#pragma once

// In-memory key-value store, TTL cache, and pubsub broker skeletons.
// Gap: real implementations in 04-data.md own persistence, replication,
// durability guarantees, and multi-instance sharing.

#include <cstdint>
#include <functional>
#include <map>
#include <mutex>
#include <string>
#include <vector>

namespace molo::example::fw {

class KvStore {
 public:
  bool set(const std::string& key, const std::string& value);
  bool get(const std::string& key, std::string& out) const;
  bool del(const std::string& key);
  std::size_t size() const;

 private:
  mutable std::mutex mu_;
  std::map<std::string, std::string> data_;
};

struct CacheEntry {
  std::string value;
  long expires_at = 0;
};

class Cache {
 public:
  void put(const std::string& key, const std::string& value, long ttl_sec,
           long now);
  bool lookup(const std::string& key, std::string& out, long now);
  void invalidate(const std::string& key);
  std::size_t size() const;

 private:
  mutable std::mutex mu_;
  std::map<std::string, CacheEntry> data_;
};

using PubsubHandler = std::function<void(const std::string& message)>;

class Pubsub {
 public:
  bool subscribe(const std::string& topic, PubsubHandler handler);
  std::size_t publish(const std::string& topic, const std::string& message);
  std::vector<std::string> history(const std::string& topic) const;
  std::vector<std::string> topics() const;

 private:
  mutable std::mutex mu_;
  std::map<std::string, std::vector<PubsubHandler>> subs_;
  std::map<std::string, std::vector<std::string>> history_;
};

}  // namespace molo::example::fw