<?php
/**
 * Connect / OAuth-style redirect flow and sync scaffolding.
 *
 * @package Gcco\AiViewSync
 */

namespace Gcco\AiViewSync;

defined( 'ABSPATH' ) || exit;

/**
 * Handles "Connect to AI View", callback, disconnect, and sync hook.
 */
class Connector {

	const TRANSIENT_PREFIX = 'aivisy_oauth_';

	/** @var string Hint from AI View OAuth — pre-select only; real bind happens in the wizard. */
	const TRANSIENT_SUGGESTED_PROPERTY = 'aivisy_suggested_property_id';

	/** @var string Optional label for the suggested property (display only). */
	const TRANSIENT_SUGGESTED_LABEL = 'aivisy_suggested_property_label';

	/**
	 * One sanitized string from the request query. Handles the case where duplicate keys cause PHP
	 * to supply an array; returns only the first element in that case.
	 *
	 * Uses direct $_GET access with explicit sanitization. The OAuth callback has no WP nonce; state
	 * token validation in handle_callback_request() is the authorization mechanism instead.
	 *
	 * @param string $key Query parameter name.
	 * @return string
	 */
	protected static function get_get_string( $key ) {
		$key = sanitize_key( (string) $key );
		if ( '' === $key ) {
			return '';
		}
		// phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized, WordPress.Security.NonceVerification.Recommended -- sanitized immediately below; no WP nonce exists on an external OAuth callback — authorization is handled by the state transient in handle_callback_request().
		$raw = isset( $_GET[ $key ] ) ? wp_unslash( $_GET[ $key ] ) : null;
		if ( null === $raw || false === $raw ) {
			return '';
		}
		if ( is_array( $raw ) ) {
			$sanitized = array_map( 'sanitize_text_field', $raw );
			$first     = reset( $sanitized );
			return is_string( $first ) ? $first : '';
		}
		return sanitize_text_field( (string) $raw );
	}

	/**
	 * One URL string from the request query (same duplicate-key behavior as get_get_string()).
	 *
	 * @param string $key Query parameter name.
	 * @return string
	 */
	protected static function get_get_esc_url_raw( $key ) {
		$key = sanitize_key( (string) $key );
		if ( '' === $key ) {
			return '';
		}
		// phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized, WordPress.Security.NonceVerification.Recommended -- sanitized immediately below; no WP nonce exists on an external OAuth callback — authorization is handled by the state transient in handle_callback_request().
		$raw = isset( $_GET[ $key ] ) ? wp_unslash( $_GET[ $key ] ) : null;
		if ( null === $raw || false === $raw ) {
			return '';
		}
		if ( is_array( $raw ) ) {
			$sanitized = array_map( 'esc_url_raw', $raw );
			$first     = reset( $sanitized );
			return is_string( $first ) ? $first : '';
		}
		return esc_url_raw( (string) $raw );
	}

	/**
	 * Build the WordPress return URL (admin) for AI View to redirect to after authorization.
	 *
	 * @return string
	 */
	public function get_callback_url() {
		return add_query_arg(
			array(
				'page'               => 'ai-view-llms-txt',
				'ai_view_llms_oauth' => '1',
			),
			admin_url( 'admin.php' )
		);
	}

	/**
	 * Base URL for the remote connect screen. Filterable; constant overrides empty default.
	 *
	 * @return string
	 */
	public function get_connect_base_url() {
		$base = '';
		if ( defined( 'AIVISY_CONNECT_BASE' ) && is_string( AIVISY_CONNECT_BASE ) ) {
			$base = trim( AIVISY_CONNECT_BASE );
		}
		// One-line setup: AI View app base (no trailing slash) → connect opens …/login.php.
		if ( '' === $base && defined( 'AIVISY_APP_URL' ) && is_string( AIVISY_APP_URL ) && '' !== trim( AIVISY_APP_URL ) ) {
			$base = rtrim( trim( AIVISY_APP_URL ), '/' ) . '/login.php';
		}
		/**
		 * Base URL for the AI View "connect WordPress" entrypoint (typically …/login.php).
		 *
		 * @param string $base Full URL or empty if not configured.
		 */
		return (string) apply_filters( 'aivisy_connect_base_url', $base );
	}

	/**
	 * Allow wp_safe_redirect() to the AI View app host (external — not the WordPress site).
	 *
	 * Without this, WordPress falls back to wp-admin and the connect flow appears to "refresh only".
	 *
	 * @param array<int, string> $hosts Allowed redirect hostnames.
	 * @return array<int, string>
	 */
	public function filter_allowed_redirect_hosts( $hosts ) {
		if ( ! is_array( $hosts ) ) {
			$hosts = array();
		}
		$candidates = array();
		if ( defined( 'AIVISY_APP_URL' ) && is_string( AIVISY_APP_URL ) && '' !== trim( AIVISY_APP_URL ) ) {
			$candidates[] = trim( AIVISY_APP_URL );
		}
		if ( defined( 'AIVISY_CONNECT_BASE' ) && is_string( AIVISY_CONNECT_BASE ) && '' !== trim( AIVISY_CONNECT_BASE ) ) {
			$candidates[] = trim( AIVISY_CONNECT_BASE );
		}
		foreach ( $candidates as $url ) {
			$p = wp_parse_url( $url );
			if ( ! empty( $p['host'] ) ) {
				$hosts[] = $p['host'];
			}
		}
		return array_unique( $hosts );
	}

