#include "model.h"
#include "utils.h"

Model::Model()
{
	mShader = new Shader;
}

void Model::Init(const char*modelPath) {
	int nFileSize = 0;
	fileContent = LoadFileContent(modelPath, nFileSize);

	if (fileContent == nullptr) {
		printf("load obj model fail\n");
		exit;
	}

	//解析模型数据
	parseModel();
	delete fileContent;

	//填充VertexBuffer
	createVertexBuffer();
}

void Model::parseModel()
{
	std::stringstream ssObjFile((char*)fileContent);
	char szOneLine[256];

	while (!ssObjFile.eof()) {
		memset(szOneLine, 0, 256);
		ssObjFile.getline(szOneLine, 256);
		if (strlen(szOneLine) > 0) {
			parseLine(szOneLine);
		}
	}
}

void Model::parseLine(const char * line)
{
	if (line[0] == 'v') {
		if (line[1] == 't') {
			parseTexcoord(line);
		}
		else if (line[1] == 'n') {
			parseNormal(line);
		}
		else {
			parsePosition(line);
		}
	}

	if (line[0] == 'f') {
		parseFace(line);
	}
}

void Model::parseTexcoord(const char * line)
{
	glm::float3 f3 = parseFloat(line);
	texcoord.push_back(f3);
}

void Model::parseNormal(const char * line)
{
	glm::float3 f3 = parseFloat(line);
	normal.push_back(f3);
}

void Model::parsePosition(const char * line)
{
	glm::float3 f3 = parseFloat(line);
	position.push_back(f3);
}

glm::float3 Model::parseFloat(const char * line)
{
	std::string t;
	std::stringstream ssOneLine(line);
	ssOneLine >> t;
	glm::float3 f3;
	ssOneLine >> f3.x;
	ssOneLine >> f3.y;
	if (line[1] == 't') {
		f3.z = 0;
	}
	else {
		ssOneLine >> f3.z;
	}
	return f3;
}

void Model::parseFace(const char * line)
{
	std::string temp;
	std::stringstream ssOneLine(line);
	ssOneLine >> temp; //去除 f

	std::string pointerIndexStr;
	for (int i = 0; i < 3; i++) {
		//解析每一个点
		ssOneLine >> pointerIndexStr;
		VertexIndex vi = parseVertexIndex(pointerIndexStr);

		//把点加到vertices
		int index = addVertices(vi);
	}
}

VertexIndex Model::parseVertexIndex(std::string pointStr)
{
	size_t pos = pointStr.find_first_of('/');
	std::string positionIndexStr = pointStr.substr(0, pos);
	size_t pos2 = pointStr.find_first_of('/', pos + 1);
	std::string texcoordIndexStr = pointStr.substr(pos + 1, pos2 - pos - 1);
	std::string normalIndexStr = pointStr.substr(pos2 + 1, pointStr.length() - pos2 - 1);

	VertexIndex ret;
	ret.position = atoi(positionIndexStr.c_str()) - 1;
	ret.texcoord = atoi(texcoordIndexStr.c_str()) - 1;
	ret.normal = atoi(normalIndexStr.c_str()) - 1;

	return ret;
}

int Model::addVertices(VertexIndex indexes)
{
	int currentIndex = -1;
	size_t currentVerticeCount = vertices.size();
	currentIndex = vertices.size();
	vertices.push_back(indexes);
	return currentIndex;
}


void Model::createVertexBuffer()
{
	int vertexCount = (int)vertices.size();
	mVertexBuffer = new VertexBuffer;
	glm::float3 t;
	mVertexBuffer->SetSize(vertexCount);
	for (int i = 0; i < vertexCount; ++i) {
		t = position[vertices[i].position];
		mVertexBuffer->SetPosition(i, t[0], t[1], t[2]);
		t = texcoord[vertices[i].texcoord];
		mVertexBuffer->SetTexcoord(i, t[0], t[1]);
		t = normal[vertices[i].normal];
		mVertexBuffer->SetNormal(i, t[0], t[1], t[2]);
	}
}

void Model::Draw(glm::mat4 & viewMatrix, glm::mat4 projectionMatrix, float x, float y, float z) {
	mShader->SetVec4("U_CameraPos", x, y, z, 1.0);
	glEnable(GL_DEPTH_TEST);
	mVertexBuffer->Bind();
	if (mShader->mProgram > 0) {
		mShader->Bind(glm::value_ptr(mModelMatrix), glm::value_ptr(viewMatrix), glm::value_ptr(projectionMatrix));
		glm::mat4 it = glm::inverseTranspose(mModelMatrix);
		GLint itLocation = glGetUniformLocation(mShader->mProgram, "IT_ModelMatrix");
		glUniformMatrix4fv(itLocation, 1, GL_FALSE, glm::value_ptr(it));
		itLocation = glGetUniformLocation(mShader->mProgram, "LightViewMatrix");
		if (itLocation >= 0 && mLightViewMatrix != nullptr) {
			glUniformMatrix4fv(itLocation, 1, GL_FALSE, mLightViewMatrix);
		}
		itLocation = glGetUniformLocation(mShader->mProgram, "LightProjectionMatrix");
		if (itLocation >= 0 && mLightProjectionMatrix != nullptr) {
			glUniformMatrix4fv(itLocation, 1, GL_FALSE, mLightProjectionMatrix);
		}
	}
	glDrawArrays(GL_TRIANGLES, 0, mVertexBuffer->mVertexCount);
	mVertexBuffer->Unbind();
}

void Model::SetPosition(float x, float y, float z) {
	mModelMatrix = glm::translate(x, y, z);
}
void Model::SetAmbientMaterial(float r, float g, float b, float a) {
	mShader->SetVec4("U_AmbientMaterial", r, g, b, a);
}
void Model::SetDiffuseMaterial(float r, float g, float b, float a) {
	mShader->SetVec4("U_DiffuseMaterial", r, g, b, a);
}
void Model::SetSpecularMaterial(float r, float g, float b, float a) {
	mShader->SetVec4("U_SpecularMaterial", r, g, b, a);
}
void Model::SetTexture(const char*imagePath) {
	mShader->SetTexture("U_Texture", imagePath);
}