/*
 * This file is part of LanternServer, licensed under the MIT License (MIT).
 *
 * Copyright (c) LanternPowered <https://www.lanternpowered.org>
 * 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.
 */
/*
 * Copyright (c) 2011-2014 Glowstone - Tad Hardesty
 * Copyright (c) 2010-2011 Lightstone - Graham Edgecombe
 *
 * 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.lanternpowered.server.data.io.anvil;

import com.github.benmanes.caffeine.cache.Cache;
import com.github.benmanes.caffeine.cache.Caffeine;
import com.google.common.base.Throwables;
import org.lanternpowered.server.game.Lantern;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.regex.Pattern;

/**
 * A simple cache and wrapper for efficiently accessing multiple RegionFiles
 * simultaneously.
 */
final class RegionFileCache {

    private static final String DEFAULT_REGION_FILE_EXTENSION = "mca";

    private static final int REGION_COORDINATE_BITS = 5;
    static final int REGION_SIZE = 1 << REGION_COORDINATE_BITS;
    static final int REGION_AREA = REGION_SIZE * REGION_SIZE;
    static final int REGION_MASK = REGION_SIZE - 1;

    private static final int MAX_CACHE_SIZE = 256;

    private final Cache<Long, RegionFile> cache;
    private final String extension;
    private final Pattern filePattern;
    private final Path regionDir;

    RegionFileCache(Path basePath) {
        this(basePath, DEFAULT_REGION_FILE_EXTENSION);
    }

    RegionFileCache(Path basePath, String extension) {
        this.extension = extension;
        this.regionDir = basePath.resolve("region");
        this.filePattern = Pattern.compile("^r\\.([-]?[0-9]+)\\.([-]?[0-9]+)\\." + extension + "$");

        try {
            Files.createDirectories(this.regionDir);
        } catch (IOException e){
            Lantern.getLogger().warn("Failed to create directory: " + this.regionDir);
        }

        this.cache = Caffeine.newBuilder()
                .maximumSize(MAX_CACHE_SIZE)
                .softValues()
                .removalListener((key, value, cause) -> {
                    if (value != null) {
                        try {
                            ((RegionFile) value).close();
                        } catch (IOException e) {
                            throw Throwables.propagate(e);
                        }
                    }
                })
                .build();
    }

    public Path[] getRegionFiles() {
        try {
            return Files.list(this.regionDir).filter(file -> this.filePattern.matcher(file.getFileName().toString()).matches()).toArray(Path[]::new);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    public RegionFile getRegionFileByChunk(int chunkX, int chunkZ) throws IOException {
        final int regionX = chunkX >> REGION_COORDINATE_BITS;
        final int regionZ = chunkZ >> REGION_COORDINATE_BITS;
        return this.getRegionFile(regionX, regionZ);
    }

    public RegionFile getRegionFile(int regionX, int regionZ) throws IOException {
        final long coords = (regionZ & 0xffffffffL) << 32 | regionX & 0xffffffffL;
        return this.cache.get(coords, coords0 -> {
            try {
                return new RegionFile(this.regionDir.resolve("r." + regionX + "." + regionZ + "." + this.extension), regionX, regionZ);
            } catch (IOException e) {
                Lantern.getLogger().error("Failed to load the region file (%s;%s)", regionX, regionZ);
                throw Throwables.propagate(e);
            }
        });
    }

    public void clear() {
        this.cache.invalidateAll();
    }

    public Pattern getFilePattern() {
        return this.filePattern;
    }
}