#include "Renderer3d.h"
#include "Camera3d.h"
#include "WebglContext.h"

const char* vertexSrc =
	"attribute vec3 position;\n"
	"attribute vec3 normal;\n"
	"attribute vec4 color;\n"
	"uniform mat4 projection;\n"
	"uniform mat4 view;\n"
	"uniform mat4 model;\n"
	"varying lowp vec4 VertexColor;\n"
	"varying lowp vec3 VertexNormal;\n"
	"void main() { \n"
	"    vec4 fragmentPosition = projection * view * model * vec4(position, 1);"
	"    gl_Position = fragmentPosition;\n"
	"    VertexColor = color;\n"
    "	 mat3 normalMatrix = mat3(model);\n"
	"    VertexNormal = normalize(normalMatrix * normal);\n"
	"}\n";

const char* fragmentSrc = 
	"precision mediump float;\n"
	"varying lowp vec4 VertexColor; \n"
	"varying lowp vec3 VertexNormal; \n"
	"vec4 ambientColor = vec4(0.2, 0.2, 0.2, 1.0);\n"
    "vec3 lightDirection = vec3(0.0, 1.0, 0.0);\n"
    "vec4 lightColor = vec4(0.7, 0.7, 0.7, 1.0);\n"
	"void main() { \n"
	"	 vec4 finalColor = VertexColor * ambientColor;\n"
    "    float normalDotDir = max(0.0, dot(VertexNormal, lightDirection));\n"
    "    if (normalDotDir <= 0.0001) {"
	"		finalColor += vec4(0, 0, 0, 0);"
	"	 }\n"
    "    else {\n"
    "        float cosTheta = clamp(normalDotDir, 0.0, 1.0);\n"
    "        vec4 diffuseFactor = VertexColor * cosTheta;\n"
	"        finalColor += lightColor * diffuseFactor; \n"
    "    }\n"
	"    gl_FragColor = finalColor;\n"
	"}";


void Renderer3d::load(WebglContext* context) {
	printf("Compiling 3d shader...\n");

	shader = loadShader(vertexSrc, fragmentSrc);

	useShader(shader);
	attributes.position = getShaderAttribute(shader, "position");
	attributes.color = getShaderAttribute(shader, "color");
	attributes.normal = getShaderAttribute(shader, "normal");

	uniforms.projection = getShaderUniform(shader, "projection");
	uniforms.view = getShaderUniform(shader, "view");
	uniforms.model = getShaderUniform(shader, "model");

	printf("3d shader compiled.\n");
}

void Renderer3d::render(Camera3d* camera) {
	glEnable(GL_DEPTH_TEST);
	glDepthFunc(GL_LEQUAL);
	glDepthMask(GL_TRUE);
	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
	glEnable(GL_BLEND);
	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, camera->projection);
	setShaderMat4(uniforms.view, camera->view);
}

void Renderer3d::unload() {
	glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);
	glDeleteProgram(shader);
}

void Mesh3d::load(Vertex3d* inVertices, uint32 inNumVertices, uint32* inIndices, uint32 inNumIndices, Renderer3d* renderer) {
	numIndices = inNumIndices;
	useShader(renderer->shader);

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

	glGenBuffers(1, &vbo);
	glGenBuffers(1, &ebo);
	
	glBindBuffer(GL_ARRAY_BUFFER, vbo);
	glBufferData(GL_ARRAY_BUFFER, inNumVertices * sizeof(Vertex3d), &inVertices[0], GL_STATIC_DRAW);

	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
	glBufferData(GL_ELEMENT_ARRAY_BUFFER, inNumIndices * sizeof(uint32), &inIndices[0], GL_STATIC_DRAW);

	glEnableVertexAttribArray(renderer->attributes.position);
	glVertexAttribPointer(renderer->attributes.position, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex3d), (GLvoid *)0);

	glEnableVertexAttribArray(renderer->attributes.normal);
	glVertexAttribPointer(renderer->attributes.normal, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex3d), (GLvoid *)offsetof(Vertex3d, normal));

	glEnableVertexAttribArray(renderer->attributes.color);
	glVertexAttribPointer(renderer->attributes.color, 4, GL_FLOAT, GL_FALSE, sizeof(Vertex3d), (GLvoid *)offsetof(Vertex3d, color));

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

void Mesh3d::render(Renderer3d* renderer, GLenum drawType) {
	setShaderMat4(renderer->uniforms.model, model);

	glBindVertexArray(vao);
	glDrawElements(drawType, numIndices, GL_UNSIGNED_INT, 0);
	glBindVertexArray(0);
}

void Mesh3d::unload() {
	glDeleteVertexArrays(1, &vao);
	glDeleteBuffers(1, &vbo);
}