addon-level/src/main/java/world/bentobox/level/LevelsManager.java

package world.bentobox.level;

import java.math.BigInteger;
import java.text.DecimalFormat;
import java.util.AbstractMap;
import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Objects;
import java.util.TreeMap;
import java.util.UUID;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ConcurrentHashMap;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import org.bukkit.Bukkit;
import org.bukkit.World;
import org.eclipse.jdt.annotation.NonNull;
import org.eclipse.jdt.annotation.Nullable;

import com.google.common.collect.Maps;

import world.bentobox.bentobox.database.Database;
import world.bentobox.bentobox.database.objects.Island;
import world.bentobox.level.calculators.Results;
import world.bentobox.level.events.IslandLevelCalculatedEvent;
import world.bentobox.level.events.IslandPreLevelEvent;
import world.bentobox.level.objects.IslandLevels;
import world.bentobox.level.objects.LevelsData;
import world.bentobox.level.objects.TopTenData;

public class LevelsManager {
    private static final String INTOPTEN = "intopten";
    private static final TreeMap<BigInteger, String> LEVELS;
    private static final BigInteger THOUSAND = BigInteger.valueOf(1000);
    static {
	LEVELS = new TreeMap<>();

	LEVELS.put(THOUSAND, "k");
	LEVELS.put(THOUSAND.pow(2), "M");
	LEVELS.put(THOUSAND.pow(3), "G");
	LEVELS.put(THOUSAND.pow(4), "T");
    }
    private final Level addon;

    // Database handler for level data
    private final Database<IslandLevels> handler;
    // A cache of island levels.
    private final Map<String, IslandLevels> levelsCache;
    // Top ten lists
    private final Map<World, TopTenData> topTenLists;

    public LevelsManager(Level addon) {
	this.addon = addon;
	// Get the BentoBox database
	// Set up the database handler to store and retrieve data
	// Note that these are saved by the BentoBox database
	handler = new Database<>(addon, IslandLevels.class);
	// Initialize the cache
	levelsCache = new HashMap<>();
	// Initialize top ten lists
	topTenLists = new ConcurrentHashMap<>();
    }

    public void migrate() {
	Database<LevelsData> oldDb = new Database<>(addon, LevelsData.class);
	oldDb.loadObjects().forEach(ld -> {
	    try {
		UUID owner = UUID.fromString(ld.getUniqueId());
		// Step through each world
		ld.getLevels().keySet().stream()
			// World
			.map(Bukkit::getWorld).filter(Objects::nonNull)
			// Island
			.map(w -> addon.getIslands().getIsland(w, owner)).filter(Objects::nonNull).forEach(i -> {
			    // Make new database entry
			    World w = i.getWorld();
			    IslandLevels il = new IslandLevels(i.getUniqueId());
			    il.setInitialLevel(ld.getInitialLevel(w));
			    il.setLevel(ld.getLevel(w));
			    il.setMdCount(ld.getMdCount(w));
			    il.setPointsToNextLevel(ld.getPointsToNextLevel(w));
			    il.setUwCount(ld.getUwCount(w));
			    // Save it
			    handler.saveObjectAsync(il);
			});
		// Now delete the old database entry
		oldDb.deleteID(ld.getUniqueId());
	    } catch (Exception e) {
		addon.logError("Could not migrate level data database! " + e.getMessage());
		e.printStackTrace();
		return;
	    }
	});
    }

    /**
     * Add an island to a top ten
     * 
     * @param island - island to add
     * @param lv     - level
     * @return true if successful, false if not added
     */
    private boolean addToTopTen(Island island, long lv) {
	if (island != null && island.getOwner() != null && hasTopTenPerm(island.getWorld(), island.getOwner())) {
	    topTenLists.computeIfAbsent(island.getWorld(), k -> new TopTenData(island.getWorld())).getTopTen()
		    .put(island.getUniqueId(), lv);
	    return true;
	}
	return false;
    }

