/*
 * Copyright 2011-2014 Branimir Karadzic. All rights reserved.
 * License: http://www.opensource.org/licenses/BSD-2-Clause
 */

#include <string>
#include <vector>

#include "common.h"

#include <bgfx.h>
#include <bx/timer.h>
#include <bx/readerwriter.h>
#include "entry/entry.h"
#include "fpumath.h"

#include <stdio.h>
#include <string.h>

static const char* s_shaderPath = NULL;
static bool s_flipV = false;

static void shaderFilePath(char* _out, const char* _name)
{
	strcpy(_out, s_shaderPath);
	strcat(_out, _name);
	strcat(_out, ".bin");
}

long int fsize(FILE* _file)
{
	long int pos = ftell(_file);
	fseek(_file, 0L, SEEK_END);
	long int size = ftell(_file);
	fseek(_file, pos, SEEK_SET);
	return size;
}

static const bgfx::Memory* load(const char* _filePath)
{
	FILE* file = fopen(_filePath, "rb");
	if (NULL != file)
	{
		uint32_t size = (uint32_t)fsize(file);
		const bgfx::Memory* mem = bgfx::alloc(size+1);
		size_t ignore = fread(mem->data, 1, size, file);
		BX_UNUSED(ignore);
		fclose(file);
		mem->data[mem->size-1] = '\0';
		return mem;
	}

	return NULL;
}

static const bgfx::Memory* loadShader(const char* _name)
{
	char filePath[512];
	shaderFilePath(filePath, _name);
	return load(filePath);
}

static bgfx::ProgramHandle loadProgram(const char* _vsName, const char* _fsName)
{
	const bgfx::Memory* mem;

	// Load vertex shader.
	mem = loadShader(_vsName);
	bgfx::VertexShaderHandle vsh = bgfx::createVertexShader(mem);

	// Load fragment shader.
	mem = loadShader(_fsName);
	bgfx::FragmentShaderHandle fsh = bgfx::createFragmentShader(mem);

	// Create program from shaders.
	bgfx::ProgramHandle program = bgfx::createProgram(vsh, fsh);

	// We can destroy vertex and fragment shader here since
	// their reference is kept inside bgfx after calling createProgram.
	// Vertex and fragment shader will be destroyed once program is
	// destroyed.
	bgfx::destroyVertexShader(vsh);
	bgfx::destroyFragmentShader(fsh);

	return program;
}

struct Aabb
{
	float m_min[3];
	float m_max[3];
};

struct Obb
{
	float m_mtx[16];
};

struct Sphere
{
	float m_center[3];
	float m_radius;
};

struct Primitive
{
	uint32_t m_startIndex;
	uint32_t m_numIndices;
	uint32_t m_startVertex;
	uint32_t m_numVertices;

	Sphere m_sphere;
	Aabb m_aabb;
	Obb m_obb;
};

typedef std::vector<Primitive> PrimitiveArray;

struct Group
{
	Group()
	{
		reset();
	}

	void reset()
	{
		m_vbh.idx = bgfx::invalidHandle;
		m_ibh.idx = bgfx::invalidHandle;
		m_prims.clear();
	}

	bgfx::VertexBufferHandle m_vbh;
	bgfx::IndexBufferHandle m_ibh;
	Sphere m_sphere;
	Aabb m_aabb;
	Obb m_obb;
	PrimitiveArray m_prims;
};

struct Mesh
{
	void load(const char* _filePath)
	{
#define BGFX_CHUNK_MAGIC_VB BX_MAKEFOURCC('V', 'B', ' ', 0x0)
#define BGFX_CHUNK_MAGIC_IB BX_MAKEFOURCC('I', 'B', ' ', 0x0)
#define BGFX_CHUNK_MAGIC_PRI BX_MAKEFOURCC('P', 'R', 'I', 0x0)

		bx::CrtFileReader reader;
		reader.open(_filePath);

		Group group;

		uint32_t chunk;
		while (4 == bx::read(&reader, chunk) )
		{
			switch (chunk)
			{
			case BGFX_CHUNK_MAGIC_VB:
				{
					bx::read(&reader, group.m_sphere);
					bx::read(&reader, group.m_aabb);
					bx::read(&reader, group.m_obb);

					bx::read(&reader, m_decl);
					uint16_t stride = m_decl.getStride();

					uint16_t numVertices;
					bx::read(&reader, numVertices);
					const bgfx::Memory* mem = bgfx::alloc(numVertices*stride);
					bx::read(&reader, mem->data, mem->size);

					group.m_vbh = bgfx::createVertexBuffer(mem, m_decl);
				}
				break;

			case BGFX_CHUNK_MAGIC_IB:
				{
					uint32_t numIndices;
					bx::read(&reader, numIndices);
					const bgfx::Memory* mem = bgfx::alloc(numIndices*2);
					bx::read(&reader, mem->data, mem->size);
					group.m_ibh = bgfx::createIndexBuffer(mem);
				}
				break;

			case BGFX_CHUNK_MAGIC_PRI:
				{
					uint16_t len;
					bx::read(&reader, len);

					std::string material;
					material.resize(len);
					bx::read(&reader, const_cast<char*>(material.c_str() ), len);

					uint16_t num;
					bx::read(&reader, num);

					for (uint32_t ii = 0; ii < num; ++ii)
					{
						bx::read(&reader, len);

						std::string name;
						name.resize(len);
						bx::read(&reader, const_cast<char*>(name.c_str() ), len);

