/*
 * Copyright 2011-2023 Branimir Karadzic. All rights reserved.
 * License: https://github.com/bkaradzic/bgfx/blob/master/LICENSE
 */

#include "common.h"
#include "bgfx_utils.h"
#include "imgui/imgui.h"

namespace
{

struct PosVertex
{
	float m_x;
	float m_y;
	float m_z;

	static void init()
	{
		ms_layout
			.begin()
			.add(bgfx::Attrib::Position, 3, bgfx::AttribType::Float)
			.end();
	};

	static bgfx::VertexLayout ms_layout;
};

bgfx::VertexLayout PosVertex::ms_layout;

struct ColorVertex
{
	uint32_t m_abgr;

	static void init()
	{
		ms_layout
			.begin()
			.add(bgfx::Attrib::Color0, 4, bgfx::AttribType::Uint8, true)
			.end();
	};

	static bgfx::VertexLayout ms_layout;
};

bgfx::VertexLayout ColorVertex::ms_layout;

static PosVertex s_cubePosVertices[] =
{
	{-1.0f,  1.0f,  1.0f },
	{ 1.0f,  1.0f,  1.0f },
	{-1.0f, -1.0f,  1.0f },
	{ 1.0f, -1.0f,  1.0f },
	{-1.0f,  1.0f, -1.0f },
	{ 1.0f,  1.0f, -1.0f },
	{-1.0f, -1.0f, -1.0f },
	{ 1.0f, -1.0f, -1.0f },
};

static ColorVertex s_cubeColorVertices[] =
{
	{ 0xff000000 },
	{ 0xff0000ff },
	{ 0xff00ff00 },
	{ 0xff00ffff },
	{ 0xffff0000 },
	{ 0xffff00ff },
	{ 0xffffff00 },
	{ 0xffffffff },
};

static const uint16_t s_cubeTriList[] =
{
	0, 1, 2, // 0
	1, 3, 2,
	4, 6, 5, // 2
	5, 6, 7,
	0, 2, 4, // 4
	4, 2, 6,
	1, 5, 3, // 6
	5, 7, 3,
	0, 4, 1, // 8
	4, 5, 1,
	2, 3, 6, // 10
	6, 3, 7,
};

static const uint16_t s_cubeTriStrip[] =
{
	0, 1, 2,
	3,
	7,
	1,
	5,
	0,
	4,
	2,
	6,
	7,
	4,
	5,
};

class ExampleMvs : public entry::AppI
{
public:
	ExampleMvs(const char* _name, const char* _description, const char* _url)
		: entry::AppI(_name, _description, _url)
	{
	}

	void init(int32_t _argc, const char* const* _argv, uint32_t _width, uint32_t _height) override
	{
		BX_UNUSED(s_cubeTriList, s_cubeTriStrip);

		Args args(_argc, _argv);

		m_width  = _width;
		m_height = _height;
		m_debug  = BGFX_DEBUG_NONE;
		m_reset  = BGFX_RESET_VSYNC;

		bgfx::Init init;
		init.type     = args.m_type;
		init.vendorId = args.m_pciId;
		init.platformData.nwh  = entry::getNativeWindowHandle(entry::kDefaultWindowHandle);
		init.platformData.ndt  = entry::getNativeDisplayHandle();
		init.platformData.type = entry::getNativeWindowHandleType();
		init.resolution.width  = m_width;
		init.resolution.height = m_height;
		init.resolution.reset  = m_reset;
		bgfx::init(init);

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

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

		// Create vertex stream declaration.
		PosVertex::init();
		ColorVertex::init();

		// Create static vertex buffer.
		m_vbh[0] = bgfx::createVertexBuffer(
				// Static data can be passed with bgfx::makeRef
				  bgfx::makeRef(s_cubePosVertices, sizeof(s_cubePosVertices) )
				, PosVertex::ms_layout
				);

		m_vbh[1] = bgfx::createVertexBuffer(
				// Static data can be passed with bgfx::makeRef
				  bgfx::makeRef(s_cubeColorVertices, sizeof(s_cubeColorVertices) )
				, ColorVertex::ms_layout
				);

