//===----------------------------------------------------------------------===//
//
// This source file is part of the SwiftNIO open source project
//
// Copyright (c) 2017-2018 Apple Inc. and the SwiftNIO project authors
// Licensed under Apache License v2.0
//
// See LICENSE.txt for license information
// See CONTRIBUTORS.txt for the list of SwiftNIO project authors
//
// SPDX-License-Identifier: Apache-2.0
//
//===----------------------------------------------------------------------===//

import NIOCore

/// An operation code for a websocket frame.
public struct WebSocketOpcode: Sendable {
    @usableFromInline
    let networkRepresentation: UInt8

    @inlinable
    public static var continuation: WebSocketOpcode {
        WebSocketOpcode(rawValue: 0x0)
    }

    @inlinable
    public static var text: WebSocketOpcode {
        WebSocketOpcode(rawValue: 0x1)
    }

    @inlinable
    public static var binary: WebSocketOpcode {
        WebSocketOpcode(rawValue: 0x2)
    }

    @inlinable
    public static var connectionClose: WebSocketOpcode {
        WebSocketOpcode(rawValue: 0x8)
    }

    @inlinable
    public static var ping: WebSocketOpcode {
        WebSocketOpcode(rawValue: 0x9)
    }

    @inlinable
    public static var pong: WebSocketOpcode {
        WebSocketOpcode(rawValue: 0xA)
    }

    /// Create an opcode from the encoded representation.
    ///
    /// - Parameters
    ///   - encoded: The encoded representation of the opcode as an 8-bit integer.
    ///          Must be no more than 4 bits large.
    @inlinable
    public init?(encodedWebSocketOpcode encoded: UInt8) {
        guard encoded < 0x10 else {
            return nil
        }

        self.networkRepresentation = encoded
    }

    /// Create an opcode directly with no validation.
    ///
    /// Used only to create the static vars on this structure.
    @inlinable
    init(rawValue: UInt8) {
        self.networkRepresentation = rawValue
    }

    /// Whether the opcode is in the control range: that is, if the
    /// high bit of the opcode nibble is `1`.
    @inlinable
    public var isControlOpcode: Bool {
        self.networkRepresentation & 0x8 == 0x8
    }
}

extension WebSocketOpcode: Equatable {}

extension WebSocketOpcode: Hashable {}

extension WebSocketOpcode: CaseIterable {
    @inlinable
    public static var allCases: [WebSocketOpcode] {
        get { (0..<0x10).map { WebSocketOpcode(rawValue: $0) } }

        @available(*, deprecated)
        set {}
    }
}

extension WebSocketOpcode: CustomStringConvertible {
    public var description: String {
        switch self {
        case .continuation:
            return "WebSocketOpcode.continuation"
        case .text:
            return "WebSocketOpcode.text"
        case .binary:
            return "WebSocketOpcode.binary"
        case .connectionClose:
            return "WebSocketOpcode.connectionClose"
        case .ping:
            return "WebSocketOpcode.ping"
        case .pong:
            return "WebSocketOpcode.pong"
        case let x where x.isControlOpcode:
            return "WebSocketOpcode.unknownControl(\(x.networkRepresentation))"
        case let x:
            return "WebSocketOpcode.unknownNonControl(\(x.networkRepresentation))"
        }
    }
}

extension UInt8 {
    /// Create a UInt8 corresponding to a given `WebSocketOpcode`.
    ///
    /// This places the opcode in the four least-significant bits, in
    /// a form suitable for sending on the wire.
    ///
    /// - Parameters:
    ///   - opcode: The `WebSocketOpcode`.
    @inlinable
    public init(webSocketOpcode opcode: WebSocketOpcode) {
        precondition(opcode.networkRepresentation < 0x10)
        self = opcode.networkRepresentation
    }
}

extension Int {
    /// Create a UInt8 corresponding to the integer value for a given `WebSocketOpcode`.
    ///
    /// - Parameters:
    ///   - opcode: The `WebSocketOpcode`.
    @inlinable
    public init(webSocketOpcode opcode: WebSocketOpcode) {
        precondition(opcode.networkRepresentation < 0x10)
        self = Int(opcode.networkRepresentation)
    }
}