<?php
if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

final class EB4TEC_API_Client {

	const BASE_URL  = 'https://www.eventbriteapi.com/v3/';
	const CACHE_TTL = 300;

	private string $token;
	private int    $rate_limit_remaining = 1000;

	public function __construct() {
		$this->token = (string) get_option( 'eb4tec_api_token', '' );
	}

	// ---------------------------------------------------------------------------
	// Credentials / user
	// ---------------------------------------------------------------------------

	public function get_user_me(): array|WP_Error {
		return $this->get( 'users/me/', cacheable: false );
	}

	// ---------------------------------------------------------------------------
	// Events
	// ---------------------------------------------------------------------------

	public function get_organization_events( string $org_id, int $page = 1 ): array|WP_Error {
		return $this->get( "organizations/{$org_id}/events/", [
			'status'      => 'draft,live,started,ended,completed',
			'expand'      => 'venue,organizer,ticket_classes',
			'page'        => $page,
			'page_size'   => 50,
			'order_by'    => 'start_asc',
		] );
	}

	public function get_event( string $eb_event_id ): array|WP_Error {
		return $this->get( "events/{$eb_event_id}/", [ 'expand' => 'venue,organizer,ticket_classes' ] );
	}

	public function create_event( array $data ): array|WP_Error {
		$org_id = (string) get_option( 'eb4tec_org_id', '' );
		return $this->post( "organizations/{$org_id}/events/", $data );
	}

	public function update_event( string $eb_event_id, array $data ): array|WP_Error {
		return $this->post( "events/{$eb_event_id}/", $data );
	}

	public function publish_event( string $eb_event_id ): array|WP_Error {
		return $this->post( "events/{$eb_event_id}/publish/", [] );
	}

	public function unpublish_event( string $eb_event_id ): array|WP_Error {
		return $this->post( "events/{$eb_event_id}/unpublish/", [] );
	}

	// ---------------------------------------------------------------------------
	// Ticket classes
	// ---------------------------------------------------------------------------

	public function get_ticket_classes( string $eb_event_id ): array|WP_Error {
		return $this->get( "events/{$eb_event_id}/ticket_classes/" );
	}

	public function create_ticket_class( string $eb_event_id, array $data ): array|WP_Error {
		return $this->post( "events/{$eb_event_id}/ticket_classes/", $data );
	}

	public function update_ticket_class( string $eb_event_id, string $class_id, array $data ): array|WP_Error {
		return $this->post( "events/{$eb_event_id}/ticket_classes/{$class_id}/", $data );
	}

	// ---------------------------------------------------------------------------
	// Attendees
	// ---------------------------------------------------------------------------

	public function create_attendee( string $eb_event_id, array $data ): array|WP_Error {
		return $this->post( "events/{$eb_event_id}/attendees/", $data );
	}

	public function get_attendees( string $eb_event_id, int $page = 1 ): array|WP_Error {
		return $this->get( "events/{$eb_event_id}/attendees/", [
			'page'      => $page,
			'page_size' => 50,
			'expand'    => 'ticket_class',
		], cacheable: false );
	}

	// ---------------------------------------------------------------------------
	// Venues
	// ---------------------------------------------------------------------------

	public function get_venue( string $venue_id ): array|WP_Error {
		return $this->get( "venues/{$venue_id}/" );
	}

	public function create_venue( string $org_id, array $data ): array|WP_Error {
		return $this->post( "organizations/{$org_id}/venues/", $data );
	}

	public function update_venue( string $venue_id, array $data ): array|WP_Error {
		return $this->post( "venues/{$venue_id}/", $data );
	}

	// ---------------------------------------------------------------------------
	// Organizers
	// ---------------------------------------------------------------------------

	public function get_organizer( string $organizer_id ): array|WP_Error {
		return $this->get( "organizers/{$organizer_id}/" );
	}

	public function create_organizer( string $org_id, array $data ): array|WP_Error {
		return $this->post( "organizations/{$org_id}/organizers/", $data );
	}

	public function update_organizer( string $organizer_id, array $data ): array|WP_Error {
		return $this->post( "organizers/{$organizer_id}/", $data );
	}

