<?php
/**
 * Admin Pages
 *
 * The list of admin screens a plugin really has, fetched once a day.
 *
 * @package Aisentic\Agent\Utils
 */

declare( strict_types = 1 );

namespace Aisentic\Agent\Utils;

use Aisentic\Util\Log;
use Aisentic\Voice\Provider_Audio_Client;

defined( 'ABSPATH' ) || exit;

/**
 * Gets the real admin page addresses of a plugin, so the model does not guess.
 *
 * Why: with only a search tool, the model wrote 11 of 12 addresses from
 * memory, and 6 did not exist (for example #/orders, #/settings/payment).
 */
class Admin_Pages {

	/**
	 * How long the list is kept before asking again.
	 *
	 * Pages change only when the plugin updates.
	 *
	 * @var int
	 */
	private const KEEP_FOR = DAY_IN_SECONDS;

	/**
	 * How long a failed fetch is remembered before asking again.
	 *
	 * Why 5 minutes: we do not ask a down provider on every turn, but we get
	 * the list again soon after it is back.
	 *
	 * @var int
	 */
	private const RETRY_AFTER = 5 * MINUTE_IN_SECONDS;

	/**
	 * How many setting names one screen carries in the prompt.
	 *
	 * Enough to tell "Checkout Settings" (purchase timer) from "General
	 * Settings" (colors, date format). Small enough that 45 pages stay at a
	 * few hundred tokens.
	 *
	 * @var int
	 */
	private const HOLDS_PER_PAGE = 5;

	/**
	 * Settings instance.
	 *
	 * @var object
	 */
	private $settings;

	/**
	 * Constructor.
	 *
	 * @param object $settings Settings instance.
	 */
	public function __construct( $settings ) {
		$this->settings = $settings;
	}

	/**
	 * Every known screen for one plugin.
	 *
	 * @param string $plugin Plugin key, e.g. "eventin".
	 * @return array List of {title, url, type}. Empty when it cannot be had.
	 */
	public function all( string $plugin ): array {
		$plugin = strtolower( preg_replace( '/[^a-z0-9_-]/i', '', $plugin ) ?? '' );

		if ( '' === $plugin ) {
			return [];
		}

		$key  = 'aisentic_admin_pages_' . $plugin;
		$kept = get_transient( $key );

		if ( is_array( $kept ) ) {
			return $kept;
		}

		$pages = $this->fetch( $plugin );

		// Cache times: failed fetch 5 minutes (as an empty list),
		// empty answer 1 hour, real list 1 day.
		if ( null === $pages ) {
			set_transient( $key, [], self::RETRY_AFTER );

			return [];
		}

		set_transient( $key, $pages, empty( $pages ) ? HOUR_IN_SECONDS : self::KEEP_FOR );

		return $pages;
	}

	/**
	 * Only the screens a person can actually be taken to.
	 *
	 * One entry per address (pages and tabs only). Up to five setting names
	 * on that page go in 'holds'.
	 * Why 'holds': a page title like "Checkout Settings" does not say the
	 * purchase timer is there, so the model picked "General Settings".
	 *
	 * @param string $plugin Plugin key.
	 * @return array List of {title, url, holds: string[]}.
	 */
	public function destinations( string $plugin ): array {
		$seen  = [];
		$holds = [];
		$all   = $this->all( $plugin );

		foreach ( $all as $page ) {
			$type  = strtolower( (string) ( $page['type'] ?? 'page' ) );
			$url   = $this->shorten( (string) $page['url'] );
			$title = trim( (string) ( $page['title'] ?? '' ) );

			if ( '' === $url || '' === $title ) {
				continue;
			}

			if ( 'setting' === $type ) {
				if ( count( $holds[ $url ] ?? [] ) < self::HOLDS_PER_PAGE ) {
					$holds[ $url ][] = $title;
				}
				continue;
			}

			if ( ( 'page' !== $type && 'tab' !== $type ) || isset( $seen[ $url ] ) ) {
				continue;
			}

			$seen[ $url ] = [
				'title' => (string) $page['title'],
				'url'   => (string) $page['url'],
			];
		}

		foreach ( $seen as $url => &$page ) {
			$page['holds'] = $holds[ $url ] ?? [];
		}
		unset( $page );

		return array_values( $seen );
	}

	/**
	 * Is this address one of the plugin's real screens?
	 *
	 * @param string $url    Address from the model, absolute or relative.
	 * @param string $plugin Plugin key.
	 * @return bool False also when the list is unknown. Callers treat
	 *              "not known" as "not real" on purpose.
	 */
	public function knows( string $url, string $plugin ): bool {
		foreach ( $this->all( $plugin ) as $page ) {
			$known = (string) ( $page['url'] ?? '' );

			if ( $this->same( $known, $url ) || $this->one_record_under( $known, $url ) ) {
				return true;
			}
		}

