#include <ft2build.h>
#include FT_FREETYPE_H
#include "Graphics.h"

#include <bx/math.h>

#include <iostream>

#define STB_IMAGE_IMPLEMENTATION
#include <stb_image.h>

namespace {
	FT_Library library;
	FT_Error error;
	FT_Face face_regular, face_bold;

	static struct PosUVVertex
	{
		f32 x;
		f32 y;
		f32 z;
		f32 u;
		f32 v;
	} quad_vert[] =
	{
		{ 0.f, 0.f, 0.0f, 0.0f, 0.0f },
		{ 0.f, 1.f, 0.0f, 0.0f, 1.0f },
		{ 1.f, 0.f, 0.0f, 1.0f, 0.0f },
		{ 1.f, 1.f, 0.0f, 1.0f, 1.0f }
	};

	static const uint16_t quad_indices[] =
	{
		0, 2, 1,
		1, 2, 3
	};

	bgfx::ShaderHandle loadShader(const char* FILENAME)
	{
		std::string shaderPath{};

		switch (bgfx::getRendererType()) {
		case bgfx::RendererType::Noop:
		case bgfx::RendererType::Direct3D9:  shaderPath = "shaders/dx9/";   break;
		case bgfx::RendererType::Direct3D11:
		case bgfx::RendererType::Direct3D12: shaderPath = "shaders/dx11/";  break;
		case bgfx::RendererType::Gnm:        shaderPath = "shaders/pssl/";  break;
		case bgfx::RendererType::Metal:      shaderPath = "shaders/metal/"; break;
		case bgfx::RendererType::OpenGL:     shaderPath = "shaders/glsl/";  break;
		case bgfx::RendererType::OpenGLES:   shaderPath = "shaders/essl/";  break;
		case bgfx::RendererType::Vulkan:     shaderPath = "shaders/spirv/"; break;
		}


		std::string filePath = shaderPath + FILENAME;

		FILE* file = fopen(filePath.c_str(), "rb");
		fseek(file, 0, SEEK_END);
		long fileSize = ftell(file);
		fseek(file, 0, SEEK_SET);

		const bgfx::Memory* mem = bgfx::alloc(fileSize + 1);
		fread(mem->data, 1, fileSize, file);
		mem->data[mem->size - 1] = '\0';
		fclose(file);

		return bgfx::createShader(mem);
	}

	bgfx::ShaderHandle a_vsh, img_vsh;
	bgfx::ShaderHandle a_fsh, img_fsh;
	bgfx::ProgramHandle a_program, img_program;
	bgfx::IndexBufferHandle ibh;
	bgfx::VertexBufferHandle vbh;
	bgfx::UniformHandle s_texColor;
	bgfx::VertexLayout pcvDecl;

	std::unordered_map<NVL::Char, bgfx::TextureHandle> cache_regular {};
	std::unordered_map<NVL::Char, bgfx::TextureHandle> cache_bold {};

	int w, h, channels;
	u8* img;
	bgfx::TextureHandle tx;
}

namespace ADVect::Graphics {
	i16 Init(u16 width, u16 height) {
		error = FT_Init_FreeType(&library);
		if (error) {
			std::cerr << "ADV: FreeType init error: " << error << std::endl;
			return -1;
		}

		error = FT_New_Face(library, "SourceHanSans-Regular.ttc", 0, &face_regular);
		error = FT_New_Face(library, "SourceHanSans-Bold.ttc", 0, &face_bold);
		if (error == FT_Err_Unknown_File_Format) {
			std::cerr << "ADV: FreeType Unknown_File_Format: " << error << std::endl;
			return -1;
		}
		else if (error) {
			std::cerr << "ADV: FreeType font loading error: " << error << std::endl;
			return -1;
		}

		error = FT_Set_Char_Size(face_regular, 0, 20 * 64, 72, 72);
		error = FT_Set_Char_Size(face_bold, 0, 20 * 64, 72, 72);
		if (error == FT_Err_Unknown_File_Format) {
			std::cerr << "ADV: FreeType Set_Char_Size error: " << error << std::endl;
			return -1;
		}

		float view[16];
		bx::mtxTranslate(view, 0.f, 0.f, 1.0f);
		float proj[16];
		bx::mtxOrtho(proj, 0.0f, width, 0.0f, height, 0.1f, 100.0f, 0.f, bgfx::getCaps()->homogeneousDepth);
		bgfx::setViewTransform(0, view, proj);

