/*
 * main.cpp
 *
 *  Created on: 07.10.2017
 *      Author: julian
 */

#include <sys/mman.h> 	// for mmap()
#include <sys/stat.h>	// for fstat()
#include <fcntl.h>		// for open()
#include <unistd.h>		// for close()
#include <errno.h>	// for perror()


#include <iostream>
#include <string>
#include <cstring>
#include <vector>
#include <map>

using namespace std;

struct Substring {
	const char * start, * end;

	Substring(const char * start, const char * end) :
		start(start), end(end) {}

	Substring(const char * str):
		start(str), end(str + strlen(str))
	{}

	Substring():
		start(nullptr), end(nullptr)
	{}


	std::string toString() const {
		std::string temp;
		temp.reserve(size());

		const char * it = start;
		while(it != end) {
			temp += *it;
			it++;
		}

		return temp;
	}
	operator std::string() {
		return toString();
	}

	std::string::size_type size() const {
		return (std::string::size_type)(end - start);
	}

	friend std::ostream &operator<<(std::ostream &out, const Substring &str);

	template <class IterA, class IterB>
	int __compare(IterA a, IterA aend, IterB b, IterB bend) const {
		while(a != aend && b != bend) {
			if (*a < * b) {
				return -1;
			}
			if (*a > *b) {
				return 1;
			}

			a++;
			b++;
		}

		if (a == aend && b == bend) {
			return 0;
		}

		if (a != aend) {
			return 1;
		}

		return -1;
	}


	int compare(const Substring &other) const {
		return __compare(start, end, other.start, other.end);
	}

	int compare(const std::string &other) const {
		return __compare(start, end, other.begin(), other.end());
	}

	template <typename T>
	bool operator<(const T &other) const {
		return compare(other) < 0;
	}

	template <typename T>
	bool operator>(const T &other) const {
		return compare(other) > 0;
	}

	template <typename T>
	bool operator==(const T &other) const {
		return compare(other) == 0;
	}

	template <typename T>
	bool operator!=(const T &other) const {
		return !(*this == other);
	}
};



std::ostream &operator<<(std::ostream &out, const Substring &str) {
	auto temp = str.start;
	while(temp != str.end) {
		out << *temp;
		temp++;
	}

	return out;
}


class InputExtractor
{
public:
	class Exception : public std::runtime_error {
	public:
		Exception(const std::string &str) : std::runtime_error(str) {}
	};

	typedef std::vector<std::string> List;
	List operator()(const Substring &input);

	std::string macroExpand(Substring input);

protected:
	Substring file;
	std::map<std::string, Substring> macros;
};

Substring readBrackets(Substring &input, const char * brackets) {
	if (input.size() <= 0 || *input.start != brackets[0]) {
		cout << "expected " << brackets[0] << ", got: '" << *input.start << "'";
		return Substring();
	}

	input.start++;

	int depth = 1;
	Substring result(input.start, input.start);

	while(depth > 0 && input.size() > 0) {
		result.end = ++input.start;

		if (*input.start == brackets[0]) {
			depth++;
		}
		if (*input.start == brackets[1]) {
			depth--;
		}
	}
	// advance beyond last bracket
	if (input.size())
		input.start++;

	return result;
}

std::string InputExtractor::macroExpand(Substring input) {
	std::string result;
	Substring name;
	std::map<std::string, Substring>::iterator lookup;
	//cout << "expanding: " << input << endl;

	while(input.size() > 0) {
		if (*input.start == '\\') {
			input.start++;
			name.start = name.end = input.start;

			while(input.size() > 0) {
				name.end = ++input.start;

				if ((lookup = macros.find(name.toString())) != macros.end()) {
					break;
				}
			}

			if (lookup == macros.end()) {
				throw Exception("unknown macro in macro expansion: " + name.toString());
			}

			result += lookup->second.toString();
		} else {
			result += *input.start;
		}
		input.start++;
	}

	return result;
}

#include <functional>
typedef std::map<std::string, std::function<void(InputExtractor::List&, std::string)>> CommandList;

std::string Extension(std::string str) {
	auto it = str.end();
	while(it != str.begin() && *it != '.' && *it != '/' && *it != '\\') {
		it--;
	}

	return std::string(it, str.end());
}

std::string Basedir(std::string path) {
	auto it = path.end();
	while(it != path.begin() && *it != '/' && *it != '\\') {
		it--;
	}

	return std::string(path.begin(), it);
}

std::string Name(std::string path) {
	auto it = path.end();
	while(it != path.begin() && *it != '/' && *it != '\\') {
		it--;
	}

	return std::string(it, path.end());
}

std::string Basename(std::string path) {
	std::string temp = Name(path);

	auto it = temp.end();
	while(it != temp.begin() && *it != '.') {
		it--;
	}

	if (it == temp.begin()) {
		return path;
	}

	return std::string(temp.begin(), it);
}

inline bool PathRelative(std::string path) {
	return path.size() && path[0] != '/';
}

#include <unistd.h>

std::string cwd() {
	ssize_t size = 100, nsize;

	while(1) {
		char buffer[size];
		if ((nsize = readlink("/proc/self/cwd", buffer, size)) < size) {
			buffer[size+1] = 0;
			return std::string(buffer);
		}
		size = nsize + 100;
	}

