/*
 * Copyright 2014-2015 Daniel Collin. All rights reserved.
 * License: https://github.com/bkaradzic/bgfx#license-bsd-2-clause
 */

#include <bgfx/bgfx.h>
#include <bgfx/embedded_shader.h>
#include <bx/allocator.h>
#include <bx/math.h>
#include <bx/timer.h>
#include <ocornut-imgui/imgui.h>

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

#ifndef USE_ENTRY
#	if defined(SCI_NAMESPACE)
#		define USE_ENTRY 1
#	else
#		define USE_ENTRY 0
#	endif // defined(SCI_NAMESPACE)
#endif // USE_ENTRY

#if USE_ENTRY
#	include "../entry/entry.h"
#endif // USE_ENTRY

#if defined(SCI_NAMESPACE)
#	include "../entry/input.h"
#	include "scintilla.h"
#endif // defined(SCI_NAMESPACE)

#include "vs_ocornut_imgui.bin.h"
#include "fs_ocornut_imgui.bin.h"
#include "vs_imgui_image.bin.h"
#include "fs_imgui_image.bin.h"

#include "roboto_regular.ttf.h"
#include "robotomono_regular.ttf.h"
#include "icons_kenney.ttf.h"
#include "icons_font_awesome.ttf.h"

static const bgfx::EmbeddedShader s_embeddedShaders[] =
{
	BGFX_EMBEDDED_SHADER(vs_ocornut_imgui),
	BGFX_EMBEDDED_SHADER(fs_ocornut_imgui),
	BGFX_EMBEDDED_SHADER(vs_imgui_image),
	BGFX_EMBEDDED_SHADER(fs_imgui_image),

	BGFX_EMBEDDED_SHADER_END()
};

struct FontRangeMerge
{
	const void* data;
	size_t      size;
	ImWchar     ranges[3];
};

static FontRangeMerge s_fontRangeMerge[] =
{
	{ s_iconsKenneyTtf,      sizeof(s_iconsKenneyTtf),      { ICON_MIN_KI, ICON_MAX_KI, 0 } },
	{ s_iconsFontAwesomeTtf, sizeof(s_iconsFontAwesomeTtf), { ICON_MIN_FA, ICON_MAX_FA, 0 } },
};

static void* memAlloc(size_t _size);
static void memFree(void* _ptr);

struct OcornutImguiContext
{
	static void renderDrawLists(ImDrawData* _drawData);

	void render(ImDrawData* _drawData)
	{
		const ImGuiIO& io = ImGui::GetIO();
		const float width  = io.DisplaySize.x;
		const float height = io.DisplaySize.y;

		bgfx::setViewName(m_viewId, "ImGui");
		bgfx::setViewMode(m_viewId, bgfx::ViewMode::Sequential);

		const bgfx::HMD*  hmd  = bgfx::getHMD();
		const bgfx::Caps* caps = bgfx::getCaps();
		if (NULL != hmd && 0 != (hmd->flags & BGFX_HMD_RENDERING) )
		{
			float proj[16];
			bx::mtxProj(proj, hmd->eye[0].fov, 0.1f, 100.0f, bgfx::getCaps()->homogeneousDepth);

			static float time = 0.0f;
			time += 0.05f;

			const float dist = 10.0f;
			const float offset0 = -proj[8] + (hmd->eye[0].viewOffset[0] / dist * proj[0]);
			const float offset1 = -proj[8] + (hmd->eye[1].viewOffset[0] / dist * proj[0]);