		pcvDecl.begin()
			.add(bgfx::Attrib::Position, 3, bgfx::AttribType::Float)
			.add(bgfx::Attrib::TexCoord0, 2, bgfx::AttribType::Float)
			.end();
		ibh = bgfx::createIndexBuffer(bgfx::makeRef(quad_indices, sizeof(quad_indices)));
		vbh = bgfx::createVertexBuffer(bgfx::makeRef(quad_vert, sizeof(quad_vert)), pcvDecl);

		img_vsh = loadShader("test.vert.bin");
		img_fsh = loadShader("test.frag.bin");
		img_program = bgfx::createProgram(img_vsh, img_fsh, true);

		a_vsh = loadShader("swizzle_aaaa.vert.bin");
		a_fsh = loadShader("swizzle_aaaa.frag.bin");
		a_program = bgfx::createProgram(a_vsh, a_fsh, true);

		s_texColor = bgfx::createUniform("s_texColor", bgfx::UniformType::Sampler);


		img = stbi_load("image.png", &w, &h, &channels, 0);
		if (img == NULL) {
			std::cerr << "ADV: STB IMAGE loading failed" << std::endl;
			return -1;
		}		
		const bgfx::Memory* buf = bgfx::makeRef(img, w * h * channels * sizeof(u8));
		tx = bgfx::createTexture2D(
			w,
			h,
			false,
			1,
			bgfx::TextureFormat::RGBA8,
			BGFX_TEXTURE_NONE | BGFX_SAMPLER_UVW_CLAMP,
			buf
		);

		return 0;
	}

	void Shutdown() {
		FT_Done_Face(face_regular);
		FT_Done_Face(face_bold);
		FT_Done_FreeType(library);


		bgfx::destroy(a_vsh);
		bgfx::destroy(a_fsh);
		bgfx::destroy(img_vsh);
		bgfx::destroy(img_fsh);
		bgfx::destroy(a_program);
		bgfx::destroy(img_program);
		bgfx::destroy(ibh);
		bgfx::destroy(vbh);
		bgfx::destroy(s_texColor);
		for (auto it = cache_regular .begin(); it != cache_regular.end(); it++) {
			bgfx::destroy(it->second);
		}
		for (auto it = cache_bold.begin(); it != cache_bold.end(); it++) {
			bgfx::destroy(it->second);
		}
		bgfx::destroy(tx);
	}

	// Draws quad with texture on Z = 0
	void DrawTexture(const bgfx::TextureHandle& tex, i32 pos_x, i32 pos_y, u32 w, u32 h) {
		float mtx1[16], mtx2[16], mtx3[16];
		bx::mtxTranslate(mtx1, pos_x, pos_y, 0.0f);
		bx::mtxScale(mtx2, w, h, 1.0f);
		bx::mtxMul(mtx3, mtx2, mtx1);

		bgfx::setTransform(mtx3);

		bgfx::setVertexBuffer(0, vbh);
		bgfx::setIndexBuffer(ibh);

		bgfx::setTexture(0, s_texColor, tex);

		bgfx::setState(BGFX_STATE_DEFAULT | BGFX_STATE_BLEND_NORMAL);
		bgfx::submit(0, img_program);
	}

	void DrawTextureStencilAlpha(const bgfx::TextureHandle& tex, i32 pos_x, i32 pos_y, u32 w, u32 h) {
		float mtx1[16], mtx2[16], mtx3[16];
		bx::mtxTranslate(mtx1, pos_x, pos_y, 0.0f);
		bx::mtxScale(mtx2, w, h, 1.0f);
		bx::mtxMul(mtx3, mtx2, mtx1);

		bgfx::setTransform(mtx3);

		bgfx::setVertexBuffer(0, vbh);
		bgfx::setIndexBuffer(ibh);

		bgfx::setTexture(0, s_texColor, tex);

		bgfx::setState((BGFX_STATE_DEFAULT | BGFX_STATE_BLEND_ALPHA) & ~(BGFX_STATE_WRITE_Z | BGFX_STATE_DEPTH_TEST_LESS));
		bgfx::submit(0, a_program);
	}

	void RenderString(const NVL::String& s, u32& pos_x, u32& pos_y, u32 col, u32 style_flags) {
		FT_Face active = face_regular;
		std::unordered_map<NVL::Char, bgfx::TextureHandle>* cache = &cache_regular;
		switch (style_flags) {
		case TEXT_NONE: break;
		case TEXT_BOLD: active = face_bold; cache = &cache_bold;  break;
		case TEXT_ITALIC: break;
		case TEXT_ITALIC | TEXT_BOLD: break;
		}


