package me.plugin.ptweaks;

import org.bukkit.Chunk;
import org.bukkit.Location;
import org.bukkit.World;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.player.PlayerMoveEvent;
import org.bukkit.event.world.ChunkLoadEvent;
import org.bukkit.event.world.ChunkUnloadEvent;

import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Map.Entry;

public class ChunkPersistance implements Runnable, Listener {
    private PerformanceTweaks mPlugin;
    private Thread mThread = new Thread(this);
    private int mLifeTime = 100000;
    private int mPruneTime = 3000;
    private int mSpawnChunkRadius = 128;
    private int mViewDistanceChunks = 10;
    // I believe a LinkedHashMap suits best, because it keeps the order like it was added, so better looping
    // Since we want to remove our first entry generally... --> Found faster
    // If you know what I mean ;) --> http://stackoverflow.com/a/2889800
    private LinkedHashMap<String, Long> mChunks = new LinkedHashMap<String, Long>();

    public ChunkPersistance(PerformanceTweaks plugin) {
        mPlugin = plugin;
        // Register the events
        plugin.getServer().getPluginManager().registerEvents(this, plugin);
    }

    public void onEnable() {
        // Get the config values
        mLifeTime = mPlugin.chunkPersistance.getInt("lifetime", 100000);
        mPruneTime = mPlugin.chunkPersistance.getInt("prune", 3000);
        mSpawnChunkRadius = mPlugin.chunkPersistance.getInt("spawnChunkRadius", 128);
        mViewDistanceChunks = mPlugin.chunkPersistance.getInt("viewDistanceChunks", 10);

        // Log the information
        mPlugin.getLogger().info(String.format("Chunk Life Time: %dms", mLifeTime));
        mPlugin.getLogger().info(String.format("Chunk Prune Time: %dms",mPruneTime));

        long time = System.currentTimeMillis();
        // Go through all worlds
        for (World world : mPlugin.getServer().getWorlds()) {
            // Go through all chunks
            for (Chunk chunk : world.getLoadedChunks()) {
                // Don't add if spawn chunk
                if (!isSpawnChunk(chunk)) {
                    String s = chunk.getWorld().getName() + ";" + chunk.getX() + ";" + chunk.getZ();
                    mChunks.put(s, time);
                }
            }
        }

        mThread.start();
    }

    public void onDisable() {
        // Disable the Thread again
        if (mThread.isAlive()) mThread.interrupt();
        // Iterate through HashMap
        for (Map.Entry<String, Long> entry: mChunks.entrySet()) {
            String[] key = entry.getKey().split(";");
            String w = key[0];
            int x = Integer.valueOf(key[1]);
            int z = Integer.valueOf(key[2]);
            World world = mPlugin.getServer().getWorld(w);
            // If the chunk is loaded, unload!
            if (world.isChunkLoaded(x, z))  world.unloadChunk(x, z);
        }
        clear();

    }

    @EventHandler
    public void onChunkLoad(ChunkLoadEvent event) {
        // If its NO spawn chunk
        if (!isSpawnChunk(event.getChunk())) {
            Chunk c = event.getChunk();
            // Better use only the name of the world
            String s = c.getWorld().getName() + ";" + c.getX() + ";" + c.getZ();
            // Save the chunk with a time
            mChunks.put(s, System.currentTimeMillis());
        }
    }

    @EventHandler
    public void onChunkUnload(ChunkUnloadEvent event) {
        // Never unload a spawn chunk!
        if (isSpawnChunk(event.getChunk())) {
            event.setCancelled(true);
            return;
        }

        Chunk c = event.getChunk();
        String s = c.getWorld().getName() + ";" + c.getX() + ";" + c.getZ();

        // Check if the chunk is on our list
        if (!mChunks.containsKey(s)) {
            return;
        }

        long age = System.currentTimeMillis() - mChunks.get(s);
        // If the age is not "old" enough, keep the chunk loaded
        if (age < mLifeTime) {
            event.setCancelled(true);
        }
        // Else remove it from the list
        else {
            mChunks.remove(s);
        }
    }

    @EventHandler
    public void onPlayerMove(PlayerMoveEvent event) {
        long time = System.currentTimeMillis();
        // I changed the code so that the chunks around the player are added/updated is customizable

        // Use minecraft method ;)
        int x = event.getPlayer().getLocation().getChunk().getX();
        int z = event.getPlayer().getLocation().getChunk().getZ();

        // Get all da chunks in a radius
        World world = event.getPlayer().getLocation().getWorld();
        for (int a = 0; a < mViewDistanceChunks; a++) {
            for (int b = 0; b < mViewDistanceChunks; b++) {
                Chunk chunk = world.getChunkAt(x + a, z + b);
                if (!isSpawnChunk(chunk)) {
                    String s = chunk.getWorld().getName() + ";" + chunk.getX() + ";" + chunk.getZ();
                    mChunks.put(s, time);
                }
            }
        }
    }

    public void clear() {
        mChunks.clear();
    }

    // Check is a chunk is a spawn chunk
    private boolean isSpawnChunk(Chunk chunk) {
        Location spawn = chunk.getWorld().getSpawnLocation();
        // Get absolute value, so we can check just with bigger than 128
        int x = Math.abs(chunk.getX() - spawn.getBlockX());
        int z = Math.abs(chunk.getZ() - spawn.getBlockZ());
        return (x > mSpawnChunkRadius) && (z > mSpawnChunkRadius);
    }

    public void run() {
        try {
            while (!mThread.isInterrupted()) {
                try {
                    Thread.sleep(mPruneTime);
                }
                catch (InterruptedException e) {
                    Thread.currentThread().interrupt();
                    return;
                }
                // Get current time
                long timeNow = System.currentTimeMillis();

                // Iterate through HashMap
                Iterator<Entry<String, Long>> iterator = mChunks.entrySet().iterator();
                while (iterator.hasNext()) {
                    Map.Entry<String, Long> entry = iterator.next();
                    String[] key = entry.getKey().split(";");
                    long time = entry.getValue();
                    long age = timeNow - time;
                    // If the liftTime of the chunk is reached
                    if (age >= mLifeTime) {
                        String w = key[0];
                        int x = Integer.valueOf(key[1]);
                        int z = Integer.valueOf(key[2]);
                        World world = mPlugin.getServer().getWorld(w);
                        // If the chunk is loaded, unload!
                        if (world.isChunkLoaded(x, z)) {
                            world.unloadChunk(x, z);
                            iterator.remove();
                        }
                    }
                }
            }
        }
        // Good to listen, since anything could happen, and I'm not sure what exactly (:
        catch (Exception e) {
            e.printStackTrace();
        }
    }
}