#!/usr/bin/env bash
# shellcheck disable=SC2034 # variable not used
# shellcheck disable=SC1090 # follow non constant source

enableErrorCheck() {
  # Do not allow use of unbound variables.
  # Use ${VAR:-} if possibly unbound
  set -o nounset
}
disableErrorCheck() {
  # Do allow the use of unbound vars.
  set +o nounset
}

# Exit on error. Append "|| true" if you expect an error.
set -o errexit
# Exit on error inside any functions or subshells.
set -o errtrace
enableErrorCheck
# Catch the error in case mysqldump fails (but gzip succeeds) in `mysqldump |gzip`
set -o pipefail
# Turn on traces, useful while debugging but commented out by default
# set -o xtrace

## Globals
{
  readonly sqr_version=16
  readonly sqr_versionMajor=0
  readonly sqr_versionMinor=0
  readonly sqr_versionString="${sqr_version}.${sqr_versionMajor}.${sqr_versionMinor}"

  ## Seq
  readonly seq_name="${_sqn_alias:-${0##*/}}"
  readonly seq_dir="$(cd -- "$(dirname -- "${0}")" && pwd)"
  readonly seq_origin="$(cd -- "$(dirname -- "$(readlink -f -- "${0}")")" && pwd)"
  readonly seq_file="$(basename -- "${0}")"
  readonly seq_fileName="${seq_file%%.*}"
  readonly seq_self="${seq_origin}/${seq_file}"
  # shellcheck disable=SC2015 # && || is not if else
  readonly seq_invocation="$(printf '%q' "${0}")$( (($#)) && printf ' %q' "$@" || true)"
  readonly seq_template="seqTemplate.sh"

  readonly _seq_configDirName=".seqs"
  _seq_configured=0
  _seq_configEdit=0
  _seq_profileList=
  _seq_stepReturn=255
  seq_args=
  seq_configFile= # Filled by initSeqConfig
  seq_profileName=
  seq_configRoot="${HOME:-"$(pwd)"}/${_seq_configDirName}"

  # May be overwritten by seq
  seq_configName="${seq_fileName}.cfg"
  seq_configTemplate="${0%.*}.cfg.example"

  ## Sequencer
  readonly sqr_dir="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
  readonly sqr_file="$(basename -- "${BASH_SOURCE[0]}")"
  readonly sqr_name="${sqr_file%%.*}"
  readonly sqr_origin="$(cd -- "$(dirname -- \
    "$(readlink -f -- "${BASH_SOURCE[0]}")")" && pwd)"
  sqr_args=
  sqr_missingConf=missingConf.log

  _sqr_contextHelp=0
  _sqr_contextExe=0
  _sqr_debug=0
  _sqr_dry=0
  _sqr_editor=
  _sqr_errno=0
  _sqr_interactive=1
  _sqr_single=0
  readonly _sqr_stepMax=512
  _sqr_verbose=0
  # Part of a pipe or output to terminal
  _sqr_term=0 && [ -t 1 ] && _sqr_term=1
  readonly _sqr_term
  _sqr_colorAlways=0

  ## Terminal colors
  col_black='\033[0;30m'
  col_darkgrey='\033[1;30m'
  col_red='\033[0;31m'
  col_lightred='\033[1;31m'
  col_green='\033[0;32m'
  col_lightgreen='\033[1;32m'
  col_orange='\033[0;33m'
  col_yellow='\033[1;33m'
  col_blue='\033[0;34m'
  col_lightblue='\033[1;34m'
  col_purple='\033[0;35m'
  col_lightpurple='\033[1;35m'
  col_cyan='\033[0;36m'
  col_lightcyan='\033[1;36m'
  col_lightgray='\033[0;37m'
  col_white='\033[1;37m'
  ## No Color
  col_off='\033[0m'

  col() {
    local colVar="col_${1:-"off"}"
    ((_sqr_term)) || ((_sqr_colorAlways)) && echo "${!colVar}"
    true
  }
}

helpSequencer() {
  cat <<USAGE_EOF
Usage: ${seq_name} [OPTIONS] [STEP NUMBER(s) or ALIAS] [STEP ARGUMENTS]

 [OPTIONS]
  --all,       -a   : Run all steps regardless of continuity
  --color           : Output color codes also within pipe
  --config,    -c   : Open sequence configuration file (also sets -qq)
  --dry-run,   -d   : Only print to console what would be done
                      ! Attention - Sequence must support this
  --help,      -h   : Display help
  --helpapi,   -ha  : Display help about build-in supporting functions
                      (e.g. exe,addConf,error,...)
  --liststeps, -ls  : List all step numbers and alias
  --profile,   -p   : Sequence configuration profile name (default: "default")
                      (if supported by sequence)
               -pl  : List available profiles
  --quiet,     -q   : Don't ask for permission to execute steps
                      If called without starting step number, only this help is shown
  --silent,    -qq  : Same as --quiet but suppresses regular sequencer.sh output
  --single,    -s   : Execute only one step
                      If more than one step is requested, only the first will be executed
  --verbose,   -v   : Verbose output (use exe() function to call shell commands in seqs)
                      ( e.g.: exe apt update )
  --version         : Display version of sequencer and revision of sequence
  --                : End options marker
  ++                : Quick start step 1 (-qq) and skipping [STEP NUMBER(s) or ALIAS]

 [STEP NUMBER"(s)" 1-${_sqr_stepMax} or ALIAS]
        No STEP  or ALIAS : assume 1 as starting point
    Single STEP  or ALIAS : starting point of sequential process
  Multiple STEPS or ALIAS : execute only given steps
                            (e.g. $0 "2 4 12")
                            multiple steps need to be given as string
 [STEP ARGUMENTS]
                        * : Arguments will be passed to selected steps and step infos as:
                            \$2 ...
                            \$1 is always the step number
USAGE_EOF
}

helpApi(){
  cat <<USAGE_API
sequencer.sh API

The sequencer.sh build-in functions are available in all sequence functions:
- seq_config()
  If optional seq_config is defined in the sequence, it will be called once before execution of steps.
- step_[1-${_sqr_stepMax}]_info()
- step_[1-${_sqr_stepMax}]_alias()
- step_[1-${_sqr_stepMax}]_noconf=
  No need to call seq_config for this step.
- step_[1-${_sqr_stepMax}]()

sequencer.sh global variables:

 \${LOG_LEVEL}
    Control log level directly
    4 - debug -> 0 - silent
 \${LOG_TIME}
    1 - Show time stamps before log outputs
 \${sqr_args}
    String of all given options
 \${seq_configRoot}
    Path to user specific seq configuration directory
 \${seq_configFile}
    Path to user specific seq configuration file
    Will be empty if unused
 \${seq_profileName}
    Profile string selected with -p argument

sequencer.sh build-in functions:
USAGE_API
  echo -e "$(col green) addConf <OPTIONS> <SOURCE> <DESTINATION FILE>$(col off)"
  cat <<USAGE_API
    Trying to write or append text or a file (<SOURCE>) to a destination file.
    If the CONFIGFILE exists, a backup (name_%Y%m%d-%H%M%S.bck) is saved at the same location.
    If -s fails or -m, "$(realpath "${sqr_missingConf}")" is created with the conflicts
    to be resolved by the user.
      <OPTIONS>
        -c : create a new file
        -a : append to existing file
        -s : skip if CONFIGFILE exists (no backup and entry in missing conf)
        -m : only add content to missing conf and warn user
        -e : enable interpretation of backslash escapes (ignored for -f)
        -f : <SOURCE> is a file
      <SOURCE>
        Text or file (-f) to create or added to <DESTINATION FILE>
      <DESTINATION FILE>
        Target file to be created or modified.

