<?php
/**
 * Reading this site's stats from ReaderCount's API (api.readercount.com) with the owner's read-only key.
 * The key stays on the server: it never goes into a page.
 *
 * @package ReaderCount
 */

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

/**
 * Asks ReaderCount's API for something about this site.
 *
 * @param string $endpoint Such as 'overview' or 'check'.
 * @param array  $args     Query arguments, such as array( 'period' => '7d' ).
 * @return array|WP_Error The answer, or what went wrong in words the owner can act on.
 */
function readercount_api( $endpoint, $args = array() ) {
	$key = (string) get_option( READERCOUNT_KEY_OPTION, '' );
	if ( '' === $key ) {
		return new WP_Error( 'readercount_no_key', __( 'Add a ReaderCount API key in Settings, ReaderCount to see your stats here.', 'readercount' ) );
	}
	$response = wp_remote_get(
		add_query_arg( array_map( 'rawurlencode', $args ), READERCOUNT_API . $endpoint ),
		array(
			'timeout' => 10,
			'headers' => array(
				'Authorization' => 'Bearer ' . $key,
				'Accept'        => 'application/json',
			),
		)
	);
	if ( is_wp_error( $response ) ) {
		return new WP_Error( 'readercount_offline', __( 'We couldn\'t reach ReaderCount just now. Try again in a minute.', 'readercount' ) );
	}
	$status = (int) wp_remote_retrieve_response_code( $response );
	$body   = json_decode( wp_remote_retrieve_body( $response ), true );
	if ( 200 === $status && is_array( $body ) ) {
		return $body;
	}
	if ( 401 === $status ) {
		return new WP_Error( 'readercount_key', __( 'ReaderCount doesn\'t recognise this API key. It may have been deleted. Make a new one on your stats page and add it in Settings, ReaderCount.', 'readercount' ) );
	}
	if ( 402 === $status ) {
		return new WP_Error( 'readercount_plan', __( 'Your ReaderCount trial has ended. Pick a plan on ReaderCount to see your stats again. Counting carries on in the meantime.', 'readercount' ) );
	}
	if ( 429 === $status ) {
		return new WP_Error( 'readercount_busy', __( 'Too many requests to ReaderCount in the last minute. Try again shortly.', 'readercount' ) );
	}
	$message = is_array( $body ) && isset( $body['error'] ) ? (string) $body['error'] : __( 'ReaderCount didn\'t answer as expected. Try again in a minute.', 'readercount' );
	return new WP_Error( 'readercount_error', $message );
}

/**
 * The last 7 days' stats, kept for 10 minutes so the Dashboard doesn't ask ReaderCount on every visit.
 *
 * @return array|WP_Error
 */
function readercount_week() {
	$cached = get_transient( 'readercount_week' );
	if ( is_array( $cached ) ) {
		return $cached;
	}
	$answer = readercount_api( 'overview', array( 'period' => '7d' ) );
	if ( ! is_wp_error( $answer ) ) {
		set_transient( 'readercount_week', $answer, 10 * MINUTE_IN_SECONDS );
	}
	return $answer;
}

/**
 * Forgets the kept stats, for when the key changes.
 */
function readercount_forget_stats() {
	delete_transient( 'readercount_week' );
}