<?php
/**
 * Plugin Name: AI Provider for ChatGPT - ChatGPT Connector, No API Key Needed
 * Plugin URI: https://github.com/Abdalsalaam/ai-provider-for-chatgpt
 * Description: Registers OpenAI as a WordPress AI provider using Sign in with ChatGPT. Usage is billed to the connected ChatGPT Plus, Pro or Go plan.
 * Requires at least: 6.9
 * Requires PHP: 7.4
 * Version: 1.1.0
 * Author: Abdalsalaam Halawa
 * Author URI: https://halawa.io
 * License: GPL-2.0-or-later
 * License URI: https://spdx.org/licenses/GPL-2.0-or-later.html
 * Text Domain: ai-provider-for-chatgpt
 *
 * @package Halawa\ChatGptAiProvider
 */

declare(strict_types=1);

namespace Halawa\ChatGptAiProvider;

use WordPress\AiClient\AiClient;
use WordPress\AiClient\Providers\Http\DTO\ApiKeyRequestAuthentication;
use Halawa\ChatGptAiProvider\Admin\Assets;
use Halawa\ChatGptAiProvider\Admin\SettingsPage;
use Halawa\ChatGptAiProvider\Admin\Upgrade;
use Halawa\ChatGptAiProvider\Authentication\TokenStore;
use Halawa\ChatGptAiProvider\Cache\TransientCache;
use Halawa\ChatGptAiProvider\OAuth\TokenRefresher;
use Halawa\ChatGptAiProvider\Provider\ChatGptProvider;
use Halawa\ChatGptAiProvider\Rest\CacheController;
use Halawa\ChatGptAiProvider\Rest\ConnectionController;
use Halawa\ChatGptAiProvider\Rest\DiagnosticsController;
use Halawa\ChatGptAiProvider\Rest\SettingsController;
use Halawa\ChatGptAiProvider\Settings\ModelSettings;

if ( ! defined( 'ABSPATH' ) ) {
	return;
}

require_once __DIR__ . '/vendor/autoload.php';

/**
 * Plugin version, also used in the User-Agent header.
 *
 * @since 1.0.0
 */
const VERSION = '1.1.0';

/**
 * Sign in with ChatGPT endpoints and identifiers (OpenAI open-source app flow).
 *
 * @since 1.0.0
 */
const AUTHORIZE_ENDPOINT   = 'https://auth.openai.com/api/accounts/authorize';
const TOKEN_ENDPOINT       = 'https://auth.openai.com/api/accounts/oauth/token';
const REVOKE_ENDPOINT      = 'https://auth.openai.com/api/accounts/oauth/revoke';
const JWKS_URI             = 'https://auth.openai.com/.well-known/jwks.json';
const ISSUER               = 'https://auth.openai.com';
const RESOURCE             = 'https://api.openai.com/v1';
const API_BASE_URL         = 'https://api.openai.com/v1';
const SCOPES               = 'openid profile email offline_access resource.invoke chatgpt.tokens.use.direct';
const PLAN_SCOPE           = 'chatgpt.tokens.use.direct';
const AGENT_NAME           = 'AI Provider for ChatGPT';
const DYNAMIC_CLIENT_ID    = 'dynamic_agent_client';
const DEFAULT_REDIRECT_URI = 'http://127.0.0.1:1455/auth/callback';
const USAGE_URL            = 'https://chatgpt.com/settings/usage';

/**
 * Returns the redirect URI sent on authorize and code exchange.
 *
 * @since 1.0.0
 *
 * @return string The redirect URI.
 */
function redirect_uri(): string {
	/**
	 * Filters the OAuth redirect URI, for a registered https client.
	 *
	 * @since 1.0.0
	 *
	 * @param string $uri Default loopback redirect URI.
	 */
	$value = apply_filters( 'halawa_chatgpt_redirect_uri', DEFAULT_REDIRECT_URI );
	return is_string( $value ) && '' !== $value ? $value : DEFAULT_REDIRECT_URI;
}

/**
 * Returns the client id from the CHATGPT_OAUTH_CLIENT_ID constant, if set.
 *
 * @since 1.0.0
 *
 * @return string|null The configured client id, or null.
 */
function configured_client_id(): ?string {
	if ( ! defined( 'CHATGPT_OAUTH_CLIENT_ID' ) ) {
		return null;
	}
	$value = constant( 'CHATGPT_OAUTH_CLIENT_ID' );
	return is_string( $value ) && '' !== $value ? $value : null;
}

/**
 * Returns the stable ext_agent_host_id for this site.
 *
 * @since 1.0.0
 *
 * @return string The host id, "urn:uuid:" plus the installation uuid.
 */
function host_id(): string {
	$id = get_option( 'halawa_chatgpt_installation_id', '' );
	if ( ! is_string( $id ) || '' === $id ) {
		// add_option() keeps an id another request wrote first.
		add_option( 'halawa_chatgpt_installation_id', wp_generate_uuid4(), '', false );
		$id = (string) get_option( 'halawa_chatgpt_installation_id', '' );
	}
	return 'urn:uuid:' . $id;
}

