/*
 * slcl-android, an Android frontend for slcl
 * Copyright (C) 2023-2024  Xavier Del Campo Romero
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

package org.slcl.core;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
import java.io.IOException;
import java.text.ParsePosition;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;

public final class Cookie {
    final String username, cookie;
    final CookieDate date;

    private final class Results {
        final String username, cookie;
        final CookieDate date;

        Results(String username, String cookie, final CookieDate date)
        {
            this.username = username;
            this.cookie = cookie;
            this.date = date;
        }
    }

    public Cookie(final File f)
        throws IOException {
        final FileInputStream fis = new FileInputStream(f);
        final InputStreamReader ir = new InputStreamReader(fis);
        final BufferedReader r = new BufferedReader(ir);
        final Results res = from_data(null, r.readLine());

        username = res.username;
        cookie = res.cookie;
        date = res.date;
        fis.close();
    }

    private final class CookieDate {
        final private String FMT = "EEE, dd MMM yyyy hh:mm:ss z";
        Date date;

        public CookieDate(final String[] tokens) throws IOException
        {
            for (int i = 1; i < tokens.length; i++) {
                final String[] date_tokens = tokens[i].split("=");

                if (date_tokens.length != 2) {
                    continue;
                }

                final String header = date_tokens[0].trim();

                if (!header.equalsIgnoreCase("Expires")) {
                    continue;
                }

                ParsePosition pos = new ParsePosition(0);
                final SimpleDateFormat fmt = new SimpleDateFormat(FMT);
                final Date d = fmt.parse(date_tokens[1], pos);

                if (d != null) {
                    // TODO: check pos.
                    date = d;
                    return;
                }
            }

            throw new IOException("missing expiration date");
        }

        public String toString()
        {
            final SimpleDateFormat fmt = new SimpleDateFormat(FMT);

            return fmt.format(date, null, null).toString();
        }

        public Date getDate() {
            return date;
        }
    }

    private Results from_data(final String exp_username, final String data)
        throws IOException
    {
        final int sep = data.indexOf('=');

        if (sep <= 0) {
            throw new IOException("expected key=value format");
        }

        final String username = data.substring(0, sep);

        if (exp_username != null
            && !username.equals(exp_username)) {
            throw new IOException("wrong username");
        }

        final String[] tokens = data.substring(sep + 1).split(";");

        if (tokens.length < 2) {
            throw new IOException("expected at least two tokens");
        }

        return new Results(username, tokens[0], new CookieDate(tokens));
    }

    public Cookie(final String exp_username, final String data)
        throws IOException
    {
        final Results r = from_data(exp_username, data);

        username = r.username;
        cookie = r.cookie;
        date = r.date;
    }

    public void store(final File f) throws IOException
    {
        final FileOutputStream fos = new FileOutputStream(f);
        final String datestr = "Expires=" + date.toString();

        fos.write(cookie.getBytes());
        fos.write(';');
        fos.write(datestr.getBytes());
        fos.write('\n');
        fos.close();
    }

    public String getCookie() {
        return cookie;
    }
}