#!/bin/sh
# vi:syntax=bash

# Copyright 2024 Paul Hänsch
# 
# Permission to use, copy, modify, and/or distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
# 
# THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
# SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR
# IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.


. "$_EXEC/cgilite/cgilite.sh"
. "$_EXEC/acl.sh"
. "$_EXEC/tools.sh"
. "$_EXEC/datetime.sh"

tags='' ntags='' dir='' depth='' glob_system_pages=false
label='' labeltype='' altlabel='' cnt=0

set -- "$@" --
while [ $# -gt 0 ]; do case $1 in
  --system) glob_system_pages=true; shift 1;;
  --depth)  depth="$2" shift 2;;
  \#*) tags="${tags}${tags:+ }${1###}"; shift 1;;
  \!*) ntags="${ntags}${ntags:+ }${1##!}"; shift 1;;
  --date|--from) fromdate="$2"; shift 2;;
  --weekstart|--ws|-ws) ws="$2"; shift 2;;
  --) shift 1; break;;
  *) if [ ! "$dir" ]; then
      dir="$1"
      set -- "$@" "$1"; shift 1;
    elif [ ! "$depth" ]; then
      depth="$1"; shift 1;
    else
      set -- "$@" "$1"; shift 1;
    fi;;
esac; done

[ "$*" ] || set -- "."
[ "$depth" -ge 0 -o "$depth" -le 0 ] 2>&- || depth=0

read DY DM DD <<-EOF
	$(isdate "$fromdate" \
	  && date -ud "$fromdate" +"%Y %m %d" \
	  || date -u +"%Y %m %d"
	)
	EOF

case $ws in
  0|[sS]*) ws=0;;
  1|[mM]*) ws=1;;
  *) ws=0;;
esac

rrexpand() {
  # Recurrence Expansion
  # read recurring event specifications and expand them to a list of
  # single events within the specified time frame

  local dstart="$1" dend="$2"
  local junk1 start end rrfreq rrint rrend evtitle evlink junk2

  while read -r junk1 start end rrfreq rrint rrend evtitle evlink junk2; do
    [ ! "$start" ] && continue  # empty line
    [ "$rrend" -eq -1 ] && rrend=9999999999

    if [ "$start" -lt "$dend" ] &&
       [ "$end" -gt "$dstart" -o "$rrend" -gt "$dstart" ]; then
      case $rrint in
        day) rrex_day;;
        week) rrex_week;;
        month) rrex_month;;
        year) rrex_year;;
        weekday)
          [ "$rrfreq" -ge 0 ] && rrex_weekday \
                              || rrex_lastweekday
          ;;
        *):
          printf '%i	%i	%s	%s\n' "$start" "$end" "$evtitle" "$evlink"
          ;;
      esac
    fi
  done
}

rrex_day() {
  # helper for rrexpand daily/N-day expansion
  local nstart nend

  nend=$(( rrfreq * 86400 - (dstart - end) % (rrfreq * 86400) + dstart ))
  nstart=$(( start - end + nend))
  while [ "$nstart" -lt "$rrend" -a "$nstart" -lt "$dend" ]; do
    [ "$nstart" -ge "$start" ] \
    && printf '%i	%i	%s	%s\n' "$nstart" "$nend" "$evtitle" "$evlink"
    nstart="$((nstart + rrfreq * 86400))"
      nend="$((nstart - start + end))"
  done
}

rrex_week() {
  # helper for rrexpand weekly/N-week expansion
  local nstart nend

  nend=$(( 0 * 604800 - (dstart - end) % (rrfreq * 604800) + dstart ))
  nstart=$(( start - end + nend))
  while [ "$nstart" -lt "$rrend" -a "$nstart" -lt "$dend" ]; do
    [ "$nstart" -ge "$start" -a "$nstart" -ge "$dstart" ] \
    && printf '%i	%i	%s	%s\n' "$nstart" "$nend" "$evtitle" "$evlink"
    nstart="$((nstart + rrfreq * 7 * 86400))"
      nend="$((nstart - start + end))"
  done
}

rrex_month() {
  # helper for rrexpand monthly/N-month expansion
  local nstart nend

