//
// Copyright 2012-2013, Syoyo Fujita.
//
// Licensed under 2-clause BSD liecense.
//

// Erwin Coumans: improved performance, especially in debug mode on Visual Studio (25sec -> 4sec)
//
// version 0.9.5: Parse multiple group name.
//                Add support of specifying the base path to load material file.
// version 0.9.4: Initial suupport of group tag(g)
// version 0.9.3: Fix parsing triple 'x/y/z'
// version 0.9.2: Add more .mtl load support
// version 0.9.1: Add initial .mtl load support
// version 0.9.0: Initial
//

#include <cstdlib>
#include <cstring>
#include <cassert>

#include <string>
#include <vector>
#include <map>
#include <fstream>
#include <sstream>

#include "tiny_obj_loader.h"

namespace tinyobj
{
//See http://stackoverflow.com/questions/6089231/getting-std-ifstream-to-handle-lf-cr-and-crlf
std::istream& safeGetline(std::istream& is, std::string& t)
{
	t.clear();

	// The characters in the stream are read one-by-one using a std::streambuf.
	// That is faster than reading them one-by-one using the std::istream.
	// Code that uses streambuf this way must be guarded by a sentry object.
	// The sentry object performs various tasks,
	// such as thread synchronization and updating the stream state.

	std::istream::sentry se(is, true);
	std::streambuf* sb = is.rdbuf();

	for (;;)
	{
		int c = sb->sbumpc();
		switch (c)
		{
			case '\n':
				return is;
			case '\r':
				if (sb->sgetc() == '\n')
					sb->sbumpc();
				return is;
			case EOF:
				// Also handle the case when the last line has no line ending
				if (t.empty())
					is.setstate(std::ios::eofbit);
				return is;
			default:
				t += (char)c;
		}
	}
}

struct vertex_index
{
	int v_idx, vt_idx, vn_idx, dummy;
};
struct MyIndices
{
	int m_offset;
	int m_numIndices;
};

// for std::map
static inline bool operator<(const vertex_index& a, const vertex_index& b)
{
	if (a.v_idx != b.v_idx) return (a.v_idx < b.v_idx);
	if (a.vn_idx != b.vn_idx) return (a.vn_idx < b.vn_idx);
	if (a.vt_idx != b.vt_idx) return (a.vt_idx < b.vt_idx);

	return false;
}

static inline bool isSpace(const char c)
{
	return (c == ' ') || (c == '\t');
}

static inline bool isNewLine(const char c)
{
	return (c == '\r') || (c == '\n') || (c == '\0');
}

// Make index zero-base, and also support relative index.
static inline int fixIndex(int idx, int n)
{
	int i;

	if (idx > 0)
	{
		i = idx - 1;
	}
	else if (idx == 0)
	{
		i = 0;
	}
	else
	{  // negative value = relative
		i = n + idx;
	}
	return i;
}

static inline std::string parseString(const char*& token)
{
	std::string s;
	int b = strspn(token, " \t");
	int e = strcspn(token, " \t\r");
	s = std::string(&token[b], &token[e]);

	token += (e - b);
	return s;
}

static inline float parseFloat(const char*& token)
{
	token += strspn(token, " \t");
	float f = (float)atof(token);
	token += strcspn(token, " \t\r");
	return f;
}

static inline void parseFloat2(
	float& x, float& y,
	const char*& token)
{
	x = parseFloat(token);
	y = parseFloat(token);
}

static inline void parseFloat3(
	float& x, float& y, float& z,
	const char*& token)
{
	x = parseFloat(token);
	y = parseFloat(token);
	z = parseFloat(token);
}

// Parse triples: i, i/j/k, i//k, i/j
static vertex_index parseTriple(
	const char*& token,
	int vsize,
	int vnsize,
	int vtsize)
{
	vertex_index vi;
	vi.vn_idx = -1;
	vi.vt_idx = -1;
	vi.v_idx = -1;

	vi.v_idx = fixIndex(atoi(token), vsize);
	token += strcspn(token, "/ \t\r");
	if (token[0] != '/')
	{
		return vi;
	}
	token++;

