#!/usr/bin/env bash
# author: joe.zheng
# version: 23.11.11

set -e

SELF="$(basename $0)"
SELF_VERSION="$(sed -n '1,4s/# version: \(.*\)/\1/p' $0)"

SUDO=""
if [[ $(id -u) != "0" ]]; then
  SUDO="sudo"
fi

DIR_DEBS="${DIR_DEBS:-$(dirname $0)/debs}"
DIR_EMPTY="$DIR_DEBS/empty"
DIR_FILE="$DIR_DEBS/file"
SVC_CONF="$DIR_DEBS/file.conf"

NO_CLOBBER="${NO_CLOBBER:-n}"

SVC_NAME="${SVC_NAME:-debs}" # container name
SVC_PORT="${SVC_PORT:-9090}" # port number

function usage() {
  cat <<EOF
Usage: $SELF [command] [args]
  Mirror and serve Debian packages as a local repo

  You should "sudo apt-get update" first to list deb urls, installed
  packages will not be listed.

Commands:
  list <pkg>...    list all the deb urls for the target packages
  pull [<url>...]  pull the deb packages, read from stdin if no url
  serve            serve the local deb repo

Environment variables:
  DRY_RUN:     print out information only if it is "y"
  DIR_DEBS:    dir to save deb packages, default: $DIR_DEBS
  NO_CLOBBER:  do not overwrite existing files, default: $NO_CLOBBER
  SVC_NAME:    container name to use: default: $SVC_NAME
  SVC_PORT:    port number to listen: default: $SVC_PORT

Examples:

  1. List and pull deb packages
    sudo apt update && $SELF list iftop ifstat | $SELF pull

  2. Start web server to serve local repo
    $SELF serve

  3. Configure apt to use the local repo
    cat <<EOC | sudo tee /etc/apt/sources.list.d/local.list
deb [trusted=yes] http://localhost:$SVC_PORT /
EOC
    sudo apt update && apt-cache policy iftop

Version: $SELF_VERSION
EOF
}

function msg {
  echo "> $@"
}

function err {
  echo "> $@" >&2
}

function list_deb_url {
  # there should not be any deb files in the cache folder
  apt-get install --print-uris -qq -o Dir::Cache::Archives=$DIR_EMPTY $@ \
  | grep '\.deb' | cut -d "'" -f2
}

function pull_deb {
  url="$1"
  msg "pulling $url"
  file="${url##*/}"
  msg "saving $file"

  if [[ "$NO_CLOBBER" == 'y' ]]; then
    if [[ -e "$file" ]]; then
      msg "file exists, skip"
      return
    fi
  fi
  if [[ "$DRY_RUN" != 'y' ]]; then
    wget -q -c $url
  fi
}

function create_svc_conf {
  mkdir -p "$(dirname $1)"
  cat <<'EOF' > $1
server {
    listen       8080;
    server_name  localhost;
    location / {
        root /file;
        autoindex on;
        autoindex_exact_size off;
        autoindex_localtime on;
        charset utf-8;
    }
}
EOF

}

if [[ -z "$1" || "$1" == "-h" ]]; then
  usage && exit
else
  cmd="$1"
  shift
fi

mkdir -p $DIR_DEBS $DIR_FILE $DIR_EMPTY

if [[ "$cmd" == "list" ]]; then
  if [[ -z "$1" ]]; then
    err "no repository is provided"
    exit 1
  fi
  list_deb_url "$@" && exit
elif [[ "$cmd" == "pull" ]]; then
  if [[ -t 0 ]]; then
    # pass args into stdin
    exec < <(printf '%s\n' "$@")
  fi
  while IFS= read -r url; do
    if [[ "$url" != *.deb ]]; then
      msg "ingore $url" && continue
    fi
    msg "processing $url"
    (cd $DIR_FILE && pull_deb "$url")
  done
elif [[ "$cmd" == "serve" ]]; then
  if [[ ! -f $SVC_CONF ]]; then
     msg "create $SVC_CONF"
     create_svc_conf $SVC_CONF
  fi
  if $SUDO docker container inspect -f '{{.ID}}' $SVC_NAME >/dev/null; then
    msg "stop and delete the old container: $SVC_NAME"
    $SUDO docker rm -f $SVC_NAME
  fi
  msg "create container $SVC_NAME"
  $SUDO docker create --name $SVC_NAME \
    -v $(realpath $DIR_FILE):/file \
    -v $(realpath $SVC_CONF):/etc/nginx/conf.d/file.conf \
    -p $SVC_PORT:8080 --restart unless-stopped \
    nginx:1.23.4-alpine
  msg "start container $SVC_NAME"
  $SUDO docker start $SVC_NAME
  msg "generate deb index file"
  (cd $DIR_FILE && dpkg-scanpackages -m . > Packages)

  hostip=$(ip route get 1 | head -1 | awk '{print $7}')
  baseurl="http://$hostip:$SVC_PORT"
  cat <<EOF
# check the local repo
  no_proxy='*' curl $baseurl
# configure apt to use local repo
  cat <<EOC | sudo tee /etc/apt/sources.list.d/local.list
deb [trusted=yes] $baseurl /
EOC
  sudo apt update -o Acquire::http::Proxy::$hostip=DIRECT
EOF
else
  err "not supported cmd: $cmd"
  exit 1
fi

msg "done"