#!/bin/sh
# Script to handle local DNS testing via dnsmasq
# supports add/remove/list of CNAME and TXT records
# on dnsmasq config changes it will restart the dnsmasq container
# it also asks to add the record to the /etc/hosts file if --no-hosts is not used

# prep
set -e

# ensure directory exists before using the file
mkdir -p ./docker/dnsmasq/dnsmasq.d
# dedicated sndev.conf file
DNSMASQ_CONF_PATH="./docker/dnsmasq/dnsmasq.d/sndev.conf"

# check if running on Windows or macOS
# this script doesn't support Windows /etc/hosts editing
# sed -i has different syntax on macOS/BSD and Linux
IS_WINDOWS=false
IS_DARWIN=false

OS_NAME=$(uname -s)
case "$OS_NAME" in
  MINGW*|CYGWIN*|MSYS*)
    IS_WINDOWS=true
    ;;
  Darwin*)
    IS_DARWIN=true
    ;;
esac

# general usage
usage() {
  cat <<EOF
Set mock DNS records for custom domains in dnsmasq conf.
Use .sndev domains as they automatically resolve to 127.0.0.1.

USAGE
  $ sndev domains dns [COMMAND]

COMMANDS
  add    <cname|txt> <name> <value> [--no-hosts]
  remove <cname|txt> <name> <value> [--no-hosts]
  list   <cname|txt>

FLAGS
  --no-hosts  Skip asking to add/remove record to /etc/hosts
              Useful if you're using dnsmasq [127.0.0.1:5353] as your DNS server.

EXAMPLES
  $ sndev domains dns add cname www.pizza.sndev sn.sndev
  $ sndev domains dns remove txt _snverify.www.pizza.sndev "7vfyvQO...vMALqvqkTQ"
  $ sndev domains dns list cname|txt
EOF
exit 1
}

# handle flags
while [ $# -gt 0 ]; do
  case "$1" in
    -h|--help)
      usage
    ;;
    *)
      break
    ;;
  esac
done

INTENT=$1       # add, remove, list
TYPE=$2         # cname, txt
NAME=$3         # www.pizza.com
VALUE=$4        # stacker.news or "7vfyvQO...vMALqvqkTQ="
NO_HOSTS=false  # handled via --no-hosts flag

# creates a line compatible with dnsmasq config file
prepare_line() {
  if [ "$TYPE" = "cname" ]; then
    LINE="cname=${NAME},${VALUE}"
  elif [ "$TYPE" = "txt" ]; then
    escaped_quotes=$(printf '%s' "$VALUE" | sed 's/"/\\"/g')
    LINE="txt-record=${NAME},\"${escaped_quotes}\""
  else
    echo "Invalid record type: $TYPE"
    usage
  fi
}

# if we're adding or removing a record, we need to check for required args
if [ "$INTENT" = "add" ] || [ "$INTENT" = "remove" ]; then
    if [ $# -lt 4 ]; then
        echo "Not enough arguments"
        usage
    else
        prepare_line # prepare the line for the dnsmasq config file
        shift 4 # 4 args: intent, type, name, value
        # we need to get the --no-hosts flag if it's present
        if [ "$1" = "--no-hosts" ]; then
            NO_HOSTS=true
            shift
        fi
    fi
# if we're listing records, we need to have at least the TYPE arg
elif [ "$INTENT" = "list" ] && [ $# -lt 2 ]; then
    echo "No type provided"
    usage
fi

# add a record to the dnsmasq config
add_record() {
  # check if the record already exists
  if grep -Fxq "$LINE" "$DNSMASQ_CONF_PATH"; then
    echo "Record already exists: $LINE"
    exit 1
  fi

  # add the record to the dnsmasq config
  echo "Adding record: $LINE"
  printf "%s\n" "$LINE" >> "$DNSMASQ_CONF_PATH"

  # if we're adding a CNAME record and --no-hosts is not used, we need to ask to add the record to the /etc/hosts file
  if [ "$TYPE" = "cname" ] && [ "$NO_HOSTS" = false ]; then
    # dnsmasq pamphlet 
    printf "
    While sndev will use dnsmasq DNS server, your system won't use it by default.
    You can either manually point DNS to 127.0.0.1:5353 to access it system-wide,
    or add this record to /etc/hosts to access it via browser.\n\n"
    
