package model.asn1;

import model.asn1.exceptions.ParseException;
import model.asn1.parsing.BytesReader;
import ui.Utils;

import java.nio.charset.StandardCharsets;
import java.time.ZonedDateTime;

/**
 * Common base-class for models like UTCTime and GeneralizedTime. Despite all the formatting and encoding differences,
 * it stores a timestamp and corresponding timezone.
 */
public abstract class ASN1Time extends ASN1Object {
    /**
     * The time.
     */
    private ZonedDateTime timestamp;

    /**
     * EFFECTS: Initialize the time with the specific tag, parentTag, and timestamp. For tag and parentTag, consult
     * {@link ASN1Object}.
     */
    public ASN1Time(Tag tag, Tag parentTag, ZonedDateTime timestamp) {
        super(tag, parentTag);
        this.timestamp = timestamp;
    }

    /**
     * EFFECTS: Parse and decode DER bytes into the corresponding time type. For more info on decoding, take a look at
     * {@link ASN1Object}.
     * Throws {@link ParseException} if the input is invalid:
     * - Invalid date format
     * - Zero length
     * - Other circumstances (e.g., early EOF) as seen in {@link ASN1Object}
     * MODIFIES: this, encoded
     */
    public ASN1Time(BytesReader encoded, boolean hasParentTag) throws ParseException {
        super(encoded, hasParentTag);
        this.timestamp = toDate(new String(Utils.byteToByte(encoded.require(getLength(), true))));
    }

    /**
     * EFFECTS: Generate the byte array for the formatted string.
     */
    @Override
    public Byte[] encodeValueDER() {
        return Utils.byteToByte(toString().getBytes(StandardCharsets.UTF_8));
    }

    /**
     * EFFECTS: Convert the given string into corresponding timestamp.
     * Throws {@link ParseException} if the time is malformed.
     */
    public abstract ZonedDateTime toDate(String str) throws ParseException;

    /**
     * EFFECTS: Convert getTimestamp() into corresponding ASN.1 time format.
     */
    @Override
    public abstract String toString();

    public ZonedDateTime getTimestamp() {
        return timestamp;
    }
}