#pragma once

#include "kv_store.hpp"
#include <random>
#include <unordered_map>
#include <mutex>

class SessionStore {
public:
	SessionStore() : rng_(std::random_device{}()) {
		store_.set_file("sessions.txt");
	}

	std::string create() {
		std::string id = generate_id();
		std::lock_guard<std::mutex> lock(mutex_);
		sessions_[id] = {};
		return id;
	}

	std::optional<std::string> get(const std::string& id, const std::string& key) {
		std::lock_guard<std::mutex> lock(mutex_);
		auto it = sessions_.find(id);
		if (it == sessions_.end()) return std::nullopt;

		auto data_it = it->second.find(key);
		return data_it != it->second.end() ? std::optional<std::string>{data_it->second} : std::nullopt;
	}

	void set(const std::string& id, const std::string& key, const std::string& value) {
		std::lock_guard<std::mutex> lock(mutex_);
		sessions_[id][key] = value;
	}

	bool del(const std::string& id) {
		std::lock_guard<std::mutex> lock(mutex_);
		return sessions_.erase(id) > 0;
	}

	size_t size() {
		std::lock_guard<std::mutex> lock(mutex_);
		return sessions_.size();
	}

	void set_file(const std::string& filename) {
		store_.set_file(filename);
	}

	void load() {
		store_.load();
	}

	void save() {
		std::lock_guard<std::mutex> lock(mutex_);
		for (const auto& [id, data] : sessions_) {
			for (const auto& [key, value] : data) {
				store_.set(id + ":" + key, value);
			}
		}
		store_.save();
	}

private:
	std::unordered_map<std::string, std::unordered_map<std::string, std::string>> sessions_;
	mutable std::mutex mutex_;
	KeyValueStore store_;
	std::mt19937 rng_;

	std::string generate_id() {
		static const char chars[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
		std::string id;
		id.reserve(16);

		for (int i = 0; i < 16; ++i) {
			id += chars[rng_() % (sizeof(chars) - 1)];
		}

		return id;
	}
};