#include "Renderer2d.h"
#include "WebglContext.h"
#include "mathlib.h"

const char* orthographicVertex = 
"attribute vec4 position; \n"
"attribute vec4 color; \n"
"uniform mat4 projection; \n"
"uniform mat4 model; \n"
"varying lowp vec4 VertexColor; \n"
"void main() { \n"
"    vec4 fragmentPosition = projection * model * position; \n"
"    gl_Position = fragmentPosition; \n"
"    VertexColor = color; \n"
"    gl_PointSize = 4.0; \n"
"}";

const char* orthographicFragment = 
"varying lowp vec4 VertexColor; \n"
"void main() { \n"
"    gl_FragColor = VertexColor; \n"
"}";

void Renderer2d::load(WebglContext* inContext) {
	context = inContext;
	printf("Compiling orthographic shader...\n");
	shader = loadShader(orthographicVertex, orthographicFragment);

	useShader(shader);
	attributes.position = getShaderAttribute(shader, "position");
	attributes.color = getShaderAttribute(shader, "color");
	uniforms.projection = getShaderUniform(shader, "projection");
	uniforms.model = getShaderUniform(shader, "model");
	projection = Mat4x4().getOrthographicMatrix(0, context->width, 0, context->height);

	printf("Orthographic shader compiled.\n");
}
	
void Renderer2d::render() {
	glEnable(GL_DEPTH_TEST);
	glDepthFunc(GL_LEQUAL);
	glDepthMask(GL_TRUE);
	glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
	glClearDepth(1.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
	useShader(shader);
	setShaderMat4(uniforms.projection, projection);
}

void Renderer2d::unload() {
	glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);
	glDeleteProgram(shader);
}


void Mesh2d::load(Vertex2d* inVertices, uint32 inNumVertices, Renderer2d* renderer, GLenum loadType) {
    mode = MeshMode::Vertex;
	numVertices = inNumVertices;
	isDynamic = loadType == GL_DYNAMIC_DRAW;
	useShader(renderer->shader);

	glGenVertexArrays(1, &vao);
	glBindVertexArray(vao);

	glGenBuffers(1, &vbo);
	glBindBuffer(GL_ARRAY_BUFFER, vbo);
	glBufferData(GL_ARRAY_BUFFER, inNumVertices * sizeof(Vertex2d), &inVertices[0], loadType);

	glEnableVertexAttribArray(renderer->attributes.position);
	glVertexAttribPointer(renderer->attributes.position, 4, GL_FLOAT, GL_FALSE, sizeof(Vertex2d), (GLvoid *)0);

	glEnableVertexAttribArray(renderer->attributes.color);
	glVertexAttribPointer(renderer->attributes.color, 4, GL_FLOAT, GL_FALSE, sizeof(Vertex2d), (GLvoid *)offsetof(Vertex2d, color));

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

void Mesh2d::load(Vertex2d* inVertices, uint32 inNumVertices, GLuint* inIndices, uint32 inNumIndices, Renderer2d* renderer, GLenum loadType) {
	mode = MeshMode::Index;
	numVertices = inNumVertices;
	numIndices = inNumIndices;
	isDynamic = loadType == GL_DYNAMIC_DRAW;
	useShader(renderer->shader);

	glGenVertexArrays(1, &vao);
	glBindVertexArray(vao);

	glGenBuffers(1, &vbo);
	glBindBuffer(GL_ARRAY_BUFFER, vbo);
	glBufferData(GL_ARRAY_BUFFER, inNumVertices * sizeof(Vertex2d), &inVertices[0], loadType);

	glEnableVertexAttribArray(renderer->attributes.position);
	glVertexAttribPointer(renderer->attributes.position, 4, GL_FLOAT, GL_FALSE, sizeof(Vertex2d), (GLvoid *)0);

	glEnableVertexAttribArray(renderer->attributes.color);
	glVertexAttribPointer(renderer->attributes.color, 4, GL_FLOAT, GL_FALSE, sizeof(Vertex2d), (GLvoid *)offsetof(Vertex2d, color));

	glGenBuffers(1, &ebo);
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
	glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(GLuint) * numIndices, inIndices, loadType);

	glBindVertexArray(0);
}

void Mesh2d::render(Renderer2d* renderer, GLenum drawType) {
	setShaderMat4(renderer->uniforms.model, model);

	glBindVertexArray(vao);

	switch (mode) {
	case MeshMode::Vertex:
		glDrawArrays(drawType, 0, numVertices);
		break;
	case MeshMode::Index:
		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
		glDrawElements(drawType, numIndices, GL_UNSIGNED_INT, 0);
		break;
	}

	glBindVertexArray(0);
}

void Mesh2d::unload() {
	glDeleteVertexArrays(1, &vao);
	glDeleteBuffers(1, &vbo);

	if (mode == MeshMode::Index) {
		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
		glDeleteBuffers(1, &ebo);
	}
}

void Mesh2d::updateVertices(Vertex2d* vertices) {
	if (!isDynamic) {
		printf("Cannot update vertices on a non-dynamic mesh.\n");
		return;
	}
	
	glBindBuffer(GL_ARRAY_BUFFER, vbo);
    glBufferSubData(GL_ARRAY_BUFFER, 0, numVertices * sizeof(Vertex2d), &vertices[0]);
}