#!/usr/bin/env bash

# ----------
# Common functions and settings for selective SRS management scripts
#
# This file is intended to be sourced by:
#
#    activate-srs.sh
#    deactivate-srs.sh
#    install-update-srs.sh
#
# It must not make configuration changes by itself.
# ----------

# ----------
# Script paths
# ----------

SRS_COMMON_FILE="$(realpath "${BASH_SOURCE[0]}")"
SRS_HELPERS_DIR="$(dirname "$SRS_COMMON_FILE")"
SRS_SCRIPT_DIR="$(dirname "$SRS_HELPERS_DIR")"

SRS_CONF_FILE="${SRS_SCRIPT_DIR}/conf/srs.conf"
SRS_CONF_SAMPLE_FILE="${SRS_SCRIPT_DIR}/conf/srs.conf.sample"

# ----------
# System paths
# ----------

POSTFIX_CONF_DIR="/etc/postfix"
POSTFIX_MAIN_CF="${POSTFIX_CONF_DIR}/main.cf"
POSTFIX_MASTER_CF="${POSTFIX_CONF_DIR}/master.cf"

POSTFIX_SRS_DIR="/etc/postfix-srs"
POSTFIX_SRS_DELIVERY_DIR="${POSTFIX_SRS_DIR}/delivery"
SRS_STATE_FILE="${POSTFIX_SRS_DIR}/state.conf"
# SRS bounce alias ownership is tracked by a comment marker in main.cf;
# original version-1 state.conf is immutable and needs no unsafe migration.
SRS_ALIAS_HELPER="${SRS_HELPERS_DIR}/srs-virtual-alias.py"

POSTSRSD_CONF_DIR="/etc/postsrsd-srs"
POSTSRSD_CONF_FILE="${POSTSRSD_CONF_DIR}/postsrsd.conf"
POSTSRSD_SECRET_FILE="${POSTSRSD_CONF_DIR}/secret"

SRS_ALIAS_DECISION_SCRIPT="/usr/local/sbin/srs-alias-decision.py"
SRS_FORWARD_SCRIPT="/usr/local/sbin/srs-forward.py"
SRS_REVERSE_MAP_SCRIPT="/usr/local/sbin/srs-reverse-map.py"
SRS_REVERSE_POLICY_SCRIPT="/usr/local/sbin/srs-reverse-policy.py"

# ----------
# Services
# ----------

POSTFIX_SERVICE="postfix.service"
POSTSRSD_SERVICE="postsrsd-srs.service"
SRS_REVERSE_MAP_SERVICE="srs-reverse-map.service"
SRS_DELIVERY_SERVICE="postfix@srs-delivery.service"

POSTFIX_SRS_DROPIN_DIR="/etc/systemd/system/postfix.service.d"
POSTFIX_SRS_DROPIN_FILE="${POSTFIX_SRS_DROPIN_DIR}/srs.conf"

SRS_DELIVERY_DROPIN_DIR="/etc/systemd/system/postfix@srs-delivery.service.d"
SRS_DELIVERY_DROPIN_FILE="${SRS_DELIVERY_DROPIN_DIR}/srs.conf"

# ----------
# SRS network endpoints
# ----------

POSTSRSD_SOCKET_HOST="127.0.0.1"
POSTSRSD_SOCKET_PORT="10003"

SRS_REVERSE_SOCKET_HOST="127.0.0.1"
SRS_REVERSE_SOCKET_PORT="10004"

SRS_REINJECT_HOST="127.0.0.1"
SRS_REINJECT_PORT="10028"

SRS_REVERSE_HOST="127.0.0.1"
SRS_REVERSE_PORT="10029"

# ----------
# Managed block markers
# ----------

SRS_MAIN_CF_BEGIN_MARKER="# BEGIN OOPEN-SRS-MANAGED"
SRS_MAIN_CF_END_MARKER="# END OOPEN-SRS-MANAGED"

SRS_MASTER_CF_BEGIN_MARKER="# BEGIN OOPEN-SRS-MANAGED"
SRS_MASTER_CF_END_MARKER="# END OOPEN-SRS-MANAGED"

