#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <ctype.h>		// isspace()
#include <string.h>		// strlen()
#include <GL/gl.h>
#include <vector>
#include <string>
#include <iostream>
#include <fstream>
#include "WFObj.hh"
using namespace std;

#define WHITESPACE " \n\r\t\v"
#define DEBUGGL

void WFObj::clear()
{
	m_data = std::vector< std::vector<std::string> >();
}

int WFObj::filesize(const char * filename)
{
	struct stat st;
	if (stat(filename, &st))
		return -1;
	return st.st_size;
}

bool WFObj::load(const string & filename)
{
	clear();

	int size = filesize(filename.c_str());
	if (size < 1)
		return false;

	ifstream ifs(filename.c_str());
	if (!ifs.is_open())
		return false;
	char buf[size+1];

	string buildup;
	while (ifs.good())
	{
		ifs.getline(buf, size+1);
		string input = trim(buf);
		int sz = input.size();
		if (sz == 0 || input[0] == '#')
			continue;
		if (input[sz-1] == '\\')
		{
			input[sz-1] = ' ';
			buildup = input;
			continue;
		}
		if (buildup != "")
			input = buildup + input;
		buildup = "";
		processInputLine(input);
	}

	ifs.close();
	return true;
}

string WFObj::trim(string s)
{
	size_t lastpos = s.find_last_not_of(WHITESPACE);
	if (lastpos == string::npos)
		return "";
	s.erase(lastpos + 1);
	s.erase(0, s.find_first_not_of(WHITESPACE));
	return s;
}

void WFObj::processInputLine(const std::string & input)
{
	string line = input;
	vector<string> lineParts;
	for (;;)
	{
		string token = stripFirstToken(line);
		if (token == "")
			break;
		lineParts.push_back(token);
	}
	if (lineParts.size() > 0)
		m_data.push_back(lineParts);
}

string WFObj::stripFirstToken(string & input)
{
	size_t firstnonspace = input.find_first_not_of(WHITESPACE);
	if (firstnonspace == string::npos)
		return "";
	size_t spaceafter = input.find_first_of(WHITESPACE, firstnonspace);
	string token = input.substr(firstnonspace, spaceafter - firstnonspace);
	input.erase(0, spaceafter);
	return token;
}

