#!/bin/sh

set -eu
# TODO: Make sensitive to failures. I don't want to miss appointments!
# TODO Ensure safe use of delimiters

err() {
  echo "❌ $1" >/dev/tty
}

if [ -z "${FZF_VCAL_USE_EXPORTED:-}" ]; then
  # Read configuration
  CONFIGFILE="$HOME/.config/fzf-vcal/config"
  if [ ! -f "$CONFIGFILE" ]; then
    err "Configuration '$CONFIGFILE' not found."
    exit 1
  fi
  # shellcheck source=/dev/null
  . "$CONFIGFILE"
  if [ -z "${ROOT:-}" ] || [ -z "${SYNC_CMD:-}" ] || [ -z "${COLLECTION_LABELS:-}" ]; then
    err "Configuration is incomplete."
    exit 1
  fi
  export ROOT
  export SYNC_CMD
  export COLLECTION_LABELS

  DAY_START=${DAY_START:-8}
  DAY_END=${DAY_END:-18}
  export DAY_START
  export DAY_END

  # Tools
  if command -v "fzf" >/dev/null; then
    FZF="fzf"
  else
    err "Did not find the command-line fuzzy finder fzf."
    exit 1
  fi
  export FZF

  if command -v "uuidgen" >/dev/null; then
    UUIDGEN="uuidgen"
  else
    err "Did not find the uuidgen command."
    exit 1
  fi
  export UUIDGEN

  if command -v "bat" >/dev/null; then
    CAT="bat"
  elif command -v "batcat" >/dev/null; then
    CAT="batcat"
  fi
  CAT=${CAT:+$CAT --color=always --style=numbers --language=md}
  CAT=${CAT:-cat}
  export CAT

  ### AWK SCRIPTS
  AWK_LINES=$(
    cat <<'EOF'
@@include src/awk/lines.awk
EOF
  )
  export AWK_LINES

  AWK_MERGE=$(
    cat <<'EOF'
@@include src/awk/merge.awk
EOF
  )
  export AWK_MERGE

  AWK_PARSE=$(
    cat <<'EOF'
@@include src/awk/parse.awk
EOF
  )
  export AWK_PARSE

  AWK_WEEKVIEW=$(
    cat <<'EOF'
@@include src/awk/weekview.awk
EOF
  )
  export AWK_WEEKVIEW

  AWK_DAYVIEW=$(
    cat <<'EOF'
@@include src/awk/dayview.awk
EOF
  )
  export AWK_DAYVIEW

  AWK_GET=$(
    cat <<'EOF'
@@include src/awk/get.awk
EOF
  )
  export AWK_GET

  AWK_UPDATE=$(
    cat <<'EOF'
@@include src/awk/update.awk
EOF
  )
  export AWK_UPDATE

  AWK_NEW=$(
    cat <<'EOF'
@@include src/awk/new.awk
EOF
  )
  export AWK_NEW
  ### END OF AWK SCRIPTS

  ## Colors
  export GREEN="\033[1;32m"
  export RED="\033[1;31m"
  export WHITE="\033[1;97m"
  export CYAN="\033[1;36m"
  export ITALIC="\033[3m"
  export FAINT="\033[2m"
  export OFF="\033[m"

  export FZF_VJOUR_USE_EXPORTED="yes"
fi

__load_approx_data() {
  find "$ROOT" -type f -name '*.ics' -print0 |
    xargs -0 -P0 \
      awk \
      -v collection_labels="$COLLECTION_LABELS" \
      "$AWK_LINES"
}

__load_weeks() {
  dates=$(awk -F'|' '{ print $2; print $3 }' "$APPROX_DATA_FILE")
  file_dates=$(mktemp)
  echo "$dates" | date --file="/dev/stdin" +"%s" >"$file_dates"
  awk "$AWK_MERGE" "$file_dates" "$APPROX_DATA_FILE"
  rm "$file_dates"
}

