintf( 'You are a teacher. Based on the following business description, \'%s\', describe to a child exactly what this store is selling in one or two words and be as precise as you can possibly be. Do not reply with generic words that could cause confusion and be associated with other businesses as a response. Make sure you do not add double quotes in your response. Do not add any explanations in the response', $business_description );

		$response = $ai_connection->fetch_ai_response( $token, $prompt, 30 );

		if ( is_wp_error( $response ) ) {
			return $response;
		}

		if ( isset( $response['code'] ) && 'completion_error' === $response['code'] ) {
			return new \WP_Error( 'search_term_definition_failed', __( 'The search term definition failed.', 'woocommerce' ) );
		}

		if ( ! isset( $response['completion'] ) ) {
			return new \WP_Error( 'search_term_definition_failed', __( 'The search term definition failed.', 'woocommerce' ) );
		}

		return $response['completion'];
	}

	/**
	 * Refine the results returned by Pexels API.
	 *
	 * @param  Connection $ai_connection  The AI connection.
	 * @param  string     $token  The JWT token.
	 * @param  string     $business_description  The business description.
	 * @param  array      $returned_images  The returned images.
	 *
	 * @return array|\WP_Error The refined images, or WP_Error if the request failed.
	 */
	private function refine_returned_images_results( $ai_connection, $token, $business_description, $returned_images ) {
		$image_titles = array();
		foreach ( $returned_images as $returned_image ) {
			if ( isset( $returned_image['title'] ) ) {
				$image_titles[] = $returned_image['title'];
			}
		}

		$prompt = sprintf( 'Given that you own a store described as "%s", remove from the following JSON all titles that do not represent products that could be sold on your store: %s', $business_description, wp_json_encode( $image_titles ) );

		$response = $ai_connection->fetch_ai_response( $token, $prompt, 30 );

		if ( is_wp_error( $response ) || ! isset( $response['completion'] ) ) {
			return $returned_images;
		}

		$filtered_image_titles = json_decode( $response['completion'] );

		if ( ! is_array( $filtered_image_titles ) ) {
			$response = $ai_connection->fetch_ai_response( $token, $prompt, 30 );

			if ( is_wp_error( $response ) || ! isset( $response['completion'] ) ) {
				return $returned_images;
			}

			$filtered_image_titles = json_decode( $response['completion'] );
		}

		if ( ! is_array( $filtered_image_titles ) ) {
			return new \WP_Error( 'ai_service_unavailable', __( 'AI Service is unavailable, try again later.', 'woocommerce' ) );
		}

		// Remove the images that are not aligned with the business description.
		foreach ( $returned_images as $returned_image ) {
			if ( isset( $returned_image['title'] ) && ! in_array( $returned_image['title'], $filtered_image_titles, true ) ) {
				unset( $returned_image );
			}
		}

		return $returned_images;
	}

	/**
	 * Make a request to the Pexels API.
	 *
	 * @param string $search_term The search term to use.
	 * @param int    $per_page The number of images to return.
	 *
	 * @return array|\WP_Error The response body, or WP_Error if the request failed.
	 */
	private function request( string $search_term, int $per_page = 100 ) {
		$request = new \WP_REST_Request( 'GET', self::EXTERNAL_MEDIA_PEXELS_ENDPOINT );

		$request->set_param( 'search', esc_html( $search_term ) );
		$request->set_param( 'number', $per_page );
		$request->set_param( 'size', 'small' );

		$response      = rest_do_request( $request );
		$response_data = $response->get_data();

		if ( $response->is_error() ) {
			$error_msg = [
				'code' => $response->get_status(),
				'data' => $response_data,
			];

			return new \WP_Error( 'pexels_api_error', __( 'Request to the Pexels API failed.', 'woocommerce' ), $error_msg );
		}

		$response = $response_data['media'] ?? $response_data;

		if ( is_array( $response ) ) {
			shuffle( $response );

			return $response;
		}

		return array();
	}

	/**
	 * Total number of required images.
	 *
	 * @return array|\WP_Error The total number of required images, or WP_Error if the request failed.
	 */
	private function total_number_required_images() {
		$patterns_dictionary = UpdatePatterns::get_patterns_dictionary();

		if ( is_wp_error( $patterns_dictionary ) ) {
			return $patterns_dictionary;
		}

		$required_images = 0;
		foreach ( $patterns_dictionary as $pattern ) {
			if ( isset( $pattern['images_total'] ) && $pattern['images_total'] > 0 ) {
				$required_images += $pattern['images_total'];
			}
		}

		// Adding +6 images for the dummy products.
		$required_images += 6;

		return $required_images;
	}
}