/*
 * Copyright (c) 2016, 2017, 2018, 2019 FabricMC
 *
 * 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 net.fabricmc.fabric.impl.client.indigo.renderer.mesh;

import net.fabricmc.fabric.api.renderer.v1.mesh.Mesh;
import net.fabricmc.fabric.api.renderer.v1.mesh.MeshBuilder;
import net.fabricmc.fabric.api.renderer.v1.mesh.QuadEmitter;

/**
 * Our implementation of {@link MeshBuilder}, used for static mesh creation and baking.
 * Not much to it - mainly it just needs to grow the int[] array as quads are appended
 * and maintain/provide a properly-configured {@link net.fabricmc.fabric.api.renderer.v1.mesh.MutableQuadView} instance.
 * All the encoding and other work is handled in the quad base classes.
 * The one interesting bit is in {@link Maker#emitDirectly()}.
 */
public class MeshBuilderImpl implements MeshBuilder {
	private int[] data = new int[256];
	private int index = 0;
	private int limit = data.length;
	private final Maker maker = new Maker();

	public MeshBuilderImpl() {
		ensureCapacity(EncodingFormat.TOTAL_STRIDE);
		maker.data = data;
		maker.baseIndex = index;
		maker.clear();
	}

	protected void ensureCapacity(int stride) {
		if (stride > limit - index) {
			limit *= 2;
			final int[] bigger = new int[limit];
			System.arraycopy(data, 0, bigger, 0, index);
			data = bigger;
			maker.data = data;
		}
	}

	@Override
	public QuadEmitter getEmitter() {
		maker.clear();
		return maker;
	}

	@Override
	public Mesh build() {
		final int[] packed = new int[index];
		System.arraycopy(data, 0, packed, 0, index);
		index = 0;
		maker.baseIndex = index;
		maker.clear();
		return new MeshImpl(packed);
	}

	/**
	 * Our base classes are used differently so we define final
	 * encoding steps in subtypes. This will be a static mesh used
	 * at render time so we want to capture all geometry now and
	 * apply non-location-dependent lighting.
	 */
	private class Maker extends MutableQuadViewImpl {
		@Override
		public void emitDirectly() {
			computeGeometry();
			index += EncodingFormat.TOTAL_STRIDE;
			ensureCapacity(EncodingFormat.TOTAL_STRIDE);
			baseIndex = index;
		}
	}
}
