Get estimated halving date from a bitcoin node

halving.sh

#!/bin/bash
CURRENT_BLOCK="$(bitcoin-cli getblockcount)"
if [ $CURRENT_BLOCK -ge 630000 ]
then
  SUBSIDY=$(bitcoin-cli getblockstats $CURRENT_BLOCK | jq '.subsidy')
  SATS_PER_BTC=100000000
  SUBSIDY_BTC=$(bc -l <<< "scale=2; $SUBSIDY / $SATS_PER_BTC")
  echo "HALVING COMPLETE!"
  echo "Current block: $CURRENT_BLOCK"
  echo "Current subsidy: $SUBSIDY_BTC"
else
  echo "Current block: $CURRENT_BLOCK"
  CURRENT_BLOCK_HASH="$(bitcoin-cli getblockhash $CURRENT_BLOCK)"
  CURRENT_BLOCK_TIME="$(bitcoin-cli getblock $CURRENT_BLOCK_HASH | jq '.mediantime')"
  HALVING_BLOCK="$(((($CURRENT_BLOCK/210000)+1)*210000))"
  BLOCK_DELTA="$(($HALVING_BLOCK-$CURRENT_BLOCK))"
  echo "Blocks until halving: $BLOCK_DELTA"
  PREVIOUS_BLOCK="$(($CURRENT_BLOCK-$BLOCK_DELTA))"
  PREVIOUS_BLOCK_HASH="$(bitcoin-cli getblockhash $PREVIOUS_BLOCK)"
  PREVIOUS_BLOCK_TIME="$(bitcoin-cli getblock $PREVIOUS_BLOCK_HASH | jq '.mediantime')"
  DELTA_TIME="$(($CURRENT_BLOCK_TIME-$PREVIOUS_BLOCK_TIME))"
  HALVING_TIME="$(($CURRENT_BLOCK_TIME+$DELTA_TIME))"
  echo "Estimated halving time: $(date -r $HALVING_TIME)"
fi