	// i//k
	if (token[0] == '/')
	{
		token++;
		vi.vn_idx = fixIndex(atoi(token), vnsize);
		token += strcspn(token, "/ \t\r");
		return vi;
	}

	// i/j/k or i/j
	vi.vt_idx = fixIndex(atoi(token), vtsize);
	token += strcspn(token, "/ \t\r");
	if (token[0] != '/')
	{
		return vi;
	}

	// i/j/k
	token++;  // skip '/'
	vi.vn_idx = fixIndex(atoi(token), vnsize);
	token += strcspn(token, "/ \t\r");
	return vi;
}

static unsigned int
updateVertex(
	std::map<vertex_index, unsigned int>& vertexCache,
	std::vector<float>& positions,
	std::vector<float>& normals,
	std::vector<float>& texcoords,
	const std::vector<float>& in_positions,
	const std::vector<float>& in_normals,
	const std::vector<float>& in_texcoords,
	const vertex_index& i)
{
	const std::map<vertex_index, unsigned int>::iterator it = vertexCache.find(i);

	if (it != vertexCache.end())
	{
		// found cache
		return it->second;
	}

	assert(static_cast<int>(in_positions.size()) > (3 * i.v_idx + 2));

	positions.push_back(in_positions[3 * i.v_idx + 0]);
	positions.push_back(in_positions[3 * i.v_idx + 1]);
	positions.push_back(in_positions[3 * i.v_idx + 2]);

	if (i.vn_idx >= 0 && ((3 * i.vn_idx + 2) < in_normals.size()))
	{
		normals.push_back(in_normals[3 * i.vn_idx + 0]);
		normals.push_back(in_normals[3 * i.vn_idx + 1]);
		normals.push_back(in_normals[3 * i.vn_idx + 2]);
	}

	if (i.vt_idx >= 0)
	{
		int numTexCoords = in_texcoords.size();
		int index0 = 2 * i.vt_idx + 0;
		int index1 = 2 * i.vt_idx + 1;

		if (index0 >= 0 && (index0) < numTexCoords)
		{
			texcoords.push_back(in_texcoords[index0]);
		}
		if (index1 >= 0 && (index1) < numTexCoords)
		{
			texcoords.push_back(in_texcoords[index1]);
		}
	}

	unsigned int idx = positions.size() / 3 - 1;
	vertexCache[i] = idx;

	return idx;
}

static bool
exportFaceGroupToShape(
	shape_t& shape,
	const std::vector<float>& in_positions,
	const std::vector<float>& in_normals,
	const std::vector<float>& in_texcoords,
	const std::vector<MyIndices>& faceGroup,
	const material_t material,
	const std::string name,
	std::vector<vertex_index>& allIndices)
{
	if (faceGroup.empty())
	{
		return false;
	}

	// Flattened version of vertex data
	std::vector<float> positions;
	std::vector<float> normals;
	std::vector<float> texcoords;
	std::map<vertex_index, unsigned int> vertexCache;
	std::vector<unsigned int> indices;

	// Flatten vertices and indices
	for (size_t i = 0; i < faceGroup.size(); i++)
	{
		const MyIndices& face = faceGroup[i];

		vertex_index i0 = allIndices[face.m_offset];
		vertex_index i1;
		i1.vn_idx = -1;
		i1.vt_idx = -1;
		i1.v_idx = -1;
		vertex_index i2 = allIndices[face.m_offset + 1];

		size_t npolys = face.m_numIndices;  //.size();

		{
			// Polygon -> triangle fan conversion
			for (size_t k = 2; k < npolys; k++)
			{
				i1 = i2;
				i2 = allIndices[face.m_offset + k];

				unsigned int v0 = updateVertex(vertexCache, positions, normals, texcoords, in_positions, in_normals, in_texcoords, i0);
				unsigned int v1 = updateVertex(vertexCache, positions, normals, texcoords, in_positions, in_normals, in_texcoords, i1);
				unsigned int v2 = updateVertex(vertexCache, positions, normals, texcoords, in_positions, in_normals, in_texcoords, i2);

				indices.push_back(v0);
				indices.push_back(v1);
				indices.push_back(v2);
			}
		}
	}

