#!/usr/bin/env bash
# BASH3 Boilerplate: ini_val
#
# This file:
#
#  - Can read and write .ini files using pure bash
#
# Limitations:
#
#  - All keys inside a section of the .ini file must be unique
#  - Optional comment parameter for the creation of new entries
#
# Usage as a function:
#
#  source ini_val.sh
#  ini_val data.ini connection.host 127.0.0.1 "Host name or IP address"
#
# Usage as a command:
#
#  ini_val.sh data.ini connection.host 127.0.0.1 "Host name or IP address"
#
# Based on a template by BASH3 Boilerplate v2.8.0
# https://bash3boilerplate.sh/#authors
#
# The MIT License (MIT)
# Copyright (c) 2013 Kevin van Zonneveld and contributors
# You are not obligated to bundle the LICENSE file with your b3bp projects as long
# as you leave these references intact in the header comments of your source files.

function ini_val() (
  set -o errexit
  set -o errtrace
  set -o nounset
  set -o pipefail

  local file="${1:-}"
  local sectionkey="${2:-}"
  local val="${3:-}"
  local comment="${4:-}"
  local delim="="
  local comment_delim=";"
  local section=""
  local key=""
  local current=""
  local current_comment=""
  local RET=""
  # add default section
  local section_default="default"

  if [[ ! -f "${file}" ]]; then
    # touch file if not exists
    touch "${file}"
  fi

  # Split on . for section. However, section is optional
  IFS='.' read -r section key <<<"${sectionkey}"
  if [[ ! "${key}" ]]; then
    key="${section}"
    # default section if not given
    section="${section_default}"
  fi

  # get current value (if exists)
  current=$(sed -En "/^\[/{h;d;};G;s/^${key}([[:blank:]]*)${delim}(.*)\n\[${section}\]$/\2/p" "${file}" | awk '{$1=$1};1')
  # get current comment (if exists)
  current_comment=$(sed -En "/^\[${section}\]/,/^\[.*\]/ s|^(${comment_delim}\[${key}\])(.*)|\2|p" "${file}" | awk '{$1=$1};1')

  if ! grep -q "\[${section}\]" "${file}"; then
    # create section if not exists (empty line to seperate new section for better readability)
    echo >>"${file}"
    echo "[${section}]" >>"${file}"
  fi

  if [[ ! "${val}" ]]; then
    # get a value
    echo "${current}"
  else
    # set a value
    if [[ ! "${section}" ]]; then
      # if no section is given, propagate the default section
      section=${section_default}
    fi

    if [[ ! "${comment}" ]]; then
      # if no comment given, keep old comment
      comment="${current_comment}"
    fi
    # maintenance area
    # a) remove comment if new given / respect section
    sed -i.bak "/^\[${section}\]/,/^\[.*\]/ s|^\(${comment_delim}\[${key}\] \).*$||" "${file}"
    # b) remove old key / respect section
    sed -i.bak "/^\[${section}\]/,/^\[.*\]/ s|^\(${key}=\).*$||" "${file}"
    # c) remove all empty lines in ini file
    sed -i.bak '/^[[:space:]]*$/d' "${file}"
    # d) insert line break before every section for better readability
    sed -i.bak $'s/^\\[/\\\n\\[/g' "${file}"

    # add to section
    if [[ ! "${comment}" ]]; then
      # add new key/value _without_ comment
      RET="/\\[${section}\\]/a\\
${key}${delim}${val}"
    else
      # add new key/value _with_ preceeding comment
      RET="/\\[${section}\\]/a\\
${comment_delim}[${key}] ${comment}\\
${key}${delim}${val}"
    fi
    sed -i.bak -e "${RET}" "${file}"
    # this .bak dance is done for BSD/GNU portability: https://stackoverflow.com/a/22084103/151666
    rm -f "${file}.bak"
  fi
)

if [[ "${BASH_SOURCE[0]:-}" != "${0}" ]]; then
  export -f ini_val
else
  ini_val "$@"
  exit
fi