#!/bin/bash

# Spawn a new instance of Alacritty using the CWD of the currently focused
# Alacritty process.
#
# This is useful in environment like i3 where terminals are opened using a
# key-combination while another terminal is already focused.
#
# If the script is run with a non-Alacritty window in focus or a non-compliant
# version of Alacritty, the script will exit with code 1. This makes it possible
# to use the script like
#
#     spawn-alacritty-cwd || alacritty
#

ACTIVE_WINDOW=$(xdotool getactivewindow)
ACTIVE_WM_CLASS=$(xprop -id $ACTIVE_WINDOW | grep WM_CLASS)

if [[ $ACTIVE_WM_CLASS == *"Alacritty"* ]]
then
    # Get PID. If _NET_WM_PID isn't set, bail.
    PID=$(xprop -id $ACTIVE_WINDOW | grep _NET_WM_PID | grep -oP "\d+")
    if [[ "$PID" == "" ]]
    then
        exit 1
    fi

    # Get first child of terminal
    CHILD_PID=$(pgrep -P $PID)
    if [[ "$PID" == "" ]]
    then
        exit 1
    fi

    # Get current directory of child. The first child should be the shell.
    pushd "/proc/${CHILD_PID}/cwd"
    SHELL_CWD=$(pwd -P)
    popd

    # Start alacritty with the working directory
    alacritty --working-directory $SHELL_CWD
else
    exit 1
fi