#include <sys/types.h>
#include <sys/sysinfo.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/times.h>
#include <sys/vtimes.h>
#include <unistd.h>
#include "log.h"
#include "memory.h"

static unsigned long long lastTotalUser, lastTotalUserLow, lastTotalSys, lastTotalIdle;
static clock_t lastCPU, lastSysCPU, lastUserCPU;
static int numProcessors;

void getTotalVirtualMem(double* total_ram) {
    const double megabyte = 1024 * 1024;
    struct sysinfo si;
    sysinfo(&si);
    *total_ram = si.totalram / megabyte;
}

void getVirtualMemUsed(double* used_ram) {
    const double megabyte = 1024 * 1024;
    struct sysinfo si;
    sysinfo(&si);
    *used_ram = (si.totalram - si.freeram) / megabyte;
}

int parseLine(char* line) {
    // This assumes that a digit will be found and the line ends in " Kb".
    int i = strlen(line);
    const char* p = line;
    while (*p <'0' || *p > '9') p++;
    line[i-3] = '\0';
    i = atoi(p);
    return i;
}

int getVirtualMemUsedByCurrentProcess() { 
    FILE* file = fopen("/proc/self/status", "r");
    int result = -1;
    char line[128];

    while (fgets(line, 128, file) != NULL){
        if (strncmp(line, "VmSize:", 7) == 0){
            result = parseLine(line);
            break;
        }
    }
    fclose(file);
    return result / 1024;
}

void skip_lines(FILE *fp, int numlines) { 
    int cnt = 0;
    char ch;
    while ((cnt < numlines) && ((ch = getc(fp)) != EOF)) {
        if (ch == '\n') cnt++;
    }
}

void get_stats(struct cpustat *st, int cpunum) {
    FILE *fp = fopen("/proc/stat", "r");
    int lskip = cpunum+1;
    skip_lines(fp, lskip);
    char cpun[255];
    fscanf(fp, "%s %d %d %d %d %d %d %d", cpun, &(st->t_user), &(st->t_nice), 
        &(st->t_system), &(st->t_idle), &(st->t_iowait), &(st->t_irq),
        &(st->t_softirq));
    fclose(fp);
	return;
}

double calculate_load(struct cpustat *prev, struct cpustat *cur) {
    int idle_prev = (prev->t_idle) + (prev->t_iowait);
    int idle_cur = (cur->t_idle) + (cur->t_iowait);

    int nidle_prev = (prev->t_user) + (prev->t_nice) + (prev->t_system) + (prev->t_irq) + (prev->t_softirq);
    int nidle_cur = (cur->t_user) + (cur->t_nice) + (cur->t_system) + (cur->t_irq) + (cur->t_softirq);

    int total_prev = idle_prev + nidle_prev;
    int total_cur = idle_cur + nidle_cur;

    double totald = (double) total_cur - (double) total_prev;

    double idled = (double) idle_cur - (double) idle_prev;

    if (totald == 0 && idled == 0) return 0; 

    double cpu_perc = (1000 * (totald - idled) / totald + 1) / 10;

    return cpu_perc;
}