#!/bin/bash
#
#
## Debugging parameters:
#TODAY="$1"
##TODAY="20161204"
#CURRENT_YEAR="2017"

# normal parameters:
DATEFORMAT="%Y%m%d"
TODAY=`date +$DATEFORMAT`
CURRENT_YEAR=`date +%Y`
CHRISTMAS="${CURRENT_YEAR}1224"
TREE_KINGS="${CURRENT_YEAR}0106"

# Zuordnung Adventskerze <-> GPIO Pin:
CANDLE_ADDRESS[0]="17"
CANDLE_ADDRESS[1]="18"
CANDLE_ADDRESS[2]="27"
CANDLE_ADDRESS[3]="22"

# Zufallszahl zuruecksetzten
rand=""

# Verwendete Kerzen zuruesetzten
CANDLE_TO_USE[0]=""
CANDLE_TO_USE[1]=""
CANDLE_TO_USE[2]=""
CANDLE_TO_USE[3]=""

# Debugging ja/nein
DEBUG=""

function debug()
{
MESSAGE=$1
echo "$MESSAGE"
}


function random_candles()
{
if [ -n "$DEBUG" ]; then debug "Entering randomization of candle usage:"; fi
COUNTER=0
while [ $COUNTER -lt 4 ]; do
  rand=`echo $(($RANDOM % 4))`
       if [ "${CANDLE_TO_USE[$rand]}" = ""  ]; then
         CANDLE_TO_USE[$rand]=$COUNTER
         if [ -n "$DEBUG" ]; then debug "$COUNTER. Candle to use: ${CANDLE_ADDRESS[$rand]} "; fi
         COUNTER=$((COUNTER + 1))
       fi
done
}

function switch_gpio ()
{
i=$1
case $2 in
  on)
   state=0
  ;;
  off)
   state=1
  ;;
  *)
esac

if [ -n "$DEBUG" ]; then debug "Switch candle ${CANDLE_ADDRESS[$i]} $state"; fi
   gpio -g mode ${CANDLE_ADDRESS[$i]} out
   sleep .1
   gpio -g write ${CANDLE_ADDRESS[$i]} $state
   sleep .1
}

function preset_candles ()
{
if [ -n "$DEBUG" ]; then debug "Initial state: all candles off!"; fi
for i in $(seq 0 3);
do
  switch_gpio $i off
done
}

function get_advent_days ()
{
X=`date -d "$CURRENT_YEAR-12-24 - 3 weeks" +%w`
ADVENT[0]=`date -d "$CURRENT_YEAR-12-24 - 3 weeks -$X day" +$DATEFORMAT`

X=`date -d "$CURRENT_YEAR-12-24 - 2 weeks" +%w`
ADVENT[1]=`date -d "$CURRENT_YEAR-12-24 - 2 weeks -$X day" +$DATEFORMAT`

X=`date -d "$CURRENT_YEAR-12-24 - 1 weeks" +%w`
ADVENT[2]=`date -d "$CURRENT_YEAR-12-24 - 1 weeks -$X day" +$DATEFORMAT`

X=`date -d "$CURRENT_YEAR-12-24 - 0 weeks" +%w`
ADVENT[3]=`date -d "$CURRENT_YEAR-12-24 - 0 weeks -$X day" +$DATEFORMAT`
}

function print_advent_days ()
{
if [ -n "$DEBUG" ]; then debug "1. Advent in $CURRENT_YEAR ist der: ${ADVENT[0]}"; fi
if [ -n "$DEBUG" ]; then debug "2. Advent in $CURRENT_YEAR ist der: ${ADVENT[1]}"; fi
if [ -n "$DEBUG" ]; then debug "3. Advent in $CURRENT_YEAR ist der: ${ADVENT[2]}"; fi
if [ -n "$DEBUG" ]; then debug "4. Advent in $CURRENT_YEAR ist der: ${ADVENT[3]}"; fi
}

function switch_candles ()
{

if [ $TODAY -le $TREE_KINGS ] ; then
  if [ -n "$DEBUG" ]; then debug "Weihnachten ist vorbei aber die Heiligen drei Koenige sind auch noch nicht..."; fi
  if [ -n "$DEBUG" ]; then debug "Trotzdem alle Kerzen an! ;-)"; fi
    for i in $(seq 0 3);
    do
      switch_gpio ${CANDLE_TO_USE[$i]} on
    done

elif [ $TODAY -lt ${ADVENT[0]} ] ; then
  if [ -n "$DEBUG" ]; then debug "noch keine Adventszeit :-("; fi
elif [ $TODAY -ge ${ADVENT[0]}  ] && [ $TODAY -lt ${ADVENT[1]} ] ; then
  if [ -n "$DEBUG" ]; then debug "erste Adventswoche :-)"; fi
  for i in $(seq 0 0);
    do
      switch_gpio ${CANDLE_TO_USE[$i]} on
  done
elif [ $TODAY -ge ${ADVENT[1]} ] && [ $TODAY -lt ${ADVENT[2]} ] ; then
  if [ -n "$DEBUG" ]; then debug "zweite Adventswoche :-)"; fi
  for i in $(seq 0 1);
    do
      switch_gpio ${CANDLE_TO_USE[$i]} on
    done
elif [ $TODAY -ge ${ADVENT[2]} ] && [ $TODAY -lt ${ADVENT[3]} ] ; then
  if [ -n "$DEBUG" ]; then debug "dritte Adventswoche :-)"; fi
  for i in $(seq 0 2);
    do
      switch_gpio ${CANDLE_TO_USE[$i]} on
    done
elif [ $TODAY -ge ${ADVENT[3]} ] && [ $TODAY -le $CHRISTMAS ] ; then
  if [ -n "$DEBUG" ]; then debug "vierte Adventswoche :-)"; fi
  for i in $(seq 0 3);
    do
      switch_gpio ${CANDLE_TO_USE[$i]} on
    done
elif [ $TODAY -gt $CHRISTMAS ] ; then
  if [ -n "$DEBUG" ]; then debug "Weihnachten ist vorbei :-("; fi
  if [ -n "$DEBUG" ]; then debug "Trotzdem alle Kerzen an! ;-)"; fi
    for i in $(seq 0 3);
    do
      switch_gpio ${CANDLE_TO_USE[$i]} on
    done
fi
}

###### Main
#
# Check, if debugging is enabled:
if [ "$1" = "debug" ]; then
  DEBUG="true"
fi

if [ -n "$DEBUG" ]; then debug "Today: $TODAY"; fi
if [ -n "$DEBUG" ]; then debug "Year: $CURRENT_YEAR"; fi
if [ -n "$DEBUG" ]; then debug "Three Kings day: $TREE_KINGS"; fi
if [ -n "$DEBUG" ]; then debug "Christmas: $CHRISTMAS"; fi

#if [ $TODAY -lt ${ADVENT[0]} ] ; then

  preset_candles
  get_advent_days
  print_advent_days
  random_candles
  switch_candles
#echo "Zufallszahl: $rand"