package com.mojang.blaze3d.opengl;

import java.nio.ByteBuffer;
import java.util.Set;
import java.util.function.Supplier;
import net.fabricmc.api.EnvType;
import net.fabricmc.api.Environment;
import org.jetbrains.annotations.Nullable;
import org.lwjgl.opengl.GLCapabilities;
import org.lwjgl.system.MemoryUtil;

@Environment(EnvType.CLIENT)
public abstract class BufferStorage {
	public static BufferStorage create(GLCapabilities capabilities, Set<String> enabledExtensions) {
		if (capabilities.GL_ARB_buffer_storage && GlDevice.USE_GL_ARB_buffer_storage) {
			enabledExtensions.add("GL_ARB_buffer_storage");
			return new BufferStorage.Immutable();
		} else {
			return new BufferStorage.Mutable();
		}
	}

	public abstract GlBuffer createBuffer(DirectStateAccess directStateAccess, @Nullable Supplier<String> label, int usage, int size);

	public abstract GlBuffer createBuffer(DirectStateAccess directStateAccess, @Nullable Supplier<String> label, int usage, ByteBuffer data);

	public abstract GlBuffer.GlMappedView mapBuffer(DirectStateAccess directStateAccess, GlBuffer buffer, int offset, int size, int usage);

	@Environment(EnvType.CLIENT)
	static class Immutable extends BufferStorage {
		@Override
		public GlBuffer createBuffer(DirectStateAccess directStateAccess, @Nullable Supplier<String> label, int usage, int size) {
			int i = directStateAccess.createBuffer();
			directStateAccess.bufferStorage(i, size, GlConst.bufferUsageToGlFlag(usage));
			ByteBuffer byteBuffer = this.tryMapBufferPersistent(directStateAccess, usage, i, size);
			return new GlBuffer(label, directStateAccess, usage, size, i, byteBuffer);
		}

		@Override
		public GlBuffer createBuffer(DirectStateAccess directStateAccess, @Nullable Supplier<String> label, int usage, ByteBuffer data) {
			int i = directStateAccess.createBuffer();
			int j = data.remaining();
			directStateAccess.bufferStorage(i, data, GlConst.bufferUsageToGlFlag(usage));
			ByteBuffer byteBuffer = this.tryMapBufferPersistent(directStateAccess, usage, i, j);
			return new GlBuffer(label, directStateAccess, usage, j, i, byteBuffer);
		}

		@Nullable
		private ByteBuffer tryMapBufferPersistent(DirectStateAccess directStateAccess, int usage, int handle, int size) {
			int i = 0;
			if ((usage & 1) != 0) {
				i |= 1;
			}

			if ((usage & 2) != 0) {
				i |= 18;
			}

			ByteBuffer byteBuffer;
			if (i != 0) {
				GlStateManager.clearGlErrors();
				byteBuffer = directStateAccess.mapBufferRange(handle, 0, size, i | 64);
				if (byteBuffer == null) {
					throw new IllegalStateException("Can't persistently map buffer, opengl error " + GlStateManager._getError());
				}
			} else {
				byteBuffer = null;
			}

			return byteBuffer;
		}

		@Override
		public GlBuffer.GlMappedView mapBuffer(DirectStateAccess directStateAccess, GlBuffer buffer, int offset, int size, int usage) {
			if (buffer.persistentBuffer == null) {
				throw new IllegalStateException("Somehow trying to map an unmappable buffer");
			} else {
				return new GlBuffer.GlMappedView(() -> {
					if ((usage & 2) != 0) {
						directStateAccess.flushMappedBufferRange(buffer.handle, offset, size);
					}
				}, buffer, MemoryUtil.memSlice(buffer.persistentBuffer, offset, size));
			}
		}
	}

	@Environment(EnvType.CLIENT)
	static class Mutable extends BufferStorage {
		@Override
		public GlBuffer createBuffer(DirectStateAccess directStateAccess, @Nullable Supplier<String> label, int usage, int size) {
			int i = directStateAccess.createBuffer();
			directStateAccess.bufferData(i, size, GlConst.bufferUsageToGlEnum(usage));
			return new GlBuffer(label, directStateAccess, usage, size, i, null);
		}

		@Override
		public GlBuffer createBuffer(DirectStateAccess directStateAccess, @Nullable Supplier<String> label, int usage, ByteBuffer data) {
			int i = directStateAccess.createBuffer();
			int j = data.remaining();
			directStateAccess.bufferData(i, data, GlConst.bufferUsageToGlEnum(usage));
			return new GlBuffer(label, directStateAccess, usage, j, i, null);
		}

		@Override
		public GlBuffer.GlMappedView mapBuffer(DirectStateAccess directStateAccess, GlBuffer buffer, int offset, int size, int usage) {
			GlStateManager.clearGlErrors();
			ByteBuffer byteBuffer = directStateAccess.mapBufferRange(buffer.handle, offset, size, usage);
			if (byteBuffer == null) {
				throw new IllegalStateException("Can't map buffer, opengl error " + GlStateManager._getError());
			} else {
				return new GlBuffer.GlMappedView(() -> directStateAccess.unmapBuffer(buffer.handle), buffer, byteBuffer);
			}
		}
	}
}