#!/bin/bash
set -eu

gpg2 --version >/dev/null  # verify that GnuPG 2 is installed

USER_ID="${1}"
DEVICE=${DEVICE:="trezor"}  # or "ledger"
CURVE=${CURVE:="nist256p1"}  # or "ed25519"
TIMESTAMP=${TIMESTAMP:=`date +%s`}  # key creation timestamp
HOMEDIR=~/.gnupg/${DEVICE}

# Prepare new GPG home directory for hardware-based identity
rm -rf "${HOMEDIR}"
mkdir -p "${HOMEDIR}"
chmod 700 "${HOMEDIR}"

# Generate new GPG identity and import into GPG keyring
$DEVICE-gpg create -v "${USER_ID}" -t "${TIMESTAMP}" -e "${CURVE}" > "${HOMEDIR}/pubkey.asc"
gpg2 --homedir "${HOMEDIR}" --import < "${HOMEDIR}/pubkey.asc" 2> /dev/null
rm -f "${HOMEDIR}/S.gpg-agent"  # (otherwise, our agent won't be started automatically)

# Make new GPG identity with "ultimate" trust (via its fingerprint)
FINGERPRINT=$(gpg2 --homedir "${HOMEDIR}" --list-public-keys --with-fingerprint --with-colons | sed -n -E 's/^fpr:::::::::([0-9A-F]+):$/\1/p' | head -n1)
echo "${FINGERPRINT}:6" | gpg2 --homedir "${HOMEDIR}" --import-ownertrust 2> /dev/null

AGENT_PATH="$(which ${DEVICE}-gpg-agent)"

# Prepare GPG configuration file
echo "# Hardware-based GPG configuration
agent-program ${AGENT_PATH}
personal-digest-preferences SHA512
" > "${HOMEDIR}/gpg.conf"

# Prepare GPG agent configuration file
echo "# Hardware-based GPG agent emulator
log-file ${HOMEDIR}/gpg-agent.log
verbosity 2
" > "${HOMEDIR}/gpg-agent.conf"

# Prepare a helper script for setting up the new identity
echo "#!/bin/bash
set -eu
export GNUPGHOME=${HOMEDIR}
COMMAND=\$*
if [ -z \"\${COMMAND}\" ]
then
    \${SHELL}
else
    \${COMMAND}
fi
" > "${HOMEDIR}/env"
chmod u+x "${HOMEDIR}/env"

# Load agent and make sure it responds with the new identity
GNUPGHOME="$HOMEDIR" gpg2 -K 2> /dev/null