USAGE_API
  echo -e "$(col green) ask [OPTION] [QUESTION] [DEFAULT]$(col off)"
  cat <<USAGE_API
    Will ask for input even if quiet, when [DEFAULT] is empty
    [OPTION]
      -e  :  allow empty input
             Ignored if [DEFAULT] is available
      -s  :  ask for secret (don't print input)
             Does not add a newline. Usage:
             pass=\$(ask -s "Password"); echo
      --  :  End of options

USAGE_API
  echo -e "$(col green) color [FOREGROUND COLOR] [BACKGROUND COLOR]$(col off)"
  cat <<USAGE_API
    Set output color permanently until reset.
    No argument or unknown foreground color restores shell default (reset).
    Color reset happens after every step and step_info function call.
      [COLOR]: black, red, green, yellow, blue, magenta, cyan, white

USAGE_API
  echo -e "$(col green) confirm [OPTIONS] [QUESTION]$(col off)"
  cat <<USAGE_API
    Default (empty character) = no
    Invalid character trigger the default
    [OPTIONS]
      -f  :  interactive even if quiet
      -n  :  no input help
      -y  :  default = yes
      --  :  end of options

USAGE_API
  echo -e "$(col green) contextExe$(col off)"
  cat <<USAGE_API
    Returns true if current output is in execution mode.

USAGE_API
  echo -e "$(col green) contextHelp$(col off)"
  cat <<USAGE_API
    Returns true if current output is only for help purposes.

USAGE_API
  echo -e "$(col green) dry$(col off)"
  cat <<USAGE_API
    Returns true if seq runs in dry-run mode (-d)

USAGE_API
  echo -e "$(col green) echoinfo [...]$(col off)"
  cat <<USAGE_API
    echo additional correctly indented line to step info
      [...] : all parameter are forwared to echo

USAGE_API
  echo -e "$(col green) echoinfoArgs [...]$(col off)"
  cat <<USAGE_API
    echo argument description after step number or alias.
    This must be called first in the step info function.
    Does not add a newline at the end.
      [...] : no parameter are forwared to echo

USAGE_API
  echo -e "$(col green) endIfEmpty <VARIABLENAME> [DESCRIPTION]$(col off)"
  cat <<USAGE_API
    exit 6 if variable is empty
      <VARIABLENAME> : Name without \$
      [DESCRIPTION]  : Additional text for error output

USAGE_API
  echo -e "$(col green) endReturn [OPTIONS] [MESSAGE]$(col off)"
  cat <<USAGE_API
    Notifys user that there was an error (previously saved by saveReturn,
    or -o [ERRORCODE]) and asks to continue or end the sequence.
    Always exits with evaluated error code.
      [OPTIONS]
        -f           : force exit without user input, if error code is not 0
        -o ERRORCODE : override stored error code and check ERRORCODE
      [MESSAGE]
        String which is displayed in the error output

USAGE_API
  echo -e "$(col green) escpath <PATH>$(col off)"
  cat <<USAGE_API
    Escaping non-printable characters with the proposed POSIX $'' syntax
      e.g. \$(escpath /my own/ho me/path) = $(escpath /my own/ho me/path)

USAGE_API
  echo -e "$(col green) exe [COMMANDLINE]$(col off)"
  cat <<USAGE_API
    Execute command line without pipes or redirects (>,<,|).
    Supporting: dry-run (-d): only print command without execution
                verbose (-v): print command before execution

USAGE_API
  echo -e "$(col green) exep \"[COMMAND STRING(s)]\"$(col off)"
  cat <<USAGE_API
    See exe, but support for pipes or redirects.
      e.g.: exep echo hello world \\> \\'out put.log\\'
            exep echo hello world \\> out\\\\ put.log
            exep "echo hello world > 'out put.log'"
            exep "echo hello world > out\\ put.log"
    Important:
      - Shell commands cd, read, ... won't work because [COMMAND STRING(s)] is started in a new shell.
      - All apostrophes need to be esacped since the command line is given as string.

USAGE_API
  echo -e "$(col green) exists [OPTIONS] [ELEMENT]$(col off)"
  cat <<USAGE_API
    [ELEMENT]
         : either a variable- or a funtion name (-f)
    [OPTIONS]
      -f : a function
      -- : end of options
USAGE_API
  echo -e "$(col green) getReturn$(col off)"
  cat <<USAGE_API
    Return last saved error code (see saveReturn)

USAGE_API
  echo -e "$(col green) info|warning|error|debug [OPTIONS] [STRING]$(col off)"
  cat <<USAGE_API
    Output [STRING] (can be multiline) to stdout according to log level.
      [OPTIONS]
        -a  : Append [STRING] skipping leading " [ ] " prefix
        -d  : No leading " [ ] " prefix
        -e  : Output to stderr
        -n  : No newline

USAGE_API
  echo -e "$(col green) initSeqConfig [OPTION] <NAME> [TEMPLATE]$(col off)"
  cat <<USAGE_API
    Create a configuration file in ${seq_configRoot}/ and source it if already existent.
      [OPTION]
        -p  : Use profiles
        -t  : Source config also if created from template
        -e  : Create empty configuration if no template is found
      Returns
         0       : sourced configuration or
            (-t) : created and sourced configuration from template
         1       : created configuration from template but not sourced
         2       : created empty configuration
         3       : No configuration created

USAGE_API
  echo -e "$(col green) quiet$(col off)"
  cat <<USAGE_API
    Returns true if seq runs non-interactive (-q|-qq).

USAGE_API
  echo -e "$(col green) rmold [OPTION] <DIRECTORY>$(col off)"
  cat <<USAGE_API
    Remove oldest non hidden files in DIRECTORY and retain given NUMBER (default 5).
      [OPTION]
        -h          : Remove also hidden files
        -r <NUMBER> : Retain NUMBER files in Directory

USAGE_API
  echo -e "$(col green) root$(col off)"
  cat <<USAGE_API
    Returns true if current user is root.
    e.g. root || echo "Not root"

USAGE_API
  echo -e "$(col green) running$(col off)"
  cat <<USAGE_API
    Returns true if same script already runs.
    e.g. running && exit 1

USAGE_API
  echo -e "$(col green) saveReturn [ERRORCODE]$(col off)"
  cat <<USAGE_API
    Save ERRORCODE if it is != 0 for later use with endReturn

USAGE_API
  echo -e "$(col green) silent$(col off)"
  cat <<USAGE_API
    Returns true if seq runs interactive.