__show_day() {
  weeknr=$(date -d "$DISPLAY_DATE" +"%s")
  weeknr=$(((weeknr - 259200) / 604800)) # shift, because epoch origin is a Thursday
  files=$(grep "^$weeknr " "$WEEKLY_DATA_FILE" | cut -d " " -f 2-)
  # Find relevant files in list of week files
  sef=$({
    set -- $files
    for file in "$@"; do
      file="$ROOT/$file"
      awk \
        -v collection_labels="$COLLECTION_LABELS" \
        "$AWK_PARSE" "$file"
    done
  })
  if [ -n "$sef" ]; then
    today=$(date -d "$DISPLAY_DATE" +"%D")
    sef=$(echo "$sef" | while IFS= read -r line; do
      set -- $line
      starttime="$1"
      shift
      endtime="$1"
      shift
      fpath="$(echo "$1" | sed 's/|/ /g')" # we will use | as delimiter (need to convert back!)
      shift
      description="$(echo "$*" | sed 's/|/:/g')" # we will use | as delimiter
      #
      daystart=$(date -d "$today 00:00:00" +"%s")
      dayend=$(date -d "$today 23:59:59" +"%s")
      line=""
      if [ "$starttime" -gt "$daystart" ] && [ "$starttime" -lt "$dayend" ]; then
        s=$(date -d "@$starttime" +"%R")
      elif [ "$starttime" -le "$daystart" ] && [ "$endtime" -gt "$daystart" ]; then
        s="00:00"
      else
        continue
      fi
      if [ "$endtime" -gt "$daystart" ] && [ "$endtime" -lt "$dayend" ]; then
        e=$(date -d "@$endtime" +"%R")
      elif [ "$endtime" -ge "$dayend" ] && [ "$starttime" -lt "$dayend" ]; then
        e="00:00"
      else
        continue
      fi
      echo "$s|$e|$starttime|$endtime|$fpath|$description"
    done)
  fi
  echo "$sef" | sort -n | awk -v daystart="$DAY_START" -v dayend="$DAY_END" "$AWK_DAYVIEW"
}

__list() {
  weeknr=$(date -d "$DISPLAY_DATE" +"%s")
  weeknr=$(((weeknr - 259200) / 604800)) # shift, because epoch origin is a Thursday
  files=$(grep "^$weeknr " "$WEEKLY_DATA_FILE" | cut -d " " -f 2-)
  dayofweek=$(date -d "$DISPLAY_DATE" +"%u")
  delta=$((1 - dayofweek))
  startofweek=$(date -d "$DISPLAY_DATE -$delta days" +"%D")
  # loop over files
  sef=$({
    set -- $files
    for file in "$@"; do
      file="$ROOT/$file"
      awk \
        -v collection_labels="$COLLECTION_LABELS" \
        "$AWK_PARSE" "$file"
    done
  })
  if [ -n "$sef" ]; then
    sef=$(echo "$sef" | while IFS= read -r line; do
      set -- $line
      starttime="$1"
      shift
      endtime="$1"
      shift
      #fpath="$1"
      shift
      description="$*"
      for i in $(seq 0 7); do
        daystart=$(date -d "$startofweek +$i days 00:00:00" +"%s")
        dayend=$(date -d "$startofweek +$i days 23:59:59" +"%s")
        if [ "$starttime" -gt "$daystart" ] && [ "$starttime" -lt "$dayend" ]; then
          s=$(date -d "@$starttime" +"%H:%M")
          s="$s -"
        elif [ "$starttime" -le "$daystart" ] && [ "$endtime" -gt "$daystart" ]; then
          s="00:00 -"
        else
          continue
        fi
        if [ "$endtime" -gt "$daystart" ] && [ "$endtime" -lt "$dayend" ]; then
          e=$(date -d "@$endtime" +"%H:%M")
          e="- $e"
        elif [ "$endtime" -ge "$dayend" ] && [ "$starttime" -lt "$dayend" ]; then
          e="- 00:00"
        else
          continue
        fi
        echo "$i $s$e >$description"
      done
    done)
  fi
  sef=$({
    echo "$sef"
    seq 0 7
  } | sort -n)
  echo "$sef" | awk -v startofweek="$startofweek" "$AWK_WEEKVIEW"
  #seq -f "$startofweek +%g days" 0 6 |
  #  LC_ALL=c xargs -I {} date -d "{}" +"%a %e %b %Y"
}

