#!/usr/bin/env bash
# shellcheck disable=SC2128,SC2086,SC2155

###############################################################################
#     Expand environment variables using envsubst and macros using m4 to      #
#     implement custom conditional logic in aerc configuration files. In      #
#       addition, for the accounts configuration file keepassxc-cli is        #
#                     used to populate email credentials.                     #
###############################################################################

config_home=${XDG_CONFIG_HOME:-~/.config}/aerc
main=$config_home/aerc.conf
accounts=$config_home/accounts.conf
binds=$config_home/binds.conf
aerc=$(which --skip-tilde aerc)

database=${KEEPASSXC_DATABASE:-~/database.kdbx}
keyfile=${KEEPASSXC_KEYFILE:-} # optional
timeout=600

# https://stackoverflow.com/a/10660730
function rawurlencode(){
  local pos char

  for (( pos=0 ; pos<${#1} ; pos++ )); do
     char=${1:$pos:1}
     case "$char" in
        [-_.~a-zA-Z0-9])
          echo -n "${char}"
          ;;
        *)
          printf '%%%02x' "'$char"
     esac
  done
}

function get_accounts(){
  while IFS= read -r line; do
    if [[ "$line" =~ ^\[(.+)\]$ ]]; then
      echo "${BASH_REMATCH[1]}"
    fi
  done < "$@"
}

function load_credentials(){
  local entry secrets passwd="$(keyctl print "%user:$0" 2>/dev/null)" IFS=$'\n'

  for entry in $(get_accounts "$@"); do
    coproc keepassxc-cli show -a UserName -a Email -a Password -k "$keyfile" \
      ${passwd:+--quiet} "$database" "$entry"

    if [[ -z "$passwd" ]]; then
      read -rs passwd
    fi

    exec 3>&"${COPROC[0]}"
    echo "$passwd">&"${COPROC[1]}"
    wait $COPROC_PID
    read -rd '' -u 3 -a secrets

    # if we misspelled the password, try again
    if [[ "${#secrets[@]}" -eq 0 ]]; then
      load_credentials "$@"
      return
    fi

    export ${entry@U}_USER=${secrets[0]}
    export ${entry@U}_MAIL=${secrets[1]}
    export ${entry@U}_PASS="$(rawurlencode ${secrets[2]})"
  done

  keyctl add user "$0" "$passwd" @u >/dev/null
  keyctl timeout "%user:$0" "$timeout"
}

function expand(){
  envsubst "$(compgen -eP '$')" <<< "$(< "$@")" | m4
}

if [[ "$BASH_SOURCE" == "$0" ]]; then
  exec 3< <(
    trap 'kill -- -$$' INT
    load_credentials "$accounts"
    expand "$accounts"
  )

  wait $!

  exec "$aerc" -C <(expand "$main") -B <(expand "$binds") -A /dev/fd/3 "$@"
fi