	//
	// Construct shape.
	//
	shape.name = name;
	shape.mesh.positions.swap(positions);
	shape.mesh.normals.swap(normals);
	shape.mesh.texcoords.swap(texcoords);
	shape.mesh.indices.swap(indices);

	shape.material = material;

	return true;
}

void InitMaterial(material_t& material)
{
	material.name = "";
	material.ambient_texname = "";
	material.diffuse_texname = "";
	material.specular_texname = "";
	material.normal_texname = "";
	for (int i = 0; i < 3; i++)
	{
		material.ambient[i] = 0.f;
		material.diffuse[i] = 0.f;
		material.specular[i] = 0.f;
		material.transmittance[i] = 0.f;
		material.emission[i] = 0.f;
	}
	material.shininess = 1.f;
	material.transparency = 1.f;
}

std::string LoadMtl(
	std::map<std::string, material_t>& material_map,
	const char* filename,
	const char* mtl_basepath)
{
	material_map.clear();
	std::stringstream err;

	std::string filepath;

	if (mtl_basepath)
	{
		filepath = std::string(mtl_basepath) + std::string(filename);
	}
	else
	{
		filepath = std::string(filename);
	}

	std::ifstream ifs(filepath.c_str());
	if (!ifs)
	{
		err << "Cannot open file [" << filepath << "]" << std::endl;
		return err.str();
	}

	material_t material;

	int maxchars = 8192;              // Alloc enough size.
	std::vector<char> buf(maxchars);  // Alloc enough size.
	while (ifs.peek() != -1)
	{
		std::string linebuf;
		safeGetline(ifs, linebuf);

		// Trim newline '\r\n' or '\r'
		if (linebuf.size() > 0)
		{
			if (linebuf[linebuf.size() - 1] == '\n') linebuf.erase(linebuf.size() - 1);
		}
		if (linebuf.size() > 0)
		{
			if (linebuf[linebuf.size() - 1] == '\n') linebuf.erase(linebuf.size() - 1);
		}

		// Skip if empty line.
		if (linebuf.empty())
		{
			continue;
		}

		linebuf = linebuf.substr(0, linebuf.find_last_not_of(" \t") + 1);

		// Skip leading space.
		const char* token = linebuf.c_str();
		token += strspn(token, " \t");

		assert(token);
		if (token[0] == '\0') continue;  // empty line

		if (token[0] == '#') continue;  // comment line

		// new mtl
		if ((0 == strncmp(token, "newmtl", 6)) && isSpace((token[6])))
		{
			// flush previous material.
			material_map.insert(std::pair<std::string, material_t>(material.name, material));

			// initial temporary material
			InitMaterial(material);

			// set new mtl name
			char namebuf[4096];
			token += 7;
			sscanf(token, "%s", namebuf);
			material.name = namebuf;
			continue;
		}

		// ambient
		if (token[0] == 'K' && token[1] == 'a' && isSpace((token[2])))
		{
			token += 2;
			float r, g, b;
			parseFloat3(r, g, b, token);
			material.ambient[0] = r;
			material.ambient[1] = g;
			material.ambient[2] = b;
			continue;
		}

		// diffuse
		if (token[0] == 'K' && token[1] == 'd' && isSpace((token[2])))
		{
			token += 2;
			float r, g, b;
			parseFloat3(r, g, b, token);
			material.diffuse[0] = r;
			material.diffuse[1] = g;
			material.diffuse[2] = b;
			continue;
		}

		// specular
		if (token[0] == 'K' && token[1] == 's' && isSpace((token[2])))
		{
			token += 2;
			float r, g, b;
			parseFloat3(r, g, b, token);
			material.specular[0] = r;
			material.specular[1] = g;
			material.specular[2] = b;
			continue;
		}

		// specular
		if (token[0] == 'K' && token[1] == 't' && isSpace((token[2])))
		{
			token += 2;
			float r, g, b;
			parseFloat3(r, g, b, token);
			material.specular[0] = r;
			material.specular[1] = g;
			material.specular[2] = b;
			continue;
		}