		return false;
	}

	/**
	 * The names of the settings on one screen.
	 *
	 * These are the names the model sees next to that page in the prompt.
	 * A sentence that uses one of them was not made up.
	 *
	 * @param string $url    Address from the model, absolute or relative.
	 * @param string $plugin Plugin key.
	 * @return string[] Empty when the screen is unknown or lists no settings.
	 */
	public function holds_for( string $url, string $plugin ): array {
		foreach ( $this->destinations( $plugin ) as $page ) {
			if ( $this->same( (string) $page['url'], $url ) ) {
				return (array) $page['holds'];
			}
		}

		return [];
	}

	/**
	 * Is this a link to one record sitting under a screen from the list?
	 *
	 * Example: "#/events/edit/520831/basic" is under "#/events".
	 * The list has only pages, never one record, so an exact match rejects it.
	 *
	 * A deeper address passes only when both are true:
	 *  1. It starts with a known address followed by "/".
	 *  2. One of the extra parts is a number (a record id).
	 *
	 * Why the number: "#/events/archive" has no number, so it is a page name
	 * that is not in the list, and is rejected.
	 *
	 * @param string $known One address from the list.
	 * @param string $given One address from the model.
	 * @return bool
	 */
	private function one_record_under( string $known, string $given ): bool {
		$known = $this->shorten( $known );
		$given = $this->shorten( $given );

		if ( '' === $known || ! str_starts_with( $given, $known . '/' ) ) {
			return false;
		}

		foreach ( explode( '/', substr( $given, strlen( $known ) + 1 ) ) as $part ) {
			if ( '' !== $part && ctype_digit( $part ) ) {
				return true;
			}
		}

		return false;
	}

	/**
	 * Are these two addresses the same screen?
	 *
	 * The model may write "/wp-admin/admin.php?page=eventin#/events" or a full
	 * URL. The list has "admin.php?page=eventin#/events". Both are shortened first.
	 *
	 * @param string $known One address from the list.
	 * @param string $given One address from the model.
	 * @return bool
	 */
	private function same( string $known, string $given ): bool {
		return '' !== $known && $this->shorten( $known ) === $this->shorten( $given );
	}

	/**
	 * Cut an address down to the part that identifies the screen.
	 *
	 * @param string $url Address in any of its shapes.
	 * @return string
	 */
	private function shorten( string $url ): string {
		$url = trim( html_entity_decode( $url, ENT_QUOTES, 'UTF-8' ) );
		$url = (string) preg_replace( '#^https?://[^/]+#i', '', $url );
		$url = (string) preg_replace( '#^/?wp-admin/#i', '', $url );

		return strtolower( ltrim( $url, '/' ) );
	}

	/**
	 * Ask the provider for the list.
	 *
	 * Uses the same provider client as the voice routes, so the endpoint, key
	 * and HTTP error handling stay in one place.
	 *
	 * @param string $plugin Plugin key.
	 * @return array|null The pages, or null when the provider could not answer.
	 */
	private function fetch( string $plugin ): ?array {
		$client = new class( $this->settings ) extends Provider_Audio_Client {
			/**
			 * GET the page list, as a body string or an error.
			 *
			 * @param string $plugin Plugin key.
			 * @return string|\WP_Error
			 */
			public function pages( string $plugin ) {
				$response = wp_remote_get(
					$this->endpoint() . '/api/v1/sitemap/pages?plugin=' . rawurlencode( $plugin ),
					[
						'timeout' => 15,
						'headers' => [
							'Authorization' => 'Bearer ' . $this->api_key(),
							'Accept'        => 'application/json',
						],
					]
				);

				return $this->unwrap( $response, __( 'admin pages', 'aisentic' ) );
			}
		};

		if ( ! $client->is_configured() ) {
			return [];
		}

		$body = $client->pages( $plugin );

		if ( is_wp_error( $body ) ) {
			Log::warning( 'Admin_Pages: could not fetch the page list — ' . $body->get_error_message() );
			return null;
		}

		$data = json_decode( (string) $body, true );

		if ( ! is_array( $data ) || empty( $data['pages'] ) || ! is_array( $data['pages'] ) ) {
			return [];
		}

		$pages = [];

		foreach ( $data['pages'] as $page ) {
			$url = trim( (string) ( $page['url'] ?? '' ) );

			if ( '' === $url ) {
				continue;
			}

			$pages[] = [
				'title' => trim( (string) ( $page['title'] ?? '' ) ),
				'url'   => $url,
				// "page" and "tab" are places to go. "setting" and "button"
				// are items on a page (109 of 165 Eventin entries), so
				// destinations() does not list them as pages.
				'type'  => trim( (string) ( $page['type'] ?? 'page' ) ),
			];
		}

		return $pages;
	}
}