/*
 * WorldEdit, a Minecraft world manipulation toolkit
 * Copyright (C) sk89q <http://www.sk89q.com>
 * Copyright (C) WorldEdit team and contributors
 *
 * This program is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

package com.sk89q.worldedit.util;

import com.sk89q.worldedit.*;
import com.sk89q.worldedit.blocks.BlockID;
import com.sk89q.worldedit.blocks.BlockType;
import com.sk89q.worldedit.entity.Entity;
import com.sk89q.worldedit.internal.LocalWorldAdapter;

/**
 * This class uses an inefficient method to figure out what block a player
 * is looking towards.
 * 
 * Originally written by toi. It was ported to WorldEdit and trimmed down by
 * sk89q. Thanks to Raphfrk for optimization of toi's original class.
 * 
 * @author toi
 */
public class TargetBlock {
    private LocalWorld world;
    private int maxDistance;
    private double checkDistance, curDistance;
    private Vector targetPos = new Vector();
    private Vector targetPosDouble = new Vector();
    private Vector prevPos = new Vector();
    private Vector offset = new Vector();

    /**
     * Constructor requiring a player, uses default values
     * 
     * @param player player to work with
     */
    public TargetBlock(LocalPlayer player) {
        this.world = LocalWorldAdapter.adapt(player.getWorld());
        this.setValues(player.getPosition(), player.getYaw(), player.getPitch(),
                300, 1.65, 0.2);
    }

    /**
     * Constructor requiring a player, max distance and a checking distance
     *
     * @param player LocalPlayer to work with
     * @param maxDistance how far it checks for blocks
     * @param checkDistance how often to check for blocks, the smaller the more precise
     */
    public TargetBlock(LocalPlayer player, int maxDistance, double checkDistance) {
        this((Entity) player, maxDistance, checkDistance);
    }

    /**
     * Constructor requiring a player, max distance and a checking distance
     *
     * @param player LocalPlayer to work with
     * @param maxDistance how far it checks for blocks
     * @param checkDistance how often to check for blocks, the smaller the more precise
     */
    public TargetBlock(Entity player, int maxDistance, double checkDistance) {
        this.world = LocalWorldAdapter.adapt(player.getWorld());
        this.setValues(player.getPosition(), player.getYaw(), player.getPitch(),
                maxDistance, 1.65, checkDistance);
    }

    /**
     * Set the values, all constructors uses this function
     * 
     * @param loc location of the view
     * @param xRotation
     * @param yRotation
     * @param maxDistance how far it checks for blocks
     * @param viewHeight where the view is positioned in y-axis
     * @param checkDistance how often to check for blocks, the smaller the more precise
     */
    private void setValues(Vector loc, double xRotation, double yRotation,
            int maxDistance, double viewHeight, double checkDistance) {
        this.maxDistance = maxDistance;
        this.checkDistance = checkDistance;
        this.curDistance = 0;
        xRotation = (xRotation + 90) % 360;
        yRotation = yRotation * -1;

        double h = (checkDistance * Math.cos(Math.toRadians(yRotation)));

        offset = new Vector((h * Math.cos(Math.toRadians(xRotation))),
                            (checkDistance * Math.sin(Math.toRadians(yRotation))),
                            (h * Math.sin(Math.toRadians(xRotation))));

        targetPosDouble = loc.add(0, viewHeight, 0);
        targetPos = targetPosDouble.toBlockPoint();
        prevPos = targetPos;
    }

    /**
     * Returns any block at the sight. Returns null if out of range or if no
     * viable target was found. Will try to return the last valid air block it finds.
     * 
     * @return Block
     */
    public BlockWorldVector getAnyTargetBlock() {
        boolean searchForLastBlock = true;
        BlockWorldVector lastBlock = null;
        while (getNextBlock() != null) {
            if (world.getBlockType(getCurrentBlock()) == BlockID.AIR) {
                if (searchForLastBlock) {
                    lastBlock = getCurrentBlock();
                    if (lastBlock.getBlockY() <= 0 || lastBlock.getBlockY() >= world.getMaxY()) {
                        searchForLastBlock = false;
                    }
                }
            } else {
                break;
            }
        }
        BlockWorldVector currentBlock = getCurrentBlock();
        return (currentBlock != null ? currentBlock : lastBlock);
    }

    /**
     * Returns the block at the sight. Returns null if out of range or if no
     * viable target was found
     * 
     * @return Block
     */
    public BlockWorldVector getTargetBlock() {
        while (getNextBlock() != null && world.getBlockType(getCurrentBlock()) == 0) ;
        return getCurrentBlock();
    }

    /**
     * Returns the block at the sight. Returns null if out of range or if no
     * viable target was found
     * 
     * @return Block
     */
    public BlockWorldVector getSolidTargetBlock() {
        while (getNextBlock() != null && BlockType.canPassThrough(world.getBlock(getCurrentBlock()))) ;
        return getCurrentBlock();
    }

    /**
     * Get next block
     * 
     * @return next block position
     */
    public BlockWorldVector getNextBlock() {
        prevPos = targetPos;
        do {
            curDistance += checkDistance;

            targetPosDouble = offset.add(targetPosDouble.getX(),
                                         targetPosDouble.getY(),
                                         targetPosDouble.getZ());
            targetPos = targetPosDouble.toBlockPoint();
        } while (curDistance <= maxDistance
                && targetPos.getBlockX() == prevPos.getBlockX()
                && targetPos.getBlockY() == prevPos.getBlockY()
                && targetPos.getBlockZ() == prevPos.getBlockZ());

        if (curDistance > maxDistance) {
            return null;
        }

        return new BlockWorldVector(world, targetPos);
    }

    /**
     * Returns the current block along the line of vision
     * 
     * @return block position
     */
    public BlockWorldVector getCurrentBlock() {
        if (curDistance > maxDistance) {
            return null;
        } else {
            return new BlockWorldVector(world, targetPos);
        }
    }

    /**
     * Returns the previous block in the aimed path
     * 
     * @return block position
     */
    public BlockWorldVector getPreviousBlock() {
        return new BlockWorldVector(world, prevPos);
    }

    public WorldVectorFace getAnyTargetBlockFace() {
        getAnyTargetBlock();
        return WorldVectorFace.getWorldVectorFace(world, getCurrentBlock(), getPreviousBlock());
    }

    public WorldVectorFace getTargetBlockFace() {
        getAnyTargetBlock();
        return WorldVectorFace.getWorldVectorFace(world, getCurrentBlock(), getPreviousBlock());
    }
}