//
// Copyright (c) 2008-2014 the Urho3D project.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//

#include "Precompiled.h"
#include "Graphics.h"
#include "GraphicsImpl.h"
#include "Shader.h"
#include "ShaderVariation.h"

#include <windows.h>
#include <d3dcompiler.h>
#include <mojoshader.h>

#include "DebugNew.h"

namespace Urho3D
{

ShaderVariation::ShaderVariation(Shader* owner, ShaderType type) :
    GPUObject(owner->GetSubsystem<Graphics>()),
    owner_(owner),
    type_(type),
    compiled_(false)
{
    for (unsigned i = 0; i < MAX_TEXTURE_UNITS; ++i)
        useTextureUnit_[i] = false;
}

ShaderVariation::~ShaderVariation()
{
    Release();
}

bool ShaderVariation::Create()
{
    Release();
    
    if (!graphics_)
        return false;
    
    // Compile shader if don't have loadable bytecode
    PODVector<unsigned> byteCode;
    
    if (byteCode.Empty())
    {
        Vector<String> defines = defines_.Split(' ');
        
        // Set the entrypoint, profile and flags according to the shader being compiled
        const char* entryPoint = 0;
        const char* profile = 0;
        unsigned flags = D3DCOMPILE_OPTIMIZATION_LEVEL3;
        bool useSM3 = graphics_->GetSM3Support();
        
        if (type_ == VS)
        {
            entryPoint = "VS";
            defines.Push("COMPILEVS");
            if (!useSM3)
                profile = "vs_2_0";
            else
                profile = "vs_3_0";
        }
        else
        {
            entryPoint = "PS";
            defines.Push("COMPILEPS");
            if (!useSM3)
                profile = "ps_2_0";
            else
            {
                profile = "ps_3_0";
                flags |= D3DCOMPILE_PREFER_FLOW_CONTROL;
            }
        }
        
        if (useSM3)
            defines.Push("SM3");
        
        // Collect defines into macros
        Vector<String> defineValues;
        PODVector<D3D_SHADER_MACRO> macros;
        
        for (unsigned i = 0; i < defines.Size(); ++i)
        {
            unsigned equalsPos = defines[i].Find('=');
            if (equalsPos != String::NPOS)
            {
                defineValues.Push(defines[i].Substring(equalsPos + 1));
                defines[i].Resize(equalsPos);
            }
            else
                defineValues.Push("1");
        }
        for (unsigned i = 0; i < defines.Size(); ++i)
        {
            D3D_SHADER_MACRO macro;
            macro.Name = defines[i].CString();
            macro.Definition = defineValues[i].CString();
            macros.Push(macro);
        }
        
        D3D_SHADER_MACRO endMacro;
        endMacro.Name = 0;
        endMacro.Definition = 0;
        macros.Push(endMacro);
        
        // Compile using D3DCompile
        const String& sourceCode = owner_->GetSourceCode(type_);
        LPD3DBLOB shaderCode = 0;
        LPD3DBLOB errorMsgs = 0;
        
        if (FAILED(D3DCompile(sourceCode.CString(), sourceCode.Length(), owner_->GetName().CString(), &macros.Front(), 0,
            entryPoint, profile, flags, 0, &shaderCode, &errorMsgs)))
            compilerOutput_ = String((const char*)errorMsgs->GetBufferPointer(), errorMsgs->GetBufferSize());
        else
        {
            // Inspect the produced bytecode using MojoShader, then strip and store it
            unsigned char* bufData = (unsigned char*)shaderCode->GetBufferPointer();
            unsigned bufSize = shaderCode->GetBufferSize();
            ParseParameters(bufData, bufSize);
            CopyStrippedCode(byteCode, bufData, bufSize);
        }

        if (shaderCode)
            shaderCode->Release();
        if (errorMsgs)
            errorMsgs->Release();
        if (byteCode.Empty())
            return false;
    }
    