# ----------
# Runtime variables
# ----------

script_name="$(basename "$0")"
terminal=false

SRS_LOCK_DIR="/run/lock/oopen-srs.lock"
SRS_LOCK_OWNER_FILE="${SRS_LOCK_DIR}/pid"

log_file=""
backup_date="$(date +%Y-%m-%d-%H%M%S)"

SRS_LOCK_ACQUIRED=false
SRS_CONFIG_LOADED=false
SRS_STATE_LOADED=false

# ----------
# Base functions
# ----------

blank_line() {
   if $terminal ; then
      echo ""
   fi
}

echononl() {
   if $terminal ; then
      echo -e -n "   $*" 1>&2
   fi
}

echo_ok() {
   if $terminal ; then
      echo -e "\033[85G[ \033[32mok\033[m ]"
   fi
}

echo_failed() {
   if $terminal ; then
      echo -e "\033[85G[ \033[1;31mfailed\033[m ]"
   fi
}

echo_skipped() {
   if $terminal ; then
      echo -e "\033[85G[ \033[33m\033[1mskipped\033[m ]"
   fi
}

echo_warning() {
   if $terminal ; then
      echo -e "\033[85G[ \033[33m\033[1mwarn\033[m ]"
   fi
}


echo_differs() {
   if $terminal ; then
      echo -e "\033[85G[ \033[33m\033[1mdiffers\033[m ]"
   fi
}


echo_inactive() {
   if $terminal ; then
      echo -e "\033[85G[ \033[33m\033[1minactive\033[m ]"
   fi
}


echo_absent() {
   if $terminal ; then
      echo -e "\033[85G[ \033[33m\033[1mabsent\033[m ]"
   fi
}

info() {
   if $terminal ; then
      echo ""
      echo -e "   [ \033[32m\033[1mInfo\033[m ]  $*"
      echo ""
   else
      echo "   [ Info ] $*"
   fi
}

warn() {
   echo ""
   if $terminal ; then
      echo -e "   [ \033[33m\033[1mWarning\033[m ] $*"
   else
      echo "   [ Warning ] $*"
   fi
   echo ""
}

error() {
   echo ""
   if $terminal ; then
      echo -e "   [ \033[31m\033[1mError\033[m ] $*"
   else
      echo "   [ Error ] $*"
   fi
   echo ""
}

clean_up() {
   local rc="${1:-0}"

   if $SRS_LOCK_ACQUIRED && [[ -d "$SRS_LOCK_DIR" ]]; then
      rm -rf "$SRS_LOCK_DIR"
      SRS_LOCK_ACQUIRED=false
   fi

   [[ -n "$log_file" && -f "$log_file" ]] && rm -f "$log_file"

   blank_line
   exit "$rc"
}

fatal() {
   echo ""

   if $terminal ; then
      echo -e "   [ \033[31m\033[1mFatal\033[m ] $*"
      echo ""
      echo -e "             \033[1mScript terminated\033[m.."
   else
      echo "   [ Fatal ] $*"
      echo ""
      echo "             Script terminated.."
   fi

   echo ""
   clean_up 1
}


fatal_with_command_hint() {
   local message="$1"
   local hint="$2"
   local command="$3"

   echo ""

   if $terminal ; then
      echo -e "   [ \033[31m\033[1mFatal\033[m ] ${message}"
      echo ""
      echo -e "             \033[1mScript terminated\033[m.."
   else
      echo "   [ Fatal ] ${message}"
      echo ""
      echo "             Script terminated.."
   fi

   echo ""

   if $terminal ; then
      echo -e "   [ \033[33m\033[1mWarning\033[m ] ${hint}"
   else
      echo "   [ Warning ] ${hint}"
   fi

   echo ""
   echo "             ${command}"
   echo ""

   clean_up 1
}


fatal_with_queue_help() {
   local message="$1"
   local queue_config_dir="$2"

   echo ""

   if $terminal ; then
      echo -e "   [ \033[31m\033[1mFatal\033[m ] ${message}"
      echo ""
      echo -e "             \033[1mScript terminated\033[m.."
   else
      echo "   [ Fatal ] ${message}"
      echo ""
      echo "             Script terminated.."
   fi

   echo ""

