#!/bin/bash

set -eu

PARAMS_DIR="$HOME/.zcash-params"

REGTEST_PKEY_NAME='zc-testnet-public-alpha-proving.key'
REGTEST_VKEY_NAME='zc-testnet-public-alpha-verification.key'
REGTEST_PKEY_URL="https://z.cash/downloads/$REGTEST_PKEY_NAME"
REGTEST_VKEY_URL="https://z.cash/downloads/$REGTEST_VKEY_NAME"
REGTEST_DIR="$PARAMS_DIR/regtest"

# This should have the same params as regtest. We use symlinks for now.
TESTNET3_DIR="$PARAMS_DIR/testnet3"


# Note: This assumes cwd is set appropriately!
function fetch_params {
    local url="$1"
    local filename="$(echo "$url" | sed 's,^.*/,,')"
    if ! [ -f "$filename" ]
    then
        echo "Retrieving: $url"
        wget --progress=dot:giga "$url"
    fi
}

cat <<EOF
zcash - fetch-params.sh

EOF

# Now create PARAMS_DIR and insert a README if necessary:
if ! [ -d "$PARAMS_DIR" ]
then
    mkdir -p "$PARAMS_DIR"
    README_PATH="$PARAMS_DIR/README"
    cat >> "$README_PATH" <<EOF
This directory stores common zcash zkSNARK parameters. Note that is is
distinct from the daemon's -datadir argument because the parameters are
large and may be shared across multiple distinct -datadir's such as when
setting up test networks.
EOF

    # This may be the first time the user's run this script, so give
    # them some info, especially about bandwidth usage:
    cat <<EOF
This script will fetch the Zcash zkSNARK parameters and verify their
integrity with sha256sum.

The parameters currently are about 2GiB in size, so plan accordingly
for your bandwidth constraints. If the files are already present and
have the correct sha256sum, no networking is used.

Creating params directory. For details about this directory, see:
$README_PATH

EOF
fi

mkdir -p "$REGTEST_DIR"
cd "$REGTEST_DIR"

fetch_params "$REGTEST_PKEY_URL"
fetch_params "$REGTEST_VKEY_URL"

cd ..

echo 'Updating testnet3 symlinks to regtest parameters.'
mkdir -p "$TESTNET3_DIR"
ln -sf "../regtest/$REGTEST_PKEY_NAME" "$TESTNET3_DIR/$REGTEST_PKEY_NAME"
ln -sf "../regtest/$REGTEST_VKEY_NAME" "$TESTNET3_DIR/$REGTEST_VKEY_NAME"

# Now verify their hashes:
echo 'Verifying parameter file integrity via sha256sum...'
sha256sum --check - <<EOF
7844a96933979158886a5b69fb163f49de76120fa1dcfc33b16c83c134e61817  regtest/$REGTEST_PKEY_NAME
7844a96933979158886a5b69fb163f49de76120fa1dcfc33b16c83c134e61817  testnet3/$REGTEST_PKEY_NAME
6902fd687bface72e572a7cda57f6da5a0c606c7b9769f30becd255e57924f41  regtest/$REGTEST_VKEY_NAME
6902fd687bface72e572a7cda57f6da5a0c606c7b9769f30becd255e57924f41  testnet3/$REGTEST_VKEY_NAME
EOF