<?php
/**
 * Chrome AI integration
 */

namespace Classifai\Providers\Browser;

use Classifai\Features\ContentResizing;
use Classifai\Features\ExcerptGeneration;
use Classifai\Features\TitleGeneration;
use Classifai\Providers\Provider;
use Classifai\Providers\OpenAI\Tokenizer;
use Classifai\Normalizer;
use WP_Error;

use function Classifai\get_default_prompt;

class ChromeAI extends Provider {

	/**
	 * Provider ID
	 *
	 * @var string
	 */
	const ID = 'chrome_ai';

	/**
	 * Maximum number of tokens our model supports
	 *
	 * @var int
	 */
	protected $max_tokens = 6144;

	/**
	 * ChromeAI constructor.
	 *
	 * @param \Classifai\Features\Feature $feature_instance The feature instance.
	 */
	public function __construct( $feature_instance = null ) {
		$this->feature_instance = $feature_instance;
	}

	/**
	 * Render the provider fields.
	 */
	public function render_provider_fields() {
		do_action( 'classifai_' . static::ID . '_render_provider_fields', $this );
	}

	/**
	 * Returns the default settings for this provider.
	 *
	 * @return array
	 */
	public function get_default_provider_settings(): array {
		$common_settings = [
			'authenticated' => true,
		];

		return $common_settings;
	}

	/**
	 * Sanitize the settings for this provider.
	 *
	 * @param array $new_settings The settings array.
	 * @return array
	 */
	public function sanitize_settings( array $new_settings ): array {
		return $new_settings;
	}

	/**
	 * Common entry point for all REST endpoints for this provider.
	 *
	 * @param int    $post_id The Post ID we're processing.
	 * @param string $route_to_call The route we are processing.
	 * @param array  $args Optional arguments to pass to the route.
	 * @return string|WP_Error
	 */
	public function rest_endpoint_callback( $post_id = 0, string $route_to_call = '', array $args = [] ) {
		if ( ! $post_id || ! get_post( $post_id ) ) {
			return new WP_Error( 'post_id_required', esc_html__( 'A valid post ID is required to generate titles.', 'classifai' ) );
		}

		$route_to_call = strtolower( $route_to_call );
		$return        = '';

		// Handle all of our routes.
		switch ( $route_to_call ) {
			case 'excerpt':
				$return = $this->generate_excerpt( $post_id, $args );
				break;
			case 'title':
				$return = $this->generate_title( $post_id, $args );
				break;
			case 'resize_content':
				$return = $this->resize_content( $post_id, $args );
				break;
		}

		return $return;
	}

	/**
	 * Generate an excerpt.
	 *
	 * @param int   $post_id The Post ID we're processing
	 * @param array $args    Arguments passed in.
	 * @return string|WP_Error
	 */
	public function generate_excerpt( int $post_id = 0, array $args = [] ) {
		if ( ! $post_id || ! get_post( $post_id ) ) {
			return new WP_Error( 'post_id_required', esc_html__( 'A valid post ID is required to generate an excerpt.', 'classifai' ) );
		}

		$feature   = new ExcerptGeneration();
		$settings  = $feature->get_settings();
		$args      = wp_parse_args(
			array_filter( $args ),
			[
				'content' => '',
				'title'   => get_the_title( $post_id ),
				'author'  => '',
			]
		);
		$post_type = get_post_type( $post_id );

		// These checks (and the one above) happen in the REST permission_callback,
		// but we run them again here in case this method is called directly.
		if ( empty( $settings ) || ! $feature->is_feature_enabled() ) {
			return new WP_Error( 'not_enabled', esc_html__( 'Excerpt generation is disabled or authentication failed. Please check your settings.', 'classifai' ) );
		}

		$excerpt_length = absint( $settings['length'] ?? 55 );

		// Overwrite the prompt if we are generating an excerpt for a product.
		if ( 'product' === $post_type ) {
			$excerpt_prompt = $feature->woo_prompt;
		} else {
			$excerpt_prompt = esc_textarea( get_default_prompt( $settings['generate_excerpt_prompt'] ) ?? $feature->prompt );
		}

		// Replace our variables in the prompt.
		$prompt_search  = array( '{{WORDS}}', '{{TITLE}}', '{{AUTHOR}}' );
		$prompt_replace = array( $excerpt_length, $args['title'], $args['author'] );
		$prompt         = str_replace( $prompt_search, $prompt_replace, $excerpt_prompt );

