<?php
/**
 * Block Container Label Generation WordPress Ability implementation.
 *
 * @package WordPress\AI
 */

declare( strict_types=1 );

namespace WordPress\AI\Abilities\Block_Container_Label_Generation;

use WP_Error;
use WordPress\AI\Abstracts\Abstract_Ability;
use WordPress\AI\Experiments\Block_Container_Label_Generation\Block_Container_Label_Generation as Block_Container_Label_Generation_Experiment;

use function WordPress\AI\count_characters_excluding_spaces;
use function WordPress\AI\get_min_content_length;
use function WordPress\AI\normalize_content;

/**
 * Block Container Label Generation WordPress Ability.
 *
 * @since 1.5.0
 */
class Block_Container_Label_Generation extends Abstract_Ability {

	/**
	 * The default minimum content length in characters for the block container label generation.
	 *
	 * @since 1.5.0
	 *
	 * @var int
	 */
	public const DEFAULT_MIN_CONTENT_LENGTH = 25;

	/**
	 * {@inheritDoc}
	 *
	 * @since 1.5.0
	 */
	protected function meta(): array {
		return array(
			'show_in_rest' => true,
		);
	}

	/**
	 * {@inheritDoc}
	 *
	 * @since 1.5.0
	 */
	protected function input_schema(): array {
		return array(
			'type'       => 'object',
			'required'   => array( 'post_id', 'content' ),
			'properties' => array(
				'post_id'          => array(
					'type'              => 'integer',
					'sanitize_callback' => 'absint',
					'description'       => esc_html__( 'The ID of the post that contains the block to generate a label for.', 'ai' ),
				),
				'content'          => array(
					'type'        => 'string',
					'description' => esc_html__( 'The content of the block to generate a label for.', 'ai' ),
				),
				'document_context' => array(
					'type'        => 'string',
					'description' => esc_html__( 'The outline or contextual overview of the entire document to provide structural context.', 'ai' ),
				),
			),
		);
	}

	/**
	 * {@inheritDoc}
	 *
	 * @since 1.5.0
	 */
	protected function output_schema(): array {
		return array(
			'type'        => 'string',
			'description' => esc_html__( 'The generated label for the block.', 'ai' ),
		);
	}

	/**
	 * {@inheritDoc}
	 *
	 * @since 1.5.0
	 */
	protected function permission_callback( $args ) {
		if ( empty( $args['post_id'] ) ) {
			return new WP_Error(
				'missing_post_id',
				esc_html__( 'A post ID is required to generate a block container label.', 'ai' )
			);
		}

		$post_id = absint( $args['post_id'] );
		$post    = get_post( $post_id );

		if ( ! $post ) {
			return new WP_Error(
				'post_not_found',
				sprintf(
					/* translators: %d: post ID */
					esc_html__( 'Post with ID %d not found.', 'ai' ),
					$post_id
				)
			);
		}

		if ( ! current_user_can( 'edit_post', $post_id ) ) {
			return new WP_Error(
				'insufficient_permissions',
				esc_html__( 'You do not have permission to edit this post.', 'ai' )
			);
		}

		// Ensure the post type is allowed in REST endpoints.
		$post_type = get_post_type_object( $post->post_type );

		return $post_type && ! empty( $post_type->show_in_rest );
	}

	/**
	 * Returns a prompt builder for Block Container Label Generation.
	 *
	 * @since 1.5.0
	 *
	 * @param string $prompt The prompt to build.
	 * @return \WP_AI_Client_Prompt_Builder|\WP_Error The prompt builder, or a WP_Error if there isn't a model that supports text generation.
	 */
	private function get_prompt_builder( string $prompt ) {
		$prompt_builder = wp_ai_client_prompt( $prompt )
			->using_system_instruction(
				$this->get_system_instruction(
					'system-instruction.php'
				)
			);

		$prompt_builder = $this->filter_prompt_builder(
			$prompt_builder,
			Block_Container_Label_Generation_Experiment::class,
			array(),
			$prompt
		);

		return $this->ensure_text_generation_supported(
			$prompt_builder,
			esc_html__(
				'Label generation failed. Please ensure you have a connected provider that supports text generation.',
				'ai'
			)
		);
	}

	/**
	 * {@inheritDoc}
	 *
	 * @since 1.5.0
	 */
	protected function execute_callback( $input ) {
		$args = wp_parse_args(
			$input,
			array(
				'post_id'          => null,
				'content'          => null,
				'document_context' => null,
			)
		);

		$content = normalize_content( $args['content'] ?? '' );
		if ( empty( $content ) ) {
			return new WP_Error(
				'content_not_provided',
				esc_html__( 'No content provided to generate a label.', 'ai' )
			);
		}

		$min_content_length = get_min_content_length(
			'block-container-label-generation',
			self::DEFAULT_MIN_CONTENT_LENGTH
		);

		if ( count_characters_excluding_spaces( $content ) < $min_content_length ) {
			return new WP_Error(
				'content_too_short',
				sprintf(
					/* translators: %d: Minimum content length in characters. */
					esc_html__( 'A minimum of %d characters is required to generate a label.', 'ai' ),
					$min_content_length
				)
			);
		}

		$document_context = ! empty( $args['document_context'] )
			? trim( (string) $args['document_context'] )
			: '';

		// Escape angle brackets so content cannot break out of the tags.
		$escaped_content = str_replace( array( '<', '>' ), array( '&lt;', '&gt;' ), $content );

		if ( ! empty( $document_context ) ) {
			$escaped_context = str_replace( array( '<', '>' ), array( '&lt;', '&gt;' ), $document_context );
			$prompt          = sprintf(
				"<document-context>\n%s\n</document-context>\n<content>%s</content>",
				$escaped_context,
				$escaped_content
			);
		} else {
			$prompt = sprintf( '<content>%s</content>', $escaped_content );
		}

		$result = $this->generate_label( $prompt );

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

		if ( empty( $result ) ) {
			return new WP_Error(
				'no_results',
				esc_html__( 'No label was generated.', 'ai' )
			);
		}

		return sanitize_text_field( trim( $result, " \t\n\r\0\x0B\"'" ) );
	}

	/**
	 * Generates a label for the given content using the AI client.
	 *
	 * @since 1.5.0
	 *
	 * @param string $prompt The prompt to use for the block container label generation.
	 * @return string|\WP_Error The generated label, or a WP_Error if there was an error.
	 */
	protected function generate_label( string $prompt ) {
		$prompt  = $this->filter_prompt( $prompt );
		$builder = $this->get_prompt_builder( $prompt );

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

		return $builder->generate_text();
	}
}