[ADD][SCRIPT] Bluetoot dmenu interface btmenu

I found the base script somewhere on GitHub. It looks like a good basis
to transform it into a true bluetooth interface which could be launched
directly from demnu. To that end I wrote a little '.desktop' file to add
it to `dmenu-desktop` entries.

desktop/btmenu.desktop

@@ -0,0 +1,6 @@
+[Desktop Entry]
+Categories=Settings;HardwareSettings;
+Name=btmenu
+GenericName=Bluetooth Menu
+Exec=btmenu
+Type=Application

install.sh

@@ -15,7 +15,7 @@ stow -t ~ tridactyl
 stow -t ~ vim
 stow -t ~ zsh
 
-# Only create the symlink when the directory doesn't exist
+# Create the directory if needed
 mkdir -p ~/.scripts
 # Scripts must be in their own directory
 stow -t ~/.scripts scripts/
@@ -25,3 +25,8 @@ stow -t ~ shell/
 
 # Wallpapers
 stow -t ~ wallpapers/
+
+# Create the directory if needed
+mkdir -p ~/.local/share/applications
+# Symlink the '.desktop' files (btmenu needs one)
+stow -t ~/.local/share/applications desktop

scripts/btmenu

@@ -0,0 +1,116 @@
+#!/bin/bash
+
+# Inspired by <https://github.com/cdown/btmenu>
+
+function show_usage() {
+    echo "A simple bluetoothctl from bluez-utilies interface for dmenu(1)"
+    echo ""
+    echo "Usage:"
+    echo -e "\tbtmenu [OPTION] [DEVICE]"
+    echo -e "\t\tWithout any options, defaults to connecting to device"
+    echo "Options:"
+    echo -e "\t-h, --help\n\t\tshow this message and quit"
+    echo -e "\t-d, --disconnect\n\t\tDisconnect the device"
+    exit 0
+}
+
+function _bluetoothctl() {
+    LC_ALL=C timeout 30 bluetoothctl
+}
+
+# Connects by default
+mode=connect
+
+# Name -> MAC
+declare -A DEVICES
+while read -r _ mac name; do
+    DEVICES["$name"]=$mac
+done < <(echo "devices" | _bluetoothctl | awk '$1 == "Device"')
+
+# Notify the user about the operation
+function notify() {
+    local msg
+    local is_error
+
+    msg=${1?BUG: no message}
+    is_error=${2:-0}
+
+    if command -v notify-send >/dev/null 2>&1; then
+        notify-send "btmenu" "$msg"  # TODO: escaping
+    fi
+
+    if (( is_error )); then
+        printf 'ERROR: %s\n' "$msg" >&2
+    else
+        printf '%s\n' "$msg"
+    fi
+}
+
+function execute_mode() {
+    local mode
+    local name
+    local mac
+    local preposition
+    local expected_to_connect
+    local retries
+
+    mode=${1?BUG: missing mode}
+    retries=15
+
+    case $mode in
+        connect)
+            preposition=to
+            expected_to_connect=yes
+        ;;
+        disconnect)
+            preposition=from
+            expected_to_connect=no
+        ;;
+    esac
+
+    if ! (( ${#DEVICES[@]} )); then
+        notify "No devices found. Are they registered with D-Bus?" 1
+        return 2
+    fi
+
+    name=$(printf '%s\n' "${!DEVICES[@]}" | dmenu -l 10 -p "btmenu" "${dmenu_args[@]}")
+    [[ $name ]] || return
+    mac=${DEVICES["$name"]}
+
+    notify "Attempting to $mode $preposition $name"
+
+    while (( retries-- )); do
+        printf 'power on\n%s %s\n' "$mode" "$mac" | _bluetoothctl
+        if printf 'info %s\n' "$mac" |
+            _bluetoothctl |
+            grep -Pq '^[\t ]+Connected: '"$expected_to_connect"; then
+            notify "${mode^}ed $preposition $name"
+            return 0
+        fi
+        sleep 1
+    done
+
+    ret="$?"
+    notify "Failed to $mode $preposition $name" 1
+    return "$ret"
+}
+
+i=2
+
+# FIXME: I want to have a list of devices with their connection status instead
+# of having to launch the script with the correct argument to connect/disconnect
+for arg do
+    if [[ $arg == -- ]]; then
+        dmenu_args=( "${@:$i}" )
+        break
+    fi
+
+    case "$arg" in
+        -d|--disconnect) mode=disconnect ;;
+        -h|--help) show_usage ;;
+    esac
+
+    (( i++ ))
+done
+
+execute_mode "$mode"