  { read _y _m _d; read y m d start_time; } <<-EOF
	$(date -ud @$dstart +"%Y %_m %_d"
	  date -ud @$start  +"%Y %_m %_d %T"
	)
	EOF
  _m=$((_y * 12 + _m)) m=$((y * 12 + m))
  while :; do
    m=$(( rrfreq - ((_m - m - 1) % rrfreq + 1) + _m ))
    nstart="$(printf '%04i-%02i-%02i' "$(( (m - 1) / 12 ))" "$(( (m - 1) % 12 + 1 ))" "$d")"
    if isdate "$nstart" && [ "$(date -ud "$nstart" +%s)" -ge "$dstart" ]; then
      break
    fi >/dev/null
    _m="$((_m + rrfreq))"
  done
  nstart="$(date -ud "$nstart $start_time" +%s)"
    nend="$((end - start + nstart))"
  while [ "$nstart" -lt "$rrend" -a "$nstart" -lt "$dend" ]; do
    [ "$nstart" -ge "$start" ] \
    && printf '%i	%i	%s	%s\n' "$nstart" "$nend" "$evtitle" "$evlink"
    m="$((m + rrfreq))"
    nstart="$(printf '%04i-%02i-%02i' "$(( (m - 1) / 12 ))" "$(( (m - 1) % 12 + 1 ))" "$d")"
    nstart="$(date -ud "$nstart $start_time" +%s)"
      nend="$((nstart - start + end))"
  done
}

rrex_year() {
  # helper for rrexpand yearly/N-year expansion
  local nstart nend

  { read _y _m _d; read y m d start_time; } <<-EOF
	$(date -ud @$dstart +"%Y %_m %_d"
	  date -ud @$start  +"%Y %_m %_d %T"
	)
	EOF
  while :; do
    y=$(( rrfreq - ((_y - y - 1) % rrfreq + 1) + _y ))
    nstart="$(printf '%04i-%02i-%02i' "$y" "$m" "$d")"
    if isdate "$nstart" && [ "$(date -ud "$nstart" +%s)" -ge "$dstart" ]; then
      break
    fi >/dev/null
    _y="$((_y + rrfreq))"
  done
  nstart="$(date -ud "$nstart $start_time" +%s)"
    nend="$((end - start + nstart))"
  while [ "$nstart" -lt "$rrend" -a "$nstart" -lt "$dend" ]; do
    [ "$nstart" -ge "$start" ] \
    && printf '%i	%i	%s	%s\n' "$nstart" "$nend" "$evtitle" "$evlink"
    y="$((y + rrfreq))"
    nstart="$(printf '%04i-%02i-%02i' "$y" "$m" "$d")"
    nstart="$(date -ud "$nstart $start_time" +%s)"
      nend="$((nstart - start + end))"
  done
}

rrex_weekday() {
  # helper for rrexpand: Nth weekday of a month (e.g. 2nd tuesday, etc.)
  local nstart nend

  nth=$(( ( $(date -ud @$start +%_d) - 1) / 7))

  nend=$(( 0 * 604800 - (dstart - end) % 604800 + dstart ))
  nstart=$(( start - end + nend))

  while [ "$nstart" -lt "$rrend" -a "$nstart" -lt "$dend" ]; do
    [ "$nstart" -ge "$start" -a "$nstart" -ge "$dstart" ] \
    && [ "$(( ( $(date -ud @$nstart +%_d) -1) / 7 ))" -eq "$nth" ] \
    && printf '%i	%i	%s	%s\n' "$nstart" "$nend" "$evtitle" "$evlink"
    nstart="$((nstart + 7 * 86400))"
      nend="$((nstart - start + end))"
  done
}

rrex_lastweekday() {
  # helper for rrexpand: Nth last weekday of a month (e.g. 2nd last tuesday, etc.)
  local nstart nend Y m d nth

  read Y m d <<-EOF
	$(date -ud @$start +"%Y %_m %_d")
	EOF
  nth=$(( ( $(numdays $Y $m) - d ) / 7))

  nend=$(( 0 * 604800 - (dstart - end) % 604800 + dstart ))
  nstart=$(( start - end + nend))

  while [ "$nstart" -lt "$rrend" -a "$nstart" -lt "$dend" ]; do
    read Y m d <<-EOF
	$(date -ud @$nstart +"%Y %_m %_d")
	EOF
    [ "$nstart" -ge "$start" -a "$nstart" -ge "$dstart" ] \
    && [ "$(( ( $(numdays $Y $m) - d ) / 7 ))" -eq "$nth" ] \
    && printf '%i	%i	%s	%s\n' "$nstart" "$nend" "$evtitle" "$evlink"
    nstart="$((nstart + 7 * 86400))"
      nend="$((nstart - start + end))"
  done
}