		FT_GlyphSlot slot = active->glyph;

		for (const auto& c : s) {
			error = FT_Load_Char(active, c, FT_LOAD_RENDER);
			if (error) continue;

			if (cache->find(c) == cache->end() && slot->bitmap.width != 0) {
				const bgfx::Memory* buf = bgfx::copy(slot->bitmap.buffer, slot->bitmap.pitch * slot->bitmap.rows);

				cache->emplace(c, bgfx::createTexture2D(
					slot->bitmap.width,
					slot->bitmap.rows,
					false,
					1,
					bgfx::TextureFormat::A8,
					BGFX_TEXTURE_NONE | BGFX_SAMPLER_UVW_CLAMP,
					buf
				));
			}

			pos_x += slot->bitmap_left;
			float ypos = pos_y - (slot->bitmap.rows - slot->bitmap_top);

			if (slot->bitmap.width != 0) {
				DrawTextureStencilAlpha((*cache)[c], pos_x, ypos, slot->bitmap.width, slot->bitmap.rows);
			}

			pos_x += slot->advance.x >> 6;
			pos_y += slot->advance.y >> 6;
		}
	}

	void RenderString(const NVL::String& s, u32&& pos_x, u32&& pos_y, u32 col, u32 style_flags) {
		u32 x = pos_x, y = pos_y;
		RenderString(s, x, y, col, style_flags);
	}

	void RenderStringMarkup(const std::vector<NVL::Environment::Variable>& s, u32 pos_x, u32 pos_y, u32 col) {
		const NVL::String& str = std::get<NVL::String>(s[0].value);

		std::vector<NVL::Environment::Markup> ms{};
		for (const NVL::Environment::Variable& markup : std::get<std::vector<NVL::Environment::Variable>>(s[1].value)) {
			ms.push_back(NVL::Environment::UnpackMarkupVariable(markup));
		}
		
		if (ms.empty()) {
			RenderString(str, pos_x, pos_y, col, TEXT_NONE);
			return;
		}

		if (ms[0].begin != 0)
			RenderString(str.substr(0, ms[0].begin), pos_x, pos_y, col, TEXT_NONE);

		// We assume markups are already sorted
		for (size_t i = 0; i < ms.size(); i++) {
			u32 style_flags = TEXT_NONE;
			const NVL::String* ruby = nullptr;

			for (const auto& e : ms[i].efs) {
				if		(e.first == u"b")	{ style_flags |= TEXT_BOLD; }
				else if (e.first == u"i")	{ style_flags |= TEXT_ITALIC; }
				else if (e.first == u"u")	{ style_flags |= TEXT_UNDERLINE; }
				else if (e.first == u"s")	{ style_flags |= TEXT_STRIKETHROUGH; }
				else if (e.first == u"o")	{ style_flags |= TEXT_OVERLINE; }
				else if (e.first == u"rb")	{ ruby = &e.second[0]; }
				else {
					std::cerr << "ADV: Unrecognized text markup: " << NVL::to_std_string(e.first) << std::endl;
				}
			}

			if (ruby != nullptr) {
				u32 temp_x = pos_x, temp_y = pos_y + 20;
				RenderString(*ruby, temp_x, temp_y, col, TEXT_NONE);
			}

			RenderString(str.substr(ms[i].begin, ms[i].end - ms[i].begin), pos_x, pos_y, col, style_flags);

			if (i != ms.size() - 1 && ms[i + 1].begin - 1 != ms[i].end)
				RenderString(str.substr(ms[i].end, ms[i + 1].begin - ms[i].end), pos_x, pos_y, col, TEXT_NONE);

		}

		if (ms.back().end != str.length())
			RenderString(str.substr(ms.back().end), pos_x, pos_y, col, TEXT_NONE);
	}

	void DrawRandomShit() {

		DrawTexture(tx, 0, -40, w, h);
	}
}