#!/usr/bin/env bash

# Unofficial Bash Strict Mode
set -euo pipefail
IFS='
'

export DEBIAN_FRONTEND=noninteractive
export DEBIAN_PRIORITY=critical

# Fix Debian 10 bug (https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=905409)
PATH=/sbin:/usr/sbin:$PATH

# Debian stable OS
apt-get update
apt-get -y -o "Dpkg::Options::=--force-confdef" -o "Dpkg::Options::=--force-confold" upgrade
apt-get -y dist-upgrade

# Disable OpenStack SSH malware
mv /home/debian/.ssh/authorized_keys /root/.ssh/authorized_keys ||:
sed -i '/Generated-by-Nova/d' /root/.ssh/authorized_keys ||:
chown root:root /root/.ssh/authorized_keys ||:

# Terminal goodies
touch .hushlogin

cat <<'EOF'>> /root/.bashrc
export LS_OPTIONS="--color=auto"
eval "`dircolors`"

alias ctop="docker run --rm -it --name=ctop -v /var/run/docker.sock:/var/run/docker.sock:ro quay.io/vektorlab/ctop"
alias df="df --si"
alias du="du -cs --si"
alias free="free -h --si"
alias l="ls $LS_OPTIONS -al --si --group-directories-first"
alias less="less -i"
alias nano="nano -clDOST4"
alias pstree="pstree -palU"

export HISTCONTROL=ignoreboth
export HISTFILESIZE=
export HISTSIZE=
export HISTTIMEFORMAT="%F %T "
EOF

cat <<'EOF'>> /etc/inputrc
set completion-ignore-case
set show-all-if-ambiguous On
set show-all-if-unmodified On
EOF

cat <<'EOF'>> /etc/bash.bashrc
if ! shopt -oq posix; then
  if [ -f /usr/share/bash-completion/bash_completion ]; then
    . /usr/share/bash-completion/bash_completion
  elif [ -f /etc/bash_completion ]; then
    . /etc/bash_completion
  fi
fi
EOF

# Basic packages
apt-get -y install man bash-completion git ufw jq curl build-essential netcat wget psmisc lz4 file net-tools brotli unzip zip moreutils xauth sysfsutils rsync iperf pv tree mc screen ssh iotop whois sudo

# Enable time synchronization
timedatectl set-ntp true

# Configure screen
cat <<'EOF'>> /etc/screenrc
startup_message off
shell -$SHELL
defscrollback 100000
bind l eval clear "scrollback 0" "scrollback 100000"
EOF

# Configure SSH
cat <<'EOF'>> /etc/ssh/sshd_config
Port 521
PasswordAuthentication no
AllowUsers root
X11UseLocalhost no
EOF
systemctl restart ssh

touch /root/.Xauthority

# Firewall
ufw allow in 80/tcp
ufw allow in 443/tcp
ufw allow in 521/tcp
ufw logging off
ufw --force enable
ufw --force delete 4
ufw --force delete 4
ufw --force delete 4

# Optimize
systemctl disable unattended-upgrades.service apt-daily.timer apt-daily-upgrade.timer console-setup.service keyboard-setup.service remote-fs.target man-db.timer systemd-timesyncd.service
sed -i 's/MODULES=most/MODULES=dep/g' /etc/initramfs-tools/initramfs.conf
sed -i 's/COMPRESS=gzip/COMPRESS=lz4/g' /etc/initramfs-tools/initramfs.conf
echo 'RESUME=none' >> /etc/initramfs-tools/conf.d/resume
update-initramfs -u
echo 'GRUB_TIMEOUT=0' >> /etc/default/grub
update-grub
apt-get -y purge apparmor exim\*

for i in $(seq 0 "$(nproc --ignore 1)"); do
    echo "devices/system/cpu/cpu${i}/cpufreq/scaling_governor = performance" >> /etc/sysfs.conf
done

# Disable sleep when closing laptop screen
echo HandleLidSwitch=ignore >> /etc/systemd/logind.conf

# noatime
sed -i 's| / ext4 | / ext4 noatime,|g' /etc/fstab

# Disable swap
swapoff -a
sed -i '/swap/d' /etc/fstab

# Docker
apt-get -y install apt-transport-https ca-certificates curl gnupg2 software-properties-common
curl -fsSL https://download.docker.com/linux/debian/gpg | apt-key add -
add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/debian $(lsb_release -cs) stable"
apt-get update
apt-get -y install docker-ce docker-ce-cli containerd.io

# Docker compose
curl -L "https://github.com/docker/compose/releases/download/1.28.2/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
chmod +x /usr/local/bin/docker-compose
curl -L https://raw.githubusercontent.com/docker/compose/1.28.2/contrib/completion/bash/docker-compose -o /etc/bash_completion.d/docker-compose

# Generate SSH key
ssh-keygen -ted25519 -f ~/.ssh/id_ed25519 -N ''

# Use Cloudflare DNS server
echo 'supersede domain-name-servers 1.1.1.1;' >> /etc/dhcp/dhclient.conf

# Cleanup
sed -i '/^deb-src/d' /etc/apt/sources.list
apt-get update
apt-get -y purge unattended-upgrades
apt-get -y autoremove --purge
apt-get clean

# The end
reboot