#!/bin/bash

set -eu

# Use this script to download the latest Prysm release binary.
# Usage: ./prysm.sh PROCESS [--download-only] FLAGS
#   PROCESS can be one of beacon-chain or validator.
#   FLAGS are the flags or arguments passed to the PROCESS.
#   If --download-only flag is passed, binaries are checked for updates,
#   downloaded if necessary, no process is started.
# Downloaded binaries are saved to ./dist.
# Use USE_PRYSM_VERSION to specify a specific release version.
#   Example: USE_PRYSM_VERSION=v0.3.3 ./prysm.sh beacon-chain

readonly PRYLABS_SIGNING_KEY=0AE0051D647BA3C1A917AF4072E33E4DF1A5036E

function color() {
    # Usage: color "31;5" "string"
    # Some valid values for color:
    # - 5 blink, 1 strong, 4 underlined
    # - fg: 31 red,  32 green, 33 yellow, 34 blue, 35 purple, 36 cyan, 37 white
    # - bg: 40 black, 41 red, 44 blue, 45 purple
    printf '\033[%sm%s\033[0m\n' "$@"
}

# `readlink -f` that works on OSX too.
function get_realpath() {
    if [ "$(uname -s)" == "Darwin" ]; then
        local queue="$1"
        if [[ "${queue}" != /* ]]; then
            # Make sure we start with an absolute path.
            queue="${PWD}/${queue}"
        fi
        local current=""
        while [ -n "${queue}" ]; do
            # Removing a trailing /.
            queue="${queue#/}"
            # Pull the first path segment off of queue.
            local segment="${queue%%/*}"
            # If this is the last segment.
            if [[ "${queue}" != */* ]]; then
                segment="${queue}"
                queue=""
            else
                # Remove that first segment.
                queue="${queue#*/}"
            fi
            local link="${current}/${segment}"
            if [ -h "${link}" ]; then
                link="$(readlink "${link}")"
                queue="${link}/${queue}"
                if [[ "${link}" == /* ]]; then
                    current=""
                fi
            else
                current="${link}"
            fi
        done

        echo "${current}"
    else
        readlink -f "$1"
    fi
}

# Complain if no arguments were provided.
if [ "$#" -lt 1 ]; then
    color "31" "Usage: ./prysm.sh PROCESS FLAGS."
    color "31" "       ./prysm.sh PROCESS --download-only."
    color "31" "PROCESS can be beacon-chain, validator, or slasher."
    exit 1
fi

readonly wrapper_dir="$(dirname "$(get_realpath "${BASH_SOURCE[0]}")")/dist"
arch=$(uname -m)
arch=${arch/x86_64/amd64}
arch=${arch/aarch64/arm64}
readonly os_arch_suffix="$(uname -s | tr '[:upper:]' '[:lower:]')-$arch"

system=""
case "$OSTYPE" in
darwin*) system="darwin" ;;
linux*) system="linux" ;;
msys*) system="windows" ;;
cygwin*) system="windows" ;;
*) exit 1 ;;
esac
readonly system

if [ "$system" == "windows" ]; then
    arch="amd64.exe"
elif [[ "$os_arch_suffix" == *"arm64"* ]]; then
    arch="arm64"
fi

if [[ "$arch" == "armv7l" ]]; then
    color "31" "32-bit ARM is not supported. Please install a 64-bit operating system."
    exit 1
fi

mkdir -p $wrapper_dir

function get_prysm_version() {
    if [[ -n ${USE_PRYSM_VERSION:-} ]]; then
        readonly reason="specified in \$USE_PRYSM_VERSION"
        readonly prysm_version="${USE_PRYSM_VERSION}"
    else
        # Find the latest Prysm version available for download.
        readonly reason="automatically selected latest available version"
        prysm_version=$(curl -s https://prysmaticlabs.com/releases/latest)
        readonly prysm_version
    fi
}

function verify() {
    file=$1

    skip=${PRYSM_ALLOW_UNVERIFIED_BINARIES-0}
    if [[ $skip == 1 ]]; then
        return 0
    fi

    hash shasum 2>/dev/null || {
        echo >&2 "shasum is not available. Either install it or run with PRYSM_ALLOW_UNVERIFIED_BINARIES=1."
        exit 1
    }
    hash gpg 2>/dev/null || {
        echo >&2 "gpg is not available. Either install it or run with PRYSM_ALLOW_UNVERIFIED_BINARIES=1."
        exit 1
    }

    color "37" "Verifying binary integrity."

