#!/usr/bin/env bash
# scripts/desk.sh — Desk profile management for niri (blankpad)
#
# Desk profiles are cfg/desk-*.kdl files. The active profile is whatever
# file cfg/display.kdl symlinks to. Profiles declare the monitors they
# need via comment lines:
#
#   // requires: <niri output long name>
#   // optional: <free text>
#
# Subcommands:
#   list            list available desk profiles
#   current         show currently active profile (basename of display.kdl)
#   switch <name>   apply a specific profile (name or *.kdl)
#   cycle           apply the next profile (wraps)
#   match [--apply] pick the profile matching connected outputs
#   capture         print `// requires:` lines for current outputs
#
# Environment overrides (for tests and deploys):
#   DESK_CFG_DIR  config dir (default ~/.config/niri/cfg)
#   DESK_NIRI     niri binary (default niri)
#   DESK_NOTIFY   notification command prefix (default "noctalia msg notification-show")

set -euo pipefail

CFG_DIR="${DESK_CFG_DIR:-$HOME/.config/niri/cfg}"
NIRI="${DESK_NIRI:-niri}"
NOTIFY="${DESK_NOTIFY:-noctalia msg notification-show}"

usage() {
  sed -n '2,20p' "$0" | sed 's/^# \{0,1\}//'
}

# Profile names (basenames without .kdl), sorted.
profiles() {
  local f
  for f in "$CFG_DIR"/desk-*.kdl; do
    [ -e "$f" ] || continue
    basename "$f" .kdl
  done | sort
}

# Active profile name, or "none".
current() {
  if [ -L "$CFG_DIR/display.kdl" ]; then
    basename "$(readlink -f "$CFG_DIR/display.kdl")" .kdl
  else
    echo none
  fi
}

# Connected output long names, one per line.
outputs() {
  "$NIRI" msg outputs 2>/dev/null | grep -oP 'Output "\K[^"]+' || true
}

# requires lines of a profile, one per line.
requires() {
  grep -oP '^//\s*requires:\s*\K.+' "$CFG_DIR/$1.kdl" 2>/dev/null || true
}

notify() {
  # shellcheck disable=SC2086  # word splitting of the prefix is intended
  $NOTIFY "Desk" "$1" >/dev/null 2>/dev/null || true
}

# Apply a profile: relink, validate live config, roll back on failure,
# then reload + notify.
apply_profile() {
  local name="$1"
  local file="$CFG_DIR/$name.kdl"
  local link="$CFG_DIR/display.kdl"

  [ -f "$file" ] || { echo "error: no such profile: $name" >&2; return 1; }

  local old=""
  [ -L "$link" ] && old="$(readlink "$link")"

  ln -sfn "$name.kdl" "$link"

  if ! "$NIRI" validate >/dev/null 2>/dev/null; then
    if [ -n "$old" ]; then ln -sfn "$old" "$link"; else rm -f "$link"; fi
    echo "error: niri validate failed; kept $( [ -n "$old" ] && basename "$old" .kdl || echo 'no' ) profile" >&2
    return 1
  fi

  "$NIRI" msg action load-config-file >/dev/null 2>/dev/null || true
  notify "switched to $name"
  echo "switched to $name"
}

cmd_switch() {
  local target="${1:-}"
  [ -n "$target" ] || { echo "usage: desk.sh switch <profile>" >&2; return 1; }
  target="${target%.kdl}"
  apply_profile "$target"
}

cmd_match() {
  local apply="${1:-}"
  local connected best="" best_n=0
  connected="$(outputs)"

  local name req count
  while IFS= read -r name; do
    [ -n "$name" ] || continue
    count=0
    local ok=1
    while IFS= read -r req; do
      [ -n "$req" ] || continue
      if grep -qxF "$req" <<<"$connected"; then
        count=$((count + 1))
      else
        ok=0
        break
      fi
    done < <(requires "$name")
    # requires=0 profiles never match; ties go to more requires, then alphabetical
    [ "$ok" -eq 1 ] && [ "$count" -gt 0 ] && [ "$count" -gt "$best_n" ] && { best="$name"; best_n=$count; }
  done < <(profiles)

  if [ -z "$best" ]; then
    echo "no desk profile matches connected outputs" >&2
    return 2
  fi
  if [ "$apply" = "--apply" ]; then
    apply_profile "$best"
  else
    echo "$best"
  fi
}

cmd_cycle() {
  local list cur next
  list="$(profiles)"
  [ -n "$list" ] || { echo "no desk profiles found in $CFG_DIR" >&2; return 1; }
  cur="$(current)"
  next="$(awk -v cur="$cur" '
    { a[NR]=$0 }
    END { for (i=1;i<=NR;i++) if (a[i]==cur) { print a[(i%NR)+1]; exit }
          print a[1] }' <<<"$list")"
  apply_profile "$next"
}

cmd_capture() {
  local n
  n="$(outputs | wc -l)"
  [ "$n" -gt 0 ] || { echo "error: no connected outputs (is niri running?)" >&2; return 1; }
  echo "// paste into the profile:"
  outputs | sed 's/^/\/\/ requires: /'
}

main() {
  case "${1:-}" in
    list)    profiles ;;
    current) current ;;
    switch)  shift; cmd_switch "$@" ;;
    cycle)   cmd_cycle ;;
    match)   shift; cmd_match "${1:-}" ;;
    capture) cmd_capture ;;
    -h|--help) usage ;;
    *)       usage >&2; exit 1 ;;
  esac
}

main "$@"