__canonical_datetime_hm() {
  s="$1"
  t=$(date -d "@$s" +"%R")
  dfmt="%F"
  if [ "$t" != "00:00" ]; then
    dfmt="$dfmt %R"
  fi
  date -d "@$s" +"$dfmt"
}

__canonical_datetime() {
  s="$1"
  shift
  t=$(date -d "@$s" +"%R")
  dfmt="$*%e %b %Y"
  if [ "$t" != "00:00" ]; then
    dfmt="$dfmt %R %Z"
  fi
  date -d "@$s" +"$dfmt"
}

__edit() {
  start=$(__canonical_datetime_hm "$1")
  end=$(__canonical_datetime_hm "$2")
  fpath="$3"
  summary=$(awk -v field="SUMMARY" "$AWK_GET" "$fpath")
  description=$(awk -v field="DESCRIPTION" "$AWK_GET" "$fpath")
  filetmp=$(mktemp --suffix='.md')
  (
    echo "::: |> $start"
    echo "::: <| $end"
    echo "# $summary"
    echo ""
    echo "$description"
  ) >"$filetmp"
  checksum=$(cksum "$filetmp")
  $EDITOR "$filetmp" >/dev/tty

  # Update only if changes are detected
  if [ "$checksum" != "$(cksum "$filetmp")" ]; then
    filenew="$filetmp.ics"
    awk "$AWK_UPDATE" "$filetmp" "$fpath" >"$filenew"
    mv "$filenew" "$fpath"
  fi
  rm "$filetmp"
}

if [ -z "${APPROX_DATA_FILE:-}" ]; then
  APPROX_DATA_FILE=$(mktemp)
  __load_approx_data >"$APPROX_DATA_FILE"
  export APPROX_DATA_FILE
fi
if [ -z "${WEEKLY_DATA_FILE:-}" ]; then
  WEEKLY_DATA_FILE=$(mktemp)
  __load_weeks >"$WEEKLY_DATA_FILE"
  export WEEKLY_DATA_FILE
fi

if [ "${1:-}" = "--new" ]; then
  collection=$(echo "$COLLECTION_LABELS" | tr ';' '\n' | $FZF --delimiter='=' --with-nth=2 --accept-nth=1)
  fpath=""
  while [ -f "$fpath" ] || [ -z "$fpath" ]; do
    uuid=$($UUIDGEN)
    fpath="$ROOT/$collection/$uuid.ics"
  done
  startsec=$(date -d "$2" +"%s")
  endsec=$((startsec + 3600))
  start=$(__canonical_datetime_hm "$startsec")
  end=$(__canonical_datetime_hm "$endsec")
  filetmp=$(mktemp --suffix='.md')
  (
    echo "::: |> $start"
    echo "::: <| $end"
    echo "# <!-- write summary here -->"
    echo ""
  ) >"$filetmp"
  checksum=$(cksum "$filetmp")
  $EDITOR "$filetmp" >/dev/tty

  # Update only if changes are detected
  if [ "$checksum" != "$(cksum "$filetmp")" ]; then
    filenew="$filetmp.ics"
    awk -v uid="$uuid" "$AWK_NEW" "$filetmp" >"$filenew"
    mv "$filenew" "$fpath"
  fi
  rm "$filetmp"
fi

if [ "${1:-}" = "--preview" ]; then
  hour=$(echo "$2" | cut -d '|' -f 1)
  start=$(echo "$2" | cut -d '|' -f 2)
  end=$(echo "$2" | cut -d '|' -f 3)
  fpath=$(echo "$2" | cut -d '|' -f 4 | sed "s/ /|/g")
  if [ -n "$hour" ] && [ -n "$fpath" ]; then
    fpath="$ROOT/$fpath"
    start=$(__canonical_datetime "$start" "%a ")
    end=$(__canonical_datetime "$end" "%a ")
    echo "${GREEN}From: ${OFF}${CYAN}$start${OFF}"
    echo "${GREEN}To:   ${OFF}${CYAN}$end${OFF}"
    echo ""
    awk -v field="DESCRIPTION" "$AWK_GET" "$fpath" | $CAT
  fi
  exit
fi