GLuint WFObj::render()
{
	GLuint list = glGenLists(1);
	glNewList(list, GL_COMPILE);
	int len = m_data.size();
	enum { VERTEX, VERTEX_TEXTURE, VERTEX_NORMAL, VERTEX_TYPES };
	vector<Vertex> vertices[VERTEX_TYPES];
	int numVertsLast = 0;
	bool inFace = false;
	for (int i = 0; i < len; i++)
	{
		string type = m_data[i][0];
		if (type == "v")
			vertices[VERTEX].push_back(readVertex(m_data[i]));
		else if (type == "vt")
			vertices[VERTEX_TEXTURE].push_back(readVertex(m_data[i]));
		else if (type == "vn")
			vertices[VERTEX_NORMAL].push_back(readVertex(m_data[i]));
		else if (type == "f")
		{
			int numVerts = m_data[i].size() - 1;
			if (inFace && (numVerts != numVertsLast || numVertsLast > 4))
			{
#ifdef DEBUGGL
				cout << "glEnd()" << endl;
#endif
				glEnd();
				inFace = false;
			}
			if (!inFace)
			{
				if (numVerts == 3)
				{
#ifdef DEBUGGL
					cout << "glBegin(GL_TRIANGLES)" << endl;
#endif
					glBegin(GL_TRIANGLES);
				}
				else if (numVerts == 4)
				{
#ifdef DEBUGGL
					cout << "glBegin(GL_QUADS)" << endl;
#endif
					glBegin(GL_QUADS);
				}
				else
				{
#ifdef DEBUGGL
					cout << "glBegin(GL_POLYGON)" << endl;
#endif
					glBegin(GL_POLYGON);
				}
				inFace = true;
			}
			for (int v = 1; v <= numVerts; v++)
			{
				int vertexIndices[3] = {0, 0, 0};
				parseVertexIndices(m_data[i][v], vertexIndices);
				for (int j = 0; j < 3; j++)
				{
					if (vertexIndices[j] < 0)
						vertexIndices[j] += vertices[j].size() + 1;
				}
				bool valid = true;
				for (int j = 0; j < 3; j++)
				{
					if (vertexIndices[j] > vertices[j].size())
					{
						valid = false;
						break;
					}
				}
				if (vertexIndices[VERTEX] <= 0)
					valid = false;
				if (!valid)
					continue;
				if (vertexIndices[VERTEX_NORMAL] != 0)
				{
					/* a normal is present */
#ifdef DEBUGGL
					cout << "   glNormal3f(" <<
						vertices[VERTEX_NORMAL][vertexIndices[VERTEX_NORMAL]-1]
							[0] << ", " <<
						vertices[VERTEX_NORMAL][vertexIndices[VERTEX_NORMAL]-1]
							[1] << ", " <<
						vertices[VERTEX_NORMAL][vertexIndices[VERTEX_NORMAL]-1]
							[2] << ")" << endl;
#endif
					glNormal3fv(vertices[VERTEX_NORMAL]
							[vertexIndices[VERTEX_NORMAL]-1].getData());
				}
				if (vertexIndices[VERTEX_TEXTURE] != 0)
				{
					/* a texture coordinate is present */
#ifdef DEBUGGL
					cout << "   glTexCoord2f(" <<
						vertices[VERTEX_TEXTURE][vertexIndices[VERTEX_TEXTURE]-1]
							[0] << ", " <<
						vertices[VERTEX_TEXTURE][vertexIndices[VERTEX_TEXTURE]-1]
							[1] << ')' << endl;
#endif
					glTexCoord2fv(vertices[VERTEX_TEXTURE]
							[vertexIndices[VERTEX_TEXTURE]-1].getData());
				}
#ifdef DEBUGGL
				cout << "  glVertex3f(" <<
					vertices[VERTEX][vertexIndices[VERTEX]-1][0] << ", " <<
					vertices[VERTEX][vertexIndices[VERTEX]-1][1] << ", " <<
					vertices[VERTEX][vertexIndices[VERTEX]-1][2] << ")" <<
					"  [" << vertexIndices[VERTEX] << "]" << endl;
#endif
				glVertex3fv(vertices[VERTEX][vertexIndices[VERTEX]-1].getData());
			}

			numVertsLast = numVerts;
		}
		else if (type == "usemtl")
		{
			if (inFace)
			{
#ifdef DEBUGGL
				cout << "glEnd()" << endl;
#endif
				glEnd();
				inFace = false;
			}
		}
		else if (type == "mtllib")
		{
		}
	}
	if (inFace)
	{
#ifdef DEBUGGL
		cout << "glEnd()" << endl;
#endif
		glEnd();
		inFace = false;
	}
	glEndList();
	return list;
}

WFObj::Vertex WFObj::readVertex(const vector<string> & parts)
{
	int partslen = parts.size();
	Vertex v;
	for (int i = 1; i < partslen && i <= 4; i++)
	{
		sscanf(parts[i].c_str(), "%f", &v[i - 1]);
	}
	return v;
}

void WFObj::parseVertexIndices(const string & vtxref, int * ret)
{
	vector<string> parts = splitString(vtxref, '/');
	int num = parts.size();
	for (int i = 0; i < num && i < 3; i++)
		sscanf(parts[i].c_str(), "%d", ret + i);
}

vector<string> WFObj::splitString(const string & str, char delim)
{
	vector<string> ret;
	string s = str;
	size_t pos;
	while ( (pos = s.find(delim)) != string::npos )
	{
		string t = s.substr(0, pos);
		ret.push_back(t);
		s.erase(0, pos + 1);
	}
	if (s != "")
		ret.push_back(s);
	return ret;
}