#!/bin/bash

BLOCK_FILE=""
BLOCK_NAME='BLOCK'
BLOCK_COMMENT_CHAR="#"
# a comment added before the block
BLOCK_DESCRIPTION=""

function __update_block () {
  if [ ! -z "$BLOCK_FILE" ]; then
   mkdir -p "$(dirname $BLOCK_FILE)"
   touch $BLOCK_FILE
   tail -c1 $BLOCK_FILE | read -r _ || echo >> $BLOCK_FILE
  fi
  BLOCK_BEGIN="$BLOCK_COMMENT_CHAR --- ${BLOCK_NAME} BEGIN ---"
  BLOCK_END="$BLOCK_COMMENT_CHAR --- ${BLOCK_NAME} END ---"
  BLOCK="\n$([ -z "$BLOCK_DESCRIPTION"  ] || echo "${BLOCK_COMMENT_CHAR} ${BLOCK_DESCRIPTION}\n")${BLOCK_BEGIN}\n${BLOCK_END}"
  # for testing
  # BLOCK="a line before\n${BLOCK}\nanother line outside"

}

# set block to defaults
__update_block
  # echo -e "default block template follows use: block-set before block-add to change>\n" $BLOCK

function set_block () {

  declare OPTION
  declare OPTARG
  declare OPTIND

  while getopts ':f:c:d:n:' OPTION; do
    # echo $OPTION $OPTARG
  case "$OPTION" in
    f)
      BLOCK_FILE=$OPTARG
      echo File set to $BLOCK_FILE
      ;;
    c)
      BLOCK_COMMENT_CHAR=$OPTARG
      ;;
    d)
      BLOCK_DESCRIPTION=$OPTARG
      ;;
    n)
      BLOCK_NAME=$OPTARG
      ;;
    *)
      echo unknown option $OPTION
      ;;
  esac
done

shift $(( OPTIND - 1 ))

__update_block
  # echo -e "new block template follows use: block-add >\n" $BLOCK
  # echo ----
  echo $([ -e "$BLOCK_FILE" ] || echo "Warning: No output file set yet, use block-set -f <path>" && echo "block will be placed in $BLOCK_FILE")
  # echo -------
}

function add_block () {
block_remove_content
# only add if it doesn't exist, existance is only based on block begin
local ADD
ADD=$(echo "${BLOCK}" | sed 's/\//\\\//g')
if [ -e "$BLOCK_FILE" ]; then
sed -n '/^[ \t]*'"${BLOCK_BEGIN}"'/{q50}' "${BLOCK_FILE}"
[ $? == 50 ] && return
WHERE=${1-${BLOCK_BEGIN}}  # default is end
# echo Where $WHERE
sed -i '/'"${WHERE}"'/{s/.*/&\n'"${ADD}"'/;h};${x;/^$/{s//'"$ADD"'/;H};x}' "${BLOCK_FILE}"
[[ $1 ]] && block_add_line $1
else
  echo "no file set in which to add block, use: ${RED_COLOR}set-block -f <file path>"
fi
}

list_block () {
if [[ $1 =~ -?r(aw)? ]]; then
  echo $BLOCK
else
  local block
  block=${BLOCK##'\n'}'\n'
  printf "$block"
fi
}

get_block_file () {
 [ $BLOCK_FILE ] && echo ${BLOCK_FILE}
  [[ $1 = -v ]] && echo "no output file set, use set_block -f <file-path>"
}

modify_block () {
  sed -i '/^'"${BLOCK_BEGIN}"'/,/^'"${BLOCK_END}"$'/ {
  /'"${BLOCK_BEGIN}"'/b
  /'"${BLOCK_END}"'/b
  s/'"${1}"'/'"${2}"'/
  }' "${BLOCK_FILE}"
}

block_remove_leading () {
  printf "%s\n" "$(tac $BLOCK_FILE \
  | sed '/'"${BLOCK_BEGIN}"'/,/^./{ /^[ \t]*$/d}'  | tac)"  > $BLOCK_FILE
}

remove_block () {
  [[ "$BLOCK_DESCRIPTION" ]] || sed -ni '/'"${BLOCK_BEGIN}"'/{x;d;};1h;1!{x;p;};${x;p;}' "${BLOCK_FILE}"
  block_remove_leading
  sed -i '/^'"${BLOCK_BEGIN}"'/,/^'"${BLOCK_END}"$'/ {
  d
  }' "${BLOCK_FILE}"
}

block_remove_content () {
  sed -i '/^'"${BLOCK_BEGIN}"'/,/^'"${BLOCK_END}"$'/ {
  /'"${BLOCK_BEGIN}"'/b
  /'"${BLOCK_END}"'/b
  d
  }' "${BLOCK_FILE}"
}

block_add_line () {
# echo argument count $#, $1, $2, $3
local ADD
ADD="/^${BLOCK_BEGIN}/a\\${1}"
if [ $# -gt 1  ]; then
 if [ "$1" == "--end" ];then
  ADD="/${BLOCK_END}/i\\${2}"
else
  if [ "$1" == "--before" ];then
   ADD="/${2}/i\\${3}"
 else
  ADD="/${1}/a\\${2}"
 fi
fi
fi
# echo $ADD
sed -i '/^'"${BLOCK_BEGIN}"'/,/^'"${BLOCK_END}"$'/ {
'"${ADD}"'
}' "${BLOCK_FILE}"
}

block_remove_line () {
  sed -i '/^'"${BLOCK_BEGIN}"'/,/^'"${BLOCK_END}"$'/ {
  /'"${1}"'/d
  }' "${BLOCK_FILE}"
}

block_change_line () {
  sed -i '/^'"${BLOCK_BEGIN}"'/,/^'"${BLOCK_END}"$'/ {
  /'"${1}"'/c\'"${2}"'
  }' "${BLOCK_FILE}"
}

block_modify_line () {
  sed -i '/^'"${BLOCK_BEGIN}"'/,/^'"${BLOCK_END}"$'/ {
  /'"${BLOCK_BEGIN}"'/b
  /'"${BLOCK_END}"'/b
  /'"${1}"'/{s/'"${2}"'/'"${3}"'/}
  }' "${BLOCK_FILE}"
}