#!/usr/bin/env bash

set -euo pipefail # exit on error

# check for `fuse-overlayfs` executable
if ! command -v fuse-overlayfs &>/dev/null; then
    echo "fuse-overlayfs could not be found"
    exit 1
fi

function mount_rave {
    # check if already mounted; im /tmp so it's ephemeral
    if [ -d /tmp/media-for-rave ]; then exit 0; fi

    # mount the music directory; assumes a fstab entry like:
    # /dev/sda1 /mnt/Media ext4 defaults 0 0
    # or equivalent; as long as it mounts to /mnt/Media
    sudo mount /mnt/Media

    # create the overlayfs
    mkdir -p /tmp/overlay /tmp/work /tmp/media-for-rave /tmp/cache-for-rave

    # mount the overlayfs
    fuse-overlayfs -o lowerdir=/mnt/Media/Music -o upperdir=/tmp/overlay -o workdir=/tmp/work /tmp/media-for-rave
}

function unmount_rave {
    # check if already unmounted, but only if CLEAN isn't set
    if [ "${CLEAN:-}" != "1" ] && [ ! -d /tmp/media-for-rave ]; then exit 0; fi

    # unmount the overlayfs
    umount /tmp/media-for-rave || true

    # clean up the overlayfs if `CLEAN` is set
    if [ "${CLEAN:-}" = "1" ]; then
        rm -rf /tmp/overlay /tmp/work /tmp/media-for-rave /tmp/cache-for-rave || true
    fi

    # unmount the music directory
    sudo umount /mnt/Media || true
}

case "${1:-}" in
mount)
    mount_rave
    ;;
unmount)
    unmount_rave
    ;;
*)
    echo "Usage: $0 {mount|unmount}"
    exit 1
    ;;
esac