package ui;

import model.asn1.exceptions.ParseException;
import model.ca.Template;
import model.csr.CertificationRequest;
import model.pki.cert.Certificate;
import model.x501.Name;

/**
 * The screen that accepts a CSR and template and allows user to change its properties and issue.
 */
public class IssueScreen implements UIHandler {
    private final JCA session;

    private Template template;
    private CertificationRequest incomingCSR;

    /**
     * EFFECTS: Init with the session.
     */
    public IssueScreen(JCA session) {
        this.session = session;
    }

    /**
     * EFFECTS: Set current template and CSR in use by args.
     * REQUIRES: args.length = 2, args[0] instanceof CertificateRequest, args[1] instanceof Template
     * MODIFIES: args[1]
     */
    @Override
    public void enter(Object... args) {
        this.incomingCSR = (CertificationRequest) args[0];
        this.template = (Template) args[1];
    }

    /**
     * EFFECTS: Print help.
     */
    @Override
    public void help() {
        System.out.print("show\tView the current certificate\n"
                + "set\tSet properties or template\n"
                + "commit\tIssue the certificate\n"
                + "exit\tDiscard and go to main menu\n"
                + "help\tPrint this message\n");
    }

    /**
     * EFFECTS: Print pending cert info.
     */
    @Override
    public void show() {
        System.out.println("Requested Subject:\t" + incomingCSR.getCertificationRequestInfo().getSubject());
        System.out.println("Subject:\t" + (template.getSubject() == null
                ? incomingCSR.getCertificationRequestInfo().getSubject()
                : template.getSubject()));
        System.out.println("Template:\t" + template.getName());
        System.out.println("Validity:\t" + template.getValidity() + " days");
    }

    /**
     * EFFECTS: Issue the cert and log it.
     * MODIFIES: session
     */
    @Override
    public void commit() {
        try {
            Certificate certificate = session.getCa().signCert(incomingCSR.getCertificationRequestInfo(), template);
            session.save();
            System.out.println(Utils.toPEM(certificate.encodeDER(), "CERTIFICATE"));
            session.setScreen(Screen.MAIN);
        } catch (Throwable e) {
            System.out.println(e.getMessage());
        }
    }

    /**
     * EFFECTS: Set or unset the subject.
     * MODIFIES: this
     */
    private void handleIssueSetSubject(String val) {
        try {
            if (val == null) {
                template = new Template(template.getName(), template.isEnabled(), (Name) null, template.getValidity());
            } else {
                template = new Template(template.getName(), template.isEnabled(), val, template.getValidity());
            }
        } catch (ParseException e) {
            System.out.println(e.getMessage());
        }
    }

    /**
     * EFFECTS: Set or unset the validity.
     * MODIFIES: this
     */
    private void handleIssueSetValidity(String val) {
        if (val == null) {
            System.out.println("Cannot unset validity");
            return;
        }
        try {
            long i = Long.parseLong(val);
            if (i <= 0) {
                System.out.println("Invalid validity days");
                return;
            }
            template = new Template(template.getName(), template.isEnabled(), template.getSubject(), i);
        } catch (NumberFormatException ignored) {
            System.out.println("Invalid validity days");
        }
    }

    /**
     * EFFECTS: Handle the set command.
     * MODIFIES: this
     */
    private void handleIssueSet(String... args) {
        if (args.length != 2 && args.length != 3) {
            System.out.println("Usage: set <key> <value>");
            System.out.println("Supported keys: subject validity");
            return;
        }
        String val = args.length == 3 ? args[2] : null;
        switch (args[1]) {
            case "subject":
                handleIssueSetSubject(val);
                break;
            case "validity":
                handleIssueSetValidity(val);
                break;
            default:
                System.out.println("Unknown key");
                break;
        }
    }

    @Override
    public void command(String... args) {
        if (args[0].equals("set")) {
            handleIssueSet(args);
        } else {
            help();
        }
    }

    /**
     * EFFECTS: Clear the certificates and return main.
     * MODIFIES: this
     */
    @Override
    public Screen exit() {
        incomingCSR = null;
        template = null;
        return Screen.MAIN;
    }

    /**
     * EFFECTS: Return "/subj/ %"
     */
    @Override
    public String getPS1() {
        return String.format("/%s/ %%", template.getSubject() == null
                ? incomingCSR.getCertificationRequestInfo().getSubject()
                : template.getSubject());
    }
}