			float ortho[2][16];
			const float viewOffset = width/4.0f;
			const float viewWidth  = width/2.0f;
			bx::mtxOrtho(ortho[0], viewOffset, viewOffset + viewWidth, height, 0.0f, 0.0f, 1000.0f, offset0, caps->homogeneousDepth);
			bx::mtxOrtho(ortho[1], viewOffset, viewOffset + viewWidth, height, 0.0f, 0.0f, 1000.0f, offset1, caps->homogeneousDepth);
			bgfx::setViewTransform(m_viewId, NULL, ortho[0], BGFX_VIEW_STEREO, ortho[1]);
			bgfx::setViewRect(m_viewId, 0, 0, hmd->width, hmd->height);
		}
		else
		{
			float ortho[16];
			bx::mtxOrtho(ortho, 0.0f, width, height, 0.0f, 0.0f, 1000.0f, 0.0f, caps->homogeneousDepth);
			bgfx::setViewTransform(m_viewId, NULL, ortho);
			bgfx::setViewRect(m_viewId, 0, 0, uint16_t(width), uint16_t(height) );
		}

		// Render command lists
		for (int32_t ii = 0, num = _drawData->CmdListsCount; ii < num; ++ii)
		{
			bgfx::TransientVertexBuffer tvb;
			bgfx::TransientIndexBuffer tib;

			const ImDrawList* drawList = _drawData->CmdLists[ii];
			uint32_t numVertices = (uint32_t)drawList->VtxBuffer.size();
			uint32_t numIndices  = (uint32_t)drawList->IdxBuffer.size();

			if (!checkAvailTransientBuffers(numVertices, m_decl, numIndices) )
			{
				// not enough space in transient buffer just quit drawing the rest...
				break;
			}

			bgfx::allocTransientVertexBuffer(&tvb, numVertices, m_decl);
			bgfx::allocTransientIndexBuffer(&tib, numIndices);

			ImDrawVert* verts = (ImDrawVert*)tvb.data;
			bx::memCopy(verts, drawList->VtxBuffer.begin(), numVertices * sizeof(ImDrawVert) );

			ImDrawIdx* indices = (ImDrawIdx*)tib.data;
			bx::memCopy(indices, drawList->IdxBuffer.begin(), numIndices * sizeof(ImDrawIdx) );

			uint32_t offset = 0;
			for (const ImDrawCmd* cmd = drawList->CmdBuffer.begin(), *cmdEnd = drawList->CmdBuffer.end(); cmd != cmdEnd; ++cmd)
			{
				if (cmd->UserCallback)
				{
					cmd->UserCallback(drawList, cmd);
				}
				else if (0 != cmd->ElemCount)
				{
					uint64_t state = 0
						| BGFX_STATE_RGB_WRITE
						| BGFX_STATE_ALPHA_WRITE
						| BGFX_STATE_MSAA
						;

					bgfx::TextureHandle th = m_texture;
					bgfx::ProgramHandle program = m_program;

					if (NULL != cmd->TextureId)
					{
						union { ImTextureID ptr; struct { bgfx::TextureHandle handle; uint8_t flags; uint8_t mip; } s; } texture = { cmd->TextureId };
						state |= 0 != (IMGUI_FLAGS_ALPHA_BLEND & texture.s.flags)
							? BGFX_STATE_BLEND_FUNC(BGFX_STATE_BLEND_SRC_ALPHA, BGFX_STATE_BLEND_INV_SRC_ALPHA)
							: BGFX_STATE_NONE
							;
						th = texture.s.handle;
						if (0 != texture.s.mip)
						{
							const float lodEnabled[4] = { float(texture.s.mip), 1.0f, 0.0f, 0.0f };
							bgfx::setUniform(u_imageLodEnabled, lodEnabled);
							program = m_imageProgram;
						}
					}
					else
					{
						state |= BGFX_STATE_BLEND_FUNC(BGFX_STATE_BLEND_SRC_ALPHA, BGFX_STATE_BLEND_INV_SRC_ALPHA);
					}

					const uint16_t xx = uint16_t(bx::max(cmd->ClipRect.x, 0.0f) );
					const uint16_t yy = uint16_t(bx::max(cmd->ClipRect.y, 0.0f) );
					bgfx::setScissor(xx, yy
							, uint16_t(bx::min(cmd->ClipRect.z, 65535.0f)-xx)
							, uint16_t(bx::min(cmd->ClipRect.w, 65535.0f)-yy)
							);

