/*
 * Rick van der Zwet
 * 0433373
 * OS Assigment 2 - Part BCD
 * Licence: BSD
 * $Id: partBCD.c 508 2008-03-02 14:18:40Z rick $
 */

#include <stdio.h>
#include <stdlib.h>
#include <sysexits.h>
#include <time.h>
#include <unistd.h>

void usage(const int errno) {
    printf("Usage:\n");
    printf("-h : This screen\n");
    printf("-l <int> : <int> times to show loadavg\n");
    printf("-s <int> : Sleep <int> seconds between every loadavg line\n");
    exit(errno);
}

void partB() {
    char buffer[100];
    long int uptime_seconds = 0;
    int i, days, hours, minutes, seconds;
    FILE * file;

    /* cpuinfo */
    file = fopen("/proc/cpuinfo", "r");
    /* move to right line */
    for (i = 0; i <= 3; i++)
        while (fgetc(file) != '\n');
    /* Fix offset */
    fgets(buffer, 14, file);
    /* Read data */
    fgets(buffer, 50, file);
    fclose(file);
    printf("CPU Info: %s", buffer);

    /* Kernel version */
    file = fopen("/proc/sys/kernel/osrelease", "r");
    fgets(buffer, 50, file);
    fclose(file);
    printf("Kernel version: %s", buffer);

    /* Pretty formatted uptime */
    file = fopen("/proc/uptime", "r");
    fscanf(file, "%li", &uptime_seconds);
    fclose(file);
    days = uptime_seconds / (24 * 3600);
    uptime_seconds = uptime_seconds % (24 * 3600);
    hours = uptime_seconds / 3600;
    uptime_seconds = uptime_seconds % 3600;
    minutes = uptime_seconds / 60;
    seconds = uptime_seconds % 60;
    printf("Uptime (dd:hh:mm:ss): %02i:%02i:%02i:%02i\n",
           days, hours, minutes, seconds );
}

void partC() {
    char buffer[100];
    long int cpu_user, cpu_user_nice, cpu_system, cpu_idle;
    long int disk_read_total, disk_write_total, disk_read, disk_write;
    int i, errno;
    time_t boot_time, now, uptime;
    FILE * file;

    /* User,system, idle mode */
    file = fopen("/proc/stat", "r");
    fscanf(file, "%*s %li %li %li %li", &cpu_user, &cpu_user_nice, &cpu_system, &cpu_idle);
    fclose(file);

    printf("Buffer: %s", buffer);
    printf("CPU User   : %10li sec\n", cpu_user + cpu_user_nice);
    printf("CPU System : %10li sec\n", cpu_system);
    printf("CPU Idle   : %10li sec\n", cpu_idle);

    /* Disk operations, read/write on all disks (sum)
     * Compatible with 2.6 kernel only Legenda at Documentation/iostats.txt
     * /proc/diskstat read: field 4, write field 8
     * Partitions only has 7 fields and could easy be ignored
     */
    disk_read = 0;
    disk_write = 0;
    file = fopen("/proc/diskstats", "r");
    /* %*100c = dirty hack to move till EOL */
    while ((errno = fscanf(file, "%*s %*s %*s %li %*s %*s %*s %li %*100c",
                           &disk_read, &disk_write)) != EOF) {
        if (errno == 0)
            continue;
        disk_read_total += disk_read;
        disk_write_total += disk_write;
    }
    fclose(file);

    printf("Disk read  operations : %li\n", disk_read_total);
    printf("Disk write operations : %li\n", disk_read_total);

    /* Context switches */
    file = fopen("/proc/stat", "r");
    for (i = 0; i <= 2; i++)
        while (fgetc(file) != '\n');
    fgets(buffer, 5, file);
    fgets(buffer, 50, file);
    fclose(file);
    printf("Kernel context switches: %s", buffer);

    /* Time/Date last booted */
    file = fopen("/proc/uptime", "r");
    fscanf(file, "%li", &uptime);
    fclose(file);
    now = time(NULL);
    boot_time = now - uptime;
    printf("Time/Date last booted: %s", ctime(&boot_time));

    /* Number of processes since boot */
    file = fopen("/proc/stat", "r");
    for (i = 0; i <= 4; i++)
        while (fgetc(file) != '\n');
    fgets(buffer, 10, file);
    fgets(buffer, 50, file);
    fclose(file);
    printf("Processes since boot: %s", buffer);

}

void partDmem() {
    long int mem_available, mem_total;
    FILE * file;

    file = fopen("/proc/meminfo", "r");
    fscanf(file, "%*s %li %*s", &mem_total);
    fscanf(file, "%*s %li %*s", &mem_available);
    fclose(file);

    printf("Memory total     : %li kB\n", mem_total);
    printf("Memory available : %li kB\n", mem_available);
}

void partDloadavg(const int times, const int sleeptime) {
    float loadavg_min;
    int i;
    FILE * file;

    printf("Sleep timer: %i sec\n", sleeptime);

    for (i = 0; i < times; i++) {
        /* Might want do some forking over here to fake some load, by
         * now load needs to be generated by some external processes
         */
        sleep(sleeptime);

        file = fopen("/proc/loadavg", "r");
        fscanf(file, "%f", &loadavg_min);
        fclose(file);
        printf("%03i : %03.2f\n", i, loadavg_min);
    }
}

int main(int argc, char * argv[]) {
    int extendedinfoflag = 0;
    int loadavgtimes = 0;
    int loadavgsleep = 60;


    int ch;
    while ((ch = getopt(argc, argv, "hil:s:")) != -1)
        switch (ch) {
        case 'i':
            extendedinfoflag = 1;
            break;
        case 'l':
            loadavgtimes = atoi(optarg);
            break;
        case 's':
            loadavgsleep = atoi(optarg);
            break;
        case 'h':
            usage(EX_OK);
            /* NOTREACHED */
        default:
            usage(EX_USAGE);
            /* NOTREACHED */
        }

    partB();
    if (extendedinfoflag == 1)
        partC();

    partDmem();
    if (loadavgtimes > 0)
        partDloadavg(loadavgtimes, loadavgsleep);


    return(EX_OK);
}