// Copyright 2024 The Ebitengine Authors
//
// 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 shaderprecomp

import (
	"io"

	"github.com/hajimehoshi/ebiten/v2/internal/graphics"
	"github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver/directx"
	"github.com/hajimehoshi/ebiten/v2/internal/shaderir"
	"github.com/hajimehoshi/ebiten/v2/internal/shaderir/hlsl"
)

const (
	// HLSLVertexShaderProfile is the target profile for vertex shaders.
	HLSLVertexShaderProfile = directx.VertexShaderProfile

	// HLSLPixelShaderProfile is the target profile for pixel shaders.
	HLSLPixelShaderProfile = directx.PixelShaderProfile

	// HLSLVertexShaderEntryPoint is the entry point name for vertex shaders.
	HLSLVertexShaderEntryPoint = directx.VertexShaderEntryPoint

	// HLSLPixelShaderEntryPoint is the entry point name for pixel shaders.
	HLSLPixelShaderEntryPoint = directx.PixelShaderEntryPoint
)

// CompileToHLSL compiles the shader source to High-Level Shader Language to writers.
//
// CompileToHLSL is concurrent-safe.
func CompileToHLSL(vertexWriter, pixelWriter io.Writer, source *ShaderSource) error {
	ir, err := graphics.CompileShader(source.source)
	if err != nil {
		return err
	}
	vs, ps := hlsl.Compile(ir)
	if _, err = vertexWriter.Write([]byte(vs)); err != nil {
		return err
	}
	if _, err = pixelWriter.Write([]byte(ps)); err != nil {
		return err
	}
	return nil
}

// RegisterFXCs registers a precompiled HLSL (FXC) for a shader source.
// vertexFXC and pixelFXC must be the content of .fxc files generated by `fxc` command.
// For more details, see https://learn.microsoft.com/en-us/windows/win32/direct3dtools/dx-graphics-tools-fxc-using.
//
// RegisterFXCs is concurrent-safe.
func RegisterFXCs(source *ShaderSource, vertexFXC, pixelFXC []byte) {
	directx.RegisterPrecompiledFXCs(shaderir.SourceHash(source.ID()), vertexFXC, pixelFXC)
}