/*

 * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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package jdk.internal.jshell.tool;

import java.util.List;

import static java.util.Comparator.comparing;

import java.util.Map;

import java.util.function.BiPredicate;

import java.util.function.Supplier;

import static java.util.stream.Collectors.toList;

import java.util.stream.Stream;

import jdk.internal.jshell.tool.JShellTool.CompletionProvider;

import jdk.jshell.SourceCodeAnalysis;

import jdk.jshell.SourceCodeAnalysis.Suggestion;

class ContinuousCompletionProvider implements CompletionProvider {

    static final BiPredicate<String, String> STARTSWITH_MATCHER = String::startsWith;

    static final BiPredicate<String, String> PERFECT_MATCHER = String::equals;

    private final Supplier<Map<String, CompletionProvider>> wordCompletionProviderSupplier;

    private final BiPredicate<String, String> matcher;

    ContinuousCompletionProvider(

            Map<String, CompletionProvider> wordCompletionProvider,

            BiPredicate<String, String> matcher) {

        this(() -> wordCompletionProvider, matcher);

    }

    ContinuousCompletionProvider(

            Supplier<Map<String, CompletionProvider>> wordCompletionProviderSupplier,

            BiPredicate<String, String> matcher) {

        this.wordCompletionProviderSupplier = wordCompletionProviderSupplier;

        this.matcher = matcher;

    }

    @Override

    public List<Suggestion> completionSuggestions(String input, int cursor, int[] anchor) {

        String prefix = input.substring(0, cursor);

        int space = prefix.indexOf(' ');

        Stream<SourceCodeAnalysis.Suggestion> result;

        Map<String, CompletionProvider> wordCompletionProvider = wordCompletionProviderSupplier.get();

        if (space == (-1)) {

            result = wordCompletionProvider.keySet().stream()

                    .distinct()

                    .filter(key -> key.startsWith(prefix))

                    .map(key -> new JShellTool.ArgSuggestion(key + " "));

            anchor[0] = 0;

        } else {

            String rest = prefix.substring(space + 1);

            String word = prefix.substring(0, space);

            List<CompletionProvider> candidates = wordCompletionProvider.entrySet().stream()

                    .filter(e -> matcher.test(e.getKey(), word))

                    .map(Map.Entry::getValue)

                    .collect(toList());

            if (candidates.size() == 1) {

                result = candidates.get(0).completionSuggestions(rest, cursor - space - 1, anchor).stream();

            } else {

                result = Stream.empty();

            }

            anchor[0] += space + 1;

        }

        return result.sorted(comparing(Suggestion::continuation))

                     .collect(toList());

    }

}