#!/usr/bin/env miaou-bash

# CONSTANTS

MIAOU_IMAGE=images:debian/13
PROJECT_SANDBOX=sandbox
TEMPLATE_SANDBOX=miaou-debian13-template
TEMPLATE_REFRESH_DELAY='7 days'
BARE_MINIMAL=false

# FUNCTIONS

function usage {
  echo "$(basename "$0") <CONTAINER_NAME> [--bare-minimal]"
}

function humanize_ago {
  local seconds=$(($(date +%s) - $(date -d "$1" +%s)))

  local days=$((seconds / 86400))
  local hours=$(((seconds % 86400) / 3600))
  local minutes=$(((seconds % 3600) / 60))

  if ((days > 365)); then
    echo "$((days / 365)) year(s) ago"
  elif ((days > 30)); then
    echo "$((days / 30)) month(s) ago"
  elif ((days > 0)); then
    echo "$days day(s) ago"
  elif ((hours > 0)); then
    echo "$hours hour(s) ago"
  elif ((minutes > 0)); then
    echo "$minutes minute(s) ago"
  else
    echo "$seconds second(s) ago"
  fi
}

function parse_options {
  while [[ $# -gt 0 ]]; do
    case "$1" in
    --help | -h) usage && exit 0 ;;
    --bare-minimal) BARE_MINIMAL=true ;;
    *)
      if [[ ! -v CONTAINER ]]; then
        CONTAINER=$1
      else
        echo >&2 "Unknown option: $1" && usage && exit 2
      fi
      ;;
    esac
    shift
  done
  if [[ ! -v CONTAINER ]]; then
    usage
    exit 1
  fi
}

function mount_miaou_bash {
  local target="$1"
  local options=()
  [[ -v 2 ]] && options+=(--project "$2")

  incus "${options[@]}" config device add "$target" MIAOU-BASH disk \
    source="$MIAOU_BASH_DIR" path=/opt/miaou-bash readonly=true |
    grep -q 'Device MIAOU-BASH added'
}

function assign_host_zoneinfo {
  local target="$1"
  local options=()
  [ -v 2 ] && options+=(--project "$2")

  local host_zoneinfo
  host_zoneinfo=$(realpath /etc/localtime)
  echo "assign ZONEINFO from host: $host_zoneinfo"

  incus exec "${options[@]}" "$target" -- bash <<-EOF
ln -fs "$host_zoneinfo" /etc/localtime
dpkg-reconfigure -f noninteractive tzdata 2>/dev/null
EOF
}

function build_sandbox_project {
  if ! incus project show $PROJECT_SANDBOX >/dev/null; then
    incus project create $PROJECT_SANDBOX
    incus --project $PROJECT_SANDBOX profile device add default root disk path=/ pool=default
    incus --project $PROJECT_SANDBOX profile device add default eth0 nic name=eth0 network=incusbr0
  fi
}

function refresh_template {
  if incus --project "$PROJECT_SANDBOX" info "$TEMPLATE_SANDBOX" | grep '^Status: STOPPED'; then
    incus --project "$PROJECT_SANDBOX" start "$TEMPLATE_SANDBOX"
  fi

  script=$(
    cat <<EOF
apt-get update
apt-get dist-upgrade -y
MIAOU_BASH_DIR=/opt/miaou-bash
export MIAOU_BASH_DIR
/opt/miaou-bash/bin/miaou-bash /opt/miaou-bash/lib/initiate.bash
EOF
  )

  incus --project "$PROJECT_SANDBOX" exec "$TEMPLATE_SANDBOX" -- bash -lc "$script"
  incus --project "$PROJECT_SANDBOX" stop "$TEMPLATE_SANDBOX"

  local image_date
  image_date=$(incus --project "$PROJECT_SANDBOX" list "$TEMPLATE_SANDBOX" -f compact,noheader -cl)
  echo "template refreshed at: $image_date"
}

