RelaySelector+Wireguard.swift

//
//  RelaySelector+Wireguard.swift
//  MullvadREST
//
//  Created by Mojgan on 2024-05-17.
//  Copyright © 2024 Mullvad VPN AB. All rights reserved.
//

import MullvadSettings
import MullvadTypes

extension RelaySelector {
    public enum WireGuard {
        /// Filters relay list using given constraints.
        public static func findCandidates(
            by relayConstraint: RelayConstraint<UserSelectedRelays>,
            in relays: REST.ServerRelaysResponse,
            filterConstraint: RelayConstraint<RelayFilter>,
            daitaEnabled: Bool
        ) throws -> [RelayWithLocation<REST.ServerRelay>] {
            let mappedRelays = mapRelays(relays: relays.wireguard.relays, locations: relays.locations)

            return try applyConstraints(
                relayConstraint,
                filterConstraint: filterConstraint,
                daitaEnabled: daitaEnabled,
                relays: mappedRelays
            )
        }

        /// Picks a random relay from a list.
        public static func pickCandidate(
            from relayWithLocations: [RelayWithLocation<REST.ServerRelay>],
            relays: REST.ServerRelaysResponse,
            portConstraint: RelayConstraint<UInt16>,
            numberOfFailedAttempts: UInt
        ) throws -> RelaySelectorMatch {
            let port = applyPortConstraint(
                portConstraint,
                rawPortRanges: relays.wireguard.portRanges,
                numberOfFailedAttempts: numberOfFailedAttempts
            )

            guard let port else {
                throw NoRelaysSatisfyingConstraintsError(.invalidPort)
            }

            guard let relayWithLocation = pickRandomRelayByWeight(relays: relayWithLocations) else {
                throw NoRelaysSatisfyingConstraintsError(.relayConstraintNotMatching)
            }

            let endpoint = MullvadEndpoint(
                ipv4Relay: IPv4Endpoint(
                    ip: relayWithLocation.relay.ipv4AddrIn,
                    port: port
                ),
                ipv6Relay: nil,
                ipv4Gateway: relays.wireguard.ipv4Gateway,
                ipv6Gateway: relays.wireguard.ipv6Gateway,
                publicKey: relayWithLocation.relay.publicKey
            )

            return RelaySelectorMatch(
                endpoint: endpoint,
                relay: relayWithLocation.relay,
                location: relayWithLocation.serverLocation
            )
        }
    }
}