#include <string>
#include <csignal>
#include <sys/ioctl.h>

int w, h;

struct meminfo{
    int total = 0;
    int free = 0;
    int available = 0;
    void loadmem();
    int used(){return total-free;}
    int taken(){return total-available;}
    int percent(){if (total == 0){return 0;} else return 100*taken()/total;}
    int bufpercent(){if (total == 0){return 0;} else return 100*used()/total;}
};
void meminfo::loadmem() {
    FILE* file = fopen("/proc/meminfo", "r");
    int line = 0, n = 0;
    char c[84];
    fread(&c, 1, 84, file);
    fclose(file);
    for (int i = 0; i < 84; i++) {
        if (c[i] > 47 && c[i] < 58) ((n *= 10) += c[i] - 48);
        else if (c[i] == 10) {
            n /= 1000;
            switch (line) {
                case 0: total = n;
                case 1: free = n;
                case 2: available = n;
            }
            n = 0;
            line++;
        }
    }
}

struct cpuinfo{
    int temp = 0;
    int loadavg = 0;
    void loadcpu();
    int getloadavg();
    int gettemp();
};
int cpuinfo::getloadavg() {
    long double a[4], b[4];
    FILE *fp;
    char dump[50];
    fp = fopen("/proc/stat","r");
    fscanf(fp,"%*s %Lf %Lf %Lf %Lf",&a[0],&a[1],&a[2],&a[3]);
    fclose(fp);
    usleep(1000000);
    fp = fopen("/proc/stat","r");
    fscanf(fp,"%*s %Lf %Lf %Lf %Lf",&b[0],&b[1],&b[2],&b[3]);
    fclose(fp);
    return 100 * ((b[0]+b[1]+b[2]) - (a[0]+a[1]+a[2])) / ((b[0]+b[1]+b[2]+b[3]) - (a[0]+a[1]+a[2]+a[3]));
}

int tempfile(int i, int istemp, int& val) {
    FILE* file;
    char buf[12];

    std::string path = "/sys/class/thermal/thermal_zone";
    path.append(std::to_string(i));
    if (istemp) path.append("/temp");
    else path.append("/type");

    file = fopen(path.c_str(), "r");
    if (file == NULL) {
        return 1;
    }
    fread(&buf, 1, 12, file);
    fclose(file);

    if (istemp) val = ((int) buf[0] - 48) * 10 + ((int) buf[1] - 48);
    else val = (std::string(buf) == "x86_pkg_temp");

    return 0;
}

int cpuinfo::gettemp() {
    std::string name;
    std::string path;
    int val = 0;
    for (int i = 0;1; i++) {
        if (tempfile(i, 0, val)) break;
        if (val) {
            tempfile(i, 1, val);
            break;
        }
    }
    return val;
}
void cpuinfo::loadcpu(){
    loadavg = getloadavg();
    temp = gettemp();
}

void termsize(){
    struct winsize size;
    ioctl(STDOUT_FILENO, TIOCGWINSZ, &size);
    w = size.ws_col;
    h = size.ws_row;
}

void signal_callback_handler(int _) {
    printf("\033[?1049l\033[?25h");
    exit(0);
}

std::string padint(int n, int len){
    std::string s = std::to_string(n);
    for (; s.length() < len; s = " " + s);
    return s;
}

int graphscale(int n) {return h-1-(n*(h-6)/100);}

void plot(int x, int y, int color, std::string* s){
    if (color > 7 || color < 1) color = 7;
    if (x%2 == 0) color+=8;
    std::string print = std::string(";").append(std::to_string(x)).append("H\033[48;5;").append(std::to_string(color)).append("m \033[0m");
    for (;y<h;y++) s->append("\033[").append(std::to_string(y)).append(print);
}

int main(){
    meminfo mem;
    cpuinfo cpu;
    int cpugraph[150] = {0};
    int ramgraph[150] = {0};
    int i;
    std::string bg;
    std::string graphnum;
    std::string tmp;
    std::string outbuf;
    outbuf.reserve(1000000);
    printf("\033[?25l\033[?1049h\033[2J");
    signal(SIGINT, signal_callback_handler);
    for (;;) {
        mem.loadmem();
        cpu.loadcpu(); // contains usleep(1000000)
        termsize();
        for (i = 150; i > 0; i--) {
            cpugraph[i] = cpugraph[i-1];
            ramgraph[i] = ramgraph[i-1];
        }
        cpugraph[0] = cpu.loadavg;
        ramgraph[0] = mem.percent();

        if (w < 60 || h < 10) {
            printf("\033[2J\033[1;1HWindow too small\033[2;1HMinimum size: 60x10\n");
            continue;
        }
        if (w > 300) w = 300;
        if (h > 106) h = 106;

        outbuf.append(std::string("\033[2J")
        .append("\033[2;3HLoad: ").append(padint(cpu.loadavg, 3))
        .append("% Memory:\033[3;3HTemp: ").append(padint(cpu.temp, 3)).append("C")
        .append("\033[2;22HUsed by apps: ").append(padint(mem.taken(), 5))
        .append(" (" + std::to_string(mem.percent())).append("%)\033[2;48HUsed: ")
        .append(padint(mem.used(), 5)).append("\033[3;22HCan be freed: ").append(padint(mem.available, 5))
        .append("\033[3;48HFree: ").append(padint(mem.free, 5)));

        for (bg = ";3H\033[48;5;235m"; bg.length() < w-4+14; bg.append(" "));
        bg.append("\033[0m");
        for (i = 5; i < h; i++) {
            outbuf.append("\033[").append(std::to_string(i)).append(bg);
        }
        outbuf.append("\0");

        for (i = 3; i < w/2-2+w%2; i++) {
            plot(i, graphscale(cpugraph[w/2+1-i-3]), 4, &outbuf);
            plot(i+w/2+1, graphscale(ramgraph[w/2+1-i-3]), 6, &outbuf);
        }
        outbuf.append("\0");

        tmp = ";" + std::to_string(w/2-2) + "H -";
        for (i = 5; i < h; i++) {
            outbuf.append("\033[")
            .append(std::to_string(i))
            .append(tmp)
            .append(padint(100-(i-5)*100/(h-6), 3)).append( + "- ");
        }
        printf("%s\n", outbuf.c_str());
        outbuf.clear();
    }
    return 0;
}