		/**
		 * Filter the prompt we will send to Chrome AI.
		 *
		 * @since 3.2.0
		 * @hook classifai_chrome_ai_excerpt_prompt
		 *
		 * @param string $prompt         Prompt we are sending. Gets added before post content.
		 * @param int    $post_id        ID of post we are summarizing.
		 * @param int    $excerpt_length Length of final excerpt.
		 *
		 * @return string Prompt.
		 */
		$prompt = apply_filters( 'classifai_chrome_ai_excerpt_prompt', $prompt, $post_id, $excerpt_length );

		// Check if we are generating an excerpt for a product.
		$system_prompt = $this->system_prompt;
		if ( 'product' === $post_type && function_exists( 'wc_get_product' ) && \wc_get_product( $post_id ) ) {
			$args['content'] = $this->get_product_content( $post_id );
			$system_prompt   = $this->system_prompt_woo;
		}

		/**
		 * Filter the request body before sending to Chrome AI.
		 *
		 * @since 3.2.0
		 * @hook classifai_chrome_ai_excerpt_request_body
		 *
		 * @param array $body    Request body that will be sent.
		 * @param int   $post_id ID of post we are summarizing.
		 *
		 * @return array Request body.
		 */
		$body = apply_filters(
			'classifai_chrome_ai_excerpt_request_body',
			[
				'prompt'  => $system_prompt . ' ' . $prompt,
				'content' => $this->get_content( $post_id, $excerpt_length, false, $args['content'] ),
				'func'    => static::ID,
			],
			$post_id
		);

		return $body;
	}

	/**
	 * Generate a title using Chrome AI.
	 *
	 * @param int   $post_id The Post Id we're processing
	 * @param array $args Arguments passed in.
	 * @return string|WP_Error
	 */
	public function generate_title( int $post_id = 0, array $args = [] ) {
		if ( ! $post_id || ! get_post( $post_id ) ) {
			return new WP_Error( 'post_id_required', esc_html__( 'Post ID is required to generate titles.', 'classifai' ) );
		}

		$feature   = new TitleGeneration();
		$settings  = $feature->get_settings();
		$args      = wp_parse_args(
			array_filter( $args ),
			[
				'content' => '',
			]
		);
		$post_type = get_post_type( $post_id );

		// These checks happen in the REST permission_callback,
		// but we run them again here in case this method is called directly.
		if ( empty( $settings ) || ! $feature->is_feature_enabled() ) {
			return new WP_Error( 'not_enabled', esc_html__( 'Title generation is disabled or authentication failed. Please check your settings.', 'classifai' ) );
		}

		// Overwrite the prompt if we are generating titles for a product.
		if ( 'product' === $post_type ) {
			$prompt = $feature->woo_prompt;
		} else {
			$prompt = esc_textarea( get_default_prompt( $settings['generate_title_prompt'] ) ?? $feature->prompt );
		}

		/**
		 * Filter the prompt we will send to Chrome AI.
		 *
		 * @since 3.2.0
		 * @hook classifai_chrome_ai_title_prompt
		 *
		 * @param string $prompt  Prompt we are sending. Gets added before post content.
		 * @param int    $post_id ID of post we are summarizing.
		 * @param array  $args    Arguments passed to endpoint.
		 *
		 * @return string Prompt.
		 */
		$prompt = apply_filters( 'classifai_chrome_ai_title_prompt', $prompt, $post_id, $args );

		// Check if we are generating titles for a product.
		$system_prompt = $this->system_prompt;
		if ( 'product' === $post_type && function_exists( 'wc_get_product' ) && \wc_get_product( $post_id ) ) {
			$args['content'] = $this->get_product_content( $post_id );
			$system_prompt   = $this->system_prompt_woo;
		}