   if $terminal ; then
      echo -e "   [ \033[33m\033[1mWarning\033[m ] To inspect the SRS delivery queue, run:"
   else
      echo "   [ Warning ] To inspect the SRS delivery queue, run:"
   fi

   echo ""
   echo "             postqueue -c ${queue_config_dir} -p"
   echo ""

   if $terminal ; then
      echo -e "   [ \033[33m\033[1mWarning\033[m ] To inspect one queued message, replace QUEUE_ID and run:"
   else
      echo "   [ Warning ] To inspect one queued message, replace QUEUE_ID and run:"
   fi

   echo ""
   echo "             postcat -c ${queue_config_dir} -q QUEUE_ID"
   echo ""

   if $terminal ; then
      echo -e "   [ \033[33m\033[1mWarning\033[m ] If you really want to delete ALL messages from the SRS delivery queue, run:"
   else
      echo "   [ Warning ] If you really want to delete ALL messages from the SRS delivery queue, run:"
   fi

   echo ""
   echo "             postsuper -c ${queue_config_dir} -d ALL"
   echo ""

   clean_up 1
}

ask_yes_no() {
   local question="$1"
   local default_answer="${2:-no}"
   local answer=""
   local prompt="[yes/no]"

   if [[ "$default_answer" = "yes" ]]; then
      prompt="[yes/no, default: yes]"
   elif [[ "$default_answer" = "no" ]]; then
      prompt="[yes/no, default: no]"
   fi

   while true ; do
      echononl "$question $prompt: "
      read -r answer
      answer="${answer,,}"

      [[ -z "$answer" ]] && answer="$default_answer"

      case "$answer" in
         yes) return 0 ;;
         no)  return 1 ;;
         *)   warn "Wrong entry! Please enter 'yes' or 'no'." ;;
      esac
   done
}

# ----------
# Runtime handling
# ----------

init_srs_runtime() {
   local script_path=""
   local transcript_file=""

   if [[ -t 1 ]]; then
      terminal=true
   else
      script_path="$(realpath "$0" 2>/dev/null || printf '%s' "$0")"
      transcript_file="/tmp/${script_name%.sh}.out"

      echo ""
      echo "   [ Fatal ] Script requires an interactive terminal."
      echo ""
      echo "             Script terminated.."
      echo ""
      echo "   [ Warning ] Piping the script output, for example through 'tee',"
      echo "               removes the terminal from stdout."
      echo ""
      echo "               To run the script interactively and record its complete"
      echo "               terminal session, use:"
      echo ""
      echo "               script -q -e -c \"${script_path}\" \\"
      echo "                  ${transcript_file}"
      echo ""

      clean_up 1
   fi

   if ! mkdir "$SRS_LOCK_DIR" 2>/dev/null ; then
      if [[ -r "$SRS_LOCK_OWNER_FILE" ]]; then
         fatal "Another SRS management process seems to be running (PID $(cat "$SRS_LOCK_OWNER_FILE"))."
      else
         fatal "Cannot create SRS lock directory '${SRS_LOCK_DIR}'."
      fi
   fi

   SRS_LOCK_ACQUIRED=true

   printf '%s\n' "$$" > "$SRS_LOCK_OWNER_FILE" ||       fatal "Cannot write SRS lock owner file '${SRS_LOCK_OWNER_FILE}'."

   log_file="${SRS_LOCK_DIR}/${script_name%%.*}.log"
   : > "$log_file" || fatal "Cannot create log file '${log_file}'."
}

handle_signal() {
   trap - SIGHUP SIGINT SIGTERM
   warn "Script interrupted by signal."
   clean_up 1
}

# ----------
# Basic checks
# ----------

check_root() {
   echononl "Check if script is running as root.."

   if [[ "$(id -u)" -eq 0 ]]; then
      echo_ok
   else
      echo_failed
      fatal "This script must be run as root."
   fi
}

check_required_commands() {
   local cmd

   for cmd in "$@" ; do
      echononl "Check for command '${cmd}'.."

      if command -v "$cmd" > /dev/null 2>&1 ; then
         echo_ok
      else
         echo_failed
         fatal "Required command '${cmd}' was not found."
      fi
   done
}

check_readable_file() {
   local file="$1"
   local description="${2:-file}"

   echononl "Check ${description} '${file}'.."

