// Copyright 2021 The Tint 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.

#include <string>

#include "src/tint/val/val.h"

#include "src/tint/utils/io/command.h"
#include "src/tint/utils/io/tmpfile.h"
#include "src/tint/utils/string.h"

#ifdef _WIN32
#include <Windows.h>
#include <d3dcommon.h>
#include <d3dcompiler.h>

#include <wrl.h>
using Microsoft::WRL::ComPtr;
#endif  // _WIN32

namespace tint::val {

Result HlslUsingDXC(const std::string& dxc_path,
                    const std::string& source,
                    const EntryPointList& entry_points,
                    bool require_16bit_types) {
    Result result;

    auto dxc = utils::Command(dxc_path);
    if (!dxc.Found()) {
        result.output = "DXC not found at '" + std::string(dxc_path) + "'";
        result.failed = true;
        return result;
    }

    // Native 16-bit types, e.g. float16_t, require SM6.2. Otherwise we use SM6.0.
    const char* shader_model_version = require_16bit_types ? "6_2" : "6_0";

    utils::TmpFile file;
    file << source;

    for (auto ep : entry_points) {
        const char* stage_prefix = "";

        switch (ep.second) {
            case ast::PipelineStage::kNone:
                result.output = "Invalid PipelineStage";
                result.failed = true;
                return result;
            case ast::PipelineStage::kVertex:
                stage_prefix = "vs";
                break;
            case ast::PipelineStage::kFragment:
                stage_prefix = "ps";
                break;
            case ast::PipelineStage::kCompute:
                stage_prefix = "cs";
                break;
        }

        // Match Dawn's compile flags
        // See dawn\src\dawn_native\d3d12\RenderPipelineD3D12.cpp
        // and dawn_native\d3d12\ShaderModuleD3D12.cpp (GetDXCArguments)
        auto res = dxc(
            "-T " + std::string(stage_prefix) + "_" + std::string(shader_model_version),  // Profile
            "-E " + ep.first,                                  // Entry point
            "/Zpr",                                            // D3DCOMPILE_PACK_MATRIX_ROW_MAJOR
            "/Gis",                                            // D3DCOMPILE_IEEE_STRICTNESS
            require_16bit_types ? "-enable-16bit-types" : "",  // Enable 16-bit if required
            file.Path());
        if (!res.out.empty()) {
            if (!result.output.empty()) {
                result.output += "\n";
            }
            result.output += res.out;
        }
        if (!res.err.empty()) {
            if (!result.output.empty()) {
                result.output += "\n";
            }
            result.output += res.err;
        }
        result.failed = (res.error_code != 0);

        // Remove the temporary file name from the output to keep output deterministic
        result.output = utils::ReplaceAll(result.output, file.Path(), "shader.hlsl");
    }

    if (entry_points.empty()) {
        result.output = "No entrypoint found";
        result.failed = true;
        return result;
    }

    return result;
}

#ifdef _WIN32
Result HlslUsingFXC(const std::string& fxc_path,
                    const std::string& source,
                    const EntryPointList& entry_points) {
    Result result;

    // This library leaks if an error happens in this function, but it is ok
    // because it is loaded at most once, and the executables using HlslUsingFXC
    // are short-lived.
    HMODULE fxcLib = LoadLibraryA(fxc_path.c_str());
    if (fxcLib == nullptr) {
        result.output = "Couldn't load FXC";
        result.failed = true;
        return result;
    }

    auto* d3dCompile = reinterpret_cast<pD3DCompile>(
        reinterpret_cast<void*>(GetProcAddress(fxcLib, "D3DCompile")));
    auto* d3dDisassemble = reinterpret_cast<pD3DDisassemble>(
        reinterpret_cast<void*>(GetProcAddress(fxcLib, "D3DDisassemble")));

    if (d3dCompile == nullptr) {
        result.output = "Couldn't load D3DCompile from FXC";
        result.failed = true;
        return result;
    }
    if (d3dDisassemble == nullptr) {
        result.output = "Couldn't load D3DDisassemble from FXC";
        result.failed = true;
        return result;
    }

    for (auto ep : entry_points) {
        const char* profile = "";
        switch (ep.second) {
            case ast::PipelineStage::kNone:
                result.output = "Invalid PipelineStage";
                result.failed = true;
                return result;
            case ast::PipelineStage::kVertex:
                profile = "vs_5_1";
                break;
            case ast::PipelineStage::kFragment:
                profile = "ps_5_1";
                break;
            case ast::PipelineStage::kCompute:
                profile = "cs_5_1";
                break;
        }

        // Match Dawn's compile flags
        // See dawn\src\dawn_native\d3d12\RenderPipelineD3D12.cpp
        UINT compileFlags = D3DCOMPILE_OPTIMIZATION_LEVEL0 | D3DCOMPILE_PACK_MATRIX_ROW_MAJOR |
                            D3DCOMPILE_IEEE_STRICTNESS;

        ComPtr<ID3DBlob> compiledShader;
        ComPtr<ID3DBlob> errors;
        HRESULT res = d3dCompile(source.c_str(),    // pSrcData
                                 source.length(),   // SrcDataSize
                                 nullptr,           // pSourceName
                                 nullptr,           // pDefines
                                 nullptr,           // pInclude
                                 ep.first.c_str(),  // pEntrypoint
                                 profile,           // pTarget
                                 compileFlags,      // Flags1
                                 0,                 // Flags2
                                 &compiledShader,   // ppCode
                                 &errors);          // ppErrorMsgs
        if (FAILED(res)) {
            result.output = static_cast<char*>(errors->GetBufferPointer());
            result.failed = true;
            return result;
        } else {
            ComPtr<ID3DBlob> disassembly;
            res = d3dDisassemble(compiledShader->GetBufferPointer(),
                                 compiledShader->GetBufferSize(), 0, "", &disassembly);
            if (FAILED(res)) {
                result.output = "failed to disassemble shader";
            } else {
                result.output = static_cast<char*>(disassembly->GetBufferPointer());
            }
        }
    }

    FreeLibrary(fxcLib);

    if (entry_points.empty()) {
        result.output = "No entrypoint found";
        result.failed = true;
        return result;
    }

    return result;
}
#endif  // _WIN32

}  // namespace tint::val