<?php
/**
 * Google Analytics 4 Data and Admin APIs.
 *
 * @package TurtleReport
 */

namespace TurtleReport\Google;

use TurtleReport\Auth\ApiException;

defined( 'ABSPATH' ) || exit;

/**
 * Lists GA4 properties and runs reports.
 */
final class Analytics {

	const DATA  = 'https://analyticsdata.googleapis.com/v1beta';
	const ADMIN = 'https://analyticsadmin.googleapis.com/v1beta';

	/**
	 * HTTP client.
	 *
	 * @var HttpClient
	 */
	private $http;

	/**
	 * Constructor.
	 *
	 * @param HttpClient $http HTTP client.
	 */
	public function __construct( HttpClient $http ) {
		$this->http = $http;
	}

	/**
	 * GA4 properties the account can read, across all accounts.
	 *
	 * @param int $ttl Cache lifetime.
	 * @return array[] Items with id, name and account.
	 * @throws ApiException On failure.
	 */
	public function properties( $ttl ) {
		$out   = array();
		$token = '';
		$pages = 0;
		do {
			$url  = self::ADMIN . '/accountSummaries?pageSize=200' . ( '' !== $token ? '&pageToken=' . rawurlencode( $token ) : '' );
			$data = $this->http->get( $url, $ttl );
			foreach ( isset( $data['accountSummaries'] ) ? (array) $data['accountSummaries'] : array() as $account ) {
				$account_name = isset( $account['displayName'] ) ? $account['displayName'] : ( isset( $account['account'] ) ? $account['account'] : '' );
				foreach ( isset( $account['propertySummaries'] ) ? (array) $account['propertySummaries'] : array() as $property ) {
					if ( empty( $property['property'] ) ) {
						continue;
					}
					$out[] = array(
						'id'      => (string) $property['property'],
						'name'    => isset( $property['displayName'] ) ? (string) $property['displayName'] : (string) $property['property'],
						'account' => (string) $account_name,
					);
				}
			}
			$token = isset( $data['nextPageToken'] ) ? (string) $data['nextPageToken'] : '';
			++$pages;
		} while ( '' !== $token && $pages < 20 );
		return $out;
	}

	/**
	 * Event names the property has marked as key events in GA4.
	 *
	 * These are the events GA4 itself treats as conversions, so they are the
	 * ones worth offering first in the site editor. The read-only Analytics
	 * scope the connection already holds covers this, so nothing needs
	 * reconnecting. Properties still on the older "conversion events" surface
	 * answer the second call.
	 *
	 * @param string $property Property resource name, e.g. "properties/123".
	 * @param int    $ttl      Cache lifetime.
	 * @return string[] Event names, without duplicates.
	 * @throws ApiException On failure or an invalid property.
	 */
	public function key_events( $property, $ttl ) {
		self::check_property( $property );
		try {
			return $this->event_names( $property, 'keyEvents', $ttl );
		} catch ( ApiException $e ) {
			if ( 404 !== $e->status() && 400 !== $e->status() ) {
				throw $e;
			}
		}
		return $this->event_names( $property, 'conversionEvents', $ttl );
	}

	/**
	 * Reads one of the Admin API's event collections, following its pages.
	 *
	 * @param string $property   Property resource name.
	 * @param string $collection keyEvents or conversionEvents.
	 * @param int    $ttl        Cache lifetime.
	 * @return string[] Event names.
	 * @throws ApiException On failure.
	 */
	private function event_names( $property, $collection, $ttl ) {
		$names = array();
		$token = '';
		$pages = 0;
		do {
			$url  = self::ADMIN . '/' . $property . '/' . $collection . '?pageSize=200' . ( '' !== $token ? '&pageToken=' . rawurlencode( $token ) : '' );
			$data = $this->http->get( $url, $ttl );
			foreach ( isset( $data[ $collection ] ) ? (array) $data[ $collection ] : array() as $event ) {
				if ( ! empty( $event['eventName'] ) ) {
					$names[] = (string) $event['eventName'];
				}
			}
			$token = isset( $data['nextPageToken'] ) ? (string) $data['nextPageToken'] : '';
			++$pages;
		} while ( '' !== $token && $pages < 10 );
		return array_values( array_unique( $names ) );
	}

	/**
	 * Runs a GA4 report.
	 *
	 * @param string $property Property resource name, e.g. "properties/123".
	 * @param array  $body     runReport request body.
	 * @param int    $ttl      Cache lifetime.
	 * @return array[] Rows as ['d' => dimension values, 'm' => metric values].
	 * @throws ApiException On failure or an invalid property.
	 */
	public function run_report( $property, array $body, $ttl ) {
		self::check_property( $property );
		$data = $this->http->post( self::DATA . '/' . $property . ':runReport', $body, $ttl );
		$rows = array();
		foreach ( isset( $data['rows'] ) ? (array) $data['rows'] : array() as $row ) {
			$rows[] = array(
				'd' => array_map(
					static function ( $v ) {
						return isset( $v['value'] ) ? (string) $v['value'] : '';
					},
					isset( $row['dimensionValues'] ) ? (array) $row['dimensionValues'] : array()
				),
				'm' => array_map(
					static function ( $v ) {
						return isset( $v['value'] ) ? (float) $v['value'] : 0.0;
					},
					isset( $row['metricValues'] ) ? (array) $row['metricValues'] : array()
				),
			);
		}
		return $rows;
	}

	/**
	 * Rejects anything that isn't a GA4 property resource name.
	 *
	 * @param string $property Property resource name.
	 * @return void
	 * @throws ApiException When the name is not a property.
	 */
	private static function check_property( $property ) {
		if ( ! preg_match( '#^properties/\d+$#', $property ) ) {
			throw new ApiException( __( 'The GA4 property for this site is invalid. Choose it again on the site\'s settings.', 'turtlereport' ), ApiException::NOT_CONFIGURED ); // phpcs:ignore WordPress.Security.EscapeOutput.ExceptionNotEscaped -- Caught by the plugin; escaped where the message is shown.
		}
	}
}