    gpg --list-keys $PRYLABS_SIGNING_KEY >/dev/null 2>&1 || curl --silent https://prysmaticlabs.com/releases/pgp_keys.asc | gpg --import
    (
        cd $wrapper_dir
        shasum -a 256 -c "${file}.sha256" || failed_verification
    )
    (
        cd $wrapper_dir
        gpg -u $PRYLABS_SIGNING_KEY --verify "${file}.sig" $file || failed_verification
    )

    color "32;1" "Verified ${file} has been signed by Prysmatic Labs."
}

function failed_verification() {
    MSG=$(
        cat <<-END
Failed to verify Prysm binary. Please erase downloads in the
dist directory and run this script again. Alternatively, you can use a
A prior version by specifying environment variable USE_PRYSM_VERSION
with the specific version, as desired. Example: USE_PRYSM_VERSION=v1.0.0-alpha.5
If you must wish to continue running an unverified binary, specific the
environment variable PRYSM_ALLOW_UNVERIFIED_BINARIES=1
END
    )
    color "31" "$MSG"
    exit 1
}

get_prysm_version

color "37" "Latest Prysm version is $prysm_version."

BEACON_CHAIN_REAL="${wrapper_dir}/beacon-chain-${prysm_version}-${system}-${arch}"
VALIDATOR_REAL="${wrapper_dir}/validator-${prysm_version}-${system}-${arch}"
SLASHER_REAL="${wrapper_dir}/slasher-${prysm_version}-${system}-${arch}"

if [[ $1 == beacon-chain ]]; then
    if [[ ! -x $BEACON_CHAIN_REAL ]]; then
        color "34" "Downloading beacon chain@${prysm_version} to ${BEACON_CHAIN_REAL} (${reason})"
        file=beacon-chain-${prysm_version}-${system}-${arch}
        curl -L "https://prysmaticlabs.com/releases/${file}" -o $BEACON_CHAIN_REAL
        curl --silent -L "https://prysmaticlabs.com/releases/${file}.sha256" -o "${wrapper_dir}/${file}.sha256"
        curl --silent -L "https://prysmaticlabs.com/releases/${file}.sig" -o "${wrapper_dir}/${file}.sig"
        chmod +x $BEACON_CHAIN_REAL
    else
        color "37" "Beacon chain is up to date."
    fi
fi

if [[ $1 == validator ]]; then
    if [[ ! -x $VALIDATOR_REAL ]]; then
        color "34" "Downloading validator@${prysm_version} to ${VALIDATOR_REAL} (${reason})"

        file=validator-${prysm_version}-${system}-${arch}
        curl -L "https://prysmaticlabs.com/releases/${file}" -o $VALIDATOR_REAL
        curl --silent -L "https://prysmaticlabs.com/releases/${file}.sha256" -o "${wrapper_dir}/${file}.sha256"
        curl --silent -L "https://prysmaticlabs.com/releases/${file}.sig" -o "${wrapper_dir}/${file}.sig"
        chmod +x $VALIDATOR_REAL
    else
        color "37" "Validator is up to date."
    fi
fi

if [[ $1 == slasher ]]; then
    if [[ ! -x $SLASHER_REAL ]]; then
        color "34" "Downloading slasher@${prysm_version} to ${SLASHER_REAL} (${reason})"

        file=slasher-${prysm_version}-${system}-${arch}
        curl -L "https://prysmaticlabs.com/releases/${file}" -o $SLASHER_REAL
        curl --silent -L "https://prysmaticlabs.com/releases/${file}.sha256" -o "${wrapper_dir}/${file}.sha256"
        curl --silent -L "https://prysmaticlabs.com/releases/${file}.sig" -o "${wrapper_dir}/${file}.sig"
        chmod +x $SLASHER_REAL
    else
        color "37" "Slasher is up to date."
    fi
fi

case $1 in
beacon-chain)
    readonly process=$BEACON_CHAIN_REAL
    ;;

validator)
    readonly process=$VALIDATOR_REAL
    ;;

slasher)
    readonly process=$SLASHER_REAL
    ;;

*)
    color "31" "Usage: ./prysm.sh PROCESS FLAGS."
    color "31" "       ./prysm.sh PROCESS --download-only."
    color "31" "PROCESS can be beacon-chain, validator, or slasher."
    ;;
esac

verify $process

if [[ "$#" -gt 1 ]] && [[ $2 == --download-only ]]; then
    color "37" "Only download operation is requested, done."
    exit 0
fi

color "36" "Starting Prysm $1 ${*:2}"
exec -a "$0" "${process}" "${@:2}"