function add_feature_minimal_debian {
  local container="$1"
  local options=()
  [[ -v 2 ]] && options+=(--project "$2")
  incus "${options[@]}" file delete "$container"/etc/apt/sources.list
  incus "${options[@]}" file push --uid 0 --gid 0 --mode 644 --create-dirs /etc/apt/sources.list.d/debian.sources "$container"/etc/apt/sources.list.d/debian.sources
  cat <<EOF | incus "${options[@]}" file push --uid 0 --gid 0 --mode 644 --create-dirs - "$container"/etc/systemd/resolved.conf.d/10-disable-ipv4-listener.conf
[Resolve]
LLMNR=no
DNSStubListener=no
EOF
  echo "duplicate apt repository (debian.sources) from host"
}

function build_template_from_scratch {
  build_sandbox_project
  echo "building template from scratch..."
  incus --project "$PROJECT_SANDBOX" launch "$MIAOU_IMAGE" "$TEMPLATE_SANDBOX"
  add_feature_minimal_debian "$TEMPLATE_SANDBOX" "$PROJECT_SANDBOX"
  mount_miaou_bash "$TEMPLATE_SANDBOX" "$PROJECT_SANDBOX"
  refresh_template
  echo "template:$TEMPLATE_SANDBOX from project:$PROJECT_SANDBOX built successfully!"
}

function prepare_template_for_quick_creation {
  [[ $BARE_MINIMAL == true ]] && return

  local image_date
  image_date=$(incus list "$TEMPLATE_SANDBOX" -f compact,noheader -cl --project "$PROJECT_SANDBOX")
  if [[ -z $image_date ]]; then
    build_template_from_scratch
  else
    local true_date=$(date -d "$image_date" +%s)
    local expiration_date=$(date -d "$TEMPLATE_REFRESH_DELAY ago" +%s)
    if ((true_date < expiration_date)); then
      echo "template exists $(humanize_ago "$image_date"), needs a refresh..."
      refresh_template
    else
      :
      # echo "template already exists $(humanize_ago "$image_date")!"
    fi
  fi
}

function customize_host {
  local target domain
  target="$1"
  domain=$(incus network get incusbr0 dns.domain)
  domain=${domain:-incus}

  printf "127.0.1.1\t$target.$domain $target\n127.0.0.1\tlocalhost\n" | incus file push - $target/etc/hosts
  echo "$target.$domain" | incus file push - $target/etc/hostname
}

function assert_not_sandboxing {
  if [[ $(incus project get-current) == "$PROJECT_SANDBOX" ]]; then
    >&2 echo MIAOU_INCUS_ERROR: actual sandboxing project, please switch back to your 'default' project
    builtin exit 30
  fi
}

function assert_unique_name {
  if incus info "$CONTAINER" >/dev/null 2>&1; then
    >&2 echo "MIAOU_INCUS_ERROR: a container named <$CONTAINER> already exists!"
    builtin exit 31
  fi
}

function create {
  if [[ "$BARE_MINIMAL" == true ]]; then
    incus launch "$MIAOU_IMAGE" "$CONTAINER"
    add_feature_minimal_debian "$CONTAINER"
    assign_host_zoneinfo "$CONTAINER"
  else
    if incus --project "$PROJECT_SANDBOX" info "$TEMPLATE_SANDBOX" | grep '^Status: RUNNING'; then
      incus --project "$PROJECT_SANDBOX" stop "$TEMPLATE_SANDBOX"
    fi
    incus --project "$PROJECT_SANDBOX" copy --instance-only "$TEMPLATE_SANDBOX" "$CONTAINER" --target-project $(incus project get-current)
    incus file delete "$CONTAINER/etc/machine-id"
    incus config unset "$CONTAINER" volatile.eth0.hwaddr
    incus start "$CONTAINER"
  fi
  customize_host "$CONTAINER"
}

# MAIN

parse_options "$@"
assert_not_sandboxing
assert_unique_name
prepare_template_for_quick_creation
create
echo Success