using System;

using Org.BouncyCastle.Asn1.X509;
using Org.BouncyCastle.Utilities;

namespace Org.BouncyCastle.Asn1.IsisMtt.X509
{
    /**
    * Attribute to indicate admissions to certain professions.
    * <p/>
    * <pre>
    *     AdmissionSyntax ::= SEQUENCE
    *     {
    *       admissionAuthority GeneralName OPTIONAL,
    *       contentsOfAdmissions SEQUENCE OF Admissions
    *     }
    * <p/>
    *     Admissions ::= SEQUENCE
    *     {
    *       admissionAuthority [0] EXPLICIT GeneralName OPTIONAL
    *       namingAuthority [1] EXPLICIT NamingAuthority OPTIONAL
    *       professionInfos SEQUENCE OF ProfessionInfo
    *     }
    * <p/>
    *     NamingAuthority ::= SEQUENCE
    *     {
    *       namingAuthorityId OBJECT IDENTIFIER OPTIONAL,
    *       namingAuthorityUrl IA5String OPTIONAL,
    *       namingAuthorityText DirectoryString(SIZE(1..128)) OPTIONAL
    *     }
    * <p/>
    *     ProfessionInfo ::= SEQUENCE
    *     {
    *       namingAuthority [0] EXPLICIT NamingAuthority OPTIONAL,
    *       professionItems SEQUENCE OF DirectoryString (SIZE(1..128)),
    *       professionOIDs SEQUENCE OF OBJECT IDENTIFIER OPTIONAL,
    *       registrationNumber PrintableString(SIZE(1..128)) OPTIONAL,
    *       addProfessionInfo OCTET STRING OPTIONAL
    *     }
    * </pre>
    * <p/>
    * <p/>
    * ISIS-MTT PROFILE: The relatively complex structure of AdmissionSyntax
    * supports the following concepts and requirements:
    * <ul>
    * <li> External institutions (e.g. professional associations, chambers, unions,
    * administrative bodies, companies, etc.), which are responsible for granting
    * and verifying professional admissions, are indicated by means of the data
    * field admissionAuthority. An admission authority is indicated by a
    * GeneralName object. Here an X.501 directory name (distinguished name) can be
    * indicated in the field directoryName, a URL address can be indicated in the
    * field uniformResourceIdentifier, and an object identifier can be indicated in
    * the field registeredId.</li>
    * <li> The names of authorities which are responsible for the administration of
    * title registers are indicated in the data field namingAuthority. The name of
    * the authority can be identified by an object identifier in the field
    * namingAuthorityId, by means of a text string in the field
    * namingAuthorityText, by means of a URL address in the field
    * namingAuthorityUrl, or by a combination of them. For example, the text string
    * can contain the name of the authority, the country and the name of the title
    * register. The URL-option refers to a web page which contains lists with
    * officially registered professions (text and possibly OID) as well as
    * further information on these professions. Object identifiers for the
    * component namingAuthorityId are grouped under the OID-branch
    * id-isis-at-namingAuthorities and must be applied for.</li>
    * <li>See http://www.teletrust.de/anwend.asp?Id=30200&amp;Sprache=E_&amp;HomePG=0
    * for an application form and http://www.teletrust.de/links.asp?id=30220,11
    * for an overview of registered naming authorities.</li>
    * <li> By means of the data type ProfessionInfo certain professions,
    * specializations, disciplines, fields of activity, etc. are identified. A
    * profession is represented by one or more text strings, resp. profession OIDs
    * in the fields professionItems and professionOIDs and by a registration number
    * in the field registrationNumber. An indication in text form must always be
    * present, whereas the other indications are optional. The component
    * addProfessionInfo may contain additional applicationspecific information in
    * DER-encoded form.</li>
    * </ul>
    * <p/>
    * By means of different namingAuthority-OIDs or profession OIDs hierarchies of
    * professions, specializations, disciplines, fields of activity, etc. can be
    * expressed. The issuing admission authority should always be indicated (field
    * admissionAuthority), whenever a registration number is presented. Still,
    * information on admissions can be given without indicating an admission or a
    * naming authority by the exclusive use of the component professionItems. In
    * this case the certification authority is responsible for the verification of
    * the admission information.
    * <p/>
    * <p/>
    * <p/>
    * This attribute is single-valued. Still, several admissions can be captured in
    * the sequence structure of the component contentsOfAdmissions of
    * AdmissionSyntax or in the component professionInfos of Admissions. The
    * component admissionAuthority of AdmissionSyntax serves as default value for
    * the component admissionAuthority of Admissions. Within the latter component
    * the default value can be overwritten, in case that another authority is
    * responsible. The component namingAuthority of Admissions serves as a default
    * value for the component namingAuthority of ProfessionInfo. Within the latter
    * component the default value can be overwritten, in case that another naming
    * authority needs to be recorded.
    * <p/>
    * The length of the string objects is limited to 128 characters. It is
    * recommended to indicate a namingAuthorityURL in all issued attribute
    * certificates. If a namingAuthorityURL is indicated, the field professionItems
    * of ProfessionInfo should contain only registered titles. If the field
    * professionOIDs exists, it has to contain the OIDs of the professions listed
    * in professionItems in the same order. In general, the field professionInfos
    * should contain only one entry, unless the admissions that are to be listed
    * are logically connected (e.g. they have been issued under the same admission
    * number).
    *
    * @see Org.BouncyCastle.Asn1.IsisMtt.X509.Admissions
    * @see Org.BouncyCastle.Asn1.IsisMtt.X509.ProfessionInfo
    * @see Org.BouncyCastle.Asn1.IsisMtt.X509.NamingAuthority
    */
    public class AdmissionSyntax
        : Asn1Encodable
    {
        private readonly GeneralName admissionAuthority;
        private readonly Asn1Sequence contentsOfAdmissions;

        public static AdmissionSyntax GetInstance(
            object obj)
        {
            if (obj == null || obj is AdmissionSyntax)
            {
                return (AdmissionSyntax)obj;
            }

            if (obj is Asn1Sequence)
            {
                return new AdmissionSyntax((Asn1Sequence)obj);
            }

            throw new ArgumentException("unknown object in factory: " + Platform.GetTypeName(obj), "obj");
        }