    /**
     * Calculate the island level, set all island member's levels to the result and
     * try to add the owner to the top ten
     * 
     * @param targetPlayer - uuid of targeted player - owner or team member
     * @param island       - island to calculate
     * @return completable future with the results of the calculation
     */
    public CompletableFuture<Results> calculateLevel(UUID targetPlayer, Island island) {
	CompletableFuture<Results> result = new CompletableFuture<>();
	// Fire pre-level calc event
	IslandPreLevelEvent e = new IslandPreLevelEvent(targetPlayer, island);
	Bukkit.getPluginManager().callEvent(e);
	if (e.isCancelled()) {
	    return CompletableFuture.completedFuture(null);
	}
	// Add island to the pipeline
	addon.getPipeliner().addIsland(island).thenAccept(r -> {
	    // Results are irrelevant because the island is unowned or deleted, or
	    // IslandLevelCalcEvent is cancelled
	    if (r == null || fireIslandLevelCalcEvent(targetPlayer, island, r)) {
		result.complete(null);
	    }
	    // Save result
	    setIslandResults(island, r);
	    // Save the island scan details
	    result.complete(r);
	});
	return result;
    }

    /**
     * Fires the IslandLevelCalculatedEvent and returns true if it is canceled
     * 
     * @param targetPlayer - target player
     * @param island       - island
     * @param results      - results set
     * @return true if canceled
     */
    private boolean fireIslandLevelCalcEvent(UUID targetPlayer, Island island, Results results) {
	// Fire post calculation event
	IslandLevelCalculatedEvent ilce = new IslandLevelCalculatedEvent(targetPlayer, island, results);
	Bukkit.getPluginManager().callEvent(ilce);
	if (ilce.isCancelled())
	    return true;
	// Set the values if they were altered
	results.setLevel((Long) ilce.getKeyValues().getOrDefault("level", results.getLevel()));
	results.setInitialLevel((Long) ilce.getKeyValues().getOrDefault("initialLevel", results.getInitialLevel()));
	results.setDeathHandicap((int) ilce.getKeyValues().getOrDefault("deathHandicap", results.getDeathHandicap()));
	results.setPointsToNextLevel(
		(Long) ilce.getKeyValues().getOrDefault("pointsToNextLevel", results.getPointsToNextLevel()));
	results.setTotalPoints((Long) ilce.getKeyValues().getOrDefault("totalPoints", results.getTotalPoints()));
	return ((Boolean) ilce.getKeyValues().getOrDefault("isCancelled", false));
    }

    /**
     * Get the string representation of the level. May be converted to shorthand
     * notation, e.g., 104556 = 10.5k
     * 
     * @param lvl - long value to represent
     * @return string of the level.
     */
    public String formatLevel(@Nullable Long lvl) {
	if (lvl == null)
	    return "";
	String level = String.valueOf(lvl);
	// Asking for the level of another player
	if (addon.getSettings().isShorthand()) {
	    BigInteger levelValue = BigInteger.valueOf(lvl);

	    Map.Entry<BigInteger, String> stage = LEVELS.floorEntry(levelValue);

	    if (stage != null) { // level > 1000
		// 1 052 -> 1.0k
		// 1 527 314 -> 1.5M
		// 3 874 130 021 -> 3.8G
		// 4 002 317 889 -> 4.0T
		level = new DecimalFormat("#.#").format(
			levelValue.divide(stage.getKey().divide(THOUSAND)).doubleValue() / 1000.0) + stage.getValue();
	    }
	}
	return level;
    }

    /**
     * Get the initial level of the island. Used to zero island levels
     * 
     * @param island - island
     * @return initial level of island
     */
    public long getInitialLevel(Island island) {
	return getLevelsData(island).getInitialLevel();
    }

    /**
     * Get level of island from cache for a player.
     * 
     * @param world        - world where the island is
     * @param targetPlayer - target player UUID
     * @return Level of the player's island or zero if player is unknown or UUID is
     *         null
     */
    public long getIslandLevel(@NonNull World world, @Nullable UUID targetPlayer) {
	if (targetPlayer == null)
	    return 0L;
	// Get the island
	Island island = addon.getIslands().getIsland(world, targetPlayer);
	return island == null ? 0L : getLevelsData(island).getLevel();
    }

    /**
     * Get the maximum level ever given to this island
     * 
     * @param world        - world where the island is
     * @param targetPlayer - target player UUID
     * @return Max level of the player's island or zero if player is unknown or UUID
     *         is null
     */
    public long getIslandMaxLevel(@NonNull World world, @Nullable UUID targetPlayer) {
	if (targetPlayer == null)
	    return 0L;
	// Get the island
	Island island = addon.getIslands().getIsland(world, targetPlayer);
	return island == null ? 0L : getLevelsData(island).getMaxLevel();
    }

    /**
     * Returns a formatted string of the target player's island level
     * 
     * @param world        - world where the island is
     * @param targetPlayer - target player's UUID
     * @return Formatted level of player or zero if player is unknown or UUID is
     *         null
     */
    public String getIslandLevelString(@NonNull World world, @Nullable UUID targetPlayer) {
	return formatLevel(getIslandLevel(world, targetPlayer));
    }