					bgfx::setState(state);
					bgfx::setTexture(0, s_tex, th);
					bgfx::setVertexBuffer(0, &tvb, 0, numVertices);
					bgfx::setIndexBuffer(&tib, offset, cmd->ElemCount);
					bgfx::submit(cmd->ViewId, program);
				}

				offset += cmd->ElemCount;
			}
		}
	}

	void create(float _fontSize, bx::AllocatorI* _allocator)
	{
		m_allocator = _allocator;

		if (NULL == _allocator)
		{
			static bx::DefaultAllocator allocator;
			m_allocator = &allocator;
		}

		m_viewId = 255;
		m_lastScroll = 0;
		m_last = bx::getHPCounter();

		ImGuiIO& io = ImGui::GetIO();
		io.RenderDrawListsFn = renderDrawLists;
		io.MemAllocFn = memAlloc;
		io.MemFreeFn  = memFree;

		io.DisplaySize = ImVec2(1280.0f, 720.0f);
		io.DeltaTime   = 1.0f / 60.0f;
		io.IniFilename = NULL;

		setupStyle(true);

#if defined(SCI_NAMESPACE)
		io.KeyMap[ImGuiKey_Tab]        = (int)entry::Key::Tab;
		io.KeyMap[ImGuiKey_LeftArrow]  = (int)entry::Key::Left;
		io.KeyMap[ImGuiKey_RightArrow] = (int)entry::Key::Right;
		io.KeyMap[ImGuiKey_UpArrow]    = (int)entry::Key::Up;
		io.KeyMap[ImGuiKey_DownArrow]  = (int)entry::Key::Down;
		io.KeyMap[ImGuiKey_Home]       = (int)entry::Key::Home;
		io.KeyMap[ImGuiKey_End]        = (int)entry::Key::End;
		io.KeyMap[ImGuiKey_Delete]     = (int)entry::Key::Delete;
		io.KeyMap[ImGuiKey_Backspace]  = (int)entry::Key::Backspace;
		io.KeyMap[ImGuiKey_Enter]      = (int)entry::Key::Return;
		io.KeyMap[ImGuiKey_Escape]     = (int)entry::Key::Esc;
		io.KeyMap[ImGuiKey_A]          = (int)entry::Key::KeyA;
		io.KeyMap[ImGuiKey_C]          = (int)entry::Key::KeyC;
		io.KeyMap[ImGuiKey_V]          = (int)entry::Key::KeyV;
		io.KeyMap[ImGuiKey_X]          = (int)entry::Key::KeyX;
		io.KeyMap[ImGuiKey_Y]          = (int)entry::Key::KeyY;
		io.KeyMap[ImGuiKey_Z]          = (int)entry::Key::KeyZ;
#endif // defined(SCI_NAMESPACE)

		bgfx::RendererType::Enum type = bgfx::getRendererType();
		m_program = bgfx::createProgram(
			  bgfx::createEmbeddedShader(s_embeddedShaders, type, "vs_ocornut_imgui")
			, bgfx::createEmbeddedShader(s_embeddedShaders, type, "fs_ocornut_imgui")
			, true
			);

		u_imageLodEnabled = bgfx::createUniform("u_imageLodEnabled", bgfx::UniformType::Vec4);
		m_imageProgram = bgfx::createProgram(
			  bgfx::createEmbeddedShader(s_embeddedShaders, type, "vs_imgui_image")
			, bgfx::createEmbeddedShader(s_embeddedShaders, type, "fs_imgui_image")
			, true
			);

		m_decl
			.begin()
			.add(bgfx::Attrib::Position,  2, bgfx::AttribType::Float)
			.add(bgfx::Attrib::TexCoord0, 2, bgfx::AttribType::Float)
			.add(bgfx::Attrib::Color0,    4, bgfx::AttribType::Uint8, true)
			.end();