   if [[ -r "$file" ]]; then
      echo_ok
   else
      echo_failed
      fatal "${description^} '${file}' does not exist or is not readable."
   fi
}

check_service_exists() {
   local service="$1"

   echononl "Check systemd service '${service}'.."

   if systemctl cat "$service" > /dev/null 2>&1 ; then
      echo_ok
   else
      echo_failed
      fatal "Systemd service '${service}' was not found."
   fi
}

check_service_active() {
   local service="$1"

   echononl "Check systemd service '${service}' is active.."

   if systemctl is-active --quiet "$service" ; then
      echo_ok
   else
      echo_failed
      fatal "Systemd service '${service}' is not active."
   fi
}

# ----------
# Security checks for sourced files
# ----------

check_secure_source_file() {
   local file="$1"
   local description="${2:-configuration file}"
   local owner_uid
   local owner_gid
   local mode

   echononl "Check security of ${description} '${file}'.."

   if [[ ! -f "$file" || ! -r "$file" ]]; then
      echo_failed
      fatal "${description^} '${file}' does not exist or is not readable."
   fi

   owner_uid="$(stat -c '%u' "$file" 2>/dev/null)" || {
      echo_failed
      fatal "Cannot determine owner of '${file}'."
   }

   owner_gid="$(stat -c '%g' "$file" 2>/dev/null)" || {
      echo_failed
      fatal "Cannot determine group of '${file}'."
   }

   mode="$(stat -c '%a' "$file" 2>/dev/null)" || {
      echo_failed
      fatal "Cannot determine permissions of '${file}'."
   }

   if [[ "$owner_uid" -ne 0 || "$owner_gid" -ne 0 ]]; then
      echo_failed
      fatal "${description^} '${file}' must be owned by root:root."
   fi

   if (( (8#$mode & 0022) != 0 )); then
      echo_failed
      fatal "${description^} '${file}' must not be writable by group or others."
   fi

   echo_ok
}


check_state_file_permissions() {
   local mode

   echononl "Check permissions of persistent SRS state '${SRS_STATE_FILE}'.."

   if [[ ! -f "$SRS_STATE_FILE" ]]; then
      echo_failed
      fatal "Persistent SRS state '${SRS_STATE_FILE}' does not exist."
   fi

   if [[ "$(stat -c '%U:%G' "$SRS_STATE_FILE" 2>/dev/null)" != "root:root" ]]; then
      echo_failed
      fatal "Persistent SRS state '${SRS_STATE_FILE}' must be owned by root:root."
   fi

   mode="$(stat -c '%a' "$SRS_STATE_FILE" 2>/dev/null)" || {
      echo_failed
      fatal "Cannot determine permissions of '${SRS_STATE_FILE}'."
   }

   if [[ "$mode" != "600" ]]; then
      echo_failed
      fatal "Persistent SRS state '${SRS_STATE_FILE}' must have mode 0600 (current: ${mode})."
   fi

   echo_ok
}


# ----------
# SRS configuration
# ----------

load_srs_config() {

   if [[ ! -r "$SRS_CONF_FILE" ]]; then
      fatal "SRS configuration '${SRS_CONF_FILE}' does not exist or is not readable. Use '${SRS_CONF_SAMPLE_FILE}' as template."
   fi

   check_secure_source_file "$SRS_CONF_FILE" "SRS configuration"

   echononl "Read SRS configuration '${SRS_CONF_FILE}'.."

   unset _SRS_DOMAIN

   # shellcheck source=/dev/null
   source "$SRS_CONF_FILE"

   if [[ -z "${_SRS_DOMAIN:-}" ]]; then
      echo_failed
      fatal "Variable '_SRS_DOMAIN' is not set in '${SRS_CONF_FILE}'."
   fi

   if [[ "$_SRS_DOMAIN" =~ [[:space:]] ]]; then
      echo_failed
      fatal "Invalid SRS domain '${_SRS_DOMAIN}': whitespace is not allowed."
   fi

   if [[ ! "$_SRS_DOMAIN" =~ ^([A-Za-z0-9]([A-Za-z0-9-]{0,61}[A-Za-z0-9])?\.)+[A-Za-z]{2,63}$ ]]; then
      echo_failed
      fatal "Invalid SRS domain '${_SRS_DOMAIN}'."
   fi