/**
 * Returns the User-Agent sent to OpenAI.
 *
 * @since 1.0.0
 *
 * @return string The User-Agent header value.
 */
function user_agent(): string {
	return 'ai-provider-for-chatgpt/' . VERSION . ' (WordPress/' . get_bloginfo( 'version' ) . ')';
}

/**
 * Tells whether TransientCache matches the cache interface this AI Client expects.
 *
 * Core bundles the SDK with prefixed PSR interfaces that TransientCache does not
 * implement, and loading it without the plain interface is a fatal error.
 *
 * @since 1.0.1
 *
 * @return bool True when TransientCache can be passed to AiClient::setCache().
 */
function can_use_transient_cache(): bool {
	if ( ! interface_exists( 'Psr\\SimpleCache\\CacheInterface' ) ) {
		return false;
	}
	try {
		$params = ( new \ReflectionMethod( AiClient::class, 'setCache' ) )->getParameters();
		$type   = isset( $params[0] ) ? $params[0]->getType() : null;
	} catch ( \ReflectionException $e ) {
		return false;
	}
	return $type instanceof \ReflectionNamedType && 'Psr\\SimpleCache\\CacheInterface' === ltrim( $type->getName(), '\\' );
}

/**
 * Registers the ChatGPT provider with the WordPress AI Client.
 *
 * Registration happens unconditionally so the connector is discoverable in
 * the AI picker even before the admin imports an auth bundle. When no tokens
 * are stored, the availability check will mark the provider as unavailable
 * and the SettingsPage tells the admin how to connect.
 *
 * @since 0.1.0
 *
 * @return void
 */
function register_provider(): void {
	if ( ! class_exists( AiClient::class ) ) {
		return;
	}

	// Wire a transient-backed PSR-16 cache so the SDK's `/models` lookup is
	// persisted across requests. Without this the SDK falls back to a
	// per-request in-memory array, which means the /models endpoint
	// is hit on every admin page load. Idempotent if called more than once.
	if ( null === AiClient::getCache() && can_use_transient_cache() ) {
		AiClient::setCache( new TransientCache() );
	}

	$registry = AiClient::defaultRegistry();
	if ( ! $registry->hasProvider( ChatGptProvider::class ) ) {
		$registry->registerProvider( ChatGptProvider::class );
	}

	/*
	 * Plant a placeholder ApiKeyRequestAuthentication in the registry when a
	 * token bundle is present. The SDK uses this to flip the provider's
	 * "configured" flag for WP core's AI picker. The placeholder is never
	 * actually used to authenticate requests — our model classes override
	 * getRequestAuthentication() to return ChatGptAccountAuthentication.
	 */
	if ( ( new TokenStore() )->get_access_token() !== null ) {
		try {
			$registry->setProviderRequestAuthentication(
				ChatGptProvider::class,
				new ApiKeyRequestAuthentication( TokenStore::CORE_API_KEY_PLACEHOLDER )
			);
		} catch ( \Throwable $e ) {
			// Registry not ready or auth-type mismatch; provider stays usable.
			if ( defined( 'WP_DEBUG' ) && WP_DEBUG ) {
				// phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_error_log -- Diagnostic under WP_DEBUG only.
				error_log( 'ai-provider-for-chatgpt: registry auth wiring failed: ' . $e->getMessage() );
			}
		}
	}
}

add_action( 'init', __NAMESPACE__ . '\\register_provider', 5 );

/**
 * Registers the REST routes that back the React settings UI.
 *
 * @since 0.1.0
 *
 * @return void
 */
function register_rest_controllers(): void {
	$store = new TokenStore();
	( new ConnectionController( $store ) )->register_routes();
	( new DiagnosticsController( $store ) )->register_routes();
	( new CacheController() )->register_routes();
	( new SettingsController() )->register_routes();
}

add_action( 'rest_api_init', __NAMESPACE__ . '\\register_rest_controllers' );

ModelSettings::register();

add_action( TokenRefresher::CRON_HOOK, array( TokenRefresher::class, 'run_cron' ) );

/**
 * Schedules the weekly refresh when a live connection already exists.
 *
 * @since 1.0.0
 *
 * @return void
 */
function activate(): void {
	if ( ( new TokenStore() )->is_connected() ) {
		TokenRefresher::schedule();
	}
}

/**
 * Removes the weekly refresh; the connection itself is kept.
 *
 * @since 1.0.0
 *
 * @return void
 */
function deactivate(): void {
	TokenRefresher::unschedule();
}

register_activation_hook( __FILE__, __NAMESPACE__ . '\\activate' );
register_deactivation_hook( __FILE__, __NAMESPACE__ . '\\deactivate' );

if ( is_admin() ) {
	( new SettingsPage() )->register();
	( new Assets() )->register();
	( new Upgrade() )->register();
}