libsignal/swift/Sources/LibSignalClient/ServiceId.swift

//
// Copyright 2023 Signal Messenger, LLC.
// SPDX-License-Identifier: AGPL-3.0-only
//

import Foundation
import SignalFfi

internal typealias ServiceIdStorage = SignalServiceIdFixedWidthBinaryBytes

internal func == (_ lhs: ServiceIdStorage, _ rhs: ServiceIdStorage) -> Bool {
    // swift-format-ignore
    // (vertical alignment is clearer)
    return lhs.0 == rhs.0 &&
        lhs.1 == rhs.1 &&
        lhs.2 == rhs.2 &&
        lhs.3 == rhs.3 &&
        lhs.4 == rhs.4 &&
        lhs.5 == rhs.5 &&
        lhs.6 == rhs.6 &&
        lhs.7 == rhs.7 &&
        lhs.8 == rhs.8 &&
        lhs.9 == rhs.9 &&
        lhs.10 == rhs.10 &&
        lhs.11 == rhs.11 &&
        lhs.12 == rhs.12 &&
        lhs.13 == rhs.13 &&
        lhs.14 == rhs.14 &&
        lhs.15 == rhs.15 &&
        lhs.16 == rhs.16
}

internal func != (_ lhs: ServiceIdStorage, _ rhs: ServiceIdStorage) -> Bool {
    return !(lhs == rhs)
}

public enum ServiceIdKind: UInt8, Sendable {
    case aci = 0
    case pni = 1
}

public enum ServiceIdError: Error {
    case invalidServiceId
    case wrongServiceIdKind
}

/// Typed representation of a Signal service ID, which can be one of various types.
///
/// Conceptually this is a UUID in a particular "namespace" representing a particular way to reach a
/// user on the Signal service.
///
/// The sort order for ServiceIds is first by kind (ACI, then PNI), then lexicographically by the
/// bytes of the UUID.
public class ServiceId: @unchecked Sendable {
    private var storage: ServiceIdStorage = (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)

    fileprivate init(fromFixedWidthBinary storage: ServiceIdStorage) {
        self.storage = storage
    }

    fileprivate init(_ kind: ServiceIdKind, _ uuid: UUID) {
        self.storage.0 = kind.rawValue
        withUnsafeMutableBytes(of: &self.storage) { storageBuffer in
            storageBuffer.storeBytes(of: uuid.uuid, toByteOffset: 1, as: uuid_t.self)
        }
    }

    public var kind: ServiceIdKind {
        return ServiceIdKind(rawValue: self.storage.0)!
    }

    public var rawUUID: UUID {
        let uuid = withUnsafeBytes(of: self.storage) { storageBuffer in
            storageBuffer.load(fromByteOffset: 1, as: uuid_t.self)
        }
        return UUID(uuid: uuid)
    }

    public var serviceIdString: String {
        failOnError {
            try withUnsafePointer(to: self.storage) { ptr in
                try invokeFnReturningString {
                    signal_service_id_service_id_string($0, ptr)
                }
            }
        }
    }

    public var serviceIdUppercaseString: String {
        return self.serviceIdString.uppercased()
    }

    public var logString: String {
        failOnError {
            try withUnsafePointer(to: self.storage) { ptr in
                try invokeFnReturningString {
                    signal_service_id_service_id_log($0, ptr)
                }
            }
        }
    }

    public var serviceIdBinary: Data {
        return failOnError {
            try withUnsafePointer(to: self.storage) { ptr in
                try invokeFnReturningData {
                    signal_service_id_service_id_binary($0, ptr)
                }
            }
        }
    }

    public var serviceIdFixedWidthBinary: Data {
        return withUnsafeBytes(of: self.storage) { Data($0) }
    }

    private func downcast<SpecificId: ServiceId>(to subclass: SpecificId.Type) throws -> SpecificId {
        guard let downcastResult = self as? SpecificId else {
            throw ServiceIdError.wrongServiceIdKind
        }
        return downcastResult
    }

    public static func parseFrom(serviceIdString s: String) throws -> Self {
        let result = try invokeFnReturningServiceId {
            signal_service_id_parse_from_service_id_string($0, s)
        }
        return try result.downcast(to: Self.self)
    }

    public static func parseFrom<
        Bytes: ContiguousBytes
    >(serviceIdBinary sourceBytes: Bytes) throws -> Self {
        let result = try sourceBytes.withUnsafeBorrowedBuffer { buffer in
            try invokeFnReturningServiceId {
                signal_service_id_parse_from_service_id_binary($0, buffer)
            }
        }
        return try result.downcast(to: Self.self)
    }

    internal static func parseFrom(
        fixedWidthBinary bytes: ServiceIdStorage
    ) throws -> Self {
        let result: ServiceId
        switch bytes.0 {
        case ServiceIdKind.aci.rawValue:
            result = Aci(fromFixedWidthBinary: bytes)
        case ServiceIdKind.pni.rawValue:
            result = Pni(fromFixedWidthBinary: bytes)
        default:
            throw ServiceIdError.invalidServiceId
        }
        return try result.downcast(to: Self.self)
    }

    internal func withPointerToFixedWidthBinary<R>(
        _ callback: (UnsafePointer<ServiceIdStorage>) throws -> R
    ) rethrows -> R {
        return try callback(&self.storage)
    }

    internal static func concatenatedFixedWidthBinary(_ serviceIds: some Collection<ServiceId>) -> Data {
        var result = Data(count: serviceIds.count * MemoryLayout<ServiceIdStorage>.size)
        var offset = 0
        for next in serviceIds {
            withUnsafeBytes(of: next.storage) {
                result.replaceSubrange(offset..<(offset + $0.count), with: $0)
            }
            offset += MemoryLayout<ServiceIdStorage>.size
        }
        return result
    }
}

extension ServiceId: Equatable {
    public static func == (_ lhs: ServiceId, _ rhs: ServiceId) -> Bool {
        return lhs.storage == rhs.storage
    }
}

extension ServiceId: Comparable {
    public static func < (_ lhs: ServiceId, _ rhs: ServiceId) -> Bool {
        return withUnsafeBytes(of: lhs.storage) { lhsBytes in
            withUnsafeBytes(of: rhs.storage) { rhsBytes in
                lhsBytes.lexicographicallyPrecedes(rhsBytes)
            }
        }
    }
}

extension ServiceId: Hashable {
    public func hash(into hasher: inout Hasher) {
        withUnsafeBytes(of: self.storage) { buffer in
            hasher.combine(bytes: buffer)
        }
    }
}

extension ServiceId: CustomDebugStringConvertible {
    public var debugDescription: String {
        return self.logString
    }
}

public class Aci: ServiceId, @unchecked Sendable {
    public init(fromUUID uuid: UUID) {
        super.init(.aci, uuid)
    }

    override internal init(fromFixedWidthBinary bytes: ServiceIdStorage) {
        super.init(fromFixedWidthBinary: bytes)
    }
}

public class Pni: ServiceId, @unchecked Sendable {
    public init(fromUUID uuid: UUID) {
        super.init(.pni, uuid)
    }

    override internal init(fromFixedWidthBinary bytes: ServiceIdStorage) {
        super.init(fromFixedWidthBinary: bytes)
    }
}