#include <unistd.h>
#include <stdio.h>
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#define db 0

void debug(int desc, char * tekst, char * pid)  {
    char *MSG = (char *) malloc((2 + strlen(pid) + strlen(tekst)));
    strcpy(MSG, pid);
    strcat(MSG, "\n");
    strcat(MSG, tekst);
    write(desc, MSG, (int)strlen(MSG));
}

int main(int argc, char *argv[]) {
    int writer_number = atoi(argv[1]);

    pid_t parent = getppid();
    char parent_str[20];
    sprintf(parent_str, "%d", parent);

    pid_t pid = getpid();
    char pid_str[20];
    sprintf(pid_str, "%d", pid);

    int inst;
    if(db == 1) inst = open("test.txt", O_CREAT | O_WRONLY | O_APPEND , S_IRUSR | S_IWUSR);

    int fd;

    if ((mkfifo(parent_str, S_IRWXU | S_IRWXG | S_IRWXO)) != 0) {
        if (errno == EEXIST) {
            if(db == 1) debug(inst, "  WRITER. Fifo DUZE juz stworzone. Otwieram do odczytu.\n", pid_str);
            if ((fd = open(parent_str, O_WRONLY|O_APPEND)) == -1) exit(1);
        } else {
            exit(1);
        }
    } else {
        if(db == 1) debug(inst, "  WRITER. Fifo DUZE nie stworzone. Tworzę i otwieram do odczytu.\n", pid_str);
        if ((fd = open(parent_str, O_WRONLY|O_APPEND)) == -1) exit(1);
    }

    int wd;
    int special = 0;

    char writer_parent_str[20];
    sprintf(writer_parent_str, "%d", parent);
    writer_parent_str[strlen(writer_parent_str) + 1] = writer_parent_str[strlen(writer_parent_str)];
    writer_parent_str[strlen(writer_parent_str)] = 'W';

    if ((mkfifo(writer_parent_str, S_IRWXU | S_IRWXG | S_IRWXO)) != 0) {
        if (errno == EEXIST) {
            if(db == 1) debug(inst, "  WRITER. Nie zostane specjalnym writerem.\n", pid_str);
            if ((wd = open(writer_parent_str, O_WRONLY|O_APPEND)) == -1) exit(1);
            special = 0;
        } else {
            exit(1);
        }
    } else {
        if(db == 1) debug(inst, "  WRITER. Zostalem specjalnym writerem.\n", pid_str);
        if ((wd = open(writer_parent_str, O_RDONLY)) == -1) exit(1);
        special = 1;
    }

    int val;
    char buf[20];

    fd_set readfds;
    int ok_3 = 1;
    int ok_4 = 1;

    if(db == 1) debug(inst, "  WRITER. Zaczynam produkcje liczb.\n", pid_str);

    while(ok_3 == 1 || ok_4 == 1) {
        FD_ZERO(&readfds);
        if(ok_3) FD_SET(3, &readfds);
        if(ok_4) FD_SET(4, &readfds);

        int ready_for_reading = select(5, &readfds, NULL, NULL, NULL);

        if(ready_for_reading) {
            if (FD_ISSET(3, &readfds)) {
                if (read(3, &val, 4) > 0) {
                    int i;
                    int n = sprintf(buf, "%d", val);
                    for (i = n; i < 20; i++) buf[i] = ' ';
                    buf[19] = '\n';
                    if (n > 0) write(fd, buf, 20);
                } else {
                    ok_3 = 0;
                    if(db == 1) debug(inst, "  WRITER. Trojka skonczyla prace.\n", pid_str);
                }
            }
            if (FD_ISSET(4, &readfds)) {
                if (read(4, &val, 4) > 0) {
                    int i;
                    int n = sprintf(buf, "%d", val);
                    for (i = n; i < 20; i++) buf[i] = ' ';
                    buf[19] = '\n';
                    if (n > 0) write(fd, buf, 20);
                } else {
                    ok_4 = 0;
                    if(db == 1) debug(inst, "  WRITER. Czworka skonczyla prace.\n", pid_str);
                }
            }
        }
    }

    if(db == 1) debug(inst, "  WRITER. Wgl producenci skonczyli produkcje.\n", pid_str);

    if(special == 0) {
        write(wd, "1", 1);
        if(db == 1) debug(inst, "  WRITER. Nie jestem specjalny wiec zapisuje jedynke.\n", pid_str);
    } else {
        int count = 0;
        char buff[2];
        buff[1] = '\n';
        if(db == 1) debug(inst, "  WRITER. Jestem specjalny czekam na reszte.\n", pid_str);
        while(count != writer_number - 1){
            buff[0] = '0';
            if(read(wd, &buff, 1) > 0) {
                if (buff[0] == '1') {
                    if(db == 1) debug(inst, "  WRITER. Ktos zakonczyl i sie odrejestrowal.\n", pid_str);
                    count++;
                }
            }
        }

        if(db == 1) debug(inst, "  WRITER. Wszyscy skonczyli.\n", pid_str);

        char del[100];
        del[0] = 'r';
        del[1] = 'm';
        del[2] = ' ';
        int i = 3, k = 0;
        for(k = 0; k < strlen(parent_str); k++, i++) {
            del[i] = parent_str[k];
        }
        del[i++] = ' ';
        for(k = 0; k < strlen(writer_parent_str); k++, i++) {
            del[i] = writer_parent_str[k];
        }
        system(del);

        if(db == 1) debug(inst, "  WRITER. Posprzatalem, koncze robote.\n", pid_str);
    }

    if(db == 1) close(inst);
    close(fd);
    close(wd);
    close(3);
    close(4);

    return 0;
}