#pragma once

#include <condition_variable>
#include <cstddef>
#include <chrono>
#include <mutex>
#include <thread>
#include <vector>

#include "delivery_store.hpp"

namespace telegrammer
{

/// Delivers queued callbacks with bounded concurrency and retries.
class Dispatcher
{
public:
    /// Construct a dispatcher with a fixed number of callback workers.
    Dispatcher(DeliveryStore& store, std::size_t worker_count = 4);

    /// Start callback workers.
    void start();

    /// Request workers to stop and wait for active callbacks.
    void stop();

    /// Wake workers after new delivery jobs are committed.
    void notify();

private:
    DeliveryStore& store_;
    std::size_t worker_count_;
    std::mutex mutex_;
    std::condition_variable_any condition_;
    std::mutex purge_mutex_;
    std::chrono::steady_clock::time_point next_purge_{};
    std::vector<std::jthread> workers_;

    bool shouldPurge();
    void run(std::stop_token stop_token);
};

} // namespace telegrammer