#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>
#define CPUSTATES 7
#define IDLEI 3
/* long names:
 * user - nice - system - idle - iowait - irq - soft irq */
char *cpustatenames[] = {"user",   "nice", "system",  "idle",
                         "iowait", "irq",  "softirq", NULL};

#define LIMIT 95

static const char usage[] =
    "\n usage: cpusage [ -hos ] [ -a | -l limit | -o ] [ -c CPU ]\n";

char *appname;

static float cpu_perc[CPUSTATES];
static float cpu_max[CPUSTATES];
static float cpu_min[CPUSTATES];

int cpunum; /* -1 all, 0-n CPU/Core 0-n */

int output;

int breakloop;

/* returns 1-n yielding the number of CPU's/Cores */
int getNumCPU() {
  char buffer[32768];
  int fd, len, i;
  char *test;

  fd = open("/proc/stat", O_RDONLY);
  if (fd <= 0)
    fprintf(stderr, "%s: cannot open /proc/stat \n", appname);

  len = read(fd, buffer, sizeof(buffer) - 1);
  close(fd);
  buffer[len] = '\0';

  i = 0;

  test = strstr(buffer, "cpu");
  if (test != NULL) {
    test += sizeof("cpu");
    test = strstr(test, "cpu");
  }

  while (test != NULL) {
    test += sizeof("cpu");
    /* fprintf(stderr, "%s: DEBUG: %s\n", appname, test); */
    i++;
    test = strstr(test, "cpu");
  }
  return i;
}

void getSysinfo(unsigned long *ptr, size_t size) {
  char buffer[4096];
  char match[100];
  char *start;
  int fd, len, j;

  for (j = 0; j < size; j++)
    ptr[j] = 0;

  fd = open("/proc/stat", O_RDONLY);
  if (fd <= 0)
    fprintf(stderr, "%s: cannot open /proc/stat\n", appname);

  len = read(fd, buffer, sizeof(buffer) - 1);
  close(fd);
  buffer[len] = '\0';

  strcpy(match, "cpu ");
  start = buffer;
  if (cpunum != -1) {
    sprintf(match, "cpu%d ", cpunum);
    start = strstr(buffer, match);
  }

  strcat(match, "%ld %ld %ld %ld %ld %ld %ld");
  if (sscanf(start, match, &ptr[0], &ptr[1], &ptr[2], &ptr[3], &ptr[4], &ptr[5],
             &ptr[6]) != 7) {
    fprintf(stderr, "%s: wrong /proc/stat format\n", appname);
  }
}

long perc(int cpustates, long *cp_time, long *cp_old, long *cp_diff) {

  int i = 0;
  long total = 0;

  for (i = 0; i < cpustates; i++) {
    cp_diff[i] = cp_time[i] - cp_old[i];
    total += cp_diff[i];
  }

  for (i = 0; i < cpustates; i++) {
    cpu_perc[i] = ((float)cp_diff[i] * 100.0 / total);
    /* new max ? */
    if (cpu_perc[i] > cpu_max[i])
      cpu_max[i] = cpu_perc[i];
    /* new min ? */
    if (cpu_perc[i] < cpu_min[i])
      cpu_min[i] = cpu_perc[i];
  }

  return total;
}

void print_perc(float *perc, const char *head) {
  int i;
  time_t Zeitstempel;
  struct tm *now;

  /* human readable */
  if ((output == 0) && (head != ""))
    printf("%s: ", head);

  /* machine readable */
  if ((output == 1) && (head != ""))
    printf("%s;", head);

  /* timestamp */
  time(&Zeitstempel);
  now = localtime(&Zeitstempel);
  if (output == 0)
    printf("timestamp: %04d-%02d-%02d %02d.%02d.%02d, ", now->tm_year + 1900,
           now->tm_mon + 1, now->tm_mday, now->tm_hour, now->tm_min,
           now->tm_sec);
  else
    printf("%04d-%02d-%02d;%02d:%02d:%02d;", now->tm_year + 1900,
           now->tm_mon + 1, now->tm_mday, now->tm_hour, now->tm_min,
           now->tm_sec);

  if (output == 0)
    printf("%s: %5.1f%%, ", cpustatenames[0], perc[0]);
  else
    printf("%.1f", perc[0]);

  /* print out calculated information in percentages */
  for (i = 1; i < CPUSTATES; i++) {
    if (output == 0)
      printf("%s: %5.1f%%, ", cpustatenames[i], perc[i]);
    else
      printf(";%.1f", perc[i]);
  }
  printf("\n");
}

