#include "client_registry.h"
#include "freertos/FreeRTOS.h"
#include "freertos/idf_additions.h"
#include <string.h>

typedef struct {
  client_info_t info;
  bool active;
} client_slot_t;

static client_slot_t s_clients[CLIENT_REGISTRY_MAX];

static uint32_t now_ms(void) {
  return (uint32_t)(xTaskGetTickCount() * portTICK_PERIOD_MS);
}

static bool mac_equal(const uint8_t *a, const uint8_t *b) {
  return memcmp(a, b, CLIENT_MAC_LEN) == 0;
}

void client_registry_init(void) { memset(s_clients, 0, sizeof(s_clients)); }

const client_info_t *
client_registry_find_by_mac(const uint8_t mac[CLIENT_MAC_LEN]) {
  if (mac == NULL) {
    return NULL;
  }
  for (size_t i = 0; i < CLIENT_REGISTRY_MAX; i++) {
    if (s_clients[i].active && mac_equal(s_clients[i].info.mac, mac)) {
      return &s_clients[i].info;
    }
  }
  return NULL;
}

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) {
  if (mac == NULL) {
    return ESP_ERR_INVALID_ARG;
  }

  uint32_t ts = now_ms();
  client_slot_t *slot = NULL;
  bool is_new = false;

  for (size_t i = 0; i < CLIENT_REGISTRY_MAX; i++) {
    if (s_clients[i].active && mac_equal(s_clients[i].info.mac, mac)) {
      slot = &s_clients[i];
      break;
    }
  }

  if (slot == NULL) {
    for (size_t i = 0; i < CLIENT_REGISTRY_MAX; i++) {
      if (!s_clients[i].active) {
        slot = &s_clients[i];
        slot->active = true;
        memcpy(slot->info.mac, mac, CLIENT_MAC_LEN);
        is_new = true;
        break;
      }
    }
    if (slot == NULL) {
      return ESP_ERR_NO_MEM;
    }
  }

  slot->info.id = id;
  slot->info.version = version;
  slot->info.available = available;
  slot->info.used = used;
  slot->info.last_ping = ts;
  slot->info.last_success_ping = ts;

  if (out_is_new != NULL) {
    *out_is_new = is_new;
  }
  return ESP_OK;
}

size_t client_registry_count(void) {
  size_t n = 0;
  for (size_t i = 0; i < CLIENT_REGISTRY_MAX; i++) {
    if (s_clients[i].active) {
      n++;
    }
  }
  return n;
}

const client_info_t *client_registry_at(size_t index) {
  size_t n = 0;
  for (size_t i = 0; i < CLIENT_REGISTRY_MAX; i++) {
    if (!s_clients[i].active) {
      continue;
    }
    if (n == index) {
      return &s_clients[i].info;
    }
    n++;
  }
  return NULL;
}