// TLV.swift
// This file is part of MiKee.
//
// Copyright © 2019 Maxime Epain. All rights reserved.
//
// MiKee is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// MiKee is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with MiKee. If not, see <https://www.gnu.org/licenses/>.

import Foundation

public struct TLV<Type, Lenght> where Lenght: BinaryInteger {

    public let type: Type

    public var value: Bytes

    public init(type: Type, value: Bytes) {
        self.type = type
        self.value = value
    }

    public func get<T>() throws -> T where T: Readable {
        let stream = Input(bytes: value)
        return try stream.read()
    }

    public mutating func set<T>(_ value: T) throws where T: Writable {
        self.value = withUnsafeBytes(of: value) { Bytes($0) }
    }
}

extension TLV: Readable where Type: Readable, Lenght: Readable {

    public init(from input: Input) throws {
        type = try input.read()
        let lenght = try input.read() as Lenght
        value = try input.read(lenght: Int(lenght))
    }

}

extension TLV: Writable where Type: Writable, Lenght: Writable {

    public func write(to output: Output) throws {
        try output.write(type)
        try output.write(Lenght(value.lenght))
        try output.write(value)
    }

}

extension TLV: CustomDebugStringConvertible {

    public var debugDescription: String {
        "(T:\(type) L:\(value.lenght))"
    }

}