// Copyright (C) 2003 Dolphin Project.

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, version 2.0.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License 2.0 for more details.

// A copy of the GPL 2.0 should have been included with the program.
// If not, see http://www.gnu.org/licenses/

// Official SVN repository and contact information can be found at
// http://code.google.com/p/dolphin-emu/

#ifndef _SHADERGENCOMMON_H
#define _SHADERGENCOMMON_H

#include <stdio.h>
#include <stdarg.h>
#include <string>
#include <vector>
#include <algorithm>

#include "CommonTypes.h"
#include "VideoCommon.h"

/**
 * Common interface for classes that need to go through the shader generation path (GenerateVertexShader, GeneratePixelShader)
 * In particular, this includes the shader code generator (ShaderCode).
 * A different class (ShaderUid) can be used to uniquely identify each ShaderCode object.
 * More interesting things can be done with this, e.g. ShaderConstantProfile checks what shader constants are being used. This can be used to optimize buffer management.
 * Each of the ShaderCode, ShaderUid and ShaderConstantProfile child classes only implement the subset of ShaderGeneratorInterface methods that are required for the specific tasks.
 */
class ShaderGeneratorInterface
{
public:
	/*
	 * Used when the shader generator would write a piece of ShaderCode.
	 * Can be used like printf.
	 * @note In the ShaderCode implementation, this does indeed write the parameter string to an internal buffer. However, you're free to do whatever you like with the parameter.
	 */
	void Write(const char* fmt, ...) {}

	/*
	 * Returns a read pointer to the internal buffer.
	 * @note When implementing this method in a child class, you likely want to return the argument of the last SetBuffer call here
	 * @note SetBuffer() should be called before using GetBuffer().
	 */
	const char* GetBuffer() { return NULL; }

	/*
	 * Can be used to give the object a place to write to. This should be called before using Write().
	 * @param buffer pointer to a char buffer that the object can write to
	 */
	void SetBuffer(char* buffer) { }

	/*
	 * Tells us that a specific constant range (including last_index) is being used by the shader
	 */
	inline void SetConstantsUsed(unsigned int first_index, unsigned int last_index) {}

	/*
	 * Returns a pointer to an internally stored object of the uid_data type.
	 * @warning since most child classes use the default implementation you shouldn't access this directly without adding precautions against NULL access (e.g. via adding a dummy structure, cf. the vertex/pixel shader generators)
	 */
	template<class uid_data>
	uid_data& GetUidData() { return *(uid_data*)NULL; }
};

/**
 * Shader UID class used to uniquely identify the ShaderCode output written in the shader generator.
 * uid_data can be any struct of parameters that uniquely identify each shader code output.
 * Unless performance is not an issue, uid_data should be tightly packed to reduce memory footprint.
 * Shader generators will write to specific uid_data fields; ShaderUid methods will only read raw u32 values from a union.
 */
template<class uid_data>
class ShaderUid : public ShaderGeneratorInterface
{
public:
	ShaderUid()
	{
		// TODO: Move to Shadergen => can be optimized out
		memset(values, 0, sizeof(values));
	}

	bool operator == (const ShaderUid& obj) const
	{
		return memcmp(this->values, obj.values, sizeof(values)) == 0;
	}

	bool operator != (const ShaderUid& obj) const
	{
		return memcmp(this->values, obj.values, sizeof(values)) != 0;
	}

	// determines the storage order inside STL containers
	bool operator < (const ShaderUid& obj) const
	{
		// TODO: Store last frame used and order by that? makes much more sense anyway...
		for (unsigned int i = 0; i < sizeof(uid_data) / sizeof(u32); ++i)
		{
			if (this->values[i] < obj.values[i])
				return true;
			else if (this->values[i] > obj.values[i])
				return false;
		}
		return false;
	}

	template<class T>
	inline T& GetUidData() { return data; }

private:
	union
	{
		uid_data data;
		u32 values[sizeof(uid_data) / sizeof(u32)];
	};
};

class ShaderCode : public ShaderGeneratorInterface
{
public:
	ShaderCode() : buf(NULL), write_ptr(NULL)
	{

