#!/bin/sh
# Display mode manager: laptop-off ↔ side-by-side.
#   (no arg)  toggle between modes (F7 / Super+x d).
#   apply     re-apply the saved mode (used by display-watcher after
#             hotplug). First boot defaults to laptop-off.
#   init      force laptop-off; used by the hotplug watcher when a
#             newly-plugged external should preempt whatever was saved.
#
# State is persisted as a sway-include file at $OUTPUTS_CONF so that
# sway's own config parser applies the layout natively on every reload
# — no side-by-side flash before override. The script also issues live
# swaymsg commands so toggles are immediate without needing a reload.

STATE_FILE="${XDG_RUNTIME_DIR:-/tmp}/display-mode"
OUTPUTS_CONF="${XDG_CONFIG_HOME:-$HOME/.config}/sway/outputs.conf"

write_conf() {
  # $1 = mode (laptop-off | side-by-side | laptop-only)
  # remaining args are the sway `output ...` directives, one per arg.
  {
    printf '# Auto-generated by display-toggle.sh; do not edit.\n'
    printf '# Current mode: %s\n' "$1"
    shift
    for line in "$@"; do printf '%s\n' "$line"; done
  } >"$OUTPUTS_CONF"
}

OUTPUTS=$(swaymsg -t get_outputs -r)
LAPTOP=$(echo "$OUTPUTS" | jq -r '[.[] | select(.name | test("^eDP")) | .name] | first // empty')
EXTERNAL=$(echo "$OUTPUTS" | jq -r '[.[] | select(.name | test("^eDP") | not) | .name] | first // empty')

if [ -z "$EXTERNAL" ]; then
  # No external connected: make sure the laptop screen is on. This recovers
  # from an earlier "laptop-off" state after the external was unplugged.
  if [ -n "$LAPTOP" ]; then
    swaymsg output "$LAPTOP" enable pos 0 0 || true
    echo "laptop-only" >"$STATE_FILE"
    write_conf "laptop-only" "output $LAPTOP enable pos 0 0"
  fi
  [ -z "${1:-}" ] && notify-send "Display" "No external display connected"
  exit 0
fi

[ -z "$LAPTOP" ] && exit 0

LAPTOP_WIDTH=$(echo "$OUTPUTS" | jq -r ".[] | select(.name == \"$LAPTOP\") | .current_mode.width // .modes[0].width")
[ -z "$LAPTOP_WIDTH" ] && LAPTOP_WIDTH=1920

if [ "${1:-}" = "apply" ]; then
  NEXT=$(cat "$STATE_FILE" 2>/dev/null || echo "laptop-off")
elif [ "${1:-}" = "init" ]; then
  NEXT="laptop-off"
else
  CURRENT=$(cat "$STATE_FILE" 2>/dev/null || echo "laptop-off")
  case "$CURRENT" in
    laptop-off) NEXT="side-by-side" ;;
    *) NEXT="laptop-off" ;;
  esac
fi

case "$NEXT" in
  laptop-off)
    swaymsg output "$LAPTOP" disable || true
    swaymsg output "$EXTERNAL" enable || true
    swaymsg workspace number 1 || true
    echo "laptop-off" >"$STATE_FILE"
    write_conf "laptop-off" \
      "output $LAPTOP disable" \
      "output $EXTERNAL enable"
    [ -z "${1:-}" ] && notify-send "Display" "Laptop screen off"
    ;;
  side-by-side)
    swaymsg output "$LAPTOP" enable pos 0 0 || true
    swaymsg output "$EXTERNAL" enable pos "$LAPTOP_WIDTH" 0 || true
    echo "side-by-side" >"$STATE_FILE"
    write_conf "side-by-side" \
      "output $LAPTOP enable pos 0 0" \
      "output $EXTERNAL enable pos $LAPTOP_WIDTH 0"
    [ -z "${1:-}" ] && notify-send "Display" "Side by side"
    ;;
esac