#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 <map>
#include <iostream>
#include <fstream>
#include "WFMtl.hh"
using namespace std;

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

void WFMtl::clear()
{
	m_data = map< string, vector< vector<string> > >();
	m_currentMaterialName = "";
	m_attributesPushed = false;
}

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

bool WFMtl::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);
	}

	/* DEBUG */
	map<string, vector< vector<string> > >::iterator it = m_data.begin();
	while (it != m_data.end())
	{
		cout << "Material '" << it->first << "':" << endl;
		for (int i = 0; i < it->second.size(); i++)
		{
			cout << "  ";
			for (int j = 0; j < it->second[i].size(); j++)
			{
				cout << '\'' << it->second[i][j] << "' ";
			}
			cout << endl;
		}
		it++;
	}
	/* END DEBUG */

	ifs.close();
	return true;
}

string WFMtl::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 WFMtl::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)
	{
		if ( (lineParts.size() >= 2) && (lineParts[0] == "newmtl") )
		{
			m_currentMaterialName = lineParts[1];
		}
		else if (m_currentMaterialName != "")
		{
			m_data[m_currentMaterialName].push_back(lineParts);
		}
	}
}

string WFMtl::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;
}

void WFMtl::renderBegin(const string & mtlname)
{
	map< string, vector< vector<string> > >::iterator it = m_data.find(mtlname);
	if (it == m_data.end())
		return;
	vector< vector<string> > & stmts = it->second;
	int num_stmts = stmts.size();
	bool foundTexture = false;
	bool didSomething = false;
	for (int i = 0; i < num_stmts; i++)
	{
		string & type = stmts[i][0];
		if (type == "Ka")				/* set ambient color */
		{
			if ( (stmts[i].size() == 4) && (stmts[i][1] != "spectral") )
			{
				pushAttributes();
				float mat[4] = {0.0f, 0.0f, 0.0f, 1.0f};
				for (int j = 0; j < 3; j++)
					sscanf(stmts[i][j+1].c_str(), "%f", &mat[j]);
#ifdef DEBUGGL
				cout << " glMaterialfv(GL_FRONT, GL_AMBIENT, {";
				for (int j = 0; j < 4; j++)
					cout << mat[j] << (j < 3 ? ", " : "})");
				cout << endl;
#endif
				glMaterialfv(GL_FRONT, GL_AMBIENT, mat);
				didSomething = true;
			}
		}
		else if (type == "Kd")			/* set diffuse color */
		{
			if ( (stmts[i].size() == 4) && (stmts[i][1] != "spectral") )
			{
				pushAttributes();
				float mat[4] = {0.0f, 0.0f, 0.0f, 1.0f};
				for (int j = 0; j < 3; j++)
					sscanf(stmts[i][j+1].c_str(), "%f", &mat[j]);
#ifdef DEBUGGL
				cout << " glMaterialfv(GL_FRONT, GL_DIFFUSE, {";
				for (int j = 0; j < 4; j++)
					cout << mat[j] << (j < 3 ? ", " : "})");
				cout << endl;
#endif
				glMaterialfv(GL_FRONT, GL_DIFFUSE, mat);
				didSomething = true;
			}
		}
		else if (type == "Ks")			/* set specular color */
		{
			if ( (stmts[i].size() == 4) && (stmts[i][1] != "spectral") )
			{
				pushAttributes();
				float mat[4] = {0.0f, 0.0f, 0.0f, 1.0f};
				for (int j = 0; j < 3; j++)
					sscanf(stmts[i][j+1].c_str(), "%f", &mat[j]);
#ifdef DEBUGGL
				cout << " glMaterialfv(GL_FRONT, GL_SPECULAR, {";
				for (int j = 0; j < 4; j++)
					cout << mat[j] << (j < 3 ? ", " : "})");
				cout << endl;
#endif
				glMaterialfv(GL_FRONT, GL_SPECULAR, mat);
				didSomething = true;
			}
		}
		else if (type == "map_Kd")		/* load a diffuse texture */
		{
			/* TODO: figure out how i want to load the texture */
			foundTexture = true;
			didSomething = true;
		}
	}
	if (didSomething)
	{
		pushAttributes();
		if (foundTexture)
		{
#ifdef DEBUGGL
			cout << " glEnable(GL_TEXTURE_2D)" << endl;
#endif
			glEnable(GL_TEXTURE_2D);
		}
		else
		{
#ifdef DEBUGGL
			cout << " glDisable(GL_TEXTURE_2D)" << endl;
#endif
			glDisable(GL_TEXTURE_2D);
		}
	}
}

void WFMtl::pushAttributes()
{
	if (m_attributesPushed)
		return;
	m_attributesPushed = true;
#ifdef DEBUGGL
	cout << " glPushAttrib(GL_LIGHTING_BIT | GL_TEXTURE_BIT)" << endl;
#endif
	glPushAttrib(GL_LIGHTING_BIT | GL_TEXTURE_BIT);
}

void WFMtl::renderEnd(const string & mtlname)
{
	map< string, vector< vector<string> > >::iterator it = m_data.find(mtlname);
	if (it == m_data.end())
		return;
	if (m_attributesPushed)
	{
#ifdef DEBUGGL
		cout << " glPopAttrib()" << endl;
#endif
		glPopAttrib();
	}
}