#include <psemek/log/log.hpp>

#include <chrono>
#include <ctime>
#include <iostream>
#include <sstream>
#include <iomanip>
#include <mutex>
#include <unordered_map>
#include <thread>
#include <atomic>
#include <vector>

namespace psemek::log
{

	static std::atomic<std::size_t> max_thread_name_length = 3;

	static std::mutex thread_names_mutex;
	static std::unordered_map<std::thread::id, std::string> thread_names;

	static std::mutex sinks_mutex;
	static std::vector<std::pair<std::unique_ptr<io::ostream>, level>> sinks;

	static void put_message(level l, std::string const & message, std::string const & thread_name);

	void register_thread(std::string name)
	{
		register_thread(std::this_thread::get_id(), std::move(name));
	}

	void register_thread(std::thread::id id, std::string name)
	{
		{
			std::lock_guard lock{thread_names_mutex};

			auto it = thread_names.find(id);
			if (it != thread_names.end())
				throw std::runtime_error("Thread \"" + name + "\" already registered!");

			thread_names[id] = name;
		}

		max_thread_name_length = std::max(max_thread_name_length.load(), name.size());

		put_message(level::info, "Thread \"" + name + "\" registered");
	}

	void unregister_thread(std::thread::id id)
	{
		std::string name;
		{
			std::lock_guard lock{thread_names_mutex};

			auto it = thread_names.find(id);
			if (it == thread_names.end())
			{
				std::ostringstream os;
				os << "Thread " << id << " not found!";
				throw std::runtime_error(os.str());
			}

			name = std::move(it->second);
			thread_names.erase(it);
		}

		if (id == std::this_thread::get_id())
			put_message(level::info, "Thread \"" + name + "\" unregistered", name);
		else
			put_message(level::info, "Thread \"" + name + "\" unregistered");
	}

	static ::tm safe_localtime(std::time_t const & time)
	{
		static std::mutex mutex;
		std::lock_guard lock{mutex};
		return *std::localtime(&time);
	}

	static void put_message(level l, std::string const & message, std::string const & thread_name)
	{
		using clock = std::chrono::system_clock;

		auto const time = clock::to_time_t(clock::now());
		auto const tm = safe_localtime(time);

		auto const millis = std::chrono::duration_cast<std::chrono::milliseconds>(clock::now().time_since_epoch()).count() % 1000;

		std::ostringstream os;
		os
			<< '[' << std::put_time(&tm, "%Y %b %d  %H:%M:%S.") << std::setw(3) << std::setfill('0') << millis << ']'
			<< '[' << std::setw(max_thread_name_length) << std::setfill(' ') << thread_name << ']'
			<< '[' << std::setw(7) << l << ']'
			<< ' ' << message << '\n';

		auto const str = os.str();

		std::lock_guard lock{sinks_mutex};

		for (auto const & sink : sinks)
		{
			if (static_cast<int>(l) >= static_cast<int>(sink.second))
				sink.first->write(str.data(), str.size());
		}
	}

	void add_sink(std::unique_ptr<io::ostream> stream, level l)
	{
		std::lock_guard lock{sinks_mutex};
		sinks.push_back({std::move(stream), l});
	}

	void put_message(level l, std::string const & message)
	{
		static std::string unknown_thread_name = "???";

		auto const id = std::this_thread::get_id();

		std::string const * thread_name = nullptr;
		{
			std::lock_guard lock{thread_names_mutex};
			auto const it = thread_names.find(id);
			if (it == thread_names.end())
				thread_name = &unknown_thread_name;
			else
				thread_name = &(it->second);
		}

		put_message(l, message, *thread_name);
	}

}