#!/bin/bash
# label <label@rockylinux.org>
# Supports only CentOS 8.3
set -e
unset CDPATH

if [ "$(id -u)" -ne 0 ]; then
  echo "You must run this script as root."
  echo "Either use sudo or 'su -c ${0}'"
fi

SUPPORTED_RELEASE="8.3"
SUPPORTED_MAJOR="8"
current_url=https://mirror.rockylinux.org/rocky
# These are packages that can be swapped safely over and will have more added over time.
packages_to_swap=(
  centos-backgrounds \
  centos-indexhtml \
  centos-linux-repos \
  centos-logos \
  centos-gpg-keys \
  centos-linux-release)

# Release packages that are part of SIG's should be listed below when they are available.
#sigs_to_swap=()

# Defaults
list_enabled=("$(yum repolist enabled | awk '!/repo/ {print $1}')")
enabled_modules=("$(dnf module list --enabled | grep rhel | awk '{print $1}')")
convert_info_dir=/root/convert
reinstall_all_rpms=false
verify_all_rpms=false

usage() {
  echo "Usage: ${0##*/} [OPTIONS]"
  echo
  echo "Options:"
  echo "-h displays this help"
  echo "-r Converts to rocky"
  echo "-V Verifies switch"
  echo "-R Reinstall all packages"
  echo "   !! USE WITH CAUTION !!"
  exit 1
} >&2

exit_message() {
  echo "$1"
  final_message
  exit 1
} >&2

final_message() {
  echo "An error occurred while we were attempting to convert your system to Rocky Linux. Your system may be unstable. Script will now exit to prevent possible damage."
}

## The actual work
bin_hash() {
  hash "$1" >/dev/null 2>&1
}

bin_check() {
  if ! bin_hash "$1"; then
    exit_message "'${1}' command not found. Please ensure you are running bash or that your PATH is set correctly."
  fi
}

generate_rpm_info() {
  mkdir /root/convert
  echo "Creating a list of RPMs installed: $1"
  rpm -qa --qf "%{NAME}|%{VERSION}|%{RELEASE}|%{INSTALLTIME}|%{VENDOR}|%{BUILDTIME}|%{BUILDHOST}|%{SOURCERPM}|%{LICENSE}|%{PACKAGER}\n" | sort > "${convert_info_dir}/$(hostname)-rpm-list-$1.log"
  echo "Verifying RPMs installed against RPM database: $1"
  rpm -Va | sort -k3 > "${convert_info_dir}/$(hostname)-rpm-list-verified-$1.log"
}

package_swaps() {
  rpm -e --nodeps "${packages_to_swap[@]}"
  rpm -ihv ${current_url}/${SUPPORTED_RELEASE}/BaseOS/x86_64/os/Packages/rocky-release-${SUPPORTED_RELEASE}-1.el8.x86_64.rpm \
           ${current_url}/${SUPPORTED_RELEASE}/BaseOS/x86_64/os/Packages/rocky-repos-${SUPPORTED_MAJOR}-1.el8.x86_64.rpm
  if [ $? -eq 0 ]; then
    echo "Removing dnf cache"
    rm -rf /var/cache/{yum,dnf}
    echo "Ensuring repos are enabled before the package swap"
    dnf config-manager --set-enabled "${list_enabled[@]}"
    dnf distro-sync -y
  else
    exit_message "We failed to install the release package."
  fi
}

sig_swaps() {
  exit_message "Not Available"
}

module_check() {
  echo "Finding our modules that are enabled"
  for module in "${enabled_modules[@]}"; do
    case ${module} in
      container-tools|go-toolset|jmc|llvm-toolset|rust-toolset|virt)
        ;;
      *)
        unknown_modules+=("${module}")
        ;;
    esac
  done
  if [ ${#unknown_modules[@]} -gt 0 ]; then
    echo "There are some modules that are unsure of how to handle. This normally shouldn't happen. Do you want to resolve this yourself (Yes) or continue (No)?"
    select yn in "Yes" "No"; do
      case $yn in
        Yes)
          echo "Ensure how to switch modules, so we are leaving."
          exit 1
          ;;
        No)
          break
          ;;
      esac
    done
  fi
}

# This is just in case. There is a likelihood this will have to be done.
module_fix() {
  for module in "${enabled_modules[@]}"; do
    dnf module reset -y "${module}"
    case ${module} in
      container-tools|go-toolset|jmc|llvm-toolset|rust-toolset|virt)
        dnf module install "${module}" -y
        ;;
      *)
        echo "Unsure how to deal with the module presented."
        ;;
      esac
    # Final update
    dnf update -y
  done
}

## End actual work

while getopts "hrVR" option; do
  case "$option" in
    h)
      usage
      ;;
    r)
      reinstall_all_rpms=true
      ;;
    V)
      verify_all_rpms=true
      ;;
    R)
      reinstall_all_rpms=true
      ;;
    *)
      echo "Invalid switch."
      usage
      ;;
  esac
done

echo "Ensuring rpm, yum, and curl are here."
for pkg in rpm yum curl; do
  bin_check "${pkg}"
done

echo "Ensuring your version of CentOS is supported"
if ! old_release=$(rpm -q --whatprovides /etc/redhat-release); then
  exit_message "You are not running a supported distribution."
fi

if [ "$(echo "${old_release}" | wc -l)" -ne 1 ]; then
  exit_message "You seem to have package issues. More than one package provides redhat-release."
fi

if ! grep ${SUPPORTED_RELEASE} -q /etc/redhat-release; then
  exit_message "${SUPPORTED_RELEASE} is only supported for conversion at this time. Stream is not supported."
fi

if "${verify_all_rpms}"; then
  generate_rpm_info begin
fi

case "${old_release}" in
  centos-linux-release*);;
  rocky-release*)
    exit_message "You are already running Rocky."
    ;;
  *)
    exit_message "You are running an unsupported distribution. Good bye."
esac

# Check our modules before a swap
module_check

# Actually do the swap and distro-sync
package_swaps

# Fix up modules
module_fix

# Warning, this is potentially dangerous.
if "${reinstall_all_rpms}"; then
  echo "!! THIS MAY CAUSE ISSUES WITH YOUR SYSTEM !!"
  rpm_list=("$(rpm -qa --qf "%{NAME}-%{VERSION}-%{RELEASE} %{VENDOR}\n" | grep CentOS | awk '{print $1}')")
  if [[ -n "${rpm_list[*]}" ]]; then
    echo "Reinstalling rpms: ${rpm_list[*]}"
    dnf reinstall "${rpm_list[@]}" -y
  fi
  non_rocky_rpm=("$(rpm -qa --qf "%{NAME}-%{VERSION}-%{RELEASE}|%{VENDOR}|%{PACKAGER}\n" |grep -iv Rocky)")
  if [[ -n ${non_rocky_rpm[*]} ]]; then
    echo "Non-Rocky packages are installed. This is generally not an issue. If you see centos packages, you may need to address them and file a bug report at https://bugs.rockylinux.org"
    printf '\t%s\n' "${non_rocky_rpm[@]}"
  fi
fi

if "${verify_all_rpms}"; then
  generate_rpm_info finish
  echo "You may review the following files:"
  find /root/convert -type f -name "$(hostname)-rpms-*.log"
fi

echo "Done, please reboot your system."