if [ "${1:-}" = "--day-reload" ]; then
  __show_day
  exit
fi

if [ "${1:-}" = "--day" ]; then
  DISPLAY_DATE="$2"
  selection=$(
    __show_day |
      $FZF \
        --reverse \
        --ansi \
        --no-sort \
        --no-input \
        --margin='20%' \
        --border='double' \
        --border-label="🗓️ $(date -d "$DISPLAY_DATE" +"%A %e %B %Y")" \
        --color=label:bold:green \
        --border-label-pos=3 \
        --delimiter='|' \
        --with-nth='{5}' \
        --accept-nth='1,2,3,4' \
        --preview="$0 --preview {}" \
        --expect="ctrl-n" \
        --bind="ctrl-s:execute($SYNC_CMD ; printf 'Press <enter> to continue.'; read -r tmp)"
  )
  key=$(echo "$selection" | head -1)
  line=$(echo "$selection" | tail -1)
  hour=$(echo "$line" | cut -d '|' -f 1)
  start=$(echo "$line" | cut -d '|' -f 2)
  end=$(echo "$line" | cut -d '|' -f 3)
  fpath=$(echo "$line" | cut -d '|' -f 4 | sed "s/ /|/g")
  if [ "$key" = "ctrl-n" ]; then
    if echo "$hour" | grep ":"; then
      hour="$DAY_START"
    fi
    exec $0 --new "$DISPLAY_DATE $hour:00"
  elif [ -n "$fpath" ]; then
    fpath="$ROOT/$fpath"
    __edit "$start" "$end" "$fpath"
  fi
fi

if [ "${1:-}" = "--date" ]; then
  DISPLAY_DATE="$2"
fi
DISPLAY_DATE=${DISPLAY_DATE:-today}
DISPLAY_DATE=$(date -d "$DISPLAY_DATE" +"%D")
DISPLAY_POS=$((8 - $(date -d "$DISPLAY_DATE" +"%u")))
DISPLAY_DATE_PREV=$(date -d "$DISPLAY_DATE -1 week" +"%D")
DISPLAY_DATE_NEXT=$(date -d "$DISPLAY_DATE +1 week" +"%D")
DISPLAY_DATE_PREV_MONTH=$(date -d "$DISPLAY_DATE -1 month" +"%D")
DISPLAY_DATE_NEXT_MONTH=$(date -d "$DISPLAY_DATE +1 month" +"%D")

selection=$(
  (
    cat "$APPROX_DATA_FILE"
    yes " " | head -n 50
    __list
  ) |
    $FZF \
      --tac \
      --no-sort \
      --no-hscroll \
      --ellipsis='' \
      --delimiter='|' \
      --with-nth='{4}' \
      --accept-nth=1,2 \
      --no-info \
      --ansi \
      --no-clear \
      --no-scrollbar \
      --expect="ctrl-n" \
      --bind="load:pos($DISPLAY_POS)" \
      --bind="ctrl-u:become($0 --date '$DISPLAY_DATE_PREV')" \
      --bind="ctrl-d:become($0 --date '$DISPLAY_DATE_NEXT')" \
      --bind="ctrl-alt-u:become($0 --date '$DISPLAY_DATE_PREV_MONTH')" \
      --bind="ctrl-alt-d:become($0 --date '$DISPLAY_DATE_NEXT_MONTH')" \
      --bind="ctrl-l:become($0)"
)

key=$(echo "$selection" | head -1)
line=$(echo "$selection" | tail -1)
sign=$(echo "$line" | cut -d '|' -f 1)
startdate=$(echo "$line" | cut -d '|' -f 2)
if [ "$key" = "ctrl-n" ]; then
  # Add new
  exec $0 --new "$startdate $DAY_START:00"
fi
if [ -z "$key" ] && [ -z "$line" ]; then
  rm "$WEEKLY_DATA_FILE" "$APPROX_DATA_FILE"
  return 0
fi

if [ "$sign" = "~" ]; then
  exec $0 --date "$startdate"
else
  exec $0 --day "$startdate"
fi
echo "Going to end..."
echo "$selection"
echo "STOPPING NOW"