USAGE_API
  echo -e "$(col green) step <STEP NUMBER OR ALIAS>$(col off)"
  cat <<USAGE_API
    Executes a single step also by alias. Useful if step numbers get reorganized.
    dry-run is not applied in this function! The executed step is responsible.

USAGE_API
  echo -e "$(col green) verbose$(col off)"
  cat <<USAGE_API
    Returns true if seq runs in verbose mode (-v)

USAGE_API
}

## Logging
{
  readonly log_fatal=0
  readonly log_error=1
  readonly log_warning=2
  readonly log_info=3
  readonly log_debug=4

  LOG_LEVEL="${LOG_LEVEL:-"${log_info}"}" # 4 = debug -> 0 = fatal (stop)
  LOG_TIME="${LOG_TIME:-}"    # 1 = show time stamps

  # sqr::log [LOG LEVEL] [LOG_COLOR] [OPTIONS] [LOG MESSAGE]
  # Construct log messages
  #
  #  [OPTIONS]
  #    -a  :  append text (placeholder for info and timestamp)
  #           Uses color from last sqr::log call without -a
  #    -d  :  no info and timestamp
  #    -e  :  Output to stderr
  #    -n  :  no newline
  #    --  :  End of options
  #
  sqr::log () {
    #sqr::debugPause
    local appendText=
    local direct=0 # no prefix and timestamp
    local newline='\n'
    local col_end=
    col_end="$(col off)"
    local outp='/dev/stdout'

    local log_level="${1:-}"
    shift
    local log_color="${1:-}"
    shift

    # Only output newline on empty args
    if ! (( $# )) ; then
      direct=1
      newline='\n'
    fi

    while getopts "aden" arg ; do
      case "${arg}" in
        a) appendText=1 ;;
        d) direct=1 ;;
        e) outp='/dev/stderr' ;;
        n) newline='' ;;
        *) ;;
      esac
    done
    shift "$((OPTIND-1))"; OPTIND=1

    [[ -z "${log_color}" ]] && col_end=""

    # all remaining arguments are to be printed
    local log_line=""

    while IFS=$'\n' read -r log_line ; do
      printf '%b' "${log_color}" >${outp}
      if ! (( direct )) ; then
        if [[ -n "${LOG_TIME}" ]] ; then
          if (( appendText )) ; then
            printf '%19s' "" >${outp}
          else
            printf '%s' "$(date +"%Y-%m-%d %H:%M:%S")" >${outp}
          fi
        fi

        if (( ! appendText )) ; then
          printf " %3s " "[${log_level}]" >${outp}
          printf "%s" "${log_line}" >${outp}
        else
          # +4 : " [] "
          printf "%$((${#log_level} + 4))s%s" "" "${log_line}" >${outp}
        fi
      else
        # direct output
        printf '%s' "${log_line}"
      fi

      printf '%b'"${newline}" "${col_end}" >${outp}
    done <<< "${@:-}"
    sqr::debugContinue
  }

  fatal ()   { sqr::log "stop" "$(col red)" "${@}"; exit 1; }
  die ()     { sqr::log "end" "" "${@}"; exit 1; }
  error ()   { [[ "${LOG_LEVEL:-0}" -ge ${log_error} ]] && sqr::log "e" "$(col red)" "${@}"; true; }
  warning () { [[ "${LOG_LEVEL:-0}" -ge ${log_warning} ]] && sqr::log "w" "$(col orange)" "${@}"; true; }
  info ()    { [[ "${LOG_LEVEL:-0}" -ge ${log_info}  ]] && sqr::log "i" "" "${@}"; true; }
  debug ()   { [[ "${LOG_LEVEL:-0}" -ge ${log_debug} ]] && sqr::log "dbug" "$(col lightpurple)" "${@}"; true; }

  # internal print(s) same loglevel as error
  # shellcheck disable=SC2059 # don't use variables in format
  sqr::printf () { [[ "${LOG_LEVEL:-0}" -ge ${log_error} ]] && printf "$@"; true; }
  sqr::echo () { [[ "${LOG_LEVEL:-0}" -ge ${log_error} ]] && echo "$@"; true; }

  sqr::debugPause() {
    if (( _sqr_debug )) ; then set +o xtrace; else true; fi
  }
  sqr::debugContinue() {
    if (( _sqr_debug )) ; then set -o xtrace; else true; fi
  }

  # color <FOREGROUND COLOR> [BACKGROUND COLOR]
  color() {
    [ ! -t 1 ] && return 0
    [ -z "${1:-}" ] && tput sgr0 && return 0
    case "${1:-}" in
      black) tput setaf 0 ;;
      red) tput setaf 1 ;;
      green) tput setaf 2 ;;
      yellow) tput setaf 3 ;;
      blue) tput setaf 4 ;;
      magenta) tput setaf 5 ;;
      cyan) tput setaf 6 ;;
      white) tput setaf 7 ;;
      none) tput sgr0 && return 0 ;;
      *) tput setaf "${1:-}" ;;
    esac

    case "${2:-}" in
      black) tput setab 0 ;;
      red) tput setab 1 ;;
      green) tput setab 2 ;;
      yellow) tput setab 3 ;;
      blue) tput setab 4 ;;
      magenta) tput setab 5 ;;
      cyan) tput setab 6 ;;
      white) tput setab 7 ;;
    esac
  }

  # Echo correctly indented additional line to info
  readonly _sqr_indentHelp='         : '
  readonly _sqr_indentExe='       '
  readonly _sqr_indentAppendHelp='           '
  echoinfo() {
    if [ $_sqr_contextHelp -ne 0 ] ; then
      printf '%s' "$_sqr_indentAppendHelp"; echo "$@"
    else
      printf '%s' "$_sqr_indentExe"; echo "$@"
    fi
  }
}

## Traps
{
  sqr::trap_exit () {
    exists -f seq_trapExit && seq_trapExit
    debug "Sequencer exit"
  }
  trap sqr::trap_exit EXIT

  # requires `set -o errtrace`
  sqr::error_report() {
    local error_code=${?}
    error "Error in ${sqr_file} in function ${1} on line ${2}"
    exit ${error_code}
  }

  # Uncomment the following line for always providing an error backtrace
  # trap 'sqr::error_report "${FUNCNAME:-.}" ${LINENO}' ERR
}

# exists [-f] [--] [ELEMENT]
#  [ELEMENT]
#       : either a variable name or
#    -f : a function
exists() {
  local func=

  for _ in "$@" ; do
    case "${1:-}" in
      --) shift && break ;;
      -f) func="${2:-}"
    esac
  done
  if [[ -n "${func}" ]] ; then
    declare -F "${func}" &>>/dev/null
  else
    [[ "${1:-}" =~ ^[a-zA-Z_][a-zA-Z0-9_]*$ ]] && [[ -n "${!1:-}" ]]
  fi
}