//
//	buffer[rsize+1] = 0;
//
//	std::string result;
//	result.assign(buffer);
//	return result;
}

#include <fstream>

bool Exists(std::string path) {
	std::ifstream file(path);
	if (!file) {
		return false;
	}

	file.close();
	return true;
}

InputExtractor::List Include(std::string path) {
	InputExtractor::List list;

	int fd = open(path.c_str(), O_RDONLY);
	if (fd == -1) {
		cerr << "cannot open " << path << endl;
		return list;
	}

	struct stat fileinfo;
	if (fstat(fd, &fileinfo) == -1) {
		perror("stat");
		close(fd);
		return list;
	}

	void * memptr = mmap(NULL, fileinfo.st_size, PROT_READ, MAP_SHARED, fd, 0);

	if (memptr == NULL) {
		perror("mmap");
		close(fd);
		return list;
	}

	Substring str((const char *)memptr, (const char*)memptr + fileinfo.st_size);

	std::string basedir = Basedir(path);
	list = InputExtractor()(str);

	// add basedir to list for all relative paths
	for (auto it = list.begin(); it != list.end(); it++) {
		if (PathRelative(*it))
			*it = basedir + '/' + *it;
	}
	// cleanup
	munmap(memptr, fileinfo.st_size);
	close(fd);
	return list;
}

InputExtractor::List InputExtractor::operator()(const Substring &input){
	file = input;
	List result;
	CommandList IncludeCommands;

	IncludeCommands["input"] = [](List &l, std::string a) {
		if (a.empty()) return;
		if (Extension(a) != ".tex") a += ".tex";
		l.push_back(a);
		// try to extract all inputs of that file
		auto sub = Include(a);
		std::copy(sub.begin(), sub.end(), std::inserter(l, l.end()));
	};

	IncludeCommands["include"] = IncludeCommands["input"];
	IncludeCommands["lstinputlisting"] = [](List &l, std::string a){ l.push_back(a); };

	// skip normie text
	while(file.size()) {

		if (*file.start == '%') {
			// line commment
			while(file.size() > 0 && *file.start != '\n')
				file.start++;

			continue;
		}
		if (*file.start != '\\') {
			file.start++;
			continue;
		}

		// read macro name
		file.start++;

		// TODO: throw exception
		if (!file.size())
			throw Exception("unexpected EOF");

		Substring name;
		name.start = name.end = file.start;
		for(name.end = ++file.start; file.size() > 0 && !isspace(*file.start) && *file.start != '{' && *file.start != '\\'; name.end = (++file.start+1)) {
			auto searchHit = IncludeCommands.find(name);
			if ((searchHit = IncludeCommands.find(name)) != IncludeCommands.end()) {
				file.start++;
				cout << searchHit->first;
				cout << "[" << readBrackets(file, "[]") << "]";
				auto args = readBrackets(file, "{}");
				cout << ":" << args << endl;
				searchHit->second(result, macroExpand(args));
				break;
			} else if (name == std::string("def")) {
				file.start++;

				if (file.size() <= 0 || *file.start != '\\') {
					continue;
				}
				file.start++;

				Substring name(file.start, file.end);
				while (file.size() > 0 && *file.start != '{' && !isspace(*file.start)) {
					name.end = ++file.start;
				}

				cout << "new macro definition: " << name << endl;
				macros.insert(std::pair<std::string, Substring>(name.toString(), readBrackets(file, "{}")));
				break;
			}
		}
	}

	return result;
}

#include <experimental/filesystem>

int main(int argc, char ** args) {
	// find all the files the given tex files depend on
	cout << cwd() << std::endl;
	int fd = 0;
	struct stat filestat;

	for(;argc > 1; --argc) {
		char * filename = args[argc-1];
		cout << "looking at " << filename << std::endl;

		// try to open file
		fd = open(filename, O_RDONLY);
		if (fd == -1) {
			perror("could not open input file");
			continue;
		}

		fstat(fd, &filestat);
		//cout << "file size: " << filestat.st_size << endl;

		// try to mmap file
		void * memory_area = mmap(NULL, filestat.st_size, PROT_READ, MAP_SHARED, fd, 0);
		if (memory_area == nullptr) {
			perror("could not mmap the input");
			continue;
		}


		//cout << "mmap success, parse file" << endl;

		Substring file((const char*)memory_area, (const char*)memory_area + filestat.st_size);
		try {
			auto list = InputExtractor()(file);
			// write in makefile style
			std::ofstream output(Basename(filename) + ".d");
			if (!output) {
				std::cout << "could not create output file" << std::endl;
			} else {
				output << filename << ": ";

				for (auto it = list.begin(); it != list.end(); it++) {
					output << '\t';
					if (PathRelative(*it))  {
						if (PathRelative(filename)) {
							output << cwd();
						} else {
							output << Basename(filename);
						}
						output << "/" << *it;
					} else {
						output << *it;
					}
					output << "\t\\\n";
				}
				output << endl;
			}

			output.close();
		} catch(InputExtractor::Exception &e) {
			cout << e.what() << endl;
		}

		// cleanup
		munmap(memory_area, filestat.st_size);
		close(fd);
	}

	printf("done\n");
}