//
//  ASN1Identifier.swift
//
//  Copyright © 2017 Filippo Maguolo.
//
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the Software is
//  furnished to do so, subject to the following conditions:
//
//  The above copyright notice and this permission notice shall be included in all
//  copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
//  SOFTWARE.

import Foundation


public class ASN1Identifier : CustomStringConvertible {
    
    public enum Class : UInt8 {
        case universal = 0x00
        case application = 0x40
        case contextSpecific = 0x80
        case `private` = 0xC0
    }
    
    public enum TagNumber: UInt8 {
        case endOfContent = 0x00
        case boolean = 0x01
        case integer = 0x02
        case bitString = 0x03
        case octetString = 0x04
        case null = 0x05
        case objectIdentifier = 0x06
        case objectDescriptor = 0x07
        case external = 0x08
        case read = 0x09
        case enumerated = 0x0A
        case embeddedPdv = 0x0B
        case utf8String = 0x0C
        case relativeOid = 0x0D
        case sequence = 0x10
        case set = 0x11
        case numericString = 0x12
        case printableString = 0x13
        case t61String = 0x14
        case videotexString = 0x15
        case ia5String = 0x16
        case utcTime = 0x17
        case generalizedTime = 0x18
        case graphicString = 0x19
        case visibleString = 0x1A
        case generalString = 0x1B
        case universalString = 0x1C
        case characterString = 0x1D
        case bmpString = 0x1E
    }
    
    var rawValue: UInt8
    
    
    init(rawValue: UInt8) {
        self.rawValue = rawValue
    }
    
    
    public func typeClass() -> Class {
        for tc in [Class.application, Class.contextSpecific, Class.private] {
            if (rawValue & tc.rawValue) == tc.rawValue {
                return tc
            }
        }
        return .universal
    }
    
    public func isPrimitive() -> Bool {
        return (rawValue & 0x20) == 0
    }
    public func isConstructed() -> Bool {
        return (rawValue & 0x20) != 0
    }
    
    public func tagNumber() -> TagNumber {
        return TagNumber(rawValue: rawValue & 0x1F) ?? .endOfContent
    }
    
    public var description: String {
        if typeClass() == .universal {
            return String(describing: tagNumber())
        }
        else {
            return "\(typeClass())(\(tagNumber().rawValue))"
        }
    }
}

