state_root="${XDG_STATE_HOME:-$HOME/.local/state}/tmux-panes"
snapshot_root="${XDG_DATA_HOME:-$HOME/.local/share}/tmux/resurrect/panes"

pane_state() {
  echo "$state_root/${1#%}"
}

pane_snapshot() {
  echo "$snapshot_root/${1//\//_}"
}

case "${1:-}" in
  claude-session)
    [ -n "${TMUX_PANE:-}" ] || exit 0
    session_id="$(jq -r '.session_id')"
    dir="$(pane_state "$TMUX_PANE")"
    mkdir -p "$dir"
    printf '%s\n%s\n' "${CLAUDE_CONFIG_DIR:-}" "$session_id" > "$dir/claude"
    ;;

  save)
    mkdir -p "$(dirname "$snapshot_root")" "$state_root"
    snapshot="$(mktemp -d "$snapshot_root.XXXXXX")"
    live=()

    while IFS=$'\t' read -r id pos cmd; do
      live+=("${id#%}")
      case "$cmd" in
        claude | emacs) ;;
        *) continue ;;
      esac
      src="$(pane_state "$id")/$cmd"
      [ -f "$src" ] || continue
      dst="$snapshot/${pos//\//_}"
      mkdir -p "$dst"
      cp "$src" "$dst/$cmd"
    done < <(tmux list-panes -a -F '#{pane_id}	#S:#I.#P	#{pane_current_command}')

    rm -rf "$snapshot_root"
    mv "$snapshot" "$snapshot_root"

    for dir in "$state_root"/*/; do
      [ -d "$dir" ] || continue
      name="$(basename "$dir")"
      [[ " ${live[*]} " == *" $name "* ]] || rm -rf "$dir"
    done
    ;;

  restore)
    pos="$(tmux display-message -p -t "$TMUX_PANE" '#S:#I.#P')"
    file="$(pane_snapshot "$pos")/${2:-}"

    case "${2:-}" in
      claude)
        if [ ! -f "$file" ]; then
          echo "tmux-panes: no saved claude session for $pos" >&2
          exit 1
        fi
        { read -r config_dir; read -r session_id; } < "$file"
        CLAUDE_CONFIG_DIR="$config_dir" exec claude --resume "$session_id"
        ;;
      emacs)
        if [ -f "$file" ]; then
          buffers="$(mktemp)"
          cp "$file" "$buffers"
          TMUX_PANES_RESTORE="$buffers" exec e
        fi
        exec e
        ;;
      *)
        echo "usage: tmux-panes restore claude|emacs" >&2
        exit 1
        ;;
    esac
    ;;

  *)
    echo "usage: tmux-panes claude-session|save|restore <claude|emacs>" >&2
    exit 1
    ;;
esac