/*
 *
 * Conky, a system monitor, based on torsmo
 *
 * Please see COPYING for details
 *
 * Copyright (c) 2005-2024 Brenden Matthews, Philip Kovacs, et. al.
 *	(see AUTHORS)
 * All rights reserved.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include <libical/ical.h>
#include "../conky.h"
#include "../logging.h"

struct ical_event {
  icaltimetype start;
  icalcomponent *event;
  ical_event *next, *prev;
};

struct obj_ical {
  struct ical_event *list;
  icalcomponent *comps;
  icalparser *parser;
  unsigned int num;
};

char *read_stream(char *s, size_t size, void *d) {
  return fgets(s, size, (FILE *)d);
}

struct ical_event *add_event(struct ical_event *listend,
                             icalcomponent *new_ev) {
  struct ical_event *ev_new, *ev_cur;
  icaltimetype start;

  start = icalcomponent_get_dtstart(new_ev);
  if (icaltime_compare(
          start, icaltime_from_timet_with_zone(time(nullptr), 0, NULL)) <= 0) {
    icalproperty *rrule =
        icalcomponent_get_first_property(new_ev, ICAL_RRULE_PROPERTY);
    if (rrule) {
      icalrecur_iterator *ritr =
          icalrecur_iterator_new(icalproperty_get_rrule(rrule), start);
      icaltimetype nexttime = icalrecur_iterator_next(ritr);
      while (!icaltime_is_null_time(nexttime)) {
        if (icaltime_compare(nexttime, icaltime_from_timet_with_zone(
                                           time(nullptr), 0, NULL)) > 0) {
          start = nexttime;
          break;
        }
        nexttime = icalrecur_iterator_next(ritr);
      }
      icalrecur_iterator_free(ritr);
    } else
      return nullptr;
  }
  ev_new = (struct ical_event *)malloc(sizeof(struct ical_event));
  memset(ev_new, 0, sizeof(struct ical_event));
  ev_new->event = new_ev;
  ev_new->start = start;
  if (listend) {  // list already contains events
    ev_cur = listend;
    while (icaltime_compare(ev_new->start, ev_cur->start) <= 0) {
      if (!ev_cur->prev) {  // ev_new starts first
        ev_new->next = ev_cur;
        ev_cur->prev = ev_new;
        return listend;
      }
      ev_cur = ev_cur->prev;
    }
    if (ev_cur == listend) {  // ev_new starts last
      ev_cur->next = ev_new;
      ev_new->prev = ev_cur;
      return ev_new;
    }
    // ev_new somewhere in the middle
    ev_new->prev = ev_cur;
    ev_new->next = ev_cur->next;
    ev_cur->next->prev = ev_new;
    ev_cur->next = ev_new;
    return listend;
  }
  return ev_new;
}

void parse_ical_args(struct text_object *obj, const char *arg,
                     void *free_at_crash, void *free_at_crash2) {
  char *filename = strdup(arg);
  FILE *file;
  icalparser *parser;
  icalcomponent *allc, *curc;
  struct ical_event *ll_start, *ll_end, *ll_new;
  struct obj_ical *opaque;
  unsigned int num;

  if (sscanf(arg, "%d %s", &num, filename) != 2) {
    free(filename);
    COMMAND_ARG_ERR("ical", "wrong number of arguments for $ical");
  }
  file = fopen(filename, "r");
  if (!file) {
    SYSTEM_ERR("can't read file '{}'", filename);
    free(filename);
    return;
  }
  free(filename);
  parser = icalparser_new();
  icalparser_set_gen_data(parser, file);
  allc = icalparser_parse(parser, read_stream);
  fclose(file);
  curc = icalcomponent_get_first_component(allc, ICAL_VEVENT_COMPONENT);
  if (!curc) {
    icalparser_free(parser);
    icalcomponent_free(allc);
    LOG_WARNING("no ical events available");
    return;
  }
  ll_start = add_event(nullptr, curc);
  ll_end = ll_start;
  while (1) {
    curc = icalcomponent_get_next_component(allc, ICAL_VEVENT_COMPONENT);
    if (!curc) break;
    ll_new = add_event(ll_end, curc);
    if (!ll_start) {  // first component was not added
      ll_start = ll_new;
      ll_end = ll_new;
    } else if (ll_start->prev) {
      ll_start = ll_start->prev;
    } else if (ll_end->next) {
      ll_end = ll_end->next;
    }
  }
  opaque = (struct obj_ical *)malloc(sizeof(struct obj_ical));
  opaque->list = ll_start;
  opaque->parser = parser;
  opaque->comps = allc;
  opaque->num = num;
  obj->data.opaque = opaque;
  free(opaque);
}

void print_ical(struct text_object *obj, char *p, unsigned int p_max_size) {
  struct obj_ical *ical_obj = (struct obj_ical *)obj->data.opaque;
  struct ical_event *ll_current;

  if (!ical_obj) return;
  ll_current = ical_obj->list;
  unsigned int i = 1;
  while (1) {
    if (!ll_current) return;
    if (i > ical_obj->num) return;
    if (i == ical_obj->num) break;
    if (i < ical_obj->num) {
      ll_current = ll_current->next;
      i++;
    }
  }
  snprintf(p, p_max_size, "%s",
           icalproperty_get_summary(icalcomponent_get_first_property(
               ll_current->event, ICAL_SUMMARY_PROPERTY)));
}

void free_ical(struct text_object *obj) {
  struct obj_ical *ical_free_me = (struct obj_ical *)obj->data.opaque;

  if (!ical_free_me) return;
  icalcomponent_free(ical_free_me->comps);
  icalparser_free(ical_free_me->parser);
  while (ical_free_me->list) {
    if (ical_free_me->list->next) {
      ical_free_me->list = ical_free_me->list->next;
      free_and_zero(ical_free_me->list->prev);
    } else
      free_and_zero(ical_free_me->list);
  }
  free(obj->data.opaque);
}