/* to catch Strg+C when looping */
void loop_term_handler(int signum) { breakloop = 1; }

int main(int argc, char **argv) {

  appname = argv[0];

  int i, c, limit;
  int runonce; /* run just once and exit */
  int avg;     /* is avg measurement allready running */
  int avg_run; /* did we allready had an avg measurement */
  static long cp_time1[CPUSTATES];
  static long cp_time2[CPUSTATES];
  static long cp_avg_start[CPUSTATES];
  static long cp_avg_stop[CPUSTATES];
  static long cp_diff[CPUSTATES];

  struct sigaction sigold, signew;

  long *old = cp_time2;
  long *new = cp_time1;

  long total;
  limit = LIMIT;
  output = 0;  /* 0: human readable; 1: machine readable */
  runonce = 0; /* 0: run continuesly; 1: run once */

  cpunum = -1; /* -1: all CPUs/Cores, 0-n: special CPU/Core */

  /* reading commandline options */
  while (1) {
    c = getopt(argc, argv, "saohl:c:");

    if (c == -1) {
      break;
    }

    switch (c) {
    /*run once and exit */
    case 's':
      runonce = 1;
      break;
    /* use avg from begin to end -> same as "-l 100" */
    case 'a':
      limit = 100;
      break;
    case 'o':
      output = 1; /* machine readable */
      // header for CSV output
      printf("date;time;user;nice;system;idle;iowait;irq;softirq\n");
      break;
    /* print usage */
    case 'h':
      fprintf(stderr, "%s: %s", appname, usage);
      exit(0);
      break;
    /* set limit */
    case 'l':
      if (!(sscanf(optarg, "%d", &limit) == 1)) {
        fprintf(stderr, "%s: option for -l should be integer (is %s)\n",
                appname, optarg);
        exit(1);
      }
      break;
    /* select CPU/Core */
    case 'c':
      if (!(sscanf(optarg, "%d", &cpunum) == 1)) {
        fprintf(stderr, "%s: option for -c should be integer (is %s)\n",
                appname, optarg);
        exit(1);
      }
      break;
    }
  }

  if (cpunum != -1) {
    int numcpu = getNumCPU();
    if (cpunum < numcpu) {
      printf("-- Selected CPU %d\n", cpunum);
    } else {
      if (numcpu == 1) {
        fprintf(stderr, "%s: CPU %d not available (found %d CPU: [0])\n",
                appname, cpunum, numcpu);
      } else {
        fprintf(stderr,
                "%s: CPU %d not available (found %d CPU's: [0]-[%d])\n ",
                appname, cpunum, numcpu, numcpu - 1);
      }
      exit(1);
    }
  }

  breakloop = 0;

  for (i = 0; i < CPUSTATES; i++) {
    cpu_max[i] = 0;
    cpu_min[i] = 100;
  }

  /* get information */
  getSysinfo((unsigned long *)new, CPUSTATES);

  /* catch Strg+C when capturing to call pcap_breakloop() */
  memset(&signew, 0, sizeof(signew));
  signew.sa_handler = loop_term_handler;
  if (sigaction(SIGINT, &signew, &sigold) < 0) {
    fprintf(stderr, "Could not set signal handler -> exiting");
  }

  avg = 0;
  avg_run = 0;

  if (runonce) {
    breakloop = 1;
  }

  while (1) {
    usleep(1000000);

    if (new == cp_time1) {
      new = cp_time2;
      old = cp_time1;
    } else {
      new = cp_time1;
      old = cp_time2;
    }

    /* get information again */
    getSysinfo((unsigned long *)new, CPUSTATES);

    /* convert cp_time counts to percentages */
    total = perc(CPUSTATES, new, old, cp_diff);

    /* check for avg measurement start */
    if (!avg_run && !avg && (cpu_perc[IDLEI] <= limit)) {
      avg = 1;
      for (i = 0; i < CPUSTATES; i++)
        cp_avg_start[i] = new[i];
    }

    /* check for avg measurement stop */
    if (!avg_run && avg && (cpu_perc[IDLEI] > limit)) {
      avg = 0;
      for (i = 0; i < CPUSTATES; i++)
        cp_avg_stop[i] = new[i];
      avg_run = 1;
    }

    print_perc(cpu_perc, "");

    if (breakloop) {
      if (avg) {
        avg = 0;
        for (i = 0; i < CPUSTATES; i++)
          cp_avg_stop[i] = new[i];
      }
      break;
    }
  }

  /* Set default behaviour when loop is done */
  if (sigaction(SIGINT, &sigold, &signew) < 0) {
    fprintf(stderr, "%s: Could not restore signal handler -> exiting", appname);
  }

  if (!runonce && output == 0) {
    // print avg only when not making a one-shot msg and
    // when not writing CSV output
    printf("---Summary----\n");

    print_perc(cpu_min, "Min");

    print_perc(cpu_max, "Max");

    perc(CPUSTATES, cp_avg_start, cp_avg_stop, cp_diff);

    print_perc(cpu_perc, "Avg");
  }

  return 0;
}