		/**
		 * Filter the request body before sending to Azure OpenAI.
		 *
		 * @since 3.2.0
		 * @hook classifai_chrome_ai_title_request_body
		 *
		 * @param array $body    Request body that will be sent.
		 * @param int   $post_id ID of post we are summarizing.
		 *
		 * @return array Request body.
		 */
		$body = apply_filters(
			'classifai_chrome_ai_title_request_body',
			[
				'prompt'  => $system_prompt . ' ' . $prompt,
				'content' => $this->get_content( $post_id, 15, false, $args['content'] ),
				'func'    => static::ID,
			],
			$post_id
		);

		return $body;
	}

	/**
	 * Resizes content.
	 *
	 * @param int   $post_id The Post ID we're processing
	 * @param array $args Arguments passed in.
	 * @return string|WP_Error
	 */
	public function resize_content( int $post_id, array $args = array() ) {
		if ( ! $post_id || ! get_post( $post_id ) ) {
			return new WP_Error( 'post_id_required', esc_html__( 'Post ID is required to resize content.', 'classifai' ) );
		}

		$feature  = new ContentResizing();
		$settings = $feature->get_settings();

		if ( 'shrink' === $args['resize_type'] ) {
			$prompt = esc_textarea( get_default_prompt( $settings['condense_text_prompt'] ) ?? $feature->condense_prompt );
		} else {
			$prompt = esc_textarea( get_default_prompt( $settings['expand_text_prompt'] ) ?? $feature->expand_prompt );
		}

		/**
		 * Filter the resize prompt we will send to Chrome AI.
		 *
		 * @since 3.2.0
		 * @hook classifai_chrome_ai_' . $args['resize_type'] . '_content_prompt
		 *
		 * @param string $prompt  Resize prompt we are sending. Gets added as a system prompt.
		 * @param int    $post_id ID of post.
		 * @param array  $args    Arguments passed to endpoint.
		 *
		 * @return string Prompt.
		 */
		$prompt = apply_filters( 'classifai_chrome_ai_' . $args['resize_type'] . '_content_prompt', $prompt, $post_id, $args );

		/**
		 * Filter the resize request body before sending to Chrome AI.
		 *
		 * @since 3.2.0
		 * @hook classifai_chrome_ai_resize_content_request_body
		 *
		 * @param array $body Request body that will be sent.
		 * @param int   $post_id ID of post.
		 *
		 * @return array Request body.
		 */
		$body = apply_filters(
			'classifai_chrome_ai_resize_content_request_body',
			[
				'prompt'  => 'You will be provided with content delimited by triple quotes. ' . $prompt,
				'content' => esc_html( $args['content'] ),
				'func'    => static::ID,
			],
			$post_id
		);

		return $body;
	}

	/**
	 * Get our content, trimming if needed.
	 *
	 * @param int    $post_id Post ID to get content from.
	 * @param int    $return_length Word length of returned content.
	 * @param bool   $use_title Whether to use the title or not.
	 * @param string $post_content The post content.
	 * @return string
	 */
	public function get_content( int $post_id = 0, int $return_length = 0, bool $use_title = true, string $post_content = '' ): string {
		$tokenizer  = new Tokenizer( $this->max_tokens );
		$normalizer = new Normalizer();

		/**
		 * We first determine how many tokens, roughly, our returned content will require.
		 * This is determined by the number of words we expect to be returned and how
		 * many tokens are in an average word.
		 */
		$return_tokens = $tokenizer->tokens_in_words( $return_length );

		/**
		 * We then subtract those tokens from the max number of tokens ChromeAI allows
		 * in a single request, as well as subtracting out the number of tokens in our
		 * prompt (~50). ChromeAI counts both the tokens in the request and in
		 * the response towards the max.
		 */
		$max_content_tokens = $this->max_tokens - $return_tokens - 50;

		if ( empty( $post_content ) ) {
			$post         = get_post( $post_id );
			$post_content = apply_filters( 'the_content', $post->post_content );
		}

		$post_content = preg_replace( '#\[.+\](.+)\[/.+\]#', '$1', $post_content );

		// Then trim our content, if needed, to stay under the max.
		if ( $use_title ) {
			$content = $tokenizer->trim_content(
				$normalizer->normalize( $post_id, $post_content ),
				(int) $max_content_tokens
			);
		} else {
			$content = $tokenizer->trim_content(
				$normalizer->normalize_content( $post_content, '', $post_id ),
				(int) $max_content_tokens
			);
		}

		/**
		 * Filter content that will get sent to Chrome AI.
		 *
		 * @since 3.2.0
		 * @hook classifai_chrome_ai_content
		 *
		 * @param string $content Content that will be sent.
		 * @param int    $post_id ID of post we are summarizing.
		 *
		 * @return string Content.
		 */
		return apply_filters( 'classifai_chrome_ai_content', $content, $post_id );
	}
}