# check if run as root
root() { [[ $(id -u) -eq 0 ]]; }

# check if there is another PID other than this one
running() { pidof -o %PPID -x "${0##*/}">>/dev/null; }

# interactive = Started without -q to have user interactions
interactive() { (( _sqr_interactive )); }

# quiet = Started with -q to use defaults for confirmations
quiet() { (( ! _sqr_interactive )); }

# silent = Log level equals 0 (fatal)
silent() { [[ $LOG_LEVEL -eq 0 ]]; }

# Started with --dry-run
dry() { (( _sqr_dry )); }

# Started with --verbose
verbose() { (( _sqr_verbose )); }
contextHelp() { (( _sqr_contextHelp )); }
contextExe() { (( _sqr_contextExe )); }

# editor [FILE(s)..]
# Starts the detected system text editor
editor() { exe "${_sqr_editor}" "$@"; }

# Escaping non-printable characters with the proposed POSIX $'' syntax
escpath() { printf "%q" "$*"; }

### interactive
# confirm [OPTIONS] [--] [QUESTION]
#  Default (empty character) = no
#  Invalid character trigger the default
#
#  [OPTIONS]
#    -f  :  interactive even if quiet
#    -n  :  no input help
#    -y  :  default = yes
#    --  :  end of options
confirm() {
  sqr::debugPause
  local rexReply='^[Yy]+$' # default no
  local inputHelp='[y/N] ' # default no
  local noHelp=0
  local force=0
  local arg

  while getopts "fny" arg ; do
    case "${arg}" in
      f) force=1 ;;
      n) noHelp=1 ;;
      y)
        rexReply='^[^Nn]*$' # default yes
        inputHelp='[Y/n] ' # default yes
        ;;
      *) ;;
    esac
  done
  shift "$((OPTIND-1))"; OPTIND=1

  (( noHelp )) && inputHelp=
  if interactive || (( force )) ; then
    read -r -p "${1:-} ${inputHelp}" -n 1
    # Needed when read stops after one character (-n 1)
    # Add a newline only if input is not empty (just enter is pressed)
    [[ -z "$REPLY" ]] || printf '\n'
  else
    REPLY=''
  fi
  sqr::debugContinue
  [[ $REPLY =~ ${rexReply} ]]
}

# ask [OPTION] [QUESTION] [DEFAULT]
#  Will ask for input even if quiet, when [DEFAULT] is empty
#
#  [OPTION]
#    -e  :  allow empty input
#           Ignored if [DEFAULT] is available
#    -s  :  ask for secret (don't print input)
#           Does not add a newline. Usage:
#           pass=$(ask -s "Password"); echo
#    --  :  End of options
ask() {
  sqr::debugPause
  local hidden=
  local empty=0
  local arg

  while getopts "es" arg ; do
    case "${arg}" in
      e) empty=1 ;;
      s) hidden="-s" ;;
      *) ;;
    esac
  done
  shift "$((OPTIND-1))"; OPTIND=1

  local answer=
  if [[ -n "${2:-}" ]] ; then
    ! interactive && printf '%s\n' "${2}" && sqr::debugContinue && return 0
    read ${hidden?} -r -p "${1:-"User input"} ($2) " answer
  else
    read ${hidden?} -r -p "${1:-"User input"} " answer
  fi
  if [[ -z "$answer" ]] ; then
    answer="${2:-}"
  fi
  printf '%s\n' "${answer}"

  # return if answer is empty
  sqr::debugContinue
  if (( ! empty )) ; then
    [[ -n "${answer}" ]]
  fi
}

# rmold [OPTIONS] <DIRECTORY>
# Delete oldest files from DIRECTORY and keep the 5 (default) newest
#  -r <AMOUNT FILES TO KEEP>
rmold() {
  local arg
  local total
  local line
  local retain=5
  local target
  local hideOpt=

  while getopts "hr:" arg ; do
    case "${arg}" in
      h) hideOpt="-A" ;;
      r) [[ ${OPTARG} =~ [0-9]+ ]] && retain="${OPTARG}" || retain="" ;;
      *) ;;
    esac
  done
  shift "$((OPTIND-1))"; OPTIND=1

  if [ -z "${retain}" ] ; then
    error -e "Invalid retain option"
    return 1
  fi
  target="${1:-}"

  endIfEmpty target "No directory provided"
  if [ ! -x "${target}" ] ; then
    error -e "Cannot access ${target}"
    return 1
  fi

  # shellcheck disable=SC2012 # Use find instead
  total="$(ls ${hideOpt} -1 -- "${target}" | wc -l)"
  if (( total <= retain )) ; then
    info "Nothing to do"
    return 0
  fi

  info    "Deleting $((total - retain)) oldest files in ${target}"
  info -a "and retaining ${retain}."
  exe cd "${target}"
  # It is easier to sort with ls
  # shellcheck disable=SC2012 # Use find instead
  while IFS= read -r line; do
    exe rm -f "${line}"
  done < <(ls ${hideOpt} -rt1 "${target}" | head -$((total - retain)))
}

# saveReturn <ERRNO>
# Function returns with <ERRNO> in case step wants additional evaluation
saveReturn() {
  (( ${1:-"0"} )) && _sqr_errno=${1}
  return "${_sqr_errno}"
}

# getReturn
# Returns latest saved $_sqr_errno
getReturn() { return "${_sqr_errno}"; }

# endReturn [-f] [-o ERRORCODE] [MESSAGE]
#         -f : force exit with $_sqr_errno without user input
#         -o : override and check given [ERRORCODE]
#  [MESSAGE] : Custom error message
#
endReturn() {
  local forceExit=0
  local errorCode=${_sqr_errno}
  local endMessage=""

  for _ in "$@" ; do
    case "${1:-}" in
      -f) forceExit=1 && shift ;;
      -o)
        shift
        local rex='^[-]*[0-9]+$'
        # Check if string is a number or alias
        if [[ "${1:?}" =~ ${rex} ]] ; then
          errorCode="${1:?}"
        else
          warning "Ignoring invalid error code: $1"
        fi
        shift ;;
      "") break ;;
      *) endMessage="$*" && break ;;
    esac
  done

  if ( [[ ${errorCode} -ne 0 ]] && ! interactive ) \
      || [[ ${errorCode} -ne 0 && $forceExit -ne 0 ]] ; then
    sqr::echo
    if [[ -n "${endMessage}" ]] ; then
      error -e    "${endMessage}"
      error -e -a "Sequence stopped"
    else
      error -e "Return value ${errorCode} detected."
      error -e -a "Sequence stopped"
    fi
    exit "${errorCode}"
  fi
  if [[ "${errorCode}" -ne 0 ]] ; then
    sqr::echo
    if [ "${endMessage}" != "" ]; then
      error -e "${endMessage}"
    else
      error -e "Return value ${errorCode} detected."
    fi
    if confirm -y "End sequence" ; then
      error -e "Sequence stopped"
      exit "${errorCode}"
    else
      # reset saved error code if user chooses to continue
      _sqr_errno=0
      sqr::echo
      warning "Continuing sequence..."
    fi
  fi
}