						Primitive prim;
						bx::read(&reader, prim.m_startIndex);
						bx::read(&reader, prim.m_numIndices);
						bx::read(&reader, prim.m_startVertex);
						bx::read(&reader, prim.m_numVertices);
						bx::read(&reader, prim.m_sphere);
						bx::read(&reader, prim.m_aabb);
						bx::read(&reader, prim.m_obb);

						group.m_prims.push_back(prim);
					}

					m_groups.push_back(group);
					group.reset();
				}
				break;

			default:
				DBG("%08x at %d", chunk, reader.seek() );
				break;
			}
		}

		reader.close();
	}

	void unload()
	{
		for (GroupArray::const_iterator it = m_groups.begin(), itEnd = m_groups.end(); it != itEnd; ++it)
		{
			const Group& group = *it;
			bgfx::destroyVertexBuffer(group.m_vbh);

			if (bgfx::isValid(group.m_ibh) )
			{
				bgfx::destroyIndexBuffer(group.m_ibh);
			}
		}
		m_groups.clear();
	}

	void submit(bgfx::ProgramHandle _program, float* _mtx)
	{
		for (GroupArray::const_iterator it = m_groups.begin(), itEnd = m_groups.end(); it != itEnd; ++it)
		{
			const Group& group = *it;

			// Set model matrix for rendering.
			bgfx::setTransform(_mtx);
			bgfx::setProgram(_program);
			bgfx::setIndexBuffer(group.m_ibh);
			bgfx::setVertexBuffer(group.m_vbh);

			// Set render states.
			bgfx::setState(0
				|BGFX_STATE_RGB_WRITE
				|BGFX_STATE_ALPHA_WRITE
				|BGFX_STATE_DEPTH_WRITE
				|BGFX_STATE_DEPTH_TEST_LESS
				|BGFX_STATE_CULL_CCW
				|BGFX_STATE_MSAA
				);

			// Submit primitive for rendering to view 0.
			bgfx::submit(0);
		}
	}

	bgfx::VertexDecl m_decl;
	typedef std::vector<Group> GroupArray;
	GroupArray m_groups;
};

int _main_(int /*_argc*/, char** /*_argv*/)
{
	uint32_t width = 1280;
	uint32_t height = 720;
	uint32_t debug = BGFX_DEBUG_TEXT;
	uint32_t reset = BGFX_RESET_VSYNC;

	bgfx::init();
	bgfx::reset(width, height, reset);

	// Enable debug text.
	bgfx::setDebug(debug);

	// Set view 0 clear state.
	bgfx::setViewClear(0
		, BGFX_CLEAR_COLOR_BIT|BGFX_CLEAR_DEPTH_BIT
		, 0x303030ff
		, 1.0f
		, 0
		);

	// Setup root path for binary shaders. Shader binaries are different 
	// for each renderer.
	switch (bgfx::getRendererType() )
	{
	default:
	case bgfx::RendererType::Direct3D9:
		s_shaderPath = "shaders/dx9/";
		break;

	case bgfx::RendererType::Direct3D11:
		s_shaderPath = "shaders/dx11/";
		break;

	case bgfx::RendererType::OpenGL:
		s_shaderPath = "shaders/glsl/";
		s_flipV = true;
		break;

	case bgfx::RendererType::OpenGLES2:
	case bgfx::RendererType::OpenGLES3:
		s_shaderPath = "shaders/gles/";
		s_flipV = true;
		break;
	}

	bgfx::UniformHandle u_time = bgfx::createUniform("u_time", bgfx::UniformType::Uniform1f);

	bgfx::ProgramHandle program = loadProgram("vs_mesh", "fs_mesh");

	Mesh mesh;
	mesh.load("meshes/bunny.bin");

	int64_t timeOffset = bx::getHPCounter();

	while (!entry::processEvents(width, height, debug, reset) )
	{
		// Set view 0 default viewport.
		bgfx::setViewRect(0, 0, 0, width, height);

		// This dummy draw call is here to make sure that view 0 is cleared
		// if no other draw calls are submitted to view 0.
		bgfx::submit(0);

		int64_t now = bx::getHPCounter();
		static int64_t last = now;
		const int64_t frameTime = now - last;
		last = now;
		const double freq = double(bx::getHPFrequency() );
		const double toMs = 1000.0/freq;
		float time = (float)( (bx::getHPCounter()-timeOffset)/double(bx::getHPFrequency() ) );
		bgfx::setUniform(u_time, &time);

		// Use debug font to print information about this example.
		bgfx::dbgTextClear();
		bgfx::dbgTextPrintf(0, 1, 0x4f, "bgfx/examples/04-mesh");
		bgfx::dbgTextPrintf(0, 2, 0x6f, "Description: Loading meshes.");
		bgfx::dbgTextPrintf(0, 3, 0x0f, "Frame: % 7.3f[ms]", double(frameTime)*toMs);

		float at[3] = { 0.0f, 1.0f, 0.0f };
		float eye[3] = { 0.0f, 1.0f, -2.5f };

		float view[16];
		float proj[16];
		mtxLookAt(view, eye, at);
		mtxProj(proj, 60.0f, float(width)/float(height), 0.1f, 100.0f);

		// Set view and projection matrix for view 0.
		bgfx::setViewTransform(0, view, proj);

		float mtx[16];
		mtxRotateXY(mtx
			, 0.0f
			, time*0.37f
			); 

		mesh.submit(program, mtx);

		// Advance to next frame. Rendering thread will be kicked to 
		// process submitted rendering primitives.
		bgfx::frame();
	}

	mesh.unload();

	// Cleanup.
	bgfx::destroyProgram(program);

	bgfx::destroyUniform(u_time);

	// Shutdown bgfx.
	bgfx::shutdown();

	return 0;
}