#define _POSIX_C_SOURCE 199309L

#include <stdio.h>

#include <stdlib.h>

#include <stdarg.h>

#include <string.h>

#include <unistd.h>

#include <poll.h>

#include <time.h>

#include <signal.h>

#include <sys/types.h>

#include <sys/wait.h>

#include <fcntl.h>

#include <errno.h>

#include <math.h>

enum DPokeSourceType_en {

    DPOKE_PROGRAM,

    DPOKE_FILE,

    DPOKE_FUNCTION,

};

typedef enum DPokeSourceType_en DPokeSourceType;

#define DPOKE_BUFFER 32

struct DPokeSource_st {

    DPokeSourceType type;

    char *path;

    int arg;

    //FILE *stream;

    int fd;

    enum DPokeSourceStatus_en {

        DPOKE_STARTED,

        DPOKE_RUNNING,

        DPOKE_DIED,

        DPOKE_FAIL,

        DPOKE_FAILED,

    } status;

    char buffer[DPOKE_BUFFER+1];

    char current[DPOKE_BUFFER+1];

    int buffer_usage;

    // DPOKE_PROGRAM-specific fields:

    int pid;

};

typedef struct DPokeSource_st DPokeSource;

#define LENGTH(X)               (sizeof X / sizeof X[0])

char* smprintf(char *fmt, ...) {

    va_list fmtargs;

    char *ret;

    int len;

    va_start(fmtargs, fmt);

    len = vsnprintf(NULL, 0, fmt, fmtargs);

    va_end(fmtargs);

    ret = malloc(++len);

    if (ret == NULL) {

        perror("malloc");

        exit(1);

    }

    va_start(fmtargs, fmt);

    vsnprintf(ret, len, fmt, fmtargs);

    va_end(fmtargs);

    return ret;

}

void display();

extern char* v[];

#include "config.h"

#ifdef DEBUG

#define errprintf(...) fprintf(stderr,...)

#else

#define errprintf(...)

#endif

char* v[LENGTH(sources)];

static struct pollfd source_fds[LENGTH(sources)];

void source_open(int source_id) {

    DPokeSource *src = &sources[source_id];

    //FILE* stream;

    int p_stdout[2];

    switch (src->type) {

        case DPOKE_PROGRAM:

            //stream = popen(src->path, "r");

            if (pipe(p_stdout)!=0) {

                perror("pipe");

                exit(7);

            }

            pid_t pid = fork();

            if (pid < 0) {

                perror("fork");

                exit(7);

            } else if (pid == 0) {

                dup2(open("/dev/null",O_RDONLY),0);

                close(p_stdout[0]);

                dup2(p_stdout[1],1);

                execl("/bin/sh", "sh", "-c", src->path, NULL);

                perror("execl");

                exit(1);

            }

            src->fd = p_stdout[0];

            src->pid = pid;

            break;

        default:

            errprintf("Don't know how to handle source type %d.\n",src->type);

            exit(2);

    }

    //src->stream = stream;

    //src->fd = fileno(stream);

    src->buffer_usage = 0;

    src->status = DPOKE_STARTED;

    source_fds[source_id].fd = sources[source_id].fd;

    source_fds[source_id].events = POLLIN;

}

static void sigchld_hdl (int sig)

{

    pid_t pid;

    while ((pid = waitpid(-1, NULL, WNOHANG)) > 0) {

        for (int i=0;i<LENGTH(sources);i++)

            if ((sources[i].type == DPOKE_PROGRAM) && (sources[i].pid == pid)) {

                sources[i].pid = -1;

                errprintf("#%d pid %d died.\n",i,pid);

                switch (sources[i].status) {

                    case DPOKE_STARTED:

                        sources[i].status = DPOKE_FAIL; break;

                    case DPOKE_RUNNING:

                        sources[i].status = DPOKE_DIED; break;

                    default:

                        errprintf("#%d died in state %d. Whaddafuck?!\n",i,sources[i].status);

                        exit(8);

                }

            }

    }

}

void source_close(int source_id) {

    DPokeSource *src = &sources[source_id];

    if (src->pid != -1) kill(src->pid,SIGTERM);

    if (src->fd != -1) close(src->fd);

    source_fds[source_id].fd = -1;

}

double dpoke_time() {

    struct timespec tp;

    if (clock_gettime(CLOCK_MONOTONIC,&tp)) {

        perror("clock_gettime");

        exit(5);

    }

    return tp.tv_sec + tp.tv_nsec*1E-9;

}

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

    struct sigaction act;

    memset (&act, 0, sizeof(act));

    act.sa_handler = sigchld_hdl;

    if (sigaction(SIGCHLD, &act, 0)) {

        perror ("sigaction");

        exit(6);

    }

    for (int i = 0; i < LENGTH(sources); i++ ) {

        source_open(i);

        v[i] = sources[i].current;

    }

    int status;

    int sleeptime = 10000;

    double prevtime=dpoke_time();

    while (1) {

        status = poll(source_fds,LENGTH(sources), sleeptime);

        if (status < 0) {

            if (errno == EINTR)

                continue;

        }

        for (int i = 0; i < LENGTH(sources); i++) {

            DPokeSource *src = sources+i;

            if (source_fds[i].revents & POLLIN) {

                int data_read = read(src->fd,src->buffer+src->buffer_usage,DPOKE_BUFFER-src->buffer_usage);

                if (data_read>0) {

                    src->buffer_usage += data_read;

                    if (src->buffer_usage==DPOKE_BUFFER) {

                        errprintf("Buffer is full for #%d.\n",i);

                    }

                    src->buffer[src->buffer_usage] = '\0';

                    char* eolpos = strchr(src->buffer + src->buffer_usage - data_read,'\n');

                    if (eolpos) {

                        memcpy(src->current,src->buffer,eolpos-src->buffer);

                        src->current[eolpos-src->buffer] = '\0';

                        src->buffer_usage -= (eolpos - src->buffer + 1);

                        memmove(src->buffer,eolpos + 1,src->buffer_usage + 1);

                    }

                    if (src->status == DPOKE_STARTED)

                        src->status = DPOKE_RUNNING;

                } else {

                    perror("read");

                    exit(3);

                }

            } else if ((source_fds[i].revents & POLLHUP)||(src->status==DPOKE_DIED)) {

                errprintf("#%d HUP\n",i);

                source_close(i);

                if (src->status==DPOKE_STARTED)

                    src->status = DPOKE_FAIL;

                else

                    source_open(i);

            } else if (source_fds[i].revents) {

                errprintf("#%d revents: %d\n",i,source_fds[i].revents);

            }

            if (src->status==DPOKE_FAIL) {

                src->status = DPOKE_FAILED;

                errprintf("#%d Marked as failure\n",i);

                strcpy(src->current,FAILURE_MSG);

            }

        }

        double curtime = dpoke_time();

        if ((curtime-prevtime)>MINTIME) {

            display();

            prevtime = curtime;

            sleeptime = 10000;

        } else {

            double sleepd = (prevtime+MINTIME - curtime)*1000;

            sleeptime = ceil(sleepd);

            errprintf("%f %f %f %f\n",prevtime,curtime,MINTIME,sleepd);

        }

        errprintf("Will sleep for %d\n",sleeptime);

    }

    return 0;

}

/*

ABCnDEF0

01234567

eolpos = 3

bu = 7

3-0+1 = 4

bu = 3

memmove:

01234567

34534567

nDEn

*/