#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
{

	namespace
	{

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

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

		std::mutex sinks_mutex;
		std::vector<std::unique_ptr<sink>> sinks;

		void put_message(level l, std::string const & str, std::string const & thread_name)
		{
			message msg
			{
				clock::now(),
				thread_name,
				l,
				str
			};

			for (auto const & sink : sinks)
			{
				sink->put_message(msg);
			}
		}

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

		struct default_sink_impl
			: sink
		{
			default_sink_impl(std::unique_ptr<io::ostream> stream, level l)
				: stream_(std::move(stream))
				, level_(l)
			{}

			void put_message(message const & msg) override
			{
				if (msg.level < level_) return;

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

				auto const millis = std::chrono::duration_cast<std::chrono::milliseconds>(msg.time.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(' ') << msg.thread_name << ']'
					<< '[' << std::setw(5) << msg.level << ']'
					<< ' ' << msg.message << '\n';

				auto const str = os.str();
				stream_->write(str.data(), str.size());
			}

		private:
			std::unique_ptr<io::ostream> stream_;
			level level_;
		};

	}

	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");
	}

	std::unique_ptr<sink> default_sink(std::unique_ptr<io::ostream> stream, level l)
	{
		return std::make_unique<default_sink_impl>(std::move(stream), l);
	}

	sink * add_sink(std::unique_ptr<sink> s)
	{
		auto ptr = s.get();
		std::lock_guard lock{sinks_mutex};
		sinks.push_back(std::move(s));
		return ptr;
	}

	std::unique_ptr<sink> remove_sink(sink * stream)
	{
		std::lock_guard lock{sinks_mutex};
		for (std::size_t i = 0; i < sinks.size(); ++i)
		{
			if (sinks[i].get() == stream)
			{
				auto result = std::move(sinks[i]);
				sinks.erase(sinks.begin() + i);
				return result;
			}
		}
		return nullptr;
	}

	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);
	}

}