#!/bin/bash

# -e          :: exit on error (do this in functions as well)
# -E          :: inherit the ERR trap to functions, command substitutions and sub-shells
# -u          :: show (and exit) when using unset variables
# -o pipefail :: exit on error in pipes
set -eE -u -o pipefail

VERSION_CODENAME='bookworm'

# shellcheck source=../helpers/log.sh
source /usr/local/bin/helpers/log.sh

_log_level_is 'trace' && QUIET='-y' || QUIET='-qq'

function _pre_installation_steps() {
  _log 'info' 'Starting package installation'
  _log 'debug' 'Running pre-installation steps'

  _log 'trace' 'Updating package signatures'
  apt-get "${QUIET}" update

  _log 'trace' 'Upgrading packages'
  apt-get "${QUIET}" upgrade

  _log 'trace' 'Installing packages that are needed early'
  # Add packages usually required by apt to:
  local EARLY_PACKAGES=(
    # Avoid logging unnecessary warnings:
    apt-utils
    # Required for adding third-party repos (/etc/apt/sources.list.d) as alternative package sources (eg: Dovecot CE and Rspamd):
    apt-transport-https ca-certificates curl gnupg
    # Avoid problems with SA / Amavis (https://github.com/docker-mailserver/docker-mailserver/pull/3403#pullrequestreview-1596689953):
    systemd-standalone-sysusers
  )
  apt-get "${QUIET}" install --no-install-recommends "${EARLY_PACKAGES[@]}" 2>/dev/null
}

# Install third-party commands to /usr/local/bin
function _install_utils() {
  local ARCH_A=$(uname -m)
  # Alternate naming convention support: x86_64 (amd64) / aarch64 (arm64)
  # https://en.wikipedia.org/wiki/X86-64#Industry_naming_conventions
  local ARCH_B
  case "${ARCH_A}" in
    ( 'x86_64' )  ARCH_B='amd64' ;;
    ( 'aarch64' ) ARCH_B='arm64' ;;
  esac

  # TIP: `*.tar.gz` releases tend to forget to reset UID/GID ownership when archiving.
  # When extracting with `tar` as `root` the archived UID/GID is kept, unless using `--no-same-owner`.
  # Likewise when the binary is in a nested location the full archived path
  # must be provided + `--strip-components` to extract the file to the target directory.
  # Doing this avoids the need for (`mv` + `rm`) or (`--to-stdout` + `chmod +x`)
  _log 'debug' 'Installing utils sourced from Github'

  _log 'trace' 'Installing jaq'
  local JAQ_TAG='v2.1.0'
  curl -sSfL "https://github.com/01mf02/jaq/releases/download/${JAQ_TAG}/jaq-${ARCH_A}-unknown-linux-gnu" -o /usr/local/bin/jaq
  chmod +x /usr/local/bin/jaq

  _log 'trace' 'Installing step'
  local STEP_RELEASE='0.28.2'
  curl -sSfL "https://github.com/smallstep/cli/releases/download/v${STEP_RELEASE}/step_linux_${STEP_RELEASE}_${ARCH_B}.tar.gz" \
    | tar -xz --directory /usr/local/bin --no-same-owner --strip-components=2 "step_${STEP_RELEASE}/bin/step"

  _log 'trace' 'Installing swaks'
  # `perl-doc` is required for `swaks --help` to work:
  apt-get "${QUIET}" install --no-install-recommends perl-doc
  local SWAKS_VERSION='20240103.0'
  local SWAKS_RELEASE="swaks-${SWAKS_VERSION}"
  curl -sSfL "https://github.com/jetmore/swaks/releases/download/v${SWAKS_VERSION}/${SWAKS_RELEASE}.tar.gz" \
    | tar -xz --directory /usr/local/bin --no-same-owner --strip-components=1 "${SWAKS_RELEASE}/swaks"
}

function _install_postfix() {
  _log 'debug' 'Installing Postfix'

  _log 'warn' 'Applying workaround for Postfix bug (see https://github.com/docker-mailserver/docker-mailserver/issues/2023#issuecomment-855326403)'

  # Debians postfix package has a post-install script that expects a valid FQDN hostname to work:
  mv /bin/hostname /bin/hostname.bak
  echo "echo 'docker-mailserver.invalid'" >/bin/hostname
  chmod +x /bin/hostname
  apt-get "${QUIET}" install --no-install-recommends postfix
  mv /bin/hostname.bak /bin/hostname

