/**
 *   This file is part of Skript.
 *
 *  Skript is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  Skript 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with Skript.  If not, see <http://www.gnu.org/licenses/>.
 *
 *
 * Copyright 2011-2017 Peter Güttinger and contributors
 */
package ch.njol.skript.expressions;

import ch.njol.skript.Skript;
import ch.njol.skript.doc.Description;
import ch.njol.skript.doc.Examples;
import ch.njol.skript.doc.Name;
import ch.njol.skript.doc.Since;
import ch.njol.skript.lang.Expression;
import ch.njol.skript.lang.ExpressionType;
import ch.njol.skript.lang.SkriptParser;
import ch.njol.skript.lang.util.SimpleExpression;
import ch.njol.skript.util.Date;
import ch.njol.skript.util.Timespan;
import ch.njol.util.Kleenean;
import org.bukkit.event.Event;
import org.eclipse.jdt.annotation.Nullable;

@Name("Date Ago/Later")
@Description("A date the specified timespan before/after another date.")
@Examples({"set {_yesterday} to 1 day ago"})
@Since("INSERT VERSION")
public class ExprDateAgoLater extends SimpleExpression<Date> {

    static {
        Skript.registerExpression(ExprDateAgoLater.class, Date.class, ExpressionType.COMBINED,
                "%timespan% (ago|in the past|before [the] [date] %-date%)",
                "%timespan% (later|(from|after) [the] [date] %-date%)");
    }

    @SuppressWarnings("null")
    private Expression<Timespan> timespan;
    @SuppressWarnings("null")
    private Expression<Date> date;
    @SuppressWarnings("null")
    private boolean ago;

    @Nullable
    @Override
    protected Date[] get(Event e) {
        Timespan timespan = this.timespan.getSingle(e);
        Date date = this.date == null ? new Date() : this.date.getSingle(e);
        if (timespan == null || date == null) {
            return null;
        }
        if (ago) {
            date.subtract(timespan);
        } else {
            date.add(timespan);
        }
        return new Date[]{date};
    }

    @Override
    public boolean isSingle() {
        return true;
    }

    @Override
    public Class<? extends Date> getReturnType() {
        return Date.class;
    }

    @Override
    public String toString(@Nullable Event e, boolean debug) {
        return timespan.toString(e, debug) + " " + (ago ? "ago" : "later");
    }

    @SuppressWarnings({"unchecked", "null"})
    @Override
    public boolean init(Expression<?>[] exprs, int matchedPattern, Kleenean isDelayed, SkriptParser.ParseResult parseResult) {
        timespan = (Expression<Timespan>) exprs[0];
        date = (Expression<Date>) exprs[1];
        ago = matchedPattern == 0;
        return true;
    }
}