    /**
     * Load a level data for the island from the cache or database.
     * 
     * @param island - UUID of island
     * @return IslandLevels object
     */
    @NonNull
    public IslandLevels getLevelsData(@NonNull Island island) {
	String id = island.getUniqueId();
	if (levelsCache.containsKey(id)) {
	    return levelsCache.get(id);
	}
	// Get from database if not in cache
	if (handler.objectExists(id)) {
	    IslandLevels ld = handler.loadObject(id);
	    if (ld != null) {
		levelsCache.put(id, ld);
	    } else {
		handler.deleteID(id);
		levelsCache.put(id, new IslandLevels(id));
	    }
	} else {
	    levelsCache.put(id, new IslandLevels(id));
	}
	// Return cached value
	return levelsCache.get(id);
    }

    /**
     * Get the number of points required until the next level since the last level
     * calc
     * 
     * @param world        - world where the island is
     * @param targetPlayer - target player UUID
     * @return string with the number required or blank if the player is unknown
     */
    public String getPointsToNextString(@NonNull World world, @Nullable UUID targetPlayer) {
	if (targetPlayer == null)
	    return "";
	Island island = addon.getIslands().getIsland(world, targetPlayer);
	return island == null ? "" : String.valueOf(getLevelsData(island).getPointsToNextLevel());
    }

    /**
     * Get the weighted top ten for this world. Weighting is based on number of
     * players per team.
     * 
     * @param world - world requested
     * @param size  - size of the top ten
     * @return sorted top ten map. The key is the island unique ID
     */
    @NonNull
    public Map<Island, Long> getWeightedTopTen(@NonNull World world, int size) {
	createAndCleanRankings(world);
	Map<Island, Long> weightedTopTen = topTenLists.get(world).getTopTen().entrySet().stream()
		.map(en -> addon.getIslands().getIslandById(en.getKey()).map(island -> {

		    long value = (long) (en.getValue() / (double) Math.max(1, island.getMemberSet().size())); // Calculate
													      // weighted
													      // value
		    return new AbstractMap.SimpleEntry<>(island, value);
		}).orElse(null)) // Handle islands that do not exist according to this ID - old deleted ones
		.filter(Objects::nonNull) // Filter out null entries
		.filter(en -> en.getValue() > 0) // Filter out entries with non-positive values
		.sorted(Collections.reverseOrder(Map.Entry.comparingByValue())) // Sort in descending order of values
		.limit(size) // Limit to the top 'size' entries
		.collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, (e1, e2) -> e1, // In case of key
												  // collision, choose
												  // the first one
			LinkedHashMap::new // Preserves the order of entries
		));

	// Return the unmodifiable map
	return Collections.unmodifiableMap(weightedTopTen);

    }

    /**
     * Get the top ten for this world. Returns offline players or players with the
     * intopten permission.
     * 
     * @param world - world requested
     * @param size  - size of the top ten
     * @return sorted top ten map. The key is the island unique ID
     */
    @NonNull
    public Map<String, Long> getTopTen(@NonNull World world, int size) {
	createAndCleanRankings(world);
	// Return the sorted map
	return Collections.unmodifiableMap(topTenLists.get(world).getTopTen().entrySet().stream()
		.filter(l -> l.getValue() > 0).sorted(Collections.reverseOrder(Map.Entry.comparingByValue()))
		.limit(size)
		.collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, (e1, e2) -> e1, LinkedHashMap::new)));
    }

    void createAndCleanRankings(@NonNull World world) {
	topTenLists.computeIfAbsent(world, TopTenData::new);
	// Remove player from top ten if they are online and do not have the perm
	topTenLists.get(world).getTopTen().keySet().removeIf(u -> addon.getIslands().getIslandById(u)
		.filter(i -> i.getOwner() == null || !hasTopTenPerm(world, i.getOwner())).isPresent());
    }

    /**
     * @return the topTenLists
     */
    public Map<World, TopTenData> getTopTenLists() {
	return topTenLists;
    }

