#!/usr/bin/env bash
# ==============================================================================
# Motion Wallpaper — auto-pause watcher.
#
# Subscribes to Hyprland's event socket (socket2) and toggles mpv pause/resume
# via the IPC socket that mpvpaper was started with. Replaces mpvpaper's own
# --auto-pause / -p flag, which is unreliable on recent Hyprland releases.
#
# This script runs as a background sibling to mpvpaper. The main toggle script
# starts it and kills it.
# ==============================================================================

set -euo pipefail

RUNTIME_DIR="${XDG_RUNTIME_DIR:-/run/user/$(id -u)}"
MPV_IPC="$RUNTIME_DIR/motion-wallpaper-mpv.sock"
LOG_FILE="${XDG_CACHE_HOME:-$HOME/.cache}/motion-wallpaper.log"

log() {
  printf '[%s] watcher: %s\n' "$(date '+%Y-%m-%d %H:%M:%S')" "$*" >> "$LOG_FILE"
}

his="${HYPRLAND_INSTANCE_SIGNATURE:-}"
if [ -z "$his" ] || [ ! -d "$RUNTIME_DIR/hypr/$his" ]; then
  # HIS is missing or stale (points to a dead session). Recover from the
  # live signature reported by `hyprctl instances`.
  sig="$(hyprctl instances 2>/dev/null | awk '/^instance /{sub(/:$/,"",$2); print $2; exit}')"
  if [ -n "$sig" ]; then
    export HYPRLAND_INSTANCE_SIGNATURE="$sig"
    log "using HYPRLAND_INSTANCE_SIGNATURE=$sig (was: ${his:-unset})"
  else
    log "HYPRLAND_INSTANCE_SIGNATURE not usable and no live instance found — exiting"
    exit 0
  fi
fi

HYPR_SOCK="$RUNTIME_DIR/hypr/$HYPRLAND_INSTANCE_SIGNATURE/.socket2.sock"
if [ ! -S "$HYPR_SOCK" ]; then
  log "hyprland event socket not found ($HYPR_SOCK) — exiting"
  exit 0
fi

if ! command -v socat >/dev/null 2>&1; then
  log "socat not installed — exiting"
  exit 0
fi

send_mpv() {
  # Best-effort — silently no-op if mpv's IPC socket isn't up yet.
  [ -S "$MPV_IPC" ] || return 0
  printf '%s\n' "$1" | socat - "UNIX-CONNECT:$MPV_IPC" >/dev/null 2>&1 || true
}

pause_mpv()  { send_mpv '{ "command": ["set_property", "pause", true] }';  }
resume_mpv() { send_mpv '{ "command": ["set_property", "pause", false] }'; }

log "watching $HYPR_SOCK"

# Kill socat child on exit so it doesn't spam "Broken pipe" to the log when
# the watcher is killed by the main toggle script.
cleanup() {
  # `[ ] && kill` short-circuits to non-zero when SOCAT_PID is unset, which
  # under `set -e` would abort the trap before `exit 0` — wrap safely.
  if [ -n "${SOCAT_PID:-}" ]; then
    kill "$SOCAT_PID" 2>/dev/null || true
  fi
  exit 0
}
trap cleanup EXIT INT TERM

# Hyprland socket2 emits newline-separated "EVENT>>DATA" lines. We only care
# about the fullscreen state. `fullscreen>>1` = entered, `fullscreen>>0` = left.
# socat stderr is dropped so EPIPE on shutdown doesn't bloat the log.
coproc SOCAT { socat -u "UNIX-CONNECT:$HYPR_SOCK" - 2>/dev/null; }
# Bash auto-exports SOCAT_PID from `coproc SOCAT`; used in cleanup trap.

while IFS= read -r line <&"${SOCAT[0]}"; do
  case "$line" in
    fullscreen\>\>1)
      log "fullscreen entered — pause"
      pause_mpv
      ;;
    fullscreen\>\>0)
      log "fullscreen left — resume"
      resume_mpv
      ;;
  esac
done