	/**
	 * Start redirect to AI View. Verifies nonce and capability.
	 *
	 * @return void
	 */
	public function handle_connect_request() {
		// Use our own query arg on the plugin screen — avoid `action=` on admin.php (reserved by core).
		// phpcs:ignore WordPress.Security.NonceVerification.Recommended
		if ( ! isset( $_GET['page'] ) || 'aivisy-settings' !== $_GET['page'] ) {
			return;
		}
		// phpcs:ignore WordPress.Security.NonceVerification.Recommended
		if ( ! isset( $_GET['aivisy_start_connect'] ) || '1' !== $_GET['aivisy_start_connect'] ) {
			return;
		}

		if ( ! current_user_can( 'manage_options' ) ) {
			wp_die( esc_html__( 'You do not have permission to connect.', 'ai-view-sync' ) );
		}

		check_admin_referer( 'aivisy_connect' );

		$base = $this->get_connect_base_url();
		if ( '' === $base ) {
			wp_safe_redirect( aivisy_make_notice_url( 'connect_config' ) );
			exit;
		}

		$state = wp_generate_password( 32, false, false );
		set_transient( self::TRANSIENT_PREFIX . md5( $state ), array( 't' => time() ), 15 * MINUTE_IN_SECONDS );

		$callback = $this->get_callback_url();
		$site_url = home_url( '/' );

		$args = array(
			'state'          => $state,
			'redirect_uri'   => $callback,
			'site_url'       => $site_url,
			'wp_admin_url'   => admin_url(),
			'client'         => 'wordpress',
			'client_version' => AIVISY_VERSION,
		);

		/**
		 * Query arguments appended to the connect base URL.
		 *
		 * @param array<string, string> $args Arguments.
		 * @param string                $state OAuth-style state.
		 */
		$args = apply_filters( 'aivisy_connect_query_args', $args, $state );

		$url = add_query_arg( $args, $base );

		/**
		 * Final redirect URL to AI View connect/login.
		 *
		 * @param string $url Full URL.
		 */
		$url = apply_filters( 'aivisy_connect_redirect_url', $url );

		wp_safe_redirect( $url );
		exit;
	}

	/**
	 * OAuth callback (admin page). Validates state, stores placeholder connection.
	 *
	 * @return void
	 */
	public function handle_callback_request() {
		// phpcs:ignore WordPress.Security.NonceVerification.Recommended -- external redirect; state validated via transient.
		if ( ! isset( $_GET['page'] ) ) {
			return;
		}
		// phpcs:ignore WordPress.Security.NonceVerification.Recommended
		$page_raw = sanitize_key( self::get_get_string( 'page' ) );
		if ( '' === $page_raw ) {
			return;
		}
		$oauth_raw  = self::get_get_string( 'ai_view_llms_oauth' );
		$oauth_main = ( 'ai-view-llms-txt' === $page_raw && '1' === $oauth_raw );
		if ( 'aivisy-callback' !== $page_raw && ! $oauth_main ) {
			return;
		}

		if ( ! current_user_can( 'manage_options' ) ) {
			wp_die( esc_html__( 'You do not have permission to complete connection.', 'ai-view-sync' ) );
		}

		$redirect_fail = aivisy_make_notice_url( 'connect_error' );

		try {
			$state = self::get_get_string( 'state' );
			$token = self::get_get_string( 'token' );
			if ( '' === $token ) {
				$token = self::get_get_string( 'code' );
			}

			if ( '' === $state ) {
				wp_safe_redirect( $redirect_fail );
				exit;
			}

			$key = self::TRANSIENT_PREFIX . md5( $state );
			if ( false === get_transient( $key ) ) {
				wp_safe_redirect( $redirect_fail );
				exit;
			}
			delete_transient( $key );

			// TODO: Exchange $token with AI View API for a stable connection secret — keep server-side only.
			$placeholder_token = $token ? $token : 'pending_' . wp_generate_password( 12, false, false );

			$av_site = self::get_get_esc_url_raw( 'av_site_url' );
			$av_prop    = self::get_get_string( 'av_property_id' );
			$prop_label = self::get_get_string( 'property' );

			$home_norm = Settings::normalize_site_url( home_url( '/' ) );
			if ( '' !== $av_site ) {
				$av_norm = Settings::normalize_site_url( $av_site );
				if ( '' === $av_norm || $av_norm !== $home_norm ) {
					wp_safe_redirect( $redirect_fail );
					exit;
				}
			}