    /**
     * Get the rank of the player in the rankings
     * 
     * @param world - world
     * @param uuid  - player UUID
     * @return rank placing - note - placing of 1 means top ranked
     */
    public int getRank(@NonNull World world, UUID uuid) {
	createAndCleanRankings(world);
	Stream<Entry<String, Long>> stream = topTenLists.get(world).getTopTen().entrySet().stream()
		.filter(l -> l.getValue() > 0).sorted(Collections.reverseOrder(Map.Entry.comparingByValue()));
	// Get player's current island
	Island island = addon.getIslands().getIsland(world, uuid);
	String id = island == null ? null : island.getUniqueId();
	return (int) (stream.takeWhile(x -> !x.getKey().equals(id)).map(Map.Entry::getKey).count() + 1);
    }

    /**
     * Checks if player has the correct top ten perm to have their level saved
     * 
     * @param world
     * @param targetPlayer
     * @return true if player has the perm or the player is offline
     */
    boolean hasTopTenPerm(@NonNull World world, @NonNull UUID targetPlayer) {
	String permPrefix = addon.getPlugin().getIWM().getPermissionPrefix(world);
	return Bukkit.getPlayer(targetPlayer) == null
		|| Bukkit.getPlayer(targetPlayer).hasPermission(permPrefix + INTOPTEN);
    }

    /**
     * Loads all the top tens from the database
     */
    public void loadTopTens() {
	topTenLists.clear();
	Bukkit.getScheduler().runTaskAsynchronously(addon.getPlugin(), () -> {
	    addon.log("Generating rankings");
	    handler.loadObjects().forEach(il -> {
		if (il.getLevel() > 0) {
		    addon.getIslands().getIslandById(il.getUniqueId())
			    .ifPresent(i -> this.addToTopTen(i, il.getLevel()));
		}
	    });
	    topTenLists.keySet().forEach(w -> addon.log("Generated rankings for " + w.getName()));
	});
    }

    /**
     * Removes an island from a world's top ten
     * 
     * @param world - world
     * @param uuid  - the island's uuid
     */
    public void removeEntry(World world, String uuid) {
	if (topTenLists.containsKey(world)) {
	    topTenLists.get(world).getTopTen().remove(uuid);
	}

    }

    /**
     * Set an initial island level
     * 
     * @param island - the island to set. Must have a non-null world
     * @param lv     - initial island level
     */
    public void setInitialIslandLevel(@NonNull Island island, long lv) {
	if (island.getWorld() == null)
	    return;
	levelsCache.computeIfAbsent(island.getUniqueId(), IslandLevels::new).setInitialLevel(lv);
	handler.saveObjectAsync(levelsCache.get(island.getUniqueId()));
    }

    /**
     * Set the island level for the owner of the island that targetPlayer is a
     * member
     * 
     * @param world  - world
     * @param island - island
     * @param lv     - level
     */
    public void setIslandLevel(@NonNull World world, @NonNull UUID targetPlayer, long lv) {
	// Get the island
	Island island = addon.getIslands().getIsland(world, targetPlayer);
	if (island != null) {
	    String id = island.getUniqueId();
	    IslandLevels il = levelsCache.computeIfAbsent(id, IslandLevels::new);
	    // Remove the initial level
	    if (addon.getSettings().isZeroNewIslandLevels()) {
		il.setLevel(lv - il.getInitialLevel());
	    } else {
		il.setLevel(lv);
	    }
	    handler.saveObjectAsync(levelsCache.get(id));
	    // Update TopTen
	    addToTopTen(island, levelsCache.get(id).getLevel());
	}
    }

    /**
     * Set the island level for the owner of the island that targetPlayer is a
     * member
     * 
     * @param world - world
     * @param owner - owner of the island
     * @param r     - results of the calculation
     */
    private void setIslandResults(Island island, Results r) {
	if (island == null)
	    return;
	IslandLevels ld = levelsCache.computeIfAbsent(island.getUniqueId(), IslandLevels::new);
	ld.setLevel(r.getLevel());
	ld.setUwCount(Maps.asMap(r.getUwCount().elementSet(), elem -> r.getUwCount().count(elem)));
	ld.setMdCount(Maps.asMap(r.getMdCount().elementSet(), elem -> r.getMdCount().count(elem)));
	ld.setPointsToNextLevel(r.getPointsToNextLevel());
	ld.setTotalPoints(r.getTotalPoints());
	levelsCache.put(island.getUniqueId(), ld);
	handler.saveObjectAsync(ld);
	// Update TopTen
	addToTopTen(island, ld.getLevel());
    }

    /**
     * Removes island from cache when it is deleted
     * 
     * @param uniqueId - id of island
     */
    public void deleteIsland(String uniqueId) {
	levelsCache.remove(uniqueId);
	handler.deleteID(uniqueId);
    }

}