#include <vector>
#include <functional>
#include "time.h"

using namespace std;
using namespace chrono;

struct TimeEntry {
	std::string indice;
	std::function<nanoseconds(const std::string&)> parser;
};

auto parsers = std::vector<TimeEntry>({
                          {"h",  [](const std::string& number) -> nanoseconds { return hours(stoll(number)); }},
                          {"m",  [](const std::string& number) -> nanoseconds { return minutes(stoll(number)); }},
                          {"s",  [](const std::string& number) -> nanoseconds { return seconds(stoll(number)); }},
                          {"ms", [](const std::string& number) -> nanoseconds { return milliseconds(stoll(number)); }},
                          {"us", [](const std::string& number) -> nanoseconds { return microseconds(stoll(number)); }},
                          {"ns", [](const std::string& number) -> nanoseconds { return nanoseconds(stoll(number)); }}
});

std::chrono::nanoseconds period::parse(const std::string& input, std::string& error) {
	nanoseconds result{};

	size_t index = 0;
	do {
		auto found = input.find(':', index);
		auto str = input.substr(index, found - index);

		auto indiceIndex = str.find_first_not_of("0123456789");
		if(indiceIndex == std::string::npos) {
			error = "Missing indice for " + str + " at " + to_string(index);
			return nanoseconds(0);
		}
		auto indice = str.substr(indiceIndex);
		auto number = str.substr(0, indiceIndex);

		bool foundIndice = false;
		for(const auto& parser : parsers) {
			if(parser.indice == indice) {
				if(number.length() == 0) {
					error = "Invalid number at " + to_string(index);
					return nanoseconds(0);
				}
				result += parser.parser(number);
				foundIndice = true;
				break;
			}
		}
		if(!foundIndice) {
			error = "Invalid indice for " + str + " at " + to_string(index + indiceIndex);
			return nanoseconds(0);
		}

		index = found + 1;
	} while(index != 0);

	return result;
}