	}

	void Write(const char* fmt, ...)
	{
		va_list arglist;
		va_start(arglist, fmt);
		write_ptr += vsprintf(write_ptr, fmt, arglist);
		va_end(arglist);
	}

	const char* GetBuffer() { return buf; }
	void SetBuffer(char* buffer) { buf = buffer; write_ptr = buffer; }

private:
	const char* buf;
	char* write_ptr;
};

/**
 * Generates a shader constant profile which can be used to query which constants are used in a shader
 */
class ShaderConstantProfile : public ShaderGeneratorInterface
{
public:
	ShaderConstantProfile(int num_constants) { constant_usage.resize(num_constants); }

	inline void SetConstantsUsed(unsigned int first_index, unsigned int last_index)
	{
		for (unsigned int i = first_index; i < last_index+1; ++i)
			constant_usage[i] = true;
	}

	inline bool ConstantIsUsed(unsigned int index)
	{
		// TODO: Not ready for usage yet
		return true;
//		return constant_usage[index];
	}
private:
	std::vector<bool> constant_usage; // TODO: Is vector<bool> appropriate here?
};

template<class T>
static void WriteRegister(T& object, API_TYPE ApiType, const char *prefix, const u32 num)
{
	if (ApiType == API_OPENGL)
		return; // Nothing to do here

	object.Write(" : register(%s%d)", prefix, num);
}

template<class T>
static void WriteLocation(T& object, API_TYPE ApiType, bool using_ubos)
{
	if (using_ubos)
		return;

	object.Write("uniform ");
}

template<class T>
static void DeclareUniform(T& object, API_TYPE api_type, bool using_ubos, const u32 num, const char* type, const char* name)
{
	WriteLocation(object, api_type, using_ubos);
	object.Write("%s %s ", type, name);
	WriteRegister(object, api_type, "c", num);
	object.Write(";\n");
}

/**
 * Common uid data used for shader generators that use lighting calculations.
 * Expected to be stored as a member called "lighting".
 */
struct LightingUidData
{
	struct
	{
		u32 matsource : 1;
		u32 enablelighting : 1;
		u32 ambsource : 1;
		u32 diffusefunc : 2;
		u32 attnfunc : 2;
		u32 light_mask : 8;
	} lit_chans[4];
};

/**
 * Checks if there has been
 */
template<class UidT, class CodeT>
void CheckForUidMismatch(CodeT& new_code, const UidT& new_uid, const char* shader_type, const char* dump_prefix)
{
	// TODO: Might be sensitive to config changes
	static std::map<UidT,std::string> s_shaders;
	static std::vector<UidT> s_uids;

	bool uid_is_indexed = std::find(s_uids.begin(), s_uids.end(), new_uid) != s_uids.end();
	if (!uid_is_indexed)
	{
		s_uids.push_back(new_uid);
		s_shaders[new_uid] = new_code.GetBuffer();
	}
	else
	{
		// uid is already in the index => check if there's a shader with the same uid but different code
		auto& old_code = s_shaders[new_uid];
		if (strcmp(old_code.c_str(), new_code.GetBuffer()) != 0)
		{
			static int num_failures = 0;

			char szTemp[MAX_PATH];
			sprintf(szTemp, "%s%ssuid_mismatch_%04i.txt", File::GetUserPath(D_DUMP_IDX).c_str(),
					dump_prefix,
					++num_failures);

			// TODO: Should also dump uids
			std::ofstream file;
			OpenFStream(file, szTemp, std::ios_base::out);
			file << "Old shader code:\n" << old_code;
			file << "\n\nNew shader code:\n" << new_code.GetBuffer();
			file.close();

			// TODO: Make this more idiot-proof
			ERROR_LOG(VIDEO, "%s shader uid mismatch!", shader_type);
		}
	}
}

#endif // _SHADERGENCOMMON_H