		// Create static index buffer.
		m_ibh = bgfx::createIndexBuffer(
				// Static data can be passed with bgfx::makeRef
				bgfx::makeRef(s_cubeTriStrip, sizeof(s_cubeTriStrip) )
				);

		// Create program from shaders.
		m_program = loadProgram("vs_cubes", "fs_cubes");

		m_timeOffset = bx::getHPCounter();

		imguiCreate();
	}

	virtual int shutdown() override
	{
		imguiDestroy();

		// Cleanup.
		bgfx::destroy(m_ibh);
		bgfx::destroy(m_vbh[0]);
		bgfx::destroy(m_vbh[1]);
		bgfx::destroy(m_program);

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

		return 0;
	}

	bool update() override
	{
		if (!entry::processEvents(m_width, m_height, m_debug, m_reset, &m_mouseState) )
		{
			imguiBeginFrame(m_mouseState.m_mx
				,  m_mouseState.m_my
				, (m_mouseState.m_buttons[entry::MouseButton::Left  ] ? IMGUI_MBUT_LEFT   : 0)
				| (m_mouseState.m_buttons[entry::MouseButton::Right ] ? IMGUI_MBUT_RIGHT  : 0)
				| (m_mouseState.m_buttons[entry::MouseButton::Middle] ? IMGUI_MBUT_MIDDLE : 0)
				,  m_mouseState.m_mz
				, uint16_t(m_width)
				, uint16_t(m_height)
				);

			showExampleDialog(this);

			imguiEndFrame();

			float time = (float)( (bx::getHPCounter()-m_timeOffset)/double(bx::getHPFrequency() ) );

			const bx::Vec3 at  = { 0.0f, 0.0f,   0.0f };
			const bx::Vec3 eye = { 0.0f, 0.0f, -35.0f };

			// Set view and projection matrix for view 0.
			{
				float view[16];
				bx::mtxLookAt(view, eye, at);

				float proj[16];
				bx::mtxProj(proj, 60.0f, float(m_width)/float(m_height), 0.1f, 100.0f, bgfx::getCaps()->homogeneousDepth);
				bgfx::setViewTransform(0, view, proj);

				// Set view 0 default viewport.
				bgfx::setViewRect(0, 0, 0, uint16_t(m_width), uint16_t(m_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::touch(0);

			// Submit 11x11 cubes.
			for (uint32_t yy = 0; yy < 11; ++yy)
			{
				for (uint32_t xx = 0; xx < 11; ++xx)
				{
					float mtx[16];
					bx::mtxRotateXY(mtx, time + xx*0.21f, time + yy*0.37f);
					mtx[12] = -15.0f + float(xx)*3.0f;
					mtx[13] = -15.0f + float(yy)*3.0f;
					mtx[14] = 0.0f;

					// Set model matrix for rendering.
					bgfx::setTransform(mtx);

					// Set vertex and index buffer.
					bgfx::setVertexBuffer(0, m_vbh[0]);
					bgfx::setVertexBuffer(1, m_vbh[1]);
					bgfx::setIndexBuffer(m_ibh);

					// Set render states.
					bgfx::setState(0
						| BGFX_STATE_DEFAULT
						| BGFX_STATE_PT_TRISTRIP
						);

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

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

			return true;
		}

		return false;
	}

	entry::MouseState m_mouseState;

	uint32_t m_width;
	uint32_t m_height;
	uint32_t m_debug;
	uint32_t m_reset;
	bgfx::VertexBufferHandle m_vbh[2];
	bgfx::IndexBufferHandle m_ibh;
	bgfx::ProgramHandle m_program;
	int64_t m_timeOffset;
};

} // namespace

ENTRY_IMPLEMENT_MAIN(
	  ExampleMvs
	, "34-mvs"
	, "Multiple vertex streams."
	, "https://bkaradzic.github.io/bgfx/examples.html#mvs"
	);