#include "logger.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>
#include <time.h>

#define WINDOW_SEC 1
#define MAX_TIMES 1000

static FILE *csv_file = NULL;
static double msg_times[MAX_TIMES];
static int msg_count = 0;

static long long current_time_ms() {
  struct timeval tv;
  gettimeofday(&tv, NULL);
  return ((long long)tv.tv_sec * 1000) + (tv.tv_usec / 1000);
}

static double current_time_sec() {
  struct timeval tv;
  gettimeofday(&tv, NULL);
  return (double)tv.tv_sec + (tv.tv_usec / 1e6);
}

static int update_throughput_window(double now) {
  int i, new_count = 0;
  for (i = 0; i < msg_count; i++) {
    if (now - msg_times[i] < WINDOW_SEC) {
      msg_times[new_count++] = msg_times[i];
    }
  }
  msg_times[new_count++] = now;
  msg_count = new_count;
  return msg_count;
}

void logger_init(const char *filename) {
  csv_file = fopen(filename, "w");
  if (!csv_file) {
    perror("Cannot open CSV file");
    exit(EXIT_FAILURE);
  }
  fprintf(csv_file,
          "timestamp,sent_ms,received_ms,rtt_ms,throughput_msg_per_s\n");
  fflush(csv_file);
}

void logger_cleanup() {
  if (csv_file) {
    fclose(csv_file);
    csv_file = NULL;
  }
}

void logger_handle_message(const void *payload, int payloadlen) {
  char *payload_str = malloc(payloadlen + 1);
  if (!payload_str)
    return;
  memcpy(payload_str, payload, payloadlen);
  payload_str[payloadlen] = '\0';

  long long sent_ms = atoll(payload_str);
  free(payload_str);

  long long received_ms = current_time_ms();
  long long rtt = received_ms - sent_ms;

  double now_sec = current_time_sec();
  int throughput = update_throughput_window(now_sec);

  time_t now = time(NULL);
  struct tm *tm_info = localtime(&now);
  char iso_time[32];
  strftime(iso_time, sizeof(iso_time), "%Y-%m-%dT%H:%M:%S", tm_info);

  if (csv_file) {
    fprintf(csv_file, "%s,%lld,%lld,%lld,%d\n", iso_time, sent_ms, received_ms,
            rtt, throughput);
    fflush(csv_file);
  }

  printf("RTT: %lld ms | Throughput: %d msg/s\n", rtt, throughput);
}