        /**
        * Constructor from Asn1Sequence.
        * <p/>
        * The sequence is of type ProcurationSyntax:
        * <p/>
        * <pre>
        *     AdmissionSyntax ::= SEQUENCE
        *     {
        *       admissionAuthority GeneralName OPTIONAL,
        *       contentsOfAdmissions SEQUENCE OF Admissions
        *     }
        * <p/>
        *     Admissions ::= SEQUENCE
        *     {
        *       admissionAuthority [0] EXPLICIT GeneralName OPTIONAL
        *       namingAuthority [1] EXPLICIT NamingAuthority OPTIONAL
        *       professionInfos SEQUENCE OF ProfessionInfo
        *     }
        * <p/>
        *     NamingAuthority ::= SEQUENCE
        *     {
        *       namingAuthorityId OBJECT IDENTIFIER OPTIONAL,
        *       namingAuthorityUrl IA5String OPTIONAL,
        *       namingAuthorityText DirectoryString(SIZE(1..128)) OPTIONAL
        *     }
        * <p/>
        *     ProfessionInfo ::= SEQUENCE
        *     {
        *       namingAuthority [0] EXPLICIT NamingAuthority OPTIONAL,
        *       professionItems SEQUENCE OF DirectoryString (SIZE(1..128)),
        *       professionOIDs SEQUENCE OF OBJECT IDENTIFIER OPTIONAL,
        *       registrationNumber PrintableString(SIZE(1..128)) OPTIONAL,
        *       addProfessionInfo OCTET STRING OPTIONAL
        *     }
        * </pre>
        *
        * @param seq The ASN.1 sequence.
        */
        private AdmissionSyntax(Asn1Sequence seq)
        {
            switch (seq.Count)
            {
            case 1:
                this.contentsOfAdmissions = Asn1Sequence.GetInstance(seq[0]);
                break;
            case 2:
                admissionAuthority = GeneralName.GetInstance(seq[0]);
                contentsOfAdmissions = Asn1Sequence.GetInstance(seq[1]);
                break;
            default:
                throw new ArgumentException("Bad sequence size: " + seq.Count);
            }
        }

        /**
        * Constructor from given details.
        *
        * @param admissionAuthority   The admission authority.
        * @param contentsOfAdmissions The admissions.
        */
        public AdmissionSyntax(
            GeneralName admissionAuthority,
            Asn1Sequence contentsOfAdmissions)
        {
            this.admissionAuthority = admissionAuthority;
            this.contentsOfAdmissions = contentsOfAdmissions;
        }

        /**
        * Produce an object suitable for an Asn1OutputStream.
        * <p/>
        * Returns:
        * <p/>
        * <pre>
        *     AdmissionSyntax ::= SEQUENCE
        *     {
        *       admissionAuthority GeneralName OPTIONAL,
        *       contentsOfAdmissions SEQUENCE OF Admissions
        *     }
        * <p/>
        *     Admissions ::= SEQUENCE
        *     {
        *       admissionAuthority [0] EXPLICIT GeneralName OPTIONAL
        *       namingAuthority [1] EXPLICIT NamingAuthority OPTIONAL
        *       professionInfos SEQUENCE OF ProfessionInfo
        *     }
        * <p/>
        *     NamingAuthority ::= SEQUENCE
        *     {
        *       namingAuthorityId OBJECT IDENTIFIER OPTIONAL,
        *       namingAuthorityUrl IA5String OPTIONAL,
        *       namingAuthorityText DirectoryString(SIZE(1..128)) OPTIONAL
        *     }
        * <p/>
        *     ProfessionInfo ::= SEQUENCE
        *     {
        *       namingAuthority [0] EXPLICIT NamingAuthority OPTIONAL,
        *       professionItems SEQUENCE OF DirectoryString (SIZE(1..128)),
        *       professionOIDs SEQUENCE OF OBJECT IDENTIFIER OPTIONAL,
        *       registrationNumber PrintableString(SIZE(1..128)) OPTIONAL,
        *       addProfessionInfo OCTET STRING OPTIONAL
        *     }
        * </pre>
        *
        * @return an Asn1Object
        */
        public override Asn1Object ToAsn1Object()
        {
            Asn1EncodableVector v = new Asn1EncodableVector(2);
            v.AddOptional(admissionAuthority);
            v.Add(contentsOfAdmissions);
            return new DerSequence(v);
        }

        /**
        * @return Returns the admissionAuthority if present, null otherwise.
        */
        public virtual GeneralName AdmissionAuthority
        {
            get { return admissionAuthority; }
        }

        /**
        * @return Returns the contentsOfAdmissions.
        */
        public virtual Admissions[] GetContentsOfAdmissions()
        {
            return contentsOfAdmissions.MapElements(Admissions.GetInstance);
        }
    }
}