#!/bin/bash

## Sequencer script is doing nothing on its own. It is included by a squence script
## which uses the sequencer.sh to provide sequencial operations with or without
## user interaction (see seqTemplate.sh)

## Start of generic script part

QUIET=0
ERNO=0
MAX_STEP=255
TEMPLATE_NAME=seqTemplateExample.sh

function helpSequencer() {
  echo "Usage: ${0##*/} [Options] [Step Number(s)]" 
  echo
  echo "  [Options]"
  echo "    -q : Don't ask for permission to execute next step"
  echo "         If called without starting step number only this help is shown"
  echo 
  echo "  [Step Number(s) 1-${MAX_STEP}]"
  echo "      Single step number  : starting point of process"
  echo "    Multiple step numbers : execute only given steps"
  echo "                            execute only one step with using special step 0"
  echo "                            ( e.g. only execute step 4: $0 4 0 )"
}

# endCheckEmpty [VariableName] [DESCRIPTION]
#    DESCRIPTION : Optional text for error
function endCheckEmpty() {
  local errorText=$1
  eval 'local ref=$'$1
  
  if [ ! -z "$2" ] ; then
    errorText=$2
  fi
  if [ -z $ref ] ; then
    echo -e "[Error] $errorText must not be empty.\nAborting installation."
    exit 666
  fi 
}

function existsFunction() {
  local NOTFOUND=0
  eval 'local ref=$'$1
  declare -F $1 &>>/dev/null || NOTFOUND=1
  return $NOTFOUND
}

function saveReturn() {
  if [ $1 -ne 0 ] ; then
    ERNO=$1
  fi
}

# endReturn [-f]
#   -f : force exit with $ERNO without user input
function endReturn() {
  if [[ ( $ERNO -ne 0 && $QUIET -ne 0 ) || ( $ERNO -ne 0 && ! -z $1 && $1 == "-f" ) ]] ; then
    echo
    echo -e "[Error] Return value $ERNO detected.\nAborting installation."
    exit $ERNO
  fi
  if [ $ERNO -ne 0 ] ; then
    echo
    echo "[Error] Return value $ERNO detected."
    read -p "End installation: y(default)/n? " answer
    case $answer in
      [nN])
         echo
         echo Continuing installation...
         ;;
      *)
         echo
         echo Installation aborted
         exit $ERNO; 
         ;;
    esac
  fi
}

# execute [-q] <Step Number>
#    -q: don't stop and don't report step functions which cannot be found 
# execute given step_<Step Number> function
function execute() {
  local NOTFOUND=0
  local NOREPORT=0
  
  if [ $1 == "-q" ] ; then
    NOREPORT=1
    shift
  fi

  # check if step function exists
  declare -F step_$1 &>>/dev/null || NOTFOUND=1
  if [ $NOTFOUND -eq 1 ] && [ $NOREPORT -ne 1 ] ; then
    echo "Step $1 not found" 
    exit 1;
  fi

  # don't execute step functions which are not available
  if [ $NOTFOUND -eq 1 ] ; then
    return $NOTFOUND
  fi 

  echo -en "\n[STEP $1] "
  existsFunction step_${1}_info
  if [ $? -eq 0 ] ; then
    step_${1}_info $1
  fi
  if [ $QUIET -ne 1 ] ; then
    read -p "Start: y/n(default)? " answer
    case $answer in
      [yY])
         step_$1 $1
         ;;
      *)
         echo Aborting installation at step $1
         exit 1; 
         ;;
    esac
  else
    step_$1 $1
  fi
}

# continous <Starting Step Number>
# (max $MAX_STEP)
# execute installation continously from given starting step
function continous() {
  for ((i=$1; i<=${MAX_STEP}; i++)); do
    execute -q $i
    local res=$?
    if [ $res -ne 0 ] ; then
      break;
    fi
  done
}

# selection <Step Number List (separated by space)>
# execute given step list
# e.g.: selection -q 1 4 12
function selection() {
  for i in $@ ; do
  # stop on step 0 
  if [ $i -eq 0 ] ; then
    break
  else 
    execute $i
  fi
  done
}

# Creating a minimal step definition template
function createTemplate() {
  if [ -f $TEMPLATE_NAME ] ; then
    return 1
  fi
  echo "#!/bin/bash" > $TEMPLATE_NAME
  echo >> $TEMPLATE_NAME
  echo "# Step 1 is mandatory" >> $TEMPLATE_NAME
  echo "step_1_info() { echo \"My custom step \$1\"; }" >> $TEMPLATE_NAME
  echo "step_1() {" >> $TEMPLATE_NAME
  echo "  echo \"Doing something...\"" >> $TEMPLATE_NAME
  echo "}" >> $TEMPLATE_NAME
  echo >> $TEMPLATE_NAME
  echo ". $0" >> $TEMPLATE_NAME
  
  chmod +x $TEMPLATE_NAME
  return 0
}

# Always display sequencer help and, if available, sequence help
function displayHelp() {
 
  helpSequencer

  # check if step definition exists by looking for step_1()
  existsFunction step_1
  if [ $? -ne 0 ] ; then
    echo -e "\n  It seems ${0##*/} was called directly."
    echo -e "  Please create a sequence script first.\n"
    read -p "  Create a template now? y/n(default)? " answer
    case $answer in
      [yY])
         createTemplate
	 if [ $? -eq 0 ] ; then
	   echo -e "\n  $TEMPLATE_NAME created."
	 else
           echo -e "\n  $TEMPLATE_NAME exists...Nothing to do!"
	 fi
         ;;
      *)
         echo -e "\n  Nothing to do!" 
         ;;
    esac
    exit 1;
  else
    echo "  Step documentation:"
    for ((i=1; i<=${MAX_STEP}; i++)); do
     
      # Display step reference in help if step function exists 
      existsFunction step_${i}
      if [ $? -ne 0 ] ; then
	continue
      fi
      printf '    Step %3s : ' $i
      
      # Display step help only if info function exists
      existsFunction step_${i}_info
      if [ $? -eq 0 ] ; then
        step_${i}_info $i 
      else
        echo " - step_${i}_info() missing"
      fi
    done
  fi
}

main() {
  # detect if option quiet is available
  if [ ! -z "$1" ] && [ $1 == "-q" ] ; then
    QUIET=1
    shift
  fi

  # display help  
  if [ -z "$1" ] ; then
    displayHelp
    START=1
    if [ $QUIET -eq 1 ] ; then
      exit 1;
    fi
  else
    START=$1
  fi

  # check if more than one step is given and select execution mode
  if [ ! -z $2 ] ; then
    selection $@  
  else
    continous $START
  fi

  echo
  echo "${0##*/} finished"
}

main "$@"
exit 0;