    // Then create shader from the bytecode
    IDirect3DDevice9* device = graphics_->GetImpl()->GetDevice();
    if (type_ == VS)
    {
        if (!device || FAILED(device->CreateVertexShader(
            (const DWORD*)&byteCode[0],
            (IDirect3DVertexShader9**)&object_)))
            compilerOutput_ = "Could not create vertex shader";
        else
            compiled_ = true;
    }
    else
    {
        if (!device || FAILED(device->CreatePixelShader(
            (const DWORD*)&byteCode[0],
            (IDirect3DPixelShader9**)&object_)))
            compilerOutput_ = "Could not create pixel shader";
        else
            compiled_ = true;
    }
    
    return compiled_;
}

void ShaderVariation::Release()
{
    if (object_)
    {
        if (!graphics_)
            return;
        
        if (type_ == VS)
        {
            if (graphics_->GetVertexShader() == this)
                graphics_->SetShaders(0, 0);
            
            ((IDirect3DVertexShader9*)object_)->Release();
        }
        else
        {
            if (graphics_->GetPixelShader() == this)
                graphics_->SetShaders(0, 0);
            
            ((IDirect3DPixelShader9*)object_)->Release();
        }
        
        object_ = 0;
        compiled_ = false;
        compilerOutput_.Clear();
        
        for (unsigned i = 0; i < MAX_TEXTURE_UNITS; ++i)
            useTextureUnit_[i] = false;
        parameters_.Clear();
    }
}

void ShaderVariation::SetName(const String& name)
{
    name_ = name.Trimmed().Replaced(' ', '_');
}

void ShaderVariation::SetDefines(const String& defines)
{
    defines_ = defines;
}

void ShaderVariation::ParseParameters(unsigned char* bufData, unsigned bufSize)
{
    MOJOSHADER_parseData const *parseData = MOJOSHADER_parse("bytecode", bufData, bufSize, 0, 0, 0, 0, 0, 0, 0);

    for (int i = 0; i < parseData->symbol_count; i++)
    {
        MOJOSHADER_symbol const& symbol = parseData->symbols[i];

        String name(symbol.name);
        unsigned reg = symbol.register_index;
        unsigned regCount = symbol.register_count;

        // Check if the parameter is a constant or a texture sampler
        bool isSampler = (name[0] == 's');
        name = name.Substring(1);
        
        if (isSampler)
        {

            // Skip if it's a G-buffer sampler, which are aliases for the standard texture units
            if (reg < MAX_TEXTURE_UNITS)
            {
                if (name != "AlbedoBuffer" && name != "NormalBuffer" && name != "DepthBuffer" && name != "LightBuffer")
                    useTextureUnit_[reg] = true;
            }
        }
        else
        {
            ShaderParameter newParam(type_, reg, regCount);
            HashMap<StringHash, ShaderParameter>::Iterator i = parameters_.Insert(MakePair(StringHash(name), newParam));
            graphics_->RegisterShaderParameter(i->first_, i->second_);
        }
    }
    
    MOJOSHADER_freeParseData(parseData);
    
    // Optimize shader parameter lookup by rehashing to next power of two
    parameters_.Rehash(NextPowerOfTwo(parameters_.Size()));
}

void ShaderVariation::CopyStrippedCode(PODVector<unsigned>& dest, unsigned char* bufData, unsigned bufSize)
{
    unsigned const D3DSIO_COMMENT = 0xFFFE;
    unsigned* srcWords = (unsigned*)bufData;
    unsigned srcWordSize = bufSize >> 2;
    
    dest.Clear();
    
    for (unsigned i = 0; i < srcWordSize; ++i)
    {
        unsigned opcode = srcWords[i] & 0xffff;
        unsigned paramLength = (srcWords[i] & 0x0f000000) >> 24;
        unsigned commentLength = srcWords[i] >> 16;
        
        // For now, skip comment only at fixed position to prevent false positives
        if (i == 1 && opcode == D3DSIO_COMMENT)
        {
            // Skip the comment
            i += commentLength;
        }
        else
        {
            // Not a comment, copy the data
            dest.Push(srcWords[i]);
        }
    }
}

}