# endIfEmpty <VariableName> [DESCRIPTION]
#    DESCRIPTION : Optional text for error
endIfEmpty() {
  local ref=
  exists "${1:-}" && ref="${!1:-}"

  if [ -z "${ref}" ] ; then
    if [ -n "${2:-}" ] ; then
      error -- "$2"
      error -a "Sequence stopped."
    else
      error -- "\${${1:-"-"}} must not be empty."
      error -a "Sequence stopped."
    fi
    exit 6
  fi
}

addConfMultiError() { 
  if [ -n "${1}" ] ; then
    error "Only one of the options (-a|-c|-m|-s) is allowed for addConf" && exit 1
  fi
}

# addConf <OPTIONS> <SOURCE> <DESTINATION_FILE>
# trying to write a file
# if exists, one attempt is made to create bck file of it
# if all fails, a log file is created with the conflicts to be resolved by the user
addConf() {
  local addConfBackup=
  local echoOpt=()
  local confMode=""
  local transferCmd="echo"

  while getopts "acefms" arg ; do
    case "${arg}" in
      c) # create a new file
        addConfMultiError "${confMode}" && confMode="-c" ;;
      a) # append to existing file
        addConfMultiError "${confMode}" && confMode="-a" ;;
      s) # skip if CONFIGFILE exists
        addConfMultiError "${confMode}" && confMode="-s" ;;
      m) # only add content to missing conf and warn user
        addConfMultiError "${confMode}" && confMode="-m" ;;
      e) # Enable backslash escapes for echo
        echoOpt+=("-e") ;;
      f) # choose if source is a file or text
        transferCmd="cat" ;;
      *) ;;
    esac
  done
  shift "$((OPTIND-1))"; OPTIND=1

  if [ -z "${confMode}" ] ; then
    error "One of the mandatory options (-a|-c|-m|-s) is missing for addConf"
    exit 0
  fi

  [[ "${transferCmd}" == "cat" ]] && echoOpt=()

  local source="${1:-}"
  local dest="${2:?}"

  if [ "${transferCmd}" == "cat" ] && [ ! -f "${source}" ] ; then
    error "Source: \"${source}\" does not exist"
    return 1
  fi
  if dry ; then
    info "Writing ${dest} ...dry-run"
    return 0
  fi
  if [ -z "${dest}" ] ; then
    error "Destination empty"
    return 1
  fi

  sqr::echo -n " [i] Writing ${dest} ..."

  if [[ ${confMode} != "-m" ]] ; then
    # try writing config directly if it doesn't exist
    if [ ! -f "$dest" ] ; then
      "${transferCmd}" "${echoOpt[@]}" "${source}" > "${dest}"
      sqr::echo "ok"
      return 0
    fi

    if [[ ${confMode} == "-s" ]] ; then
      # if skip is selected, don't try to backup but add confilict entry
      sqr::echo "skipping (exists)"
    else
      # try backup existing config
      addConfBackup="${dest}_$(date +%Y%m%d-%H%M%S).bck"
      if [ ! -f "${addConfBackup}" ] ; then
        cp -ar "${dest}" "${addConfBackup}"
        if [[ ${confMode} == "-c" ]] ; then
          "${transferCmd}" "${echoOpt[@]}" "${source}" > "${dest}"
        else
          "${transferCmd}" "${echoOpt[@]}" "${source}" >> "${dest}"
        fi
        sqr::printf 'ok\n [i] %s\n' "Existing config saved to ${addConfBackup}"
        return 0
      else
        sqr::echo "nok"
        warning -e "backup exists"
      fi
    fi
  else
    sqr::printf 'ok\n [i] %s' "no change requested"
  fi

  # add configuration to missingConf file
  if [[ "${missingDate:-}" = "" ]] ; then
    missingDate="set"
    echo -n "###  " >> "${sqr_missingConf}"
    date >> "${sqr_missingConf}"
  fi

  local helpText="needs to be added manually"
  if [[ "$confMode" == "-s" ]] ; then
    helpText="not overwritten"
  fi

  {
    printf '#--- "%s" %s (Option: %s) ---' "${dest}" "${helpText}" "${confMode}"
    "${transferCmd}" "${source}"
    echo
  } >> "${sqr_missingConf}"

  warning -e "Check $(realpath "${sqr_missingConf}") for configuration conflicts (${dest})"
  return 1
}


# checkStep <Step Number or Alias>
#  return 0 - for invalid step
#  return Step Number
# Check sanitiy of step number or
# Check if alias exists
checkStep() {
  local checkStep_rex='^[0-9]+$'
  local checkStep_ref=""
  local testRef=

  # Check if string is a number or alias
  if ! [[ "${1:-}" =~ ${checkStep_rex} ]] ; then
    if exists "_sqr_alias_${1:-}" ; then
      testRef="_sqr_alias_${1:-}"
      checkStep_ref="${!testRef}"
    else
      checkStep_ref=0
    fi

    # Catch special character after evaluation
    if ! [[ "${checkStep_ref}" =~ ${checkStep_rex} ]] ; then
      checkStep_ref=0
    fi
  else
    checkStep_ref="${1:-}"
  fi

  if (( checkStep_ref < 1 || checkStep_ref > _sqr_stepMax )) ; then
    error -e "Invalid step: ${1:-}"
    printf '0'
    return 1
  else
    if exists -f "step_$checkStep_ref" ; then
      printf '%s' "${checkStep_ref}"
      return 0
    else
      # step doesn't exist
      error -e "Invalid step: ${1:-}"
      printf '0'
      return 1
    fi
  fi
}

# step <Step Number of Alias>
# execute given step
step() {
  local stepNo=0
  local stepArgs=("$@")

  if ! stepNo="$(checkStep "${1:-}")" ; then
    return 1
  else
    "step_$stepNo" "${stepArgs[@]}"
  fi
  color
}

# Parse alias functions "step_[STEP NUBER]_alias" to create
# back reference variable of schema:
# alias_[ALIAS]=[STEP NUMBER]
sqr::parseAlias() {
  sqr::debugPause
  local i
  for ((i=1; i<=_sqr_stepMax; i++)); do
    # Check for alias definition
    exists -f "step_${i}_alias" || continue

    # Function returns step alias
    declare -g "_sqr_alias_$("step_${i}_alias")=$i"
  done
  sqr::debugContinue
}

# Creating a minimal seq (step definition) template
sqr::createTemplate() {
  [ -f "${seq_template}" ] && return 1

  exe cp "${sqr_origin}/${seq_template}" "${seq_template}"
}

# sqr::stepOptions <STEP NUMBER> [PREFIX]
sqr::stepOptions() {
  exists -f "step_${1:?}_options" && echo -n "${2:-}$(step_"${1:?}"_options)"
  true
}

