/*
 * Copyright 2013 MovingBlocks
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.terasology.logic.selection;

import org.terasology.entitySystem.entity.EntityRef;
import org.terasology.entitySystem.event.ReceiveEvent;
import org.terasology.entitySystem.systems.BaseComponentSystem;
import org.terasology.entitySystem.systems.RegisterMode;
import org.terasology.entitySystem.systems.RegisterSystem;
import org.terasology.input.cameraTarget.CameraTargetChangedEvent;
import org.terasology.logic.common.ActivateEvent;
import org.terasology.logic.location.LocationComponent;
import org.terasology.logic.players.LocalPlayer;
import org.terasology.registry.In;
import org.terasology.world.selection.BlockSelectionComponent;
import org.terasology.world.selection.event.SetBlockSelectionEndingPointEvent;
import org.terasology.world.selection.event.SetBlockSelectionStartingPointEvent;

/**
 * System to allow the use of BlockSelectionComponents. This system is a client only system, though no other player
 * will see selections done by one player.  This system uses an item's activate event to both start and end a selection,
 * then triggers a ApplyBlockSelectionEvent event.
 *
 */
@RegisterSystem(RegisterMode.CLIENT)
public class LocalPlayerBlockSelectionByItemSystem extends BaseComponentSystem {
    @In
    private LocalPlayer localPlayer;

    private EntityRef blockSelectionComponentEntity;

    @ReceiveEvent(components = {OnItemActivateSelectionComponent.class})
    public void onPlaced(ActivateEvent event, EntityRef itemEntity) {
        if (event.getTargetLocation() == null) {
            return;
        }

        EntityRef targetLocationEntity = event.getTarget();

        this.blockSelectionComponentEntity = itemEntity;
        BlockSelectionComponent blockSelectionComponent = itemEntity.getComponent(BlockSelectionComponent.class);

        if (null == blockSelectionComponent.startPosition) {
            // on the first item click, we start selecting blocks
            targetLocationEntity.send(new SetBlockSelectionStartingPointEvent(itemEntity));

            blockSelectionComponent.shouldRender = true;
        } else {
            // on the second item click, we will set the ending selection point and send an ApplyBlockSelectionEvent
            targetLocationEntity.send(new SetBlockSelectionEndingPointEvent(itemEntity));

            localPlayer.getCharacterEntity().send(new ApplyBlockSelectionEvent(itemEntity, blockSelectionComponent.currentSelection));
            blockSelectionComponent.shouldRender = false;
            blockSelectionComponent.currentSelection = null;
            blockSelectionComponent.startPosition = null;
        }
    }

    @ReceiveEvent(components = {LocationComponent.class})
    public void onCamTargetChanged(CameraTargetChangedEvent event, EntityRef entity) {
        // This method will update the block selection to whatever block is targeted in the players view
        if (null == blockSelectionComponentEntity) {
            return;
        }

        BlockSelectionComponent blockSelectionComponent = blockSelectionComponentEntity.getComponent(BlockSelectionComponent.class);
        if (blockSelectionComponent.startPosition == null) {
            return;
        }
        EntityRef target = event.getNewTarget();
        target.send(new SetBlockSelectionEndingPointEvent(blockSelectionComponentEntity));
    }

}