#!/usr/bin/env bash

# This shell script setups bluetooth to be flawless in gnome shell.
# Devices are now instantly connected when they're near the laptop.
# (It probably works as a service for random WMs too.)

# The issue is essentially that gnome-bluetooth is issuing the wrong
# dbus calls to connect the device immediately; org.bluez gets EAGAIN
# from the kernel when it processes gnome-bluetooth dbus calls (until
# it eventually succeeds, 20-30s later). However, bluetoothctl is
# flawless at it. Maybe some day gnome-bluetooth will fix this. In the
# meantime, this hack lets me have a seamless bluetooth experience.
# PS: I tried to report the bug to gnome-bluetooth but haven't figured
# out how. Apparently I need to register to 2 or 3 bug trackers? I may
# just be dense.

# To be able to run this fix, you need: bluez (which provides the
# bluetoothctl binary) and python3-gevent.

# Source: https://gist.github.com/ralt/b25095dcc1be680e581a9a53f2edcb43
# License: MIT (is that even needed for such a small amount of code?)

set -e

# Start with checking the requirements.
python3 -c 'import gevent'
which bluetoothctl

# And now the fun begins.
cd ~

# Create a systemd user service for our hack.
cat > .config/systemd/user/fix-bluetooth.service <<EOF
[Unit]
Description=Fix bluetooth

[Service]
ExecStart=/home/$USER/bin/fix-bluetooth

[Install]
WantedBy=default.target
EOF

# Now put the hack in the ~/bin folder.
mkdir -p bin
cat > bin/fix-bluetooth <<EOF
#!/usr/bin/env python3

import gevent.monkey
gevent.monkey.patch_all()

import subprocess
import time

import gevent.pool


def _refresh(device):
    while True:
        try:
            subprocess.check_call(["bluetoothctl", "connect", device])
        except subprocess.CalledProcessError:
            time.sleep(1)
        else:
            time.sleep(10)

if __name__ == "__main__":
    refreshers = {}

    while True:
        out = subprocess.check_output(["bluetoothctl", "devices"])

        devices = []
        for line in out.splitlines():
            try:
                _, device, _ = line.split(b" ", 2)
            except ValueError:
                continue

            devices.append(device)

        for device in devices:
            if device not in refreshers:
                print("Taking care of device: {}".format(device))
                refreshers[device] = gevent.spawn(_refresh, device)

        delete = []
        for device in refreshers:
            if device not in devices:
                print("Forgetting about device: {}".format(device))
                refreshers[device].kill()
                delete.append(device)

        for device in delete:
            del refreshers[device]

        time.sleep(60)
EOF

# Don't forget this or you look stupid.
chmod +x bin/fix-bluetooth

# Finally, enable and start our systemd user service.
systemctl --user enable fix-bluetooth
systemctl --user start fix-bluetooth