<?php
/**
 * Google Analytics Admin API client (accounts, properties, web data streams).
 *
 * @package Tagsmith
 */

declare(strict_types=1);

namespace Tagsmith\Google;

defined( 'ABSPATH' ) || exit;

/**
 * Lists the accounts and properties the connected Google account can see,
 * and the web data streams of a chosen property.
 */
class AdminApi extends GoogleApi {

	/**
	 * Admin API base URL.
	 *
	 * @var string
	 */
	private const BASE = 'https://analyticsadmin.googleapis.com/v1beta';

	/**
	 * Maximum number of pages to follow for a single listing, guarding
	 * against a runaway loop if Google ever returned an endless nextPageToken.
	 *
	 * @var int
	 */
	private const MAX_PAGES = 10;

	/**
	 * All GA4 account summaries (accounts and their properties) visible to
	 * the connected account, following pagination.
	 *
	 * @return array<int, array{account: string, account_name: string, properties: array<int, array{property_id: string, name: string}>}>
	 * @throws ApiError On failure.
	 */
	public function account_summaries(): array {
		$result     = array();
		$page_token = null;

		for ( $page = 0; $page < self::MAX_PAGES; $page++ ) {
			$response = $this->call( 'GET', $this->paged_url( self::BASE . '/accountSummaries?pageSize=200', $page_token ) );

			foreach ( (array) ( $response['accountSummaries'] ?? array() ) as $account ) {
				if ( ! is_array( $account ) ) {
					continue;
				}

				$result[] = array(
					'account'      => (string) ( $account['account'] ?? '' ),
					'account_name' => (string) ( $account['displayName'] ?? '' ),
					'properties'   => $this->normalize_properties( (array) ( $account['propertySummaries'] ?? array() ) ),
				);
			}

			$page_token = isset( $response['nextPageToken'] ) && is_string( $response['nextPageToken'] ) && '' !== $response['nextPageToken']
				? $response['nextPageToken']
				: null;

			if ( null === $page_token ) {
				break;
			}
		}

		return $result;
	}

	/**
	 * The web data streams of a property (app streams are excluded).
	 *
	 * @param string $property_id A property resource name, e.g. 'properties/123'.
	 * @return array<int, array{stream_id: string, name: string, measurement_id: string, default_uri: string}>
	 * @throws ApiError On failure.
	 */
	public function web_streams( string $property_id ): array {
		$this->assert_property_id( $property_id );

		$result     = array();
		$page_token = null;

		for ( $page = 0; $page < self::MAX_PAGES; $page++ ) {
			$response = $this->call( 'GET', $this->paged_url( self::BASE . '/' . $property_id . '/dataStreams', $page_token ) );

			foreach ( (array) ( $response['dataStreams'] ?? array() ) as $stream ) {
				if ( ! is_array( $stream ) || 'WEB_DATA_STREAM' !== ( $stream['type'] ?? '' ) ) {
					continue;
				}

				$web_data = is_array( $stream['webStreamData'] ?? null ) ? $stream['webStreamData'] : array();

				$result[] = array(
					'stream_id'      => (string) ( $stream['name'] ?? '' ),
					'name'           => (string) ( $stream['displayName'] ?? '' ),
					'measurement_id' => (string) ( $web_data['measurementId'] ?? '' ),
					'default_uri'    => (string) ( $web_data['defaultUri'] ?? '' ),
				);
			}

			$page_token = isset( $response['nextPageToken'] ) && is_string( $response['nextPageToken'] ) && '' !== $response['nextPageToken']
				? $response['nextPageToken']
				: null;

			if ( null === $page_token ) {
				break;
			}
		}

		return $result;
	}

	/**
	 * Normalizes an accountSummaries entry's propertySummaries.
	 *
	 * @param array<int, mixed> $properties Raw propertySummaries entries.
	 * @return array<int, array{property_id: string, name: string}>
	 */
	private function normalize_properties( array $properties ): array {
		$result = array();

		foreach ( $properties as $property ) {
			if ( ! is_array( $property ) ) {
				continue;
			}

			$result[] = array(
				'property_id' => (string) ( $property['property'] ?? '' ),
				'name'        => (string) ( $property['displayName'] ?? '' ),
			);
		}

		return $result;
	}

	/**
	 * Appends a pageToken query param to a URL when present.
	 *
	 * @param string      $url        Base URL, with its own query string already appended.
	 * @param string|null $page_token Page token, or null for the first page.
	 */
	private function paged_url( string $url, ?string $page_token ): string {
		if ( null === $page_token ) {
			return $url;
		}

		return $url . '&pageToken=' . rawurlencode( $page_token );
	}
}