// swiftlint:disable all
//
//  PKCS7_Signature.swift
//  
//  Copyright © 2020 Alexander Heinrich & 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

extension PKCS7 {
    public var signatures: [SignatureInfo]? {
        // Signer infos sequence. https://tools.ietf.org/html/rfc5652#section-5.3
        
        guard let signerInfos = mainBlock.sub(4) else {return nil}
        
        let numberOfSignatures = signerInfos.subCount()
        
        var signatures = [SignatureInfo]()
        
        for i in 0..<numberOfSignatures {
            guard let signatureInfoasn1 = signerInfos.sub(i) else {continue}
            let sigInfo = SignatureInfo(asn1: signatureInfoasn1)
            signatures.append(sigInfo)
        }

        return signatures
    }
}

/// Signature info for a PKCS7 file
/// https://tools.ietf.org/html/rfc5652#section-5.3
public class SignatureInfo {
    
    /// The version of the Signature info. Should be 1
    public let version: ASN1Object?
    /// Contains information about the signing certificate, like commonName, OU, organization, country
    public let signerIdentifier: ASN1Object?
    /// The identifier for the algorithm that was used to sign
    public let digestAlgorithmIdentifier: ASN1Object?
    /// Contains information how the signature was created. A set with a sequence. First entry is the hashing algorithm. Second is the signature algorithm (not sure if this is valid for all pkcs files)
    public let signedAttributes: ASN1Object?
    /// Algorithm used to create the signature
    public let signatureAlgorithm: ASN1Object?
    /// The actual signature
    public let signature: ASN1Object?
    
    public var signatureData: Data? {
        return signature?.rawValue
    }
    
    public var disgestAlgorithmName: String? {
        guard let oid = self.digestAlgorithmOID else {return nil}
        
        return String(describing: oid)
    }
    
    public var digestAlgorithmOID: OID? {
        let value = digestAlgorithmIdentifier?.sub(0)?.value as? String ?? ""
        return OID(rawValue: value)
    }
    
    public var signatureAlgorithmName: String? {
        guard let oid = self.signatureAlgorithmOID else {return nil}
        
        return String(describing: oid)
    }
    
    public var signatureAlgorithmOID: OID? {
        let value = signatureAlgorithm?.sub(0)?.value as? String ?? ""
        return OID(rawValue: value)
    }
    
    public init(asn1: ASN1Object) {
        version = asn1.sub(0)
        signerIdentifier = asn1.sub(1)
        digestAlgorithmIdentifier = asn1.sub(2)
        let sub3 = asn1.sub(3)
        // Signed attributes is optional according to https://tools.ietf.org/html/rfc5652#section-5.3
        // value is not present e.g. in AppStore receipts
        if sub3?.identifier?.typeClass() == ASN1Identifier.Class.contextSpecific {
            signedAttributes = sub3
            signatureAlgorithm = asn1.sub(4)
            signature = asn1.sub(5)
        } else {
            signedAttributes = nil
            signatureAlgorithm = sub3
            signature = asn1.sub(4)
        }
    }
}
// swiftlint:enable all