		s_tex = bgfx::createUniform("s_tex", bgfx::UniformType::Int1);

		uint8_t* data;
		int32_t width;
		int32_t height;
		{
			ImFontConfig config;
			config.FontDataOwnedByAtlas = false;
			config.MergeMode = false;
//			config.MergeGlyphCenterV = true;

			const ImWchar* ranges = io.Fonts->GetGlyphRangesCyrillic();
			m_font[ImGui::Font::Regular] = io.Fonts->AddFontFromMemoryTTF( (void*)s_robotoRegularTtf,     sizeof(s_robotoRegularTtf),     _fontSize,      &config, ranges);
			m_font[ImGui::Font::Mono   ] = io.Fonts->AddFontFromMemoryTTF( (void*)s_robotoMonoRegularTtf, sizeof(s_robotoMonoRegularTtf), _fontSize-3.0f, &config, ranges);

			config.MergeMode = true;
			config.DstFont   = m_font[ImGui::Font::Regular];

			for (uint32_t ii = 0; ii < BX_COUNTOF(s_fontRangeMerge); ++ii)
			{
				const FontRangeMerge& frm = s_fontRangeMerge[ii];

				io.Fonts->AddFontFromMemoryTTF( (void*)frm.data
						, (int)frm.size
						, _fontSize-3.0f
						, &config
						, frm.ranges
						);
			}
		}

		io.Fonts->GetTexDataAsRGBA32(&data, &width, &height);

		m_texture = bgfx::createTexture2D(
			  (uint16_t)width
			, (uint16_t)height
			, false
			, 1
			, bgfx::TextureFormat::BGRA8
			, 0
			, bgfx::copy(data, width*height*4)
			);
	}

	void destroy()
	{
		ImGui::Shutdown();

		bgfx::destroy(s_tex);
		bgfx::destroy(m_texture);

		bgfx::destroy(u_imageLodEnabled);
		bgfx::destroy(m_imageProgram);
		bgfx::destroy(m_program);

		m_allocator = NULL;
	}

	void setupStyle(bool _dark)
	{
		// Doug Binks' darl color scheme
		// https://gist.github.com/dougbinks/8089b4bbaccaaf6fa204236978d165a9
		ImGuiStyle& style = ImGui::GetStyle();
		if (_dark)
		{
			ImGui::StyleColorsDark(&style);
		}
		else
		{
			ImGui::StyleColorsLight(&style);
		}

		style.FrameRounding    = 4.0f;
		style.WindowBorderSize = 0.0f;
	}

	void beginFrame(
		  int32_t _mx
		, int32_t _my
		, uint8_t _button
		, int32_t _scroll
		, int _width
		, int _height
		, char _inputChar
		, bgfx::ViewId _viewId
		)
	{
		m_viewId = _viewId;

		ImGuiIO& io = ImGui::GetIO();
		if (_inputChar < 0x7f)
		{
			io.AddInputCharacter(_inputChar); // ASCII or GTFO! :(
		}

		io.DisplaySize = ImVec2( (float)_width, (float)_height);

		const int64_t now = bx::getHPCounter();
		const int64_t frameTime = now - m_last;
		m_last = now;
		const double freq = double(bx::getHPFrequency() );
		io.DeltaTime = float(frameTime/freq);

		io.MousePos = ImVec2( (float)_mx, (float)_my);
		io.MouseDown[0] = 0 != (_button & IMGUI_MBUT_LEFT);
		io.MouseDown[1] = 0 != (_button & IMGUI_MBUT_RIGHT);
		io.MouseDown[2] = 0 != (_button & IMGUI_MBUT_MIDDLE);
		io.MouseWheel = (float)(_scroll - m_lastScroll);
		m_lastScroll = _scroll;

