work

#!/usr/bin/env fish
#
# Toggle blocking of various sites in /etc/hosts
#

set HOSTS \
  reddit.com \
  www.reddit.com \
  facebook.com \
  www.facebook.com \
  news.ycombinator.com

set HOSTFILE /etc/hosts

function is_enabled
  for host in $HOSTS
    if not is_host_enabled $host
      return 1
    end
  end
end

function enable
  for host in $HOSTS
    enable_host $host
  end
end

function disable
  for host in $HOSTS
    disable_host $host
  end
end

function enable_host --argument-names host
  if is_host_enabled $host
    return 0
  end

  if is_host_commented $host
    uncomment_host $host
    return 0
  end

  add_host $host
end

function disable_host --argument-names host
  if is_host_enabled $host
    comment_host $host
  end
end

function is_host_enabled --argument-names host
  grep --quiet "^127.0.0.1 $host" $HOSTFILE
end

function is_host_commented --argument-names host
  grep --quiet "^# 127.0.0.1 $host" $HOSTFILE
end

function comment_host --argument-names host
  sudo sed --in-place "s/127.0.0.1 $host/# 127.0.0.1 $host/" $HOSTFILE
end

function uncomment_host --argument-names host
  sudo sed --in-place "s/# 127.0.0.1 $host/127.0.0.1 $host/" $HOSTFILE
end

function add_host --argument-names host
  echo "127.0.0.1 $host" | sudo tee --append $HOSTFILE
end

if not is_enabled
  echo 'Blocking sites...'
  enable
else
  echo 'Unblocking sites...'
  disable
end