/*
 * This file is part of SpongeAPI, licensed under the MIT License (MIT).
 *
 * Copyright (c) SpongePowered <https://www.spongepowered.org>
 * Copyright (c) contributors
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package org.spongepowered.api.command.args;

import static org.spongepowered.api.util.SpongeApiTranslationHelper.t;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import org.spongepowered.api.text.Text;
import org.spongepowered.api.command.CommandSource;

import java.util.List;
import java.util.Optional;
import java.util.regex.Pattern;

import javax.annotation.Nullable;

/**
 * Abstract command element that matches values based on pattern.
 */
public abstract class PatternMatchingCommandElement extends CommandElement {
    private static final Text nullKeyArg = t("argument");

    protected PatternMatchingCommandElement(@Nullable Text key) {
        super(key);
    }

    @Nullable
    @Override
    protected Object parseValue(CommandSource source, CommandArgs args) throws ArgumentParseException {
        final String unformattedPattern = args.next();
        Pattern pattern = getFormattedPattern(unformattedPattern);
        Iterable<String> filteredChoices = Iterables.filter(getChoices(source), element -> pattern.matcher(element).find());
        for (String el : filteredChoices) { // Match a single value
            if (el.equalsIgnoreCase(unformattedPattern)) {
                return getValue(el);
            }
        }
        Iterable<Object> ret = Iterables.transform(filteredChoices, this::getValue);

        if (!ret.iterator().hasNext()) {
            throw args.createError(t("No values matching pattern '%s' present for %s!", unformattedPattern, getKey() == null
                                                                                                            ? nullKeyArg : getKey()));
        }
        return ret;
    }

    @Override
    public List<String> complete(CommandSource src, CommandArgs args, CommandContext context) {
        Iterable<String> choices = getChoices(src);
        final Optional<String> nextArg = args.nextIfPresent();
        if (nextArg.isPresent()) {
            choices = Iterables.filter(choices, input -> getFormattedPattern(nextArg.get()).matcher(input).find());
        }
        return ImmutableList.copyOf(choices);
    }

    private Pattern getFormattedPattern(String input) {
        if (!input.startsWith("^")) { // Anchor matches to the beginning -- this lets us use find()
            input = "^" + input;
        }
        return Pattern.compile(input, Pattern.CASE_INSENSITIVE);

    }

    /**
     * Gets the available choices for this command source.
     *
     * @param source The source requesting choices
     * @return the possible choices
     */
    protected abstract Iterable<String> getChoices(CommandSource source);

    /**
     * Gets the value for a given choice. For any result in
     * {@link #getChoices(CommandSource)}, this must return a non-null value.
     * Otherwise, an {@link IllegalArgumentException} may be throw.
     *
     * @param choice The specified choice
     * @return the choice's value
     * @throws IllegalArgumentException if the input string is not any return
     *         value of {@link #getChoices(CommandSource)}
     */
    protected abstract Object getValue(String choice) throws IllegalArgumentException;
}

@@ -1546,16 +1546,46 @@
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+import java.util.Collections;%0A
 import j
@@ -2526,16 +2526,38 @@
  return 
+Collections.singleton(
 getValue
@@ -2560,16 +2560,17 @@
 alue(el)
+)
 ;%0A      

Make PatternMatchingCommandElement always return an Iterable