const char *iCalHeader = "BEGIN:VCALENDAR\r\n"
                         "VERSION:2.0\r\n"
                         "PRODID:-//hacksw/handcal//NONSGML v1.0//EN\r\n";
const char *iCalEvent = "BEGIN:VEVENT\r\n"
                        "UID:%s%d\r\n"
                        "DTSTAMP:%s\r\n"
                        "DTSTART:%s\r\n"
                        "DTEND:%s\r\n"
                        "SUMMARY:%s\r\n"
                        "END:VEVENT\r\n";

const char *iCalFileExtension = "ics";

/*
 * Wikipedia
 *
 *The body of the iCalendar object (the icalbody) contains single-line Calendar
 * Properties that apply to the entire calendar, as well as one or more blocks
 * of multiple lines that each define a Calendar Component such as an event,
 * journal entry, alarm, or one of several other types. Here is a simple example
 * of an iCalendar object with a single calendar containing a single Calendar
 * Component, a "Bastille Day Party" event starting at 5pm on July 14, 1997, and
 * ending at 4am the following morning:[10]



BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//hacksw/handcal//NONSGML v1.0//EN
BEGIN:VEVENT
UID:uid1@example.com
ORGANIZER;CN=John Doe:MAILTO:john.doe@example.com
DTSTART:19970714T170000Z
DTEND:19970715T040000Z
SUMMARY:Bastille Day Party
GEO:48.85299;2.36885
END:VEVENT
END:VCALENDAR


The UID field distributes updates when a scheduled event changes. When the event
is first generated a globally unique identifier is created. If a later event is
distributed with the same UID, it replaces the original one. An example UID
might be Y2007S2C131M5@example.edu, for the 5th meeting of class 131 in semester
2 at a hypothetical college. Email-style UIDs are now considered bad practice,
with a UUID recommended instead.[11]

The most common representation of date and time is a tz timestamp such as
20010911T124640Z with the format <year (4 digits)><month (2)><day (2)>T<hour
(2)><minute (2)><second (2)>Z for a total fixed length of 16 characters. Z
indicates the use of UTC (referring to its Zulu time zone).[12] When used in
DTSTART and DTEND properties, start times are inclusive while end times are not.
This allows an event's end time to be the same as a consecutive event's start
without those events overlapping and potentially creating (false) scheduling
conflicts.[13]


 */

int exportiCal(llist *events_ll) {

  llist *ev_ll = events_ll;

  llistPrintE(ev_ll);

  printf("%s", iCalHeader);

  time_t now = time(NULL);
  struct tm lc;
  localtime_r(&now, &lc);

  // gen filename & open for write
  char nameBuf[32];
  strftime(nameBuf, 32 - 12, "%F", &lc);
  strcat(nameBuf, "dayplan.ics");
  FILE *fp = fopen(nameBuf, "w");
  if (fp == NULL) {
    planLog("fopen failed!!", 1);
    return 1;
  }
  // write iCal header to file
  fprintf(fp, "%s", iCalHeader);

  // for every event in events_ll create VEVENT str and write to fp
  int count = 0;
  while (ev_ll != NULL) {
    // gen iCal compatible time str
    Event *current = ev_ll->data;
    struct tm startlc;
    struct tm endlc;
    localtime_r(&current->plannedStartTime, &startlc);
    localtime_r(&current->plannedEndTime, &endlc);
    char timeStartBuf[17];
    char timeEndBuf[17];
    char timeStamp[17];
    strftime(timeStamp, 17, "%Y%m%dT%k%M%SZ", &lc);
    printf("%s\n", timeStamp);
    strftime(timeStartBuf, 17, "%Y%m%dT%k%M%SZ", &startlc);
    printf("%s\n", timeStartBuf);
    strftime(timeEndBuf, 17, "%Y%m%dT%k%M%SZ", &endlc);
    printf("%s\n", timeEndBuf);

    fprintf(fp, iCalEvent, current->task->name, count, timeStamp, timeStartBuf,
            timeEndBuf, current->task->name);
    ev_ll = ev_ll->next;
    count += 1;
  }

  // after all events are written end cal with
  // END:VCALENDAR
  fprintf(fp, "END:VCALENDAR\r\n");
  fclose(fp);

  return 0;
}

const char *taskFileFormat = "%s,%lu,%lu,%d,%lu\n";
int taskLlToFile(llist *tll) {
  // open file
  FILE *fp = fopen("db.csv", "w");
  if (fp == NULL)
    return -1;
  llist *c = tll;
  while (c != NULL) {
    Task *ct = (Task *)c->data;
    fprintf(fp, taskFileFormat, ct->name, ct->created, ct->deadline,
            ct->priority, ct->spare);
    c = c->next;
  }
  fclose(fp);

  return 0;
}