		// emission
		if (token[0] == 'K' && token[1] == 'e' && isSpace(token[2]))
		{
			token += 2;
			float r, g, b;
			parseFloat3(r, g, b, token);
			material.emission[0] = r;
			material.emission[1] = g;
			material.emission[2] = b;
			continue;
		}

		// shininess
		if (token[0] == 'N' && token[1] == 's' && isSpace(token[2]))
		{
			token += 2;
			material.shininess = parseFloat(token);
			continue;
		}

		// transparency
		if (token[0] == 'T' && token[1] == 'r' && isSpace(token[2]))
		{
			token += 2;
			material.transparency = parseFloat(token);
			continue;
		}

		// transparency
		if (token[0] == 'd' && isSpace(token[1]))
		{
			token += 1;
			material.transparency = parseFloat(token);
			continue;
		}

		// ambient texture
		if ((0 == strncmp(token, "map_Ka", 6)) && isSpace(token[6]))
		{
			token += 7;
			material.ambient_texname = token;
			continue;
		}

		// diffuse texture
		if ((0 == strncmp(token, "map_Kd", 6)) && isSpace(token[6]))
		{
			token += 7;
			material.diffuse_texname = token;
			continue;
		}

		// specular texture
		if ((0 == strncmp(token, "map_Ks", 6)) && isSpace(token[6]))
		{
			token += 7;
			material.specular_texname = token;
			continue;
		}

		// normal texture
		if ((0 == strncmp(token, "map_Ns", 6)) && isSpace(token[6]))
		{
			token += 7;
			material.normal_texname = token;
			continue;
		}

		// unknown parameter
		const char* _space = strchr(token, ' ');
		if (!_space)
		{
			_space = strchr(token, '\t');
		}
		if (_space)
		{
			int len = _space - token;
			std::string key(token, len);
			std::string value = _space + 1;
			material.unknown_parameter.insert(std::pair<std::string, std::string>(key, value));
		}
	}
	// flush last material.
	material_map.insert(std::pair<std::string, material_t>(material.name, material));

	return err.str();
}

std::string
LoadObj(
	std::vector<shape_t>& shapes,
	const char* filename,
	const char* mtl_basepath)
{
	std::string tmp = filename;
	if (!mtl_basepath)
	{
		int last_slash = 0;
		for (int c = 0; c < (int)tmp.size(); ++c)
			if (tmp[c] == '/' || tmp[c] == '\\')
				last_slash = c;
		tmp = tmp.substr(0, last_slash);
		mtl_basepath = tmp.c_str();
		//fprintf(stderr, "MTL PATH '%s' orig '%s'\n", mtl_basepath, filename);
	}

	shapes.resize(0);
	std::vector<vertex_index> allIndices;
	allIndices.reserve(1024 * 1024);

	MyIndices face;

	std::stringstream err;

	std::ifstream ifs(filename);
	if (!ifs)
	{
		err << "Cannot open file [" << filename << "]" << std::endl;
		return err.str();
	}

	std::vector<float> v;
	v.reserve(1024 * 1024);
	std::vector<float> vn;
	vn.reserve(1024 * 1024);
	std::vector<float> vt;
	vt.reserve(1024 * 1024);
	//std::vector<std::vector<vertex_index> > faceGroup;
	std::vector<MyIndices> faceGroup;
	faceGroup.reserve(1024 * 1024);
	std::string name;

	// material
	std::map<std::string, material_t> material_map;
	material_t material;
	InitMaterial(material);

	int maxchars = 8192;              // Alloc enough size.
	std::vector<char> buf(maxchars);  // Alloc enough size.
	std::string linebuf;
	linebuf.reserve(maxchars);

	while (ifs.peek() != -1)
	{
		linebuf.resize(0);
		safeGetline(ifs, linebuf);

		// Trim newline '\r\n' or '\r'
		if (linebuf.size() > 0)
		{
			if (linebuf[linebuf.size() - 1] == '\n') linebuf.erase(linebuf.size() - 1);
		}
		if (linebuf.size() > 0)
		{
			if (linebuf[linebuf.size() - 1] == '\n') linebuf.erase(linebuf.size() - 1);
		}

