#include<stdlib.h>
#include<stdio.h>
#include<string.h>
#include<unistd.h>
#include<signal.h>
#include <time.h>
#include <math.h>
#include <pthread.h>
#ifndef NO_X
#include<X11/Xlib.h>
#endif
#ifdef __OpenBSD__
#define SIGPLUS      (SIGUSR1 + 1)
#define SIGMINUS     (SIGUSR1 - 1)
#else
#define SIGPLUS      SIGRTMIN
#define SIGMINUS     SIGRTMIN
#endif
#define LENGTH(X)    (sizeof(X) / sizeof(X[0]))
#define CMDLENGTH    50
#define SDIRLENGTH   256
#define MIN( a, b )  (a < b ? a : b)
#define STATUSLENGTH (LENGTH(blocks) * CMDLENGTH + 1)

typedef struct {
    char* icon;
    char* command;
    unsigned int interval;
    unsigned int signal;
} Block;
typedef void(*ThreadCallback)(pthread_t *);
void getcmd(const Block *block, char *output);
void getcmds(int time);
void getsigcmds(unsigned int signal);
#ifndef __OpenBSD__
void dummysighandler(int signum);
#endif
void sighandler(int signum);
void setupsignals(void);
int getstatus(char *str, char *last);
void pstdout(void);
int gcd(int n1, int n2);
void startthreads(void);
void statusloop(void);
void stopthreads(void);
void termhandler(void);
#ifndef NO_X
void setroot(void);
static void (*writestatus) (void) = setroot;
static int setupx(void);
static Display *dpy;
static int screen;
static Window root;
#else
static void (*writestatus) (void) = pstdout;
#endif

#include "blocks.h"

static char statusbar[LENGTH(blocks)][CMDLENGTH] = {0};
static char statusstr[2][STATUSLENGTH];
static int statuscontinue = 1;

static pthread_t main_thread;
static pthread_t threads[LENGTH(thread_callbacks)];
static int initdone = 0;

//opens process *cmd and stores output in *output
void getcmd(const Block *block, char *output) {
    strcpy(output, block->icon);
    FILE *cmdf = popen(block->command, "r");
    if (!cmdf) {
        return;
    }
    int i = strlen(block->icon);
    fgets(output + i, CMDLENGTH - i - delimLen, cmdf);
    i = strlen(output);
    if (i == 0) {
        //return if block and command output are both empty
        pclose(cmdf);
        return;
    }
    //only chop off newline if one is present at the end
    i = output[i - 1] == '\n' ? i - 1 : i;
    if (delim[0] != '\0') {
        strncpy(output + i, delim, delimLen);
    } else {
        output[i++] = '\0';
    }
    pclose(cmdf);
}

void getcmds(int time) {
    const Block* current;
    for (unsigned int i = 0; i < LENGTH(blocks); ++i) {
        current = blocks + i;
        if ((current->interval != 0 && time % current->interval == 0) || time == -1) {
            getcmd(current, statusbar[i]);
        }
    }
}

void getsigcmds(unsigned int signal) {
    const Block *current;
    for (unsigned int i = 0; i < LENGTH(blocks); ++i) {
        current = blocks + i;
        if (current->signal == signal) {
            getcmd(current, statusbar[i]);
        }
    }
}

#ifndef __OpenBSD__
/* this signal handler should do nothing */
void dummysighandler(int signum) {
    return;
}
#endif

void sighandler(int signum) {
    getsigcmds(signum-SIGPLUS);
    writestatus();
}

void setupsignals() {
#ifndef __OpenBSD__
    /* initialize all real time signals with dummy handler */
    for (int i = SIGRTMIN; i <= SIGRTMAX; ++i) {
        signal(i, dummysighandler);
    }
#endif

    for (unsigned int i = 0; i < LENGTH(blocks); ++i) {
        if (blocks[i].signal > 0) {
            signal(SIGMINUS + blocks[i].signal, sighandler);
        }
    }

}

int getstatus(char *str, char *last) {
    strcpy(last, str);
    str[0] = '\0';
    for (unsigned int i = 0; i < LENGTH(blocks); ++i) {
        strcat(str, statusbar[i]);
    }
    str[strlen(str)-strlen(delim)] = '\0';
    return strcmp(str, last); //0 if they are the same
}

void pstdout() {
    if (!initdone || !getstatus(statusstr[0], statusstr[1])) { //Only write out if text has changed.
        return;
    }
    printf("%s\n", statusstr[0]);
    fflush(stdout);
}

void somebar_pstdout() {
    if (!initdone || !getstatus(statusstr[0], statusstr[1])) { //Only write out if text has changed.
        return;
    }
    printf("status %s\n", statusstr[0]);
    fflush(stdout);
}

int gcd(int n1, int n2) {
	int temp;
	while (n2 > 0){
		temp = n1 % n2;
		n1 = n2;
		n2 = temp;
	}
	return n1;
}

void startthreads() {
    main_thread = pthread_self();
    for (int i = 0; i < LENGTH(thread_callbacks); ++i) {
        pthread_create(&threads[i],
                       NULL,
                       (void *(*)(void *)) thread_callbacks[i],
                       &main_thread);
    }
}

void statusloop() {
    setupsignals();
    unsigned int interval = -1;
    for (int i = 0; i < LENGTH(blocks); ++i){
        if (blocks[i].interval){
            interval = gcd(blocks[i].interval, interval);
        }
    }
    startthreads();
    int i = 0;
    getcmds(-1);
    long nsec_part = interval * 1000000;
    time_t sec_part = floor(nsec_part / 1000000000.0);
    nsec_part -= sec_part * 1000000000l;
    const struct timespec sleeptime = { sec_part, nsec_part };
    struct timespec tosleep = sleeptime;
    while (statuscontinue) {
        initdone = 1;
        if (nanosleep(&tosleep, &tosleep) < 0) {
            continue;
        }
        getcmds((i++) * interval);
        writestatus();
        tosleep = sleeptime;
    }
}

void stopthreads() {
    for (int i = 0; i < LENGTH(thread_callbacks); ++i) {
        pthread_cancel(threads[i]);
        pthread_join(threads[i], NULL);
    }
}

void termhandler() {
    statuscontinue = 0;
}

#ifndef NO_X
void setroot() {
    if (!initdone || !getstatus(statusstr[0], statusstr[1])) { //Only set root if text has changed.
        return;
    }
    XStoreName(dpy, root, statusstr[0]);
    XFlush(dpy);
}

int setupx() {
    dpy = XOpenDisplay(NULL);
    if (!dpy) {
        fprintf(stderr, "dwmblocks: Failed to open display\n");
        return 0;
    }
    screen = DefaultScreen(dpy);
    root = RootWindow(dpy, screen);
    return 1;
}
#endif

int main(int argc, char** argv) {
    for (int i = 0; i < argc; ++i) { //Handle command line arguments
        if (strcmp("-d", argv[i]) == 0) {
            strncpy(delim, argv[++i], delimLen);
        } else if (strcmp("-p", argv[i]) == 0) {
            writestatus = pstdout;
        } else if (strcmp("-s", argv[i]) == 0) {
            writestatus = somebar_pstdout;
        }
    }
#ifndef NO_X
    if (!setupx()) {
        return 1;
    }
#endif
    delimLen = MIN(delimLen, strlen(delim));
    delim[delimLen++] = '\0';
    signal(SIGTERM, (void(*)(int))termhandler);
    signal(SIGINT, (void(*)(int))termhandler);
    statusloop();
#ifndef NO_X
    XCloseDisplay(dpy);
#endif
    stopthreads();
    return 0;
}