#if defined(SCI_NAMESPACE)
		uint8_t modifiers = inputGetModifiersState();
		io.KeyShift = 0 != (modifiers & (entry::Modifier::LeftShift | entry::Modifier::RightShift) );
		io.KeyCtrl  = 0 != (modifiers & (entry::Modifier::LeftCtrl  | entry::Modifier::RightCtrl ) );
		io.KeyAlt   = 0 != (modifiers & (entry::Modifier::LeftAlt   | entry::Modifier::RightAlt  ) );
		for (int32_t ii = 0; ii < (int32_t)entry::Key::Count; ++ii)
		{
			io.KeysDown[ii] = inputGetKeyState(entry::Key::Enum(ii) );
		}
#endif // defined(SCI_NAMESPACE)

		ImGui::NewFrame();
		ImGui::PushStyleVar(ImGuiStyleVar_ViewId, (float)_viewId);

		ImGuizmo::BeginFrame();
	}

	void endFrame()
	{
		ImGui::PopStyleVar(1);
		ImGui::Render();
	}

	bx::AllocatorI*     m_allocator;
	bgfx::VertexDecl    m_decl;
	bgfx::ProgramHandle m_program;
	bgfx::ProgramHandle m_imageProgram;
	bgfx::TextureHandle m_texture;
	bgfx::UniformHandle s_tex;
	bgfx::UniformHandle u_imageLodEnabled;
	ImFont* m_font[ImGui::Font::Count];
	int64_t m_last;
	int32_t m_lastScroll;
	bgfx::ViewId m_viewId;
};

static OcornutImguiContext s_ctx;

static void* memAlloc(size_t _size)
{
	return BX_ALLOC(s_ctx.m_allocator, _size);
}

static void memFree(void* _ptr)
{
	BX_FREE(s_ctx.m_allocator, _ptr);
}

void OcornutImguiContext::renderDrawLists(ImDrawData* _drawData)
{
	s_ctx.render(_drawData);
}

void imguiCreate(float _fontSize, bx::AllocatorI* _allocator)
{
	s_ctx.create(_fontSize, _allocator);
}

void imguiDestroy()
{
	s_ctx.destroy();
}

void imguiBeginFrame(int32_t _mx, int32_t _my, uint8_t _button, int32_t _scroll, uint16_t _width, uint16_t _height, char _inputChar, bgfx::ViewId _viewId)
{
	s_ctx.beginFrame(_mx, _my, _button, _scroll, _width, _height, _inputChar, _viewId);
}

void imguiEndFrame()
{
	s_ctx.endFrame();
}

namespace ImGui
{
	void PushFont(Font::Enum _font)
	{
		PushFont(s_ctx.m_font[_font]);
	}
} // namespace ImGui

BX_PRAGMA_DIAGNOSTIC_IGNORED_MSVC(4505); // error C4505: '' : unreferenced local function has been removed
BX_PRAGMA_DIAGNOSTIC_IGNORED_CLANG_GCC("-Wunused-function"); // warning: ‘int rect_width_compare(const void*, const void*)’ defined but not used
BX_PRAGMA_DIAGNOSTIC_PUSH();
BX_PRAGMA_DIAGNOSTIC_IGNORED_CLANG("-Wunknown-pragmas")
//BX_PRAGMA_DIAGNOSTIC_IGNORED_CLANG_GCC("-Wunused-but-set-variable"); // warning: variable ‘L1’ set but not used
BX_PRAGMA_DIAGNOSTIC_IGNORED_CLANG_GCC("-Wtype-limits"); // warning: comparison is always true due to limited range of data type
#define STBTT_malloc(_size, _userData) memAlloc(_size)
#define STBTT_free(_ptr, _userData) memFree(_ptr)
#define STB_RECT_PACK_IMPLEMENTATION
#include <stb/stb_rect_pack.h>
#define STB_TRUETYPE_IMPLEMENTATION
#include <stb/stb_truetype.h>
BX_PRAGMA_DIAGNOSTIC_POP();