package themixray.repeating.mod.render.shader;

import com.mojang.blaze3d.platform.GlStateManager;
import com.mojang.blaze3d.platform.TextureUtil;
import lombok.Getter;
import lombok.SneakyThrows;
import lombok.experimental.UtilityClass;
import net.fabricmc.fabric.api.client.event.lifecycle.v1.ClientLifecycleEvents;
import net.minecraft.client.MinecraftClient;
import net.minecraft.client.gl.GlImportProcessor;
import net.minecraft.resource.Resource;
import net.minecraft.resource.ResourceFactory;
import net.minecraft.util.Identifier;
import org.apache.commons.io.IOUtils;
import org.apache.commons.lang3.StringUtils;
import org.jetbrains.annotations.Nullable;
import org.lwjgl.system.MemoryUtil;

import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.nio.charset.StandardCharsets;
import java.util.Optional;

import static org.lwjgl.opengl.GL33.*;

@UtilityClass
public class ShaderManager {
    @Getter
    private Shader positionColorShader;

    public void init() {
        ClientLifecycleEvents.CLIENT_STARTED.register(client -> loadShaders());
    }

    private void loadShaders() {
        positionColorShader = new Shader("position_color");
    }

    public int loadShaderProgram(String name, ShaderType type) {
        try {
            boolean file_present = true;
            ResourceFactory resourceFactory = MinecraftClient.getInstance().getResourceManager();
            Optional<Resource> resource = resourceFactory.getResource(new Identifier("renderer", "shader/" + name + type.fileExtension));
            int i = glCreateShader(type.glType);
            if (resource.isPresent()) {
                GlStateManager.glShaderSource(i, new GlImportProcessor() {
                    @SneakyThrows
                    @Nullable
                    @Override
                    public String loadImport(boolean inline, String name) {
                        return IOUtils.toString(resource.get().getInputStream(), StandardCharsets.UTF_8);
                    }
                }.readSource(readResourceAsString(resource.get().getInputStream())));
            } else file_present = false;
            glCompileShader(i);
            if (glGetShaderi(i, GL_COMPILE_STATUS) == 0 || !file_present) {
                String shaderInfo = StringUtils.trim(glGetShaderInfoLog(i, 32768));
                throw new IOException("Couldn't compile " + type.name + " program (" + name + ") : " + shaderInfo);
            }
            return i;
        } catch (IOException e) {
            e.printStackTrace();
        }
        return 0;
    }

    private String readResourceAsString(InputStream inputStream) {
        ByteBuffer byteBuffer = null;
        try {
            byteBuffer = TextureUtil.readResource(inputStream);
            int i = byteBuffer.position();
            byteBuffer.rewind();
            return MemoryUtil.memASCII(byteBuffer, i);
        } catch (IOException ignored) {
        } finally {
            if (byteBuffer != null) {
                MemoryUtil.memFree(byteBuffer);
            }
        }
        return null;
    }

    public enum ShaderType {
        VERTEX("vertex", ".vsh", GL_VERTEX_SHADER),
        FRAGMENT("fragment", ".fsh", GL_FRAGMENT_SHADER);
        private final String name;
        private final String fileExtension;
        private final int glType;

        ShaderType(String name, String fileExtension, int glType) {
            this.name = name;
            this.fileExtension = fileExtension;
            this.glType = glType;
        }
    }
}