#define GLM_ENABLE_EXPERIMENTAL

#include<glm/glm.hpp>
#include<glm/gtc/matrix_transform.hpp>
#include<glm/gtc/type_ptr.hpp>
#include <glm/gtx/hash.hpp>
#include <algorithm>
#include <unordered_map>
#include <vector>
#include "game.h"
#include "tiny_obj_loader.h"

namespace std {
	template<> struct hash<vertex> {
		size_t operator()(vertex const& v) const {
			return hash<glm::vec3>()(v.pos) ^ (hash<glm::vec2>()(v.tex_coord) << 1);
		}
	};
}

int loadModel(std::vector<vertex> &vertices, std::vector<uint32_t> &indices, const char *filename){
	tinyobj::attrib_t attrib;
	std::vector<tinyobj::shape_t> shapes;
	std::vector<tinyobj::material_t> materials;
	std::string warn, err;
	if(!tinyobj::LoadObj(&attrib, &shapes, &materials, &err, filename)){
		printf("Loading failed!  %s\n", err.c_str());
		return 1;
	}

	std::unordered_map<vertex, uint32_t> uniqueVertices = {};

	for(const auto& shape : shapes){
		for(const auto& index : shape.mesh.indices){
			vertex new_vertex = {};
			new_vertex.pos = {
				attrib.vertices[3 * index.vertex_index + 0],
				attrib.vertices[3 * index.vertex_index + 1],
				attrib.vertices[3 * index.vertex_index + 2]

			};		
			new_vertex.tex_coord = {
				attrib.texcoords[2 * index.texcoord_index + 0],
				1.0f - attrib.texcoords[2 * index.texcoord_index + 1]
			};
			if(uniqueVertices.count(new_vertex) == 0){
				uniqueVertices[new_vertex] = (uint32_t)vertices.size();
				vertices.push_back(new_vertex);
			}
			indices.push_back(uniqueVertices[new_vertex]);
		}
	}
	return 0;
}