events="$(
  for dir in "$@"; do
    page_glob "$dir" "$depth"
  done \
  | sort -u \
  | while read -r page; do
    pagedir="$(page_abs "$page")"
    if [ -f "$_DATA/pages/${pagedir}/#events" ] \
       && acl_read "$pagedir" \
       && has_tags "$pagedir" $tags \
       && ! has_tag "$pagedir" $ntags
    then
      cat "$_DATA/pages/${pagedir}/#events"
    fi
  done
)"

cal_list() {
  # Print list view for upcoming events
  local lday='' events sdate=$(date -ud "${DY}-${DM}-${DD}" +%s)

  events="$(
    printf %s\\n "$events" \
    | rrexpand "$sdate" "$((sdate + 42 * 86400))" \
    | sort -n
  )"
  
  printf '<ul class="macro calendar cal_list">\n'
  printf '%s\n' "${events}" \
  | while read start end name link; do
    day="$((start / 86400))"
    if [ "$day" != "$lday" ]; then
      [ "$lday" ] && printf '</ul></li>'
      date -ud "@$start" +'<li><label>%A, %F</label><ul class="day">'
      lday="$day"
    fi
    printf '<li>%s - <a href="%s">%s</a></li>' \
           "$(date -ud "@$start" +"%H:%M")" "$(URL "${link%%#*}")#$(URL "${link#*#}")" "$(HTML "${name}")"
  done
  printf '</ul></li></ul>'
}

cal_month() {
  local ws events calmonth
  local iday idow mname dcnt dow dcal start end title link n

  calmonth="$(GET calmonth || printf %i "$((DY * 12 + DM))")"
  DY="$(( (calmonth - 1) / 12 ))"
  DM="$(( (calmonth - 1) % 12 + 1 ))"

  read -r iday idow mname <<-EOF
	$(date -ud "${DY}-${DM}-01" +"%s	%u	%B")
	EOF
  dcnt=$((iday - idow * 86400 + ws * 86400))
   dow=$ws
  dcal="$(date -ud @"$dcnt" +%d)"
  events="$(
    printf %s\\n "$events" \
    | rrexpand "$dcnt" "$((dcnt + 42 * 86400))" \
    | sort -n
  )"

  printf '<table class="macro calendar cal_month">'
  printf '<thead><tr><th><a href="%s">&lt;</a></th><th colspan=5>%s</th><th><a href="%s">&gt;</a></th></tr><tr>' \
    "./?calmonth=$((DY * 12 + DM -1))" "$mname" "./?calmonth=$((DY * 12 + DM + 1))"
  for n in 0 1 2 3 4 5 6; do date -ud @"$((dcnt + n * 86400))" +'<th>%a</th>'; done
  printf '</tr></thead><tbody>'
  while :; do
    [ $dow = $ws ] && printf '<tr>'
    printf '<td><label>%02i</label>' "$dcal"

    evlist="$(
      printf %s "${events}${events:+${BR}}" \
      | while read start end title link; do
        if [ "$((start / 86400))" -lt "$((dcnt / 86400))" -a "$end" -gt "$dcnt" ]; then
          printf '<li><a href="%s\#%s">%s</a></li>' \
            "$(UNSTRING "${link%%#*}" |URL)" \
            "$(UNSTRING "${link#*#}" |URL)" \
            "$(UNSTRING "$title" |HTML)"
        elif [ "$((start / 86400))" -eq "$((dcnt / 86400))" ]; then
          printf '<li>%s - <a href="%s#%s">%s</a></li>' \
            "$(date -ud @"$start" +%H:%M)" \
            "$(UNSTRING "${link%%#*}" |URL)" \
            "$(UNSTRING "${link#*#}" |URL)" \
            "$(UNSTRING "$title" |HTML)"
        fi
      done
    )"
    [ "$evlist" ] && printf '<ul>%s</ul>' "$evlist"

    printf '</td>\n'
    [ $dow = $(( (ws + 6) % 7)) ] && printf '</tr>\n'

    dcnt=$(( dcnt + 86400 ))
     dow=$(( (dow + 1) % 7 ))
    [ $dcal -lt 28 ] \
    && dcal=$((dcal + 1)) \
    || dcal=$(date -ud @"$dcnt" +%d)
    [ $dcnt -gt $((iday + 28 * 86400)) -a $dcal -le 7 -a $dow = $ws ] \
    && break
  done
  printf '</tbody></table>'
}

# cal_list
cal_month