    # ask to add the record to the /etc/hosts file
    printf "[sudo] Do you want to add '127.0.0.1 %s' to /etc/hosts? [y/N] " "$NAME"
    read -r response
    case "$response" in
      [Yy]*)
        # add the record to the /etc/hosts file
        if ! add_record_to_hosts "$NAME"; then
          echo "/etc/hosts hasn't been touched."
        fi
        ;;
    esac
  fi
  echo "Done."
  exit 0
}

# remove a record from the dnsmasq config
remove_record() {
  # check if the record exists
  if ! grep -Fxq "$LINE" "$DNSMASQ_CONF_PATH"; then
    echo "Can't find record: $LINE"
    echo "The record may have been removed or the name/value is incorrect or incomplete."
    echo "Use 'sndev domains dns list' to see all records."
    exit 1
  fi

  # remove the record from the dnsmasq config
  echo "Removing record: $LINE"
  if [ "$IS_DARWIN" = true ]; then
    sed -i '' "/^$LINE$/d" "$DNSMASQ_CONF_PATH"
  else
    sed -i "/^$LINE$/d" "$DNSMASQ_CONF_PATH"
  fi

  # if we're removing a CNAME record and --no-hosts is not used, we need to ask to remove the record from the /etc/hosts file
  if [ "$TYPE" = "cname" ] && [ "$NO_HOSTS" = false ]; then
    # ask to remove the record from the /etc/hosts file
    printf "[sudo] Do you want to remove this record from /etc/hosts? [y/N] "
    read -r response
    case "$response" in
      [Yy]*)
        # remove the record from the /etc/hosts file
        if ! remove_record_from_hosts "$NAME"; then
          echo "/etc/hosts hasn't been touched."
        fi
        ;;
    esac
  fi
  echo "Done."
  exit 0
}

# list all records of a given type
list_records() {
  if [ "$TYPE" = "txt" ]; then
    TYPE="txt-record"
  fi
  grep "^$TYPE=" "$DNSMASQ_CONF_PATH" || echo "No $TYPE records found."
}

# add a record to the /etc/hosts file
add_record_to_hosts() {
  domain="$1"
  
  # this script doesn't support Windows /etc/hosts editing
  if [ "$IS_WINDOWS" = true ]; then
    echo "Adding records to /etc/hosts via this script is not supported on Windows"
    return 1
  fi

  # check if the record already exists in the /etc/hosts file
  if check_record_hosts_exists "$domain"; then
    echo "Record already exists in /etc/hosts: $domain"
    return 1
  fi

  # add the record to the /etc/hosts file
  echo "Adding record to /etc/hosts: $domain"
  echo "This operation will require sudo privileges"
  if ! echo "127.0.0.1 $domain" | sudo tee -a "/etc/hosts" > /dev/null; then
    echo "Failed to add record to /etc/hosts"
    return 1
  fi
  echo "$domain added to /etc/hosts."
  echo "You can now access http://$domain:3000 via browser."
  return 0
}

remove_record_from_hosts() {
  domain="$1"
  
  # this script doesn't support Windows /etc/hosts editing
  if [ "$IS_WINDOWS" = true ]; then
    echo "Removing records from /etc/hosts via this script is not supported on Windows"
    return 1
  fi

  # check if the record exists in the /etc/hosts file
  if ! check_record_hosts_exists "$domain"; then
    echo "Record not found in /etc/hosts: $domain"
    return 1
  fi

  # remove the record from the /etc/hosts file
  echo "Removing record from /etc/hosts: $domain"
  echo "This operation will require sudo privileges"
  if [ "$IS_DARWIN" = true ]; then
    if ! sudo sed -i '' "/^127.0.0.1 $domain$/d" "/etc/hosts" 2>/dev/null; then
      echo "Failed to remove record from /etc/hosts."
      return 1
    fi
  else
    if ! sudo sed -i "/^127.0.0.1 $domain$/d" "/etc/hosts" 2>/dev/null; then
      echo "Failed to remove record from /etc/hosts."
      return 1
    fi
  fi
  echo "$domain removed from /etc/hosts."
  return 0
}

# check if a record exists in the /etc/hosts file
check_record_hosts_exists() {
  domain="$1"
  
  # grep for the record
  if grep -Fxq "127.0.0.1 $domain" "/etc/hosts"; then
    return 0
  fi
  return 1
}

# switch intents
case "$INTENT" in
  add)    add_record ;;
  remove) remove_record ;;
  list)   list_records ;;
  *)      usage ;;
esac