#!/bin/bash

# TODO: Add a 'get' method that returns a single value
# Exit with 0 if found, 1 otherwise.

key_expr="[a-zA-Z][_a-zA-Z0-9]*\.[a-zA-Z][_a-zA-Z0-9]*"

format_conf() {
  local IFS==
  while read key value
  do
    printf "%-20s %-20s" "$key" "$value"
    echo
  done
}

get_conf() {
  local apps=$1
  local name=$2
  local instance=$3
  local key=$4
  local default=
  local file=$apps/$name/$instance/current/etc/app.conf

  shift 4

  if [ $# -gt 0 ]
  then
    default=$1
    shift
  fi

  if [ ! -r $file ]
  then
    echo "$default"
    return 0
  fi

  value=`sed -n "s,^${key}[ ]*=[ ]*\(.*\)$,\1,p" $file`

  if [ -z "$value" ]
  then
    echo "$default"
  fi

  echo "$value"
}

get_conf_all() {
  local apps=$1
  local name=$2
  local instance=$3
  local file=$apps/$name/$instance/current/etc/app.conf

  if [ ! -r "$file" ]
  then
    return 0
  fi

  sed -n "s,^[ ]*\($key_expr\)[ ]*=[ ]*\(.*\)$,\1=\2,p" "$file" | sort
}

get_conf_in_group() {
  local apps=$1
  local name=$2
  local instance=$3
  local group=$4

  get_conf_all "$apps" "$name" "$instance" | sed -n "s,^${group}\.\(.*\),\1,p"
}

assert_key() {
  key=$1

  local x=`echo $key | sed -n "/^$key_expr$/p"`
  if [ -z "$x" ]
  then
    echo "Invalid key: $key" >&2
    exit 1
  fi
}

conf_set() {
  local apps=$1
  local name=$2
  local instance=$3
  local key=$4
  local value=$5

  local file=$apps/$name/$instance/current/etc/app.conf

  assert_key "$key"

  if [ -r $file ]
  then
    sed "/^$key[ ]*=.*/d" $file > $file.tmp
  fi

  echo "$key=$value" >> $file.tmp
  mv $file.tmp $file
}

conf_delete() {
  local apps=$1
  local name=$2
  local instance=$3
  local key=$4

  local file=$apps/$name/$instance/current/etc/app.conf

  assert_key "$key"

  sed "/^$key[ ]*=.*/d" $file > $file.tmp
  mv $file.tmp $file
}

method_conf_list() {
  local name=$1; shift
  local instance=$1; shift

  get_conf_all "$apps" "$name" "$instance" | format_conf
}

method_conf_usage() {
  if [ -n "$1" ]
  then
    echo "Error:" $@ >&2
  fi

  echo "usage: $0 conf <method>" >&2
  echo ""
  echo "Available methods:" >&2
  echo "  list                    - list all configuration values" >&2
  echo "  list-group [group]      - list all configuration values in the specified group" >&2
  echo "  set [group.key] [value] - set a configuration parameter" >&2
  echo "  delete [group.key]      - deletes a configuration parameter" >&2
  exit 1
}

method_conf() {
  local name="$1"; shift
  local instance="$1"; shift
  local method="$1"

  if [ $# -gt 0 ]
  then
    shift
  fi

  assert_is_instance method_conf_usage "$name" "$instance"

  case "$method" in
    list)
      if [ $# -gt 0 ]
      then
        method_conf_usage "Extra options."
        exit 1
      fi

      method_conf_list "$name" "$instance"
      ;;
    list-group)
      if [ $# -ne 1 ]
      then
        method_conf_usage
        exit 1
      fi

      get_conf_in_group "$apps" "$name" "$instance" "$1" | format_conf
      ;;
    set)
      if [ $# -ne 2 ]
      then
        method_conf_usage
        exit 1
      fi

      conf_set "$apps" "$name" "$instance" "$1" "$2"
      ;;
    delete)
      if [ $# -ne 1 ]
      then
        method_conf_usage
        exit 1
      fi

      conf_delete "$apps" "$name" "$instance" "$1"
      ;;
    *)
      if [ $# -eq 0 ]
      then
        method_conf_list "$name" "$instance"
        exit 0
      fi

      if [ -z "$method" ]
      then
        method_conf_usage
      else
        method_conf_usage "Unknown method $method"
      fi
      exit 1
      ;;
  esac
}