#ifndef CLIENT_REGISTRY_H
#define CLIENT_REGISTRY_H

#include "esp_err.h"
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>

#define CLIENT_REGISTRY_MAX 16
#define CLIENT_MAC_LEN 6

typedef struct {
  uint32_t id;
  bool available;
  bool used;
  uint8_t mac[CLIENT_MAC_LEN];
  /** Milliseconds since boot when last packet was received from this client. */
  uint32_t last_ping_at;
  /** Milliseconds since boot when last heartbeat / SLAVE_INFO was accepted. */
  uint32_t last_success_ping_at;
  uint32_t version;
} client_info_t;

void client_registry_init(void);

/** Milliseconds since boot (same clock as stored ping timestamps). */
uint32_t client_registry_now_ms(void);

/** Ms elapsed since timestamp; 0 if timestamp is 0. */
uint32_t client_registry_ms_since(uint32_t timestamp);

/** Register or refresh a client; updates both ping timestamps. */
esp_err_t client_registry_upsert(const uint8_t mac[CLIENT_MAC_LEN], uint32_t id,
                                 uint32_t version, bool available, bool used,
                                 bool *out_is_new);

/**
 * Record a successful heartbeat (or initial slave info).
 * Sets available=true and updates last_success_ping_at (and last_ping_at).
 * If client was inactive, sets *out_reactivated=true.
 */
esp_err_t client_registry_heartbeat(const uint8_t mac[CLIENT_MAC_LEN],
                                    uint32_t id, uint32_t version, bool used,
                                    bool *out_is_new, bool *out_reactivated);

/** Mark clients inactive when last_success_ping_at is older than timeout_ms. */
void client_registry_check_timeouts(uint32_t timeout_ms);

size_t client_registry_count(void);
const client_info_t *client_registry_at(size_t index);
const client_info_t *client_registry_find_by_mac(const uint8_t mac[CLIENT_MAC_LEN]);

#endif