send

#!/bin/bash
set -o pipefail

source ${BASH_SOURCE%/*}/.helpers.sh

usage() {
	cat<<-EOF
	$0 --from <address> --to <address> --key <key> --amount <n>
	
	Send coins to an address.
	
	  --from|-f	Address to withdraw funds from.
	  --to|-t	Address to deposit funds to.
	  --key|-k	location of private key file for <from>.
	  --amount|-a	Amount of funds to send.
	  --help -h	Print this help message.
	EOF
}

main() {
  from='' to='' key='' amount=''
  while [ $# -gt 0 ]; do
    case "$1" in
      --from|-f) from=$2 ;  shift ; ;;
      --to|-t) to=$2 ;  shift ; ;;
      --key|-k) key=$2 ;  shift ; ;;
      --amount|-a) amount=$2 ;  shift ;;
      --help|-h) usage ; exit 0 ; ;;
      *) echo "unknown option $1 (-h for help)" >&2 ; exit 1 ; ;;
    esac
    shift
  done

  set -eu

  assert_public '--from' "$from"
  assert_public '--to' "$to"
  assert_private '--key' "$key"
  assert_int '--amount' "$amount"

  # Sign transaction
  echo "Signing transaction..."

  # Create a signature of the transactions details using the private key twin
  # of the 'from' address's public key.
  # Knowing the private key authorizes the creator to send the funds.
  # See the readme's section on public private key cryptography
  transaction="$from $to $amount"
  signature="$(sign "$key" "$transaction")"

  # Check signature with public key for the from address.
  # This is just a sanity test, it will be checked by the miner when validating
  # transaction.
  echo "Verifying that private key matches form address..."
  verify "$from" "$signature" "$transaction"

  # Just using jq to format and escape JSON.
  jq --null-input --compact-output \
    --arg from "$from" \
    --arg to "$to" \
    --arg amount "$amount" \
    --arg signature "$signature" \
    '{
       from: $from,
       to: $to,
       amount: $amount | tonumber,
       signature: $signature
     }' >> $pending

  echo "$from sent $amount coins to $to (pending)"
}

main "$@"