			// Do not save av_property_id as bound yet: AI View may send the wrong active property
			// (e.g. gcco.io vs this site). The wizard + bind API stores the correct token property.
			$suggested = trim( (string) $av_prop );
			if ( '' !== $suggested ) {
				set_transient( self::TRANSIENT_SUGGESTED_PROPERTY, $suggested, HOUR_IN_SECONDS );
				if ( '' !== $prop_label ) {
					set_transient( self::TRANSIENT_SUGGESTED_LABEL, $prop_label, HOUR_IN_SECONDS );
				} else {
					delete_transient( self::TRANSIENT_SUGGESTED_LABEL );
				}
			} else {
				delete_transient( self::TRANSIENT_SUGGESTED_PROPERTY );
				delete_transient( self::TRANSIENT_SUGGESTED_LABEL );
			}

			$update = array(
				'connected'            => true,
				'connection_token'     => $placeholder_token,
				'mode'                 => 'manual',
				'bound_site_url'       => $home_norm,
				'bound_property_id'    => '',
				'connection_site_id'   => '',
				'bound_property_label' => '',
			);

			Settings::update( $update );

			wp_safe_redirect( aivisy_make_notice_url( 'choose_property' ) );
			exit;
		} catch ( \Throwable $e ) {
			if ( function_exists( 'error_log' ) ) {
				// phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_error_log -- diagnose connect fatals without exposing details to the browser.
				error_log( 'aivisy: OAuth callback failed: ' . $e->getMessage() );
			}
			wp_safe_redirect( $redirect_fail );
			exit;
		}
	}

	/**
	 * Stub content until real sync returns llms.txt from AI View.
	 *
	 * @return string
	 */
	protected static function get_placeholder_synced_body() {
		$lines = array(
			'# LLMS.txt',
			'# This llms.txt was generated with AI View (placeholder — use Connect & Sync for live content).',
			'User-agent: *',
			'Allow: /',
			'',
			'# TODO: Replace with synced content from AI View.',
		);
		return implode( "\n", $lines );
	}

	/**
	 * "Sync now" — calls filter for HTTP client.
	 *
	 * @return bool True on success.
	 */
	public function sync_now() {
		$s = Settings::get_all();
		if ( empty( $s['connected'] ) ) {
			return false;
		}
		if ( ! Settings::is_bound_site_current() ) {
			set_transient(
				'aivisy_sync_error',
				__( 'This WordPress URL does not match the site stored for this connection. Use Connect to AI View again, or fix the site URL, then sync.', 'ai-view-sync' ),
				120
			);
			return false;
		}

		if ( Settings::needs_property_selection() ) {
			set_transient(
				'aivisy_sync_error',
				__( 'Choose which GA4 property powers this WordPress site (step below), then save and sync again.', 'ai-view-sync' ),
				120
			);
			return false;
		}

		/**
		 * Perform remote sync: return llms.txt body string, or WP_Error.
		 * $settings includes bound_site_url and bound_property_id for the AI View GA4 property.
		 *
		 * @param string|null $content New body or null to use default behavior.
		 * @param array       $settings Current settings.
		 */
		$result = apply_filters( 'aivisy_sync_fetch', null, $s );

		if ( is_wp_error( $result ) ) {
			set_transient( 'aivisy_sync_error', $result->get_error_message(), 120 );
			return false;
		}

		$api_configured = '' !== Sync_Remote::get_api_url() && ! empty( $s['connection_token'] );

		if ( is_string( $result ) && trim( $result ) !== '' ) {
			delete_transient( 'aivisy_sync_error' );
			$body = Settings::sanitize_llms_body( $result );
		} elseif ( $api_configured ) {
			set_transient(
				'aivisy_sync_error',
				__( 'AI View did not return LLMS.txt. Open the generator there, create your file, then sync again.', 'ai-view-sync' ),
				120
			);
			return false;
		} else {
			$body = self::get_placeholder_synced_body();
		}

		$merged = Llms_Merge::merge( $body, $s );
		$body   = Settings::sanitize_llms_body( $merged['content'] );
		$ga4_c  = (int) $merged['ga4_count'];
		$wp_c   = (int) $merged['wp_count'];
		Llms_Merge::maybe_write_physical_file( $body );

		Settings::update(
			array(
				'synced_content'      => $body,
				'last_synced'         => time(),
				'last_sync_ga4_count' => $ga4_c,
				'last_sync_wp_count'  => $wp_c,
			)
		);

		return true;
	}

	/**
	 * Clear connection and optionally switch to manual mode.
	 *
	 * @param bool $switch_to_manual Whether to set mode to manual.
	 */
	public function disconnect( $switch_to_manual = true ) {
		$data = array(
			'connected'             => false,
			'connection_token'      => '',
			'connection_site_id'    => '',
			'bound_site_url'        => '',
			'bound_property_id'     => '',
			'bound_property_label'  => '',
			'last_sync_ga4_count'   => 0,
			'last_sync_wp_count'    => 0,
		);
		if ( $switch_to_manual ) {
			$data['mode'] = 'manual';
		}
		Settings::update( $data );
		delete_transient( self::TRANSIENT_SUGGESTED_PROPERTY );
		delete_transient( self::TRANSIENT_SUGGESTED_LABEL );
	}
}