  # Irrelevant - Debian's default `chroot` jail config for Postfix needed a separate syslog socket:
  rm /etc/rsyslog.d/postfix.conf
}

function _install_packages() {
  _log 'debug' 'Installing all packages now'

  local ANTI_VIRUS_SPAM_PACKAGES=(
    clamav clamav-daemon
    # spamassassin is used only with amavisd-new, while pyzor + razor are used by spamassasin
    amavisd-new spamassassin pyzor razor
  )

  # predominantly for Amavis support
  local CODECS_PACKAGES=(
    altermime arj bzip2
    cabextract cpio file
    gzip lhasa liblz4-tool
    lrzip lzop nomarch
    p7zip-full pax rpm2cpio
    unrar-free unzip xz-utils
  )

  local MISCELLANEOUS_PACKAGES=(
    binutils bsd-mailx
    dbconfig-no-thanks dumb-init iproute2
    libdate-manip-perl libldap-common libmail-spf-perl libnet-dns-perl
    locales logwatch netcat-openbsd
    nftables # primarily for Fail2Ban
    rsyslog supervisor
    uuid # used for file-locking
    whois
  )

  local POSTFIX_PACKAGES=(
    pflogsumm postgrey postfix-ldap postfix-mta-sts-resolver
    postfix-pcre postfix-policyd-spf-python postsrsd
  )

  local MAIL_PROGRAMS_PACKAGES=(
    opendkim opendkim-tools
    opendmarc libsasl2-modules sasl2-bin
  )

  # These packages support community contributed features.
  # If they cause too much maintenance burden in future, they are liable for removal.
  local COMMUNITY_PACKAGES=(
    fetchmail getmail6
  )

  # `bind9-dnsutils` provides the `dig` command
  # `iputils-ping` provides the `ping` command
  DEBUG_PACKAGES=(
    bind9-dnsutils iputils-ping less nano
  )

  apt-get "${QUIET}" install --no-install-recommends \
    "${ANTI_VIRUS_SPAM_PACKAGES[@]}" \
    "${CODECS_PACKAGES[@]}" \
    "${MISCELLANEOUS_PACKAGES[@]}" \
    "${POSTFIX_PACKAGES[@]}" \
    "${MAIL_PROGRAMS_PACKAGES[@]}" \
    "${DEBUG_PACKAGES[@]}" \
    "${COMMUNITY_PACKAGES[@]}"
}

function _install_dovecot() {
  local DOVECOT_PACKAGES=(
    dovecot-core dovecot-imapd
    dovecot-ldap dovecot-lmtpd dovecot-managesieved
    dovecot-pop3d dovecot-sieve
  )

  # Additional Dovecot packages for supporting the DMS community (docs-only guide contributions).
  DOVECOT_PACKAGES+=(dovecot-auth-lua)

  # (Opt-in via ENV) Change repo source for dovecot packages to a third-party repo maintained by Dovecot.
  # NOTE: AMD64 / x86_64 is the only supported arch from the Dovecot CE repo (thus noDMS built for ARM64 / aarch64)
  # Repo: https://repo.dovecot.org/ce-2.4-latest/debian/bookworm/dists/bookworm/main/
  # Docs: https://repo.dovecot.org/#debian
  if [[ ${DOVECOT_COMMUNITY_REPO} -eq 1 ]] && [[ "$(uname --machine)" == "x86_64" ]]; then
    # WARNING: Repo only provides Debian Bookworm package support for Dovecot CE 2.4+.
    # As Debian Bookworm only packages Dovecot 2.3.x, building DMS with this alternative package repo may not yet be compatible with DMS:
    # - 2.3.19: https://salsa.debian.org/debian/dovecot/-/tree/stable/bookworm
    # - 2.3.21: https://salsa.debian.org/debian/dovecot/-/tree/stable/bookworm-backports

    _log 'trace' 'Adding third-party package repository (Dovecot)'
    curl -fsSL https://repo.dovecot.org/DOVECOT-REPO-GPG-2.4 | gpg --dearmor > /usr/share/keyrings/upstream-dovecot.gpg
    echo \
      "deb [signed-by=/usr/share/keyrings/upstream-dovecot.gpg] https://repo.dovecot.org/ce-2.4-latest/debian/${VERSION_CODENAME} ${VERSION_CODENAME} main" \
      > /etc/apt/sources.list.d/upstream-dovecot.list

    # Refresh package index:
    apt-get "${QUIET}" update

    # This repo instead provides `dovecot-auth-lua` as a transitional package to `dovecot-lua`,
    # thus this extra package is required to retain lua support:
    DOVECOT_PACKAGES+=(dovecot-lua)
  fi

  _log 'debug' 'Installing Dovecot'
  apt-get "${QUIET}" install --no-install-recommends "${DOVECOT_PACKAGES[@]}"

