package model.csr;

import annotations.Assoc;
import model.asn1.ASN1Object;
import model.asn1.Int;
import model.asn1.Tag;
import model.asn1.TagClass;
import model.asn1.exceptions.ParseException;
import model.asn1.parsing.BytesReader;
import model.pki.SubjectPublicKeyInfo;
import model.x501.Name;

import java.util.Arrays;
import java.util.Collection;
import java.util.stream.Stream;

/**
 * Represents a RFC2986 / PKCS#10 CSR CertificationRequestInfo object.
 * For more info on CRL, see {@link CertificationRequest}.
 *
 * <pre>
 *    DEFINITIONS IMPLICIT TAGS ::=
 *
 *    CertificationRequestInfo ::= SEQUENCE {
 *         version       INTEGER { v1(0) } (v1,...),
 *         subject       Name,
 *         subjectPKInfo SubjectPublicKeyInfo{{ PKInfoAlgorithms }},
 *         attributes    [0] Attributes{{ CRIAttributes }}
 *    }
 *
 * </pre>
 * <p>
 * It represents all information of a CSR (version, subject, public key, attributes).
 * It will be signed, and the signature is in {@link CertificationRequest}.
 */
public class CertificationRequestInfo extends ASN1Object {
    public static final int VERSION_V1 = 0;

    /**
     * Version of the CRL. Always {@link CertificationRequestInfo#VERSION_V1} (0).
     */
    @Assoc(partOf = true)
    private final Int version;

    /**
     * Subject of the requested certificate
     */
    @Assoc(partOf = true)
    private final Name subject;

    /**
     * The public key to request.
     */
    @Assoc(partOf = true)
    private final SubjectPublicKeyInfo subjectPKInfo;

    /**
     * The request attributes.
     */
    @Assoc(partOf = true)
    private final Attributes attributes;

    /**
     * EFFECTS: Construct with the given version, subject, pubkey, attributes, and the given tags.
     * REQUIRES: Version must be {@link CertificationRequestInfo#VERSION_V1}. The fields must have correct tags as
     * described in class specification.
     */
    public CertificationRequestInfo(Tag tag, Tag parentTag,
                                    final Int version,
                                    final Name subject,
                                    final SubjectPublicKeyInfo subjectPKInfo,
                                    final Attributes attributes) {
        super(tag, parentTag);
        this.version = version;
        this.subject = subject;
        this.subjectPKInfo = subjectPKInfo;
        this.attributes = attributes;
    }

    /**
     * EFFECTS: Parse the object with the given DER input.
     * Throws {@link ParseException} if the input is invalid:
     * - Any fields missing (version, subject, subjectPKInfo, attributes)
     * - Any fields having an incorrect tag (as seen in the ASN.1 definition)
     * - Any fields with encoding instructions that violate implicit / explicit encoding rules
     * - Other issues found during parsing the object, like early EOF (see {@link ASN1Object})
     * MODIFIES: this, encoded
     */
    public CertificationRequestInfo(BytesReader encoded, boolean hasParentTag) throws ParseException {
        super(encoded, hasParentTag);
        this.version = new Int(encoded, false);
        this.version.getTag().enforce(Int.TAG);
        if (this.version.getLong() != VERSION_V1) {
            throw new ParseException("Illegal version " + this.version.getLong());
        }

        this.subject = new Name(encoded, false);
        this.subject.getTag().enforce(TAG_SEQUENCE);

        this.subjectPKInfo = new SubjectPublicKeyInfo(encoded, false);
        this.subjectPKInfo.getTag().enforce(TAG_SEQUENCE);

        this.attributes = new Attributes(encoded, false);
        this.attributes.getTag().enforce(new Tag(TagClass.CONTEXT_SPECIFIC, true, 0));
    }

    /**
     * EFFECTS: Encode the value of that object, in the same order and format as denoted in the ASN.1 specification.
     */
    @Override
    public Byte[] encodeValueDER() {
        return Stream.of(Arrays.asList(version.encodeDER()),
                        Arrays.asList(subject.encodeDER()),
                        Arrays.asList(subjectPKInfo.encodeDER()),
                        Arrays.asList(attributes.encodeDER()))
                .flatMap(Collection::stream)
                .toArray(Byte[]::new);
    }

    public Int getVersion() {
        return version;
    }

    public Name getSubject() {
        return subject;
    }

    public SubjectPublicKeyInfo getSubjectPKInfo() {
        return subjectPKInfo;
    }

    public Attributes getAttributes() {
        return attributes;
    }
}