# displayHelp [OPTIONS] [STEP NUMBER OR ALIAS]
#    [OPTIONS]
#     -t  :  Ask for template creation
#     -s  :  Display only step help
#    [STEP NUMBER OR ALIAS]
#      [NO TEMPLATE] must be set
#       Display step info function only for given step
#
# - Display sequencer help and, if available, sequence help
# - Cluster continous (more than 1) steps visually together
displayHelp() {
  sqr::debugPause
  local i
  local answer
  local arg
  local fullHelp=1
  local clusterSize=0
  local lastClusterSize=0
  local createTemplate=0
  local stepFound=0
  local loopStart=0
  local loopEnd="${_sqr_stepMax}"
  _sqr_contextHelp=1

  while getopts "st" arg ; do
    case "${arg}" in
      s) fullHelp=0 ;;
      t) createTemplate=1 ;;
      *) ;;
    esac
  done
  shift "$((OPTIND-1))"; OPTIND=1
  
  # check if step definition exists by looking for a step_*() function
  for ((i=1; i<=_sqr_stepMax; i++)); do
    if ! exists -f "step_${i}" ; then
      continue
    fi
    stepFound=${i}
    break
  done

  # check if help is requested for a single step
  if [ -n "${1:-}" ]; then
    sqr::parseAlias
    loopStart="$(checkStep "${1}")"
  fi

  if (( ! loopStart )) ; then
    (( fullHelp )) || (( ! stepFound )) && helpSequencer
    loopStart=1
  else
    # Output loop only for one step
    loopEnd=${loopStart}
  fi

  if (( ! stepFound )) ; then
    printf '\n  %s\n' "It seems ${0##*/} was called directly."
    printf '  %s\n\n' "Please create a sequence script first."
    if (( createTemplate )) ; then
      if confirm "  Create a template now?" ; then
        if sqr::createTemplate ; then
          printf '\n  %s\n' "${seq_template} created."
        else
          printf '\n  %s\n' "${seq_template} exists...Nothing to do!"
        fi
      else
        printf '\n  Nothing to do!\n'
      fi
    fi
    exit 1
  else
    printf '\n  %s\n' "Step (= alias) [STEP ARGS] : documentation"
    for ((i=loopStart; i<=loopEnd; i++)); do

      # Display step reference in help if step function exists
      if ! exists -f "step_${i}" ; then
        if (( clusterSize )) ; then
          # Mark the end of a cluster
          lastClusterSize=$clusterSize
          clusterSize=0
        fi
        continue
      fi
      (( clusterSize+=1 ))
      if [[ $lastClusterSize -gt 1 ]] ; then
        # Add separation at the end of a cluster
        lastClusterSize=0
        echo
      elif [[ $clusterSize -eq 1 ]]; then
        # Add separation before the start of a cluster if it is not the first
        exists -f "step_$((i+1))" && [[ $i -ne $stepFound ]] && echo
      fi
      printf '    %3s ' "$i"

      # Display alias if exists
      if exists -f "step_${i}_alias" ; then
        echo -en " = $(col orange)$("step_${i}_alias")$(col off)$(sqr::stepOptions "${i}" ' ')"
        # Newline only if step info() exists
        exists -f "step_${i}_info" && printf '\n%s' "${_sqr_indentHelp}"
      else
        echo -en " : $(sqr::stepOptions "${i}")"
        exists -f "step_${i}_options" && printf '\n%s' "${_sqr_indentAppendHelp}"
      fi

      # Display step help only if info function exists
      if exists -f "step_${i}_info" ; then
        "step_${i}_info" "$i" || true
      else
        echo
      fi
      color ""
    done
    echo
  fi
  _sqr_contextHelp=0
  sqr::debugContinue
}

# listSteps [FILTER STRING]
#  [FILTER STRING]
#    show only steps and aliases starting with [FILTER STRING]
listSteps() {
  local locAlias=

  for ((i=1; i<=_sqr_stepMax; i++)); do
    # Display step reference in help if step function exists
    exists -f "step_${i}" || continue

    # Display alias if exists
    if exists -f "step_${i}_alias" ; then
      locAlias="$("step_${i}_alias")"
    else
      locAlias="$i"
    fi

    # $1 = filter regex
    if [[ "$locAlias" =~ ^${1:-.*} ]]; then
      printf '%s\n' "${locAlias}"
    fi
  done
}

# listProfiles [OPTION] [SEARCH]
# List all available profiles for current user
#  [OPTION]
#     -q : only check for profile support
listProfiles() {
  local file=
  if [[ ${_seq_configDirName} == $(basename "${seq_configRoot}") ]] \
    || [[ ! -e ${seq_configRoot} ]] ; then
    error -e "${seq_name} does not have configuration profiles"
    return 1
  fi
  [[ "${1:-}" == "-q" ]] && return 0
  for file in "${seq_configRoot}"/* ; do
    file="$(basename -- "${file}")"
    [[ ${file%.*} =~ ^${1:-.*} ]] && printf '%s\n' "${file%.*}"
  done
}

# showVersion
showVersion() {
  printf 'Sequencer:    %s\n' "${sqr_versionString}"
  printf 'Seq needs:    %s\n' "${sqr_minVersion:-"-"}"
}

# initSeqConfig [OPTION] <NAME> [TEMPLATE]
# Create a configuration file in the users' home.
# Source it if already existent
#  [OPTION]
#     -p  : <NAME> is subfolder used for profiles
#     -t  : Source config also if created from template
#     -e  : Create empty configuration if no template is found
#  Return
#      0       : Sourced configuration or
#         (-t) : created and sourced configuration from template
#      1       : Created configuration from template but not sourced
#      2       : Created empty configuration
#      3       : No configuration created
initSeqConfig() {
  local answer=n
  local retVal=255
  local sourceAlways=0
  local createEmpty=0
  local seqProfiles=0
  local configExists=
  local configDir=
  local arg

  while getopts "ept" arg ; do
    case "${arg}" in
      e) createEmpty=1 ;;
      p) seqProfiles=1 ;;
      t) sourceAlways=1 ;;
      *) ;;
    esac
  done
  shift "$((OPTIND-1))"; OPTIND=1

  local configLoc="$seq_configRoot/${1:-}"
  if [[ $seqProfiles -ne 0 ]] ; then
    [ -z "$seq_profileName" ] && seq_profileName=default
    configLoc="$seq_configRoot/${1:-}/${seq_profileName}.cfg"
  fi
  configDir="$(dirname -- "$configLoc")"
  local configTemplate="${2:-}"

  # Don't create anything if only profiles should be listed
  if [ -n "${_seq_profileList}" ] ; then
    seq_configRoot="$configDir"
    return 0
  fi

  seq_configRoot="$configDir"

  if [ -s "$configLoc" ] ; then
    info "Using configuration file: $configLoc"
    seq_configFile="$configLoc"
    . "$configLoc"
    return 0
  fi

  # Ask for config creation if not existent
  if ! quiet && ! dry ; then
    sqr::echo " [i] Configuration missing"
    confirm "Create ${configLoc} now?" || return 3
  fi

  # Create config subdir in users home
  if [ ! -e "$configDir/" ] ; then
    sqr::echo -n "Creating $(realpath -- "$configDir")..."
    # shellcheck disable=SC2015 # && || is not if else
    exe install -m 700 -d "$configDir" && sqr::echo "Ok" || sqr::echo "Nok"
  fi