   SRS_CONFIG_LOADED=true
   echo_ok
}

# ----------
# Persistent pre-SRS state
# ----------

_is_boolean_value() {
   [[ "$1" = "true" || "$1" = "false" ]]
}

load_srs_state() {

   if [[ ! -r "$SRS_STATE_FILE" ]]; then
      fatal "Persistent SRS state '${SRS_STATE_FILE}' does not exist or is not readable."
   fi

   check_state_file_permissions
   check_secure_source_file "$SRS_STATE_FILE" "persistent SRS state"

   echononl "Read persistent SRS state '${SRS_STATE_FILE}'.."

   unset _STATE_VERSION
   unset _STATE_ORIGIN
   unset _STATE_HOSTNAME

   unset _PRE_SRS_DEFAULT_TRANSPORT_SET
   unset _PRE_SRS_DEFAULT_TRANSPORT
   unset _PRE_SRS_RECIPIENT_CANONICAL_MAPS_SET
   unset _PRE_SRS_RECIPIENT_CANONICAL_MAPS
   unset _PRE_SRS_SRS_FORWARD_DESTINATION_RECIPIENT_LIMIT_SET
   unset _PRE_SRS_SRS_FORWARD_DESTINATION_RECIPIENT_LIMIT
   unset _PRE_SRS_SMTP_RECEIVE_OVERRIDE_OPTIONS_SET
   unset _PRE_SRS_SMTP_RECEIVE_OVERRIDE_OPTIONS
   unset _PRE_SRS_AMAVIS_RECEIVE_OVERRIDE_OPTIONS_SET
   unset _PRE_SRS_AMAVIS_RECEIVE_OVERRIDE_OPTIONS

   # shellcheck source=/dev/null
   source "$SRS_STATE_FILE"

   if [[ "${_STATE_VERSION:-}" != "1" ]]; then
      echo_failed
      fatal "Unsupported or missing SRS state version in '${SRS_STATE_FILE}'."
   fi

   local bool_var

   for bool_var in       _PRE_SRS_DEFAULT_TRANSPORT_SET       _PRE_SRS_RECIPIENT_CANONICAL_MAPS_SET       _PRE_SRS_SRS_FORWARD_DESTINATION_RECIPIENT_LIMIT_SET       _PRE_SRS_SMTP_RECEIVE_OVERRIDE_OPTIONS_SET       _PRE_SRS_AMAVIS_RECEIVE_OVERRIDE_OPTIONS_SET
   do
      if ! _is_boolean_value "${!bool_var:-}" ; then
         echo_failed
         fatal "Invalid boolean value for '${bool_var}' in '${SRS_STATE_FILE}'."
      fi
   done

   if [[ -n "${_STATE_HOSTNAME:-}" && "${_STATE_HOSTNAME}" != "$(hostname -f)" ]]; then
      echo_warning
      warn "SRS state was created for host '${_STATE_HOSTNAME}', current hostname is '$(hostname -f)'."
   else
      echo_ok
   fi

   SRS_STATE_LOADED=true
}

# ----------
# Managed block helpers
# ----------

count_exact_line() {
   local file="$1"
   local line="$2"

   grep -Fxc "$line" "$file" 2>/dev/null || true
}

check_managed_block_markers() {
   local file="$1"
   local begin_marker="$2"
   local end_marker="$3"
   local begin_count
   local end_count
   local begin_line
   local end_line

   begin_count="$(count_exact_line "$file" "$begin_marker")"
   end_count="$(count_exact_line "$file" "$end_marker")"

   if [[ "$begin_count" -eq 0 && "$end_count" -eq 0 ]]; then
      return 1
   fi

   if [[ "$begin_count" -ne 1 || "$end_count" -ne 1 ]]; then
      return 2
   fi

   begin_line="$(grep -Fnx "$begin_marker" "$file" | cut -d: -f1)"
   end_line="$(grep -Fnx "$end_marker" "$file" | cut -d: -f1)"

   if [[ -z "$begin_line" || -z "$end_line" ]]; then
      return 2
   fi

   if (( begin_line >= end_line )); then
      return 2
   fi

   return 0
}