	// ---------------------------------------------------------------------------
	// Webhooks
	// ---------------------------------------------------------------------------

	public function create_webhook( array $data ): array|WP_Error {
		$org_id = (string) get_option( 'eb4tec_org_id', '' );
		return $this->post( "organizations/{$org_id}/webhooks/", $data );
	}

	public function list_webhooks(): array|WP_Error {
		$org_id = (string) get_option( 'eb4tec_org_id', '' );
		return $this->get( "organizations/{$org_id}/webhooks/", cacheable: false );
	}

	public function delete_webhook( string $webhook_id ): array|WP_Error {
		return $this->delete_request( "webhooks/{$webhook_id}/" );
	}

	// ---------------------------------------------------------------------------
	// Cache helpers
	// ---------------------------------------------------------------------------

	public function bust_cache( string $endpoint ): void {
		delete_transient( $this->cache_key( $endpoint, [] ) );
	}

	// ---------------------------------------------------------------------------
	// HTTP internals
	// ---------------------------------------------------------------------------

	private function get( string $endpoint, array $query = [], bool $cacheable = true ): array|WP_Error {
		if ( $cacheable ) {
			$key    = $this->cache_key( $endpoint, $query );
			$cached = get_transient( $key );
			if ( false !== $cached ) {
				return $cached;
			}
		}

		$url    = self::BASE_URL . $endpoint;
		$result = $this->request( 'GET', $url, [ 'body' => $query ] );

		if ( ! is_wp_error( $result ) && $cacheable ) {
			set_transient( $key, $result, self::CACHE_TTL );
		}

		return $result;
	}

	private function post( string $endpoint, array $body ): array|WP_Error {
		$url = self::BASE_URL . $endpoint;
		return $this->request( 'POST', $url, [
			'body'         => wp_json_encode( $body ),
			'content-type' => 'application/json',
		] );
	}

	private function delete_request( string $endpoint ): array|WP_Error {
		$url = self::BASE_URL . $endpoint;
		return $this->request( 'DELETE', $url, [] );
	}

	private function request( string $method, string $url, array $args ): array|WP_Error {
		if ( empty( $this->token ) ) {
			return new WP_Error( 'eb4tec_no_token', __( 'Eventbrite API token is not configured.', 'eb4tec' ) );
		}

		$defaults = [
			'method'  => $method,
			'timeout' => 15,
			'headers' => [
				'Authorization' => 'Bearer ' . $this->token,
				'Content-Type'  => 'application/json',
				'Accept'        => 'application/json',
			],
		];

		$args     = array_merge( $defaults, $args );
		$response = wp_remote_request( $url, $args );

		if ( is_wp_error( $response ) ) {
			return $response;
		}

		$status = wp_remote_retrieve_response_code( $response );
		$body   = wp_remote_retrieve_body( $response );

		// Track rate limit.
		$remaining = wp_remote_retrieve_header( $response, 'x-ratelimit-remaining' );
		if ( '' !== $remaining ) {
			$this->rate_limit_remaining = (int) $remaining;
			if ( $this->rate_limit_remaining <= 10 ) {
				set_transient( 'eb4tec_rate_limit_warning', true, 60 );
			}
		}

		$decoded = json_decode( $body, true );

		if ( $status < 200 || $status >= 300 ) {
			$message = $decoded['error_description'] ?? $decoded['error'] ?? __( 'Unknown Eventbrite API error.', 'eb4tec' );
			return new WP_Error(
				'eb4tec_api_error',
				$message,
				[ 'status' => $status, 'response' => $decoded ]
			);
		}

		return $decoded ?? [];
	}

	private function cache_key( string $endpoint, array $query ): string {
		return 'eb4tec_' . md5( $endpoint . serialize( $query ) );
	}

	public function get_rate_limit_remaining(): int {
		return $this->rate_limit_remaining;
	}
}