#include "Terrain.hpp"
#include "../Util/Logger.hpp"
#include <vector>
using namespace Graphics;

Terrain::Terrain() : m_vbo(0),m_ibo(0)
{
	glGenBuffers(1, &m_vbo);
	glGenBuffers(1, &m_ibo);

	m_shader.LoadFromFile(Shader::VERTEX_SHADER, "./shader/terrain.vert");
	m_shader.LoadFromFile(Shader::FRAGMENT_SHADER, "./shader/terrain.frag");
	m_shader.Link();

	m_shader.AddUniform("MVP");
	m_shader.AddAttribute("pos");
	m_shader.AddAttribute("color");
}

Terrain::~Terrain()
{
	glDeleteBuffers(1, &m_vbo);
	glDeleteBuffers(1, &m_ibo);
}

void Terrain::Render(const glm::mat4& mvp)
{
	m_shader.Use();
	glBindBuffer(GL_ARRAY_BUFFER, m_vbo);
	glEnableVertexAttribArray(m_shader.Attribute("pos"));
	glEnableVertexAttribArray(m_shader.Attribute("color"));

	glVertexAttribPointer(m_shader.Attribute("pos"),3,GL_FLOAT,
		GL_FALSE,sizeof(Vertex),	(void*)offsetof(Vertex, pos));

	glVertexAttribPointer(m_shader.Attribute("color"),3,GL_FLOAT,
		GL_FALSE,sizeof(Vertex),(void*)offsetof(Vertex,color));

	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_ibo);
	glUniformMatrix4fv(m_shader.Uniform("MVP"), 1, false, &mvp[0][0]);

	glDrawElements(GL_TRIANGLES,  m_indicecount,
				GL_UNSIGNED_SHORT,nullptr);


	glDisableVertexAttribArray(m_shader.Attribute("pos"));
	glDisableVertexAttribArray(m_shader.Attribute("color"));
	m_shader.UnUse();
}

void Terrain::Create(const glm::ivec2& size)
{
	//Create vertices first
	std::vector<Vertex> vertices;

	for (auto y = 0; y < size.y; ++y)
	{
		for (auto x = 0; x < size.x; ++x)
		{
			auto offset = y*size.x + x;
			Vertex vert;
			vert.pos = glm::vec3(x, y, 0.0f);
			vert.color = glm::vec3(1.0f, 1.0f, 1.0f);
			vertices.push_back(vert);
		}
	}

	m_vertexcount = vertices.size();
	glBindBuffer(GL_ARRAY_BUFFER, m_vbo);
	glBufferData(GL_ARRAY_BUFFER, m_vertexcount * sizeof(Vertex), &vertices[0], GL_STATIC_DRAW);

	std::vector<uint16_t> indices;
	for (auto y = 0; y < size.y-1; ++y)
	{
		for (auto x = 0; x < size.x-1; ++x)
		{
			//lower left triangle
			indices.push_back((y + 1)*size.x + x);
			indices.push_back(y*size.x + x);
			indices.push_back(y*size.x + x+1);
			//upper right triangle
			indices.push_back((y + 1)*size.x + x);
			indices.push_back((y + 1)*size.x + x+1);
			indices.push_back(y*size.x + x + 1);
		}
	}
	m_indicecount = indices.size();
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_ibo);
	glBufferData(GL_ELEMENT_ARRAY_BUFFER, m_indicecount * sizeof(uint16_t), &indices[0], GL_STATIC_DRAW);
}