#!/bin/bash
## SPDX-FileCopyrightText: 2024 Benjamin Grande M. S. <ben.grande.b@gmail.com>
##
## SPDX-License-Identifier: AGPL-3.0-or-later

set -eu

#date_mined="20130604"
#block_number="230009"
block_hash="00000000000000ecbbff6bafb7efa2f7df05b227d5c73dca8f2635af32a2e949"
txid="54e48e5f5c656b26c3bca14a8c95aa583d07ebe84dde3b7dd4a78f4e4186e713"
dir="${HOME}"
file="bitcoin.pdf"

has(){
  cmd="$(command -v "${1}" 2>/dev/null)" || return 1
  test -x "${cmd}" || return 1
}

check_installed(){
  missing_programs=0
  for prog in "${@}"; do
    if ! has "${prog}"; then
      echo "Missing program: ${prog}" >&2
      missing_programs=1
    fi
  done
  if test "${missing_programs}"; then
    exit 1
  fi
}

validate_dir(){
  if ! test -d "${dir}"; then
    echo "Directory '${dir}' does not exist" >&2
    exit 1
  fi
  if ! test -w "${dir}"; then
    echo "Directory '${dir}' is not writable" >&2
    exit 1
  fi
}

getblock(){
  check_installed bitcoin-cli xxd
  bitcoin-cli getblock "${block_hash}" 0 \
    | tail -c+92167 \
    | for ((o=0;o<946;++o)); do read -rN420 x; echo -n "${x::130}${x:132:130}${x:264:130}" ; done \
    | xxd -r -p \
    | tail -c+9 \
    | head -c184292 \
    | tee "${output_file}" >/dev/null
}

getrawtransaction(){
  check_installed bitcoin-cli xxd
  bitcoin-cli getrawtransaction "${txid}" 0 "${block_hash}" \
    | sed 's/0100000000000000/\n/g' \
    | tail -n +2 \
    | cut -c7-136,139-268,271-400 \
    | tr -d '\n' \
    | cut -c17-368600 \
    | xxd -p -r \
    | tee "${output_file}" >/dev/null
}

gettxout(){
  check_installed bitcoin-cli jq xxd seq
  seq 0 947 \
    | (while read -r n; do bitcoin-cli gettxout "${txid}" "${n}" \
    | jq -r '.scriptPubKey.asm' \
    | awk '{ print $2 $3 $4 }'; done) \
    | tr -d '\n' \
    | cut -c 17-368600 \
    | xxd -r -p \
    | tee "${output_file}" >/dev/null
}

usage(){
  echo "Usage: ${0##*/} getblock|getrawtransaction|gettxtout [DIR]"
  echo "Note: gettxtout works with pruned node"
  echo "Note: DIR defaults to \$HOME"
  exit 1
}

case "${1:-}" in
  "getblock"|"getrawtransaction"|"gettxtout")
    test -z "${2}" || dir="${2}"
    validate_dir "${dir}"
    output_file="${dir}/${file}"
    "${1}"
    ;;
  *) usage;;
esac