#include "root.h"
#include "text.h"
#include "shader.h"
#include "texture.h"
#include "node.h"
#include "material.h"
#include "assetManager.h"

#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <iostream>
#include <algorithm>
#include <ft2build.h>
#include FT_FREETYPE_H

using namespace std;

namespace vb01{
	Text::Text(string fontPath, wstring e, u16 firstChar, u16 lastChar) : entry(e){
		init();
		applyFont(fontPath, firstChar, lastChar);
	}

	Text::~Text(){
		glDeleteVertexArrays(1, &VAO);
		glDeleteBuffers(1, &VBO);
	}

	void Text::init(){
		glGenVertexArrays(1, &VAO);
		glGenBuffers(1, &VBO);

		glBindVertexArray(VAO);
		glBindBuffer(GL_ARRAY_BUFFER, VBO);

		glBufferData(GL_ARRAY_BUFFER, sizeof(float) * 6 * 4, NULL, GL_DYNAMIC_DRAW);
		glEnableVertexAttribArray(0);
		glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 4 * sizeof(float), (void*)0);

		glBindBuffer(GL_ARRAY_BUFFER, 0);
		glBindVertexArray(0);
	}

	//TODO ensure destruction of textures when unloading the asset
	void Text::applyFont(string fontPath, u16 firstChar, u16 lastChar){
		characters.clear();

		font = (FontAsset*)AssetManager::getSingleton()->getAsset(fontPath);
		FT_Face face = font->face;
		vector<int> keys;

		for (pair<int, Texture*> p : font->glyphTextures)
		    keys.push_back(p.first);

		for(u16 i = firstChar; i < lastChar; i++){
			if(FT_Load_Char(face, i, FT_LOAD_RENDER)){
				cout << "Could not load glyph\n";
				continue;
			}

			Glyph c;
			c.ch = i;
			c.size = Vector2(face->glyph->bitmap.width, face->glyph->bitmap.rows);
			c.bearing = Vector2(face->glyph->bitmap_left, face->glyph->bitmap_top);
			c.advance = face->glyph->advance.x;
			c.texId = i;

			if(find(keys.begin(), keys.end(), i) == keys.end())
				font->glyphTextures.push_back(make_pair(i, new Texture(face)));

			characters.push_back(c);
		}
	}

	void Text::update(){
		Root *root = Root::getSingleton();
		int width = root->getWidth(), height = root->getHeight();

		material->update();
		Shader *shader = material->getShader();
		shader->setVec2(Vector2(width, height), "screen");
		shader->setVec3(node->getPosition(), "pos");

		Vector2 advanceOffset = Vector2::VEC_ZERO;

		for(int i = (leftToRight ? 0 : entry.length() - 1); (leftToRight ? (i < entry.length()) : (i >= 0)); (leftToRight ? i++ : i--)){
			Glyph *glyphPtr = getGlyph(entry[i]);

			if(!glyphPtr) continue;

			int glyphTexId = -1;
			for(int j = 0; j < font->glyphTextures.size(); j++)
				if(font->glyphTextures[j].first == glyphPtr->texId){
					glyphTexId = j;
					break;
				}

			Glyph glyph = *glyphPtr;
			prepareGlyphs(glyph, glyphTexId, advanceOffset);
			Vector2 size = glyph.size, bearing = glyph.bearing;
			int numShifts = 6;

			if(horizontal)
				advanceOffset.x += node->getScale().x * (glyph.advance >> numShifts);
			else
				advanceOffset.y += node->getScale().y * (glyph.advance >> numShifts);
		}
	}

	void Text::prepareGlyphs(Glyph glyph, int glyphTexId, Vector2 advanceOffset){
		Vector3 nodePos = node->getPosition();
		Vector2 origin = Vector2(nodePos.x, nodePos.y) + (advanceOffset * scale);
		Vector3 scale = node->getScale();

		Vector2 size = Vector2(glyph.size.x * scale.x, glyph.size.y * scale.y);
		Vector2 bearing = Vector2(glyph.bearing.x * scale.x, glyph.bearing.y * scale.y);

		float data[] = {
			origin.x + bearing.x, origin.y - bearing.y, 0, 0,
			origin.x + bearing.x + size.x, origin.y - bearing.y, 1, 0,
			origin.x + bearing.x + size.x, origin.y - bearing.y + size.y, 1, 1,

			origin.x + bearing.x + size.x, origin.y - bearing.y + size.y, 1, 1,
			origin.x + bearing.x, origin.y - bearing.y + size.y, 0, 1,
			origin.x + bearing.x, origin.y - bearing.y, 0, 0
		};

		glBindVertexArray(VAO);
		glBindBuffer(GL_ARRAY_BUFFER, VBO);
		glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(data), data);

		int id = 2;
		material->getShader()->setInt(id, "textures[1].pastTexture");
		font->glyphTextures[glyphTexId].second->select(id);

		glDrawArrays(GL_TRIANGLES, 0, 6);	
	}

	Text::Glyph* Text::getGlyph(u16 ch){
		Glyph *glyph = nullptr;

		for(Glyph &g : characters)
			if(g.ch == ch)
				glyph = &g;

		return glyph;
	}
}
