/*
 * 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 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

package com.sk89q.worldedit.session;

import com.fastasyncworldedit.core.util.MaskTraverser;
import com.sk89q.worldedit.EditSession;
import com.sk89q.worldedit.extent.Extent;
import com.sk89q.worldedit.extent.clipboard.Clipboard;
import com.sk89q.worldedit.extent.transform.BlockTransformExtent;
import com.sk89q.worldedit.function.RegionFunction;
import com.sk89q.worldedit.function.mask.ExistingBlockMask;
import com.sk89q.worldedit.function.mask.Mask;
import com.sk89q.worldedit.function.mask.MaskIntersection;
import com.sk89q.worldedit.function.mask.Masks;
import com.sk89q.worldedit.function.operation.ForwardExtentCopy;
import com.sk89q.worldedit.function.operation.Operation;
import com.sk89q.worldedit.math.BlockVector3;
import com.sk89q.worldedit.math.transform.Transform;

import static com.google.common.base.Preconditions.checkNotNull;

/**
 * Builds an operation to paste the contents of a clipboard.
 */
public class PasteBuilder {

    private final Clipboard clipboard;
    private final Transform transform;
    private final Extent targetExtent;

    private Mask sourceMask = Masks.alwaysTrue();

    private BlockVector3 to = BlockVector3.ZERO;
    private boolean ignoreAirBlocks;
    private boolean copyEntities = true; // default because it used to be this way
    private boolean copyBiomes;
    private RegionFunction canApply;

    /**
     * Create a new instance.
     *
     * @param holder the clipboard holder
     * @param targetExtent an extent
     */
    PasteBuilder(ClipboardHolder holder, Extent targetExtent) {
        checkNotNull(holder);
        checkNotNull(targetExtent);
        this.clipboard = holder.getClipboard();
        this.transform = holder.getTransform();
        this.targetExtent = targetExtent;
    }

    /**
     * Set the target location.
     *
     * @param to the target location
     * @return this builder instance
     */
    public PasteBuilder to(BlockVector3 to) {
        this.to = to;
        return this;
    }

    /**
     * Set a custom mask of blocks to ignore from the source.
     * This provides a more flexible alternative to {@link #ignoreAirBlocks(boolean)}, for example
     * one might want to ignore structure void if copying a Minecraft Structure, etc.
     *
     * @param sourceMask the mask for the source
     * @return this builder instance
     */
    public PasteBuilder maskSource(Mask sourceMask) {
        if (sourceMask == null) {
            this.sourceMask = Masks.alwaysTrue();
            return this;
        }
        this.sourceMask = sourceMask;
        return this;
    }

    /**
     * Set whether air blocks in the source are skipped over when pasting.
     *
     * @return this builder instance
     */
    public PasteBuilder ignoreAirBlocks(boolean ignoreAirBlocks) {
        this.ignoreAirBlocks = ignoreAirBlocks;
        return this;
    }

    /**
     * Set whether the copy should include source entities.
     * Note that this is true by default for legacy reasons.
     *
     * @param copyEntities if entities should be copied
     * @return this builder instance
     */
    public PasteBuilder copyEntities(boolean copyEntities) {
        this.copyEntities = copyEntities;
        return this;
    }

    /**
     * Set whether the copy should include source biomes (if available).
     *
     * @param copyBiomes if biomes should be copied
     * @return this builder instance
     */
    public PasteBuilder copyBiomes(boolean copyBiomes) {
        this.copyBiomes = copyBiomes;
        return this;
    }

    //FAWE start
    public PasteBuilder filter(RegionFunction function) {
        this.canApply = function;
        return this;
    }
    //FAWE end

    /**
     * Build the operation.
     *
     * @return the operation
     */
    public Operation build() {
        //FAWE start
        Extent extent = clipboard;
        if (!transform.isIdentity()) {
            extent = new BlockTransformExtent(extent, transform);
        }
        //FAWE end
        ForwardExtentCopy copy = new ForwardExtentCopy(extent, clipboard.getRegion(), clipboard.getOrigin(), targetExtent, to);
        copy.setTransform(transform);

        //FAWE start
        copy.setCopyingEntities(copyEntities);
        copy.setCopyingBiomes(copyBiomes && clipboard.hasBiomes());
        if (this.canApply != null) {
            copy.setFilterFunction(this.canApply);
        }
        //FAWE end
        if (ignoreAirBlocks) {
            //FAWE start - respect clipboard
            sourceMask = MaskIntersection.of(sourceMask, new ExistingBlockMask(clipboard));
        }
        if (targetExtent instanceof EditSession) {
            Mask esSourceMask = ((EditSession) targetExtent).getSourceMask();
            if (esSourceMask == Masks.alwaysFalse()) {
                return null;
            }
            if (esSourceMask != null) {
                new MaskTraverser(esSourceMask).reset(extent);
                ((EditSession) targetExtent).setSourceMask(null);
                sourceMask = MaskIntersection.of(sourceMask, esSourceMask);
            }
        }
        //FAWE end
        if (sourceMask != null && sourceMask != Masks.alwaysTrue()) {
            copy.setSourceMask(sourceMask);
        }
        copy.setCopyingEntities(copyEntities);
        copy.setCopyingBiomes(copyBiomes && clipboard.hasBiomes());
        return copy;
    }

}