  # Runtime dependency for fts_xapian (built via `compile.sh`):
  apt-get "${QUIET}" install --no-install-recommends libxapian30
}

function _install_rspamd() {
  # NOTE: DMS only supports the rspamd package via using the third-party repo maintained by Rspamd (AMD64 + ARM64):
  # Repo: https://rspamd.com/apt-stable/dists/bookworm/main/
  # Docs: https://rspamd.com/downloads.html#debian-and-ubuntu-linux
  # NOTE: Debian 12 provides Rspamd 3.4 (too old) and Rspamd discourages it's use

  _log 'trace' 'Adding third-party package repository (Rspamd)'
  curl -fsSL https://rspamd.com/apt-stable/gpg.key | gpg --dearmor > /usr/share/keyrings/upstream-rspamd.gpg
  echo \
    "deb [signed-by=/usr/share/keyrings/upstream-rspamd.gpg] https://rspamd.com/apt-stable/ ${VERSION_CODENAME} main" \
    > /etc/apt/sources.list.d/upstream-rspamd.list

  # Refresh package index:
  apt-get "${QUIET}" update

  _log 'debug' 'Installing Rspamd'
  apt-get "${QUIET}" install rspamd redis-server
}

function _install_fail2ban() {
  local FAIL2BAN_VERSION=1.1.0
  local FAIL2BAN_DEB_URL="https://github.com/fail2ban/fail2ban/releases/download/${FAIL2BAN_VERSION}/fail2ban_${FAIL2BAN_VERSION}-1.upstream1_all.deb"
  local FAIL2BAN_DEB_ASC_URL="${FAIL2BAN_DEB_URL}.asc"
  local FAIL2BAN_GPG_FINGERPRINT='8738 559E 26F6 71DF 9E2C  6D9E 683B F1BE BD0A 882C'
  local FAIL2BAN_GPG_PUBLIC_KEY_ID='0x683BF1BEBD0A882C'
  local FAIL2BAN_GPG_PUBLIC_KEY_SERVER='hkps://keyserver.ubuntu.com'

  _log 'debug' 'Installing Fail2ban'
  # Dependencies (https://github.com/docker-mailserver/docker-mailserver/pull/3403#discussion_r1306581431)
  apt-get "${QUIET}" install --no-install-recommends python3-pyinotify python3-dnspython python3-systemd

  gpg --keyserver "${FAIL2BAN_GPG_PUBLIC_KEY_SERVER}" --recv-keys "${FAIL2BAN_GPG_PUBLIC_KEY_ID}" 2>&1

  curl -fsSLo fail2ban.deb "${FAIL2BAN_DEB_URL}"
  curl -fsSLo fail2ban.deb.asc "${FAIL2BAN_DEB_ASC_URL}"

  FINGERPRINT=$(LANG=C gpg --verify fail2ban.deb.asc fail2ban.deb |& sed -n 's#Primary key fingerprint: \(.*\)#\1#p')

  if [[ -z ${FINGERPRINT} ]]; then
    echo 'ERROR: Invalid GPG signature!' >&2
    exit 1
  fi

  if [[ ${FINGERPRINT} != "${FAIL2BAN_GPG_FINGERPRINT}" ]]; then
    echo "ERROR: Wrong GPG fingerprint!" >&2
    exit 1
  fi

  dpkg -i fail2ban.deb 2>&1
  rm fail2ban.deb fail2ban.deb.asc

  _log 'debug' 'Patching Fail2ban to enable network bans'
  # Enable network bans
  # https://github.com/docker-mailserver/docker-mailserver/issues/2669
  # https://github.com/fail2ban/fail2ban/issues/3125
  sedfile -i -r 's/^_nft_add_set = .+/_nft_add_set = <nftables> add set <table_family> <table> <addr_set> \\{ type <addr_type>\\; flags interval\\; \\}/' /etc/fail2ban/action.d/nftables.conf
}

function _post_installation_steps() {
  _log 'debug' 'Running post-installation steps (cleanup)'
  _log 'debug' 'Deleting sensitive files (secrets)'
  rm /etc/postsrsd.secret

  _log 'debug' 'Deleting default logwatch cronjob'
  rm /etc/cron.daily/00logwatch

  _log 'trace' 'Removing leftovers from APT'
  apt-get "${QUIET}" clean
  rm -rf /var/lib/apt/lists/*
}

_pre_installation_steps
_install_utils
_install_postfix
_install_packages
_install_dovecot
_install_rspamd
_install_fail2ban
_post_installation_steps