#include <BitcoinExchange.hpp>
#include <cstdlib>
#include <fstream>
#include <iostream>
#include <stdexcept>

static std::string trim(const std::string& str) {
	std::string result = str;

	result.erase(result.find_last_not_of(" \t\n\r\f\v") + 1);
	result.erase(0, result.find_first_not_of(" \t\n\r\f\v"));

	return result;
}

static bool isLeapYear(int year) { return (year % 4 == 0 && year % 100 != 0) || (year % 400 == 0); }

static bool isValidDate(const std::string& date) {
	if (date.size() != 10)
		return false;

	if (date[4] != '-' || date[7] != '-')
		return false;

	for (size_t i = 0; i < date.size(); ++i) {
		if (i == 4 || i == 7)
			continue;
		if (!std::isdigit(static_cast<unsigned char>(date[i])))
			return false;
	}

	const int year = (date[0] - '0') * 1000 + (date[1] - '0') * 100 + (date[2] - '0') * 10 + (date[3] - '0');
	const int month = (date[5] - '0') * 10 + (date[6] - '0');
	const int day = (date[8] - '0') * 10 + (date[9] - '0');

	if (year <= 0)
		return false;
	if (month < 1 || month > 12)
		return false;
	if (day < 1)
		return false;

	static const int daysInMonth[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
	int maxDay = daysInMonth[month - 1];
	if (month == 2 && isLeapYear(year))
		maxDay = 29;

	return day <= maxDay;
}

static std::map<std::string, double> validateCSV(const std::string& fileName) {
	std::ifstream inputFile(fileName.c_str());

	if (!inputFile.is_open() || !inputFile.good())
		std::cerr << ("Error: could not open file.") << std::endl;

	std::string line;
	bool firstLine = true;
	static bool input = false; // smelly, pefect
	std::map<std::string, double> data;
	while (std::getline(inputFile, line)) {
		std::size_t separator = line.find(',');
		if (separator == std::string::npos) {
			separator = line.find('|'); // That is not a CSV file...

			if (separator == std::string::npos) {
				std::cerr << "Error: bad input => " + line << std::endl;
				continue;
			}
		}

		std::string first = trim(line.substr(0, separator));
		std::string second = trim(line.substr(separator + 1));

		if (second.empty()) {
			std::cerr << "Error: bad input => " + line << std::endl;
			continue;
		}

		if (firstLine) {
			firstLine = false;

			if (first != "date" || (input && second != "value") || (!input && second != "exchange_rate")) {
				std::cerr << "Error: bad => " + line << std::endl;
				continue;
			}

			continue;
		}

		if (!isValidDate(first)) {
			std::cerr << "Error: bad input => " + first << std::endl;
			continue;
		}

		bool badSecond = false;
		bool dot = false;
		bool dash = false;
		for (size_t i = 0; i < second.size(); ++i) {
			if (std::isdigit(static_cast<unsigned char>(second[i])))
				continue;

			if (!dot && second[i] == '.' && i + 1 < second.size()) {
				dot = true;
				continue;
			}

			if (!dash && second[i] == '-' && i == 0 && i + 1 < second.size()) {
				dash = true;
				continue;
			}

			std::cerr << "Error: bad input => " + second << std::endl;
			badSecond = true;
			break;
		}

		if (badSecond)
			continue;

		const double value = std::strtod(second.c_str(), NULL);
		if (value < 0) {
			std::cerr << "Error: not a positive number." << std::endl;
			continue;
		} else if (input && value > 1000) {
			std::cerr << "Error: too large a number." << std::endl;
			continue;
		}

		const std::pair<std::string, double> pair(first, value);

		if (!input && data.find(first) != data.end()) {
			std::cerr << "Error: bad input => " + first << std::endl;
			continue;
		}

		data.insert(pair);
	}

	input = true;

	return data;
}

int main(int argc, char* argv[]) {
	if (argc != 2) {
		std::cout << "Usage: " << argv[0] << " <input.csv>" << std::endl;
		return EXIT_FAILURE;
	}

	try {
		const std::map<std::string, double> data = validateCSV("data.csv");

		if (data.empty())
			throw std::runtime_error("data file is empty");

		const BitcoinExchange exchange(data);

		const std::map<std::string, double> input = validateCSV(argv[1]);

		for (std::map<std::string, double>::const_iterator it = input.begin(); it != input.end(); ++it) {
			const double value = exchange.getValue(it->first);

			std::cout << it->first << " => " << it->second << " = " << value * it->second << std::endl;
		}

	} catch (const std::exception& exception) {
		std::cerr << "Exception caught, cause: " << exception.what() << std::endl;
		return EXIT_FAILURE;
	}
}