<?php
/**
 * Server-side CEP lookups, cached.
 *
 * @package CepisWooCommerce
 */

declare(strict_types=1);

defined( 'ABSPATH' ) || exit;

/**
 * Resolves a CEP with the bundled `Cepis\Client` and remembers the answer in a
 * transient.
 *
 * Only the proxy mode goes through here. In the default direct mode the
 * browser talks to cep.is itself and no PHP runs at all.
 */
final class Cepis_Woo_Lookup {

	/**
	 * Prefix for the transient holding one CEP's answer.
	 */
	private const CACHE_PREFIX = 'cepis_woo_';

	/**
	 * How long a resolved address is kept.
	 *
	 * The DNE database behind the API is regenerated fortnightly, so a week is
	 * half a refresh cycle: an address can be at most one release behind, while
	 * a CEP a store sees repeatedly still costs one outbound request a week.
	 */
	private const HIT_TTL = WEEK_IN_SECONDS;

	/**
	 * How long a "this CEP does not exist" is kept.
	 *
	 * Much shorter than a hit, and for a different reason: a CEP absent today
	 * can appear in the next fortnightly base, and telling a shopper their
	 * brand-new street does not exist for two weeks is worse than making the
	 * request again tomorrow.
	 */
	private const MISS_TTL = DAY_IN_SECONDS;

	/**
	 * Look a CEP up, from cache when possible.
	 *
	 * Never throws: every outcome is described by the returned status and body,
	 * in exactly the shapes the public API uses, so the browser sees the same
	 * thing whichever mode the store is in.
	 *
	 * @param string $cep Eight digits, already validated by the caller.
	 *
	 * @return array{status:int, body:array<string, mixed>, retry_after:?int}
	 */
	public static function resolve( string $cep ): array {
		$cached = get_transient( self::CACHE_PREFIX . $cep );

		if ( is_array( $cached ) ) {
			return isset( $cached['miss'] )
				? self::not_found()
				: array(
					'status'      => 200,
					'body'        => $cached,
					'retry_after' => null,
				);
		}

		try {
			$address = self::client()->lookup( $cep );
		} catch ( Cepis\CepNotFoundException ) {
			set_transient( self::CACHE_PREFIX . $cep, array( 'miss' => true ), self::MISS_TTL );

			return self::not_found();
		} catch ( Cepis\InvalidCepException ) {
			return array(
				'status'      => 400,
				'body'        => array(
					'erro'     => 'cep_invalido',
					'mensagem' => 'CEP deve ter 8 dígitos',
				),
				'retry_after' => null,
			);
		} catch ( Cepis\RateLimitedException $e ) {
			return array(
				'status'      => 429,
				'body'        => array(
					'erro'     => 'limite',
					'mensagem' => 'Muitas consultas em pouco tempo',
				),
				'retry_after' => null === $e->retryAfter ? null : (int) $e->retryAfter,
			);
		} catch ( Cepis\CepisException ) {
			return array(
				'status'      => 502,
				'body'        => array(
					'erro'     => 'interno',
					'mensagem' => 'falha interna',
				),
				'retry_after' => null,
			);
		}

		$body = $address->raw;
		set_transient( self::CACHE_PREFIX . $cep, $body, self::HIT_TTL );

		return array(
			'status'      => 200,
			'body'        => $body,
			'retry_after' => null,
		);
	}

	/**
	 * Drop every cached answer.
	 *
	 * Used by the settings screen when the API root changes, since answers from
	 * one instance say nothing about another.
	 */
	public static function flush(): void {
		global $wpdb;

		$like = $wpdb->esc_like( '_transient_' . self::CACHE_PREFIX ) . '%';

		$names = $wpdb->get_col(
			$wpdb->prepare( "SELECT option_name FROM {$wpdb->options} WHERE option_name LIKE %s", $like )
		);

		foreach ( (array) $names as $name ) {
			delete_transient( substr( (string) $name, strlen( '_transient_' ) ) );
		}
	}

	/**
	 * The client, built once per request.
	 */
	private static function client(): Cepis\Client {
		static $client = null;

		if ( null === $client ) {
			$client = new Cepis\Client(
				baseUrl: Cepis_Woo_Options::base_url(),
				timeout: 5.0,
				maxAttempts: 2,
				totalTimeout: 8.0,
				userAgent: 'cepis-woocommerce/' . CEPIS_WOO_VERSION . ' (+https://cep.is)',
				transport: new Cepis_Woo_Transport(),
			);
		}

		return $client;
	}

	/**
	 * The API's own 404 body, reproduced so the browser cannot tell the two
	 * modes apart.
	 *
	 * @return array{status:int, body:array<string, mixed>, retry_after:?int}
	 */
	private static function not_found(): array {
		return array(
			'status'      => 404,
			'body'        => array(
				'erro'     => 'cep_nao_encontrado',
				'mensagem' => 'CEP não existe na base do DNE',
			),
			'retry_after' => null,
		);
	}
}