		// Skip if empty line.
		if (linebuf.empty())
		{
			continue;
		}

		// Skip leading space.
		const char* token = linebuf.c_str();
		token += strspn(token, " \t");

		assert(token);
		if (token[0] == '\0') continue;  // empty line

		if (token[0] == '#') continue;  // comment line

		// vertex
		if (token[0] == 'v' && isSpace((token[1])))
		{
			token += 2;
			float x, y, z;
			parseFloat3(x, y, z, token);
			v.push_back(x);
			v.push_back(y);
			v.push_back(z);
			continue;
		}

		// normal
		if (token[0] == 'v' && token[1] == 'n' && isSpace((token[2])))
		{
			token += 3;
			float x, y, z;
			parseFloat3(x, y, z, token);
			vn.push_back(x);
			vn.push_back(y);
			vn.push_back(z);
			continue;
		}

		// texcoord
		if (token[0] == 'v' && token[1] == 't' && isSpace((token[2])))
		{
			token += 3;
			float x, y;
			parseFloat2(x, y, token);
			vt.push_back(x);
			vt.push_back(y);
			continue;
		}

		// face
		if (token[0] == 'f' && isSpace((token[1])))
		{
			token += 2;
			token += strspn(token, " \t");

			face.m_offset = allIndices.size();
			face.m_numIndices = 0;

			while (!isNewLine(token[0]))
			{
				vertex_index vi = parseTriple(token, v.size() / 3, vn.size() / 3, vt.size() / 2);
				allIndices.push_back(vi);
				face.m_numIndices++;
				int n = strspn(token, " \t\r");
				token += n;
			}

			faceGroup.push_back(face);

			continue;
		}

		// use mtl
		if ((0 == strncmp(token, "usemtl", 6)) && isSpace((token[6])))
		{
			char namebuf[4096];
			token += 7;
			sscanf(token, "%s", namebuf);

			if (material_map.find(namebuf) != material_map.end())
			{
				material = material_map[namebuf];
			}
			else
			{
				// { error!! material not found }
				InitMaterial(material);
			}
			continue;
		}

		// load mtl
		if ((0 == strncmp(token, "mtllib", 6)) && isSpace((token[6])))
		{
			char namebuf[4096];
			token += 7;
			sscanf(token, "%s", namebuf);

			std::string err_mtl = LoadMtl(material_map, namebuf, mtl_basepath);
			if (!err_mtl.empty())
			{
				//faceGroup.resize(0);  // for safety
				//return err_mtl;
			}
			continue;
		}

		// group name
		if (token[0] == 'g' && isSpace((token[1])))
		{
			// flush previous face group.
			shape_t shape;
			bool ret = exportFaceGroupToShape(shape, v, vn, vt, faceGroup, material, name, allIndices);
			if (ret)
			{
				shapes.push_back(shape);
			}

			faceGroup.resize(0);

			std::vector<std::string> names;
			while (!isNewLine(token[0]))
			{
				std::string str = parseString(token);
				names.push_back(str);
				token += strspn(token, " \t\r");  // skip tag
			}

			assert(names.size() > 0);

			// names[0] must be 'g', so skipt 0th element.
			if (names.size() > 1)
			{
				name = names[1];
			}
			else
			{
				name = "";
			}

			continue;
		}

		// object name
		if (token[0] == 'o' && isSpace((token[1])))
		{
			// flush previous face group.
			shape_t shape;
			bool ret = exportFaceGroupToShape(shape, v, vn, vt, faceGroup, material, name, allIndices);
			if (ret)
			{
				shapes.push_back(shape);
			}

			faceGroup.resize(0);

			// @todo { multiple object name? }
			char namebuf[4096];
			token += 2;
			sscanf(token, "%s", namebuf);
			name = std::string(namebuf);

			continue;
		}

		// Ignore unknown command.
	}

	shape_t shape;
	bool ret = exportFaceGroupToShape(shape, v, vn, vt, faceGroup, material, name, allIndices);
	if (ret)
	{
		shapes.push_back(shape);
	}
	faceGroup.resize(0);  // for safety

	return err.str();
}

};  // namespace tinyobj