  # Config does not exist, check for template
  if [ -s "$configTemplate" ] ; then

    # Check first if there is an existing configuration at the templates position
    configExists="$(dirname -- "$configTemplate")/$1"
    if [ -s "$configExists" ] ; then
      exe mv "$configExists" "$configLoc"
      endReturn -o $? "Unable to use existing configuration: $configExists"

      sqr::echo " [i] Using existing configuration: $configExists"
      sqr::echo "     (Moved to $configDir)"
      . "$configLoc"
      retVal=0
    else
      # Install new template to the final location
      exe install -m 600 -T "$configTemplate" "$configLoc"
      endReturn -o $? "Failed to create configuration"

      if [ $sourceAlways -eq 0 ] ; then
        if [ $_seq_configEdit -eq 0 ] ; then
          warning    "Seq configuration created from template but not used"
          warning -a "Please modify \"$configLoc\" first"
        fi
        retVal=1
      else
        warning    "Using seq configuration from template $configTemplate"
        warning -a "     (Copied to $configDir)"
        . "$configTemplate"
        retVal=0
      fi
    fi
    seq_configFile="$configLoc"
  else
    warning "Seq configuration template not found"
  fi

  if [ $createEmpty -ne 0 ] ; then
    # Create empty config file
    warning "Created empty configuration file $configLoc"
    exe touch "$configLoc"
    exe chmod 600 "$configLoc"
    seq_configFile="$configLoc"
    retVal=2
  fi

  # Give the user a chance to edit the create config file
  if [ $retVal -eq 255 ]; then
    error "No seq configuration created"
    retVal=3
  elif interactive && ! dry && (( ! _seq_configEdit )) ; then
    # ! _seq_configEdit : Edit operation will be performed in main
    if confirm "Edit configuration file now?" ; then
      exe editor "$configLoc"
      . "$configLoc"
      retVal=0
    fi
  fi

  return $retVal
}

# execute [-q] <Step Number>
#    -q: don't stop and don't report step functions which cannot be found
# execute given step_<Step Number> function
execute() {
  local answer=
  local notFound=0
  local noReport=0
  local stepAlias=

  if [[ "${1:-}" == "-q" ]] ; then
    noReport=1
    shift
  fi

  # check if step function exists
  exists -f "step_${1:?}" || notFound=1
  if (( notFound )) && (( ! noReport )) ; then
    error "Step ${1:-"-"} not found"
    exit 1
  fi

  # don't execute step functions which are not available
  (( notFound )) && return 1

  # stop if seq_config fails
  sqr::seqConfig "${1}" || return $?

  if ! quiet ; then
    exists -f "step_${1}_alias" && stepAlias=$("step_${1}_alias")
    printf '\n [%3d] ' "${1}"
    if [ -n "${stepAlias}" ]; then
      echo -en "$(col orange)${stepAlias}$(col off)$(sqr::stepOptions "${1}" ' ')"
      # Only add newline if step info() available
      exists -f "step_${1}_info" && printf '\n%s' "${_sqr_indentExe}"
    else
      echo -en "$(sqr::stepOptions "${1}")"
      exists -f "step_${1}_options" && printf '\n%s' "${_sqr_indentExe}"
    fi

    if exists -f "step_${1}_info" ; then
      _sqr_contextExe=1
      "step_${1}_info" "$1" "${seq_args[@]}"
      _sqr_contextExe=0
      color none
    else
      # Add newline if no info is given
      echo
    fi
  fi

  if interactive ; then
    answer="$(ask "Start: (y)es/[n]o/(s)kip?" "n")"
    case "${answer}" in
      [yY])
        "step_$1" "$1" "${seq_args[@]}"
        _seq_stepReturn="$?" ;;
      [sS]) # skip step
        _seq_stepReturn=0
        return 0 ;;
      *)
        stepAlias="${1}"
        # Display alias if exists
        exists -f "step_${1}_alias" && stepAlias="$("step_${1}_alias")"

        warning "Stopping sequence at step: $stepAlias"
        exit 1 ;;
    esac
  else
    "step_$1" "$1" "${seq_args[@]}"
    _seq_stepReturn="$?"
  fi
  color none
}

# continous <Starting Step Number>
# (max $_sqr_stepMax)
# execute sequence continously from given starting step
continous() {
  local continous_all=0
  local continous_i
  local continous_step=0

  if [ "${1:-}" == "-a" ]; then
    continous_all=1
    shift
  fi

  continous_step="$(checkStep "$1")" || return 1

  info "Starting sequence ${seq_name} ..."

  for ((continous_i=continous_step; continous_i<=_sqr_stepMax; continous_i++)); do
    if ! execute -q "${continous_i}" ; then
      [ ${continous_all} -eq 0 ] && break
    fi
    [ ${_seq_stepReturn} -ne 0 ] && break
  done
  return ${_seq_stepReturn}
}

# selection <STEP ARRAY>
# execute given step list
# e.g.: selection -q (1, 4, 12)
selection() {
  local selection_i
  local selection_step=0
  local selection_array=("$@")

  [ ${#selection_array[@]} -eq 0 ] && return 1

  info "Starting sequence ${seq_name} ..."

  for selection_i in "${selection_array[@]}" ; do
    selection_step="$(checkStep "${selection_i}")" || return 1
    execute "${selection_step}"
  done
  return ${_seq_stepReturn}
}

# sqr::seqConfigEdit
sqr::seqConfigEdit() {
  # Suppress seq_config output for editing and allow it to fail
  local quietSave=${LOG_LEVEL}
  
  exists -f seq_config || return 0

  LOG_LEVEL=0
  seq_config "${seq_args[@]}" || true
  LOG_LEVEL=${quietSave}
  if [ -w "$seq_configFile" ]; then
    editor "$seq_configFile" || true
  else
    error "No configuration file available"
  fi
}

# sqr::seqConfig [STEP NUMBER]
# Handle calling of the seq_config() function
sqr::seqConfig() {
  # Check existens 
  if ! exists -f seq_config ; then
    if (( _seq_configEdit )) ; then
      error "Sequence does not have a configuration file"
      return 1
    fi
    return 0
  fi

  # Create/edit configuration file
  (( _seq_configEdit )) && sqr::seqConfigEdit

  # Stop here without step number
  [ -z "${1:-}" ] && return 1
  
  # Only call once
  (( _seq_configured )) && return 0

  local -n noconf="step_${1}_noconf"
  if checkStep "${1:-}" >/dev/null 2>&1 && [ -z "${noconf+x}" ] ; then
    _seq_configured=1
    if ! seq_config "${seq_args[@]}" ; then
      error "Configuring sequence failed"
      exit 1
    fi
  fi
  return 0
}

# exe <COMMAND>
# Handle dry run and verbose output for commands without pipe and/or redirects
exe() {
  dry && printf -- '--'
  if dry || verbose ; then
    (set -x; : "$@")
  fi

  if ! dry ; then
    "$@"
  fi
}

# exep <COMMAND AS STRING(S)>
# Handle dry run and verbose output for commands containing pipe and/or redirects
exep() {
  if dry ; then
    printf -- '--++ : %s\n' "$*"
  elif verbose ; then
    printf '++ : %s\n' "$*"
  fi

  if ! dry ; then
    bash -c "$*"
  fi
}

# Check if sequence is compatible
sqr::compatible() {
  if ! exists "sqr_minVersion"; then
    sqr_minVersion="${VERSION_SEQREV:-0}"
  fi
  if [ -z "${sqr_minVersion:-}" ] ; then
    warning "No sequence revision found. Trying anyway..."
  else
    if [ -n "${sqr_minVersion}" ] && [[ ${sqr_minVersion} -gt ${sqr_version} ]] ; then
      error "Unsupported sequence revision"
      showVersion
      return 1
    fi
    # exclude older versions if needed
    if [ -n "${sqr_minVersion}" ] && [[ ${sqr_minVersion} -le 15 ]] ; then
      error    "Unsupported sequence revision (major changes in version 16)"
      error -a "(Use 'sequpgrade.sh $(readlink -f -- "$0")' for a basic upgrade)"
      showVersion
      return 1
    fi
  fi
  return 0
}

# Used as editor if no system editor could be found
sqr::noEditor() {
  error    "No editor found (\$EDITOR,\"/etc/alternatives\",nano,vi)"
  error -a "Cannot open: $*"
}

sqr::main() {
  local emptyCall=1
  local quickStartOne=0
  local toStart=( "0" )
  local startAll=

  # options check
  for _ in "$@" ; do
    case "${1:-}" in
      ++) # end parameter and quickstart step 1 with -qq
        quickStartOne=1
        _sqr_interactive=0
        LOG_LEVEL=0
        shift && break ;;
      --) # end parameter
        shift && break ;;
      --all|-a) # execute all steps; regardless continouity
        startAll="-a"
        shift ;;
      --config|-c) # open sequence configuration file
        _seq_configEdit=1
        shift ;;
      --color) # Output color codes within pipe
        _sqr_colorAlways=1
        shift ;;
      --debug)
        sqr_args+=" $1"
        _sqr_debug="1"
        shift ;;
      --dry-run|-d)
        sqr_args+=" $1"
        _sqr_dry=1
        shift ;;
      --help) # show only full help
        local _sqr_optHelp=2
        shift ;;
      -h) # show only step help
        local _sqr_optHelp=1
        shift ;;
      --helpapi|-ha) #show build-in functions
        local _sqr_optHelpapi=1
        shift ;;
      --liststeps|-ls)
        listSteps "${2:-}"
        exit 0 ;;
      --profile|-p) # seq profile name
        sqr_args+=" $1 ${2:-}"
        shift
        # Cover the case when only -p is given without profile name
        if [ -z "${1:-}" ] ; then
          seq_profileName=default
        else
          seq_profileName="$1" && shift
        fi ;;
      -pl) # List available profiles with search
        shift
        [[ ${LOG_LEVEL} -gt 1 ]] && LOG_LEVEL=1 # "only show errors"
        _seq_profileList="${1:-".*"}"
        [ -n "${1:-}" ] && shift
        ;;
      --quiet|-q)
        sqr_args+=" $1"
        _sqr_interactive=0
        shift ;;
      --silent|-qq)
        sqr_args+=" $1"
        _sqr_interactive=0
        LOG_LEVEL=0
        shift ;;
      --single|-s) # execute only one step and stop
        sqr_args+=" $1"
        _sqr_single=1
        shift ;;
      --verbose|-v)
        sqr_args+=" $1"
        _sqr_verbose=1
        shift ;;
      --version) # version request
        showVersion
        exit 0 ;;
    esac
  done

  if (( ${_sqr_optHelp:-} )) ; then
    if [[ ${_sqr_optHelp} == 2 ]] ; then
      _sqr_optHelp=""
    else
      _sqr_optHelp="-s"
    fi
    displayHelp ${_sqr_optHelp:-} "${1:-}" | less -FREX
    exit 0
  fi
  (( ${_sqr_optHelpapi:-} )) && helpApi | less -R && exit 0

  # debug mode
  if [[ "${_sqr_debug:-}" = "1" ]]; then
    set -o xtrace
    PS4='+(${BASH_SOURCE}:${LINENO}): ${FUNCNAME[0]:+${FUNCNAME[0]}(): }'
    # Enable error backtracing
    trap 'sqr::error_report "${FUNCNAME:-.}" ${LINENO}' ERR
  fi

  # Don't show help if only configuration should be edited
  [ ${_seq_configEdit} -ne 0 ] && [ -z "${1:-}" ] && LOG_LEVEL=1

  if [ -z "${1:-}" ] && (( ! quickStartOne )) ; then
    if ! quiet && [[ ${LOG_LEVEL} -ge $log_info ]] ; then
      # Empty -> show help
      displayHelp -st
    fi
    # Assume starting at one for interactive mode
    toStart=( "1" )
  elif (( quickStartOne )) ; then
    emptyCall=0
    toStart=( "1" )
    seq_args=( "$@" )
  else
    emptyCall=0
    read -r -a toStart <<< "$1"
    shift
    seq_args=( "$@" )
  fi

  # compatibility check of sequence
  sqr::compatible || exit 1

  # dry run warning
  if dry && ! quiet ; then
    color yellow
    echo
    echo " [w] Dry run active."
    echo "     - Printed commands may not be accurate (e.g. quotation incorrect)"
    echo "     - Sequence may ignore dry run"
    color none
    confirm -fny "Press enter to continue or Ctrl + C to abort"
  fi

  # Determine system default editor
  # Change with update-alternatives --config editor
  _sqr_editor="$(realpath -eq "/etc/alternatives/editor")"
  ## Various fallbacks
  [ -z "${_sqr_editor}" ] && _sqr_editor="$EDITOR"
  [ -z "${_sqr_editor}" ] && _sqr_editor="$(command -v nano)"
  [ -z "${_sqr_editor}" ] && _sqr_editor="$(command -v vi)"
  ## Fall back to error message
  [ -z "${_sqr_editor}" ] && _sqr_editor="sqr::noEditor"

  sqr::parseAlias

  #  # Create/edit configuration file
  if (( emptyCall )) && (( _seq_configEdit )) ; then
    sqr::seqConfigEdit || true
    exit 0
  fi

  # Check for profile support
  if [ -n "${_seq_profileList}" ]; then
    listProfiles "${_seq_profileList}"
    exit $?
  elif [ -n "${seq_profileName}" ]; then
    listProfiles -q || exit 1
  fi

  # check if more than one step is given and select execution mode
  if (( _sqr_single )) ; then
    selection "${toStart[0]}"
  elif [ "${#toStart[@]}" -gt "1" ]; then
    selection "${toStart[@]}"
  else
    continous ${startAll} "${toStart[0]}"
  fi
}

sqr::main "$@"
_sqr_mainReturn="$?"

silent || printf '\n%s\n' "$seq_name finished"

exit "${_sqr_mainReturn}"