#!/bin/bash

GOLANG_VERSION=1.18

DESTDIR=$(/usr/bin/realpath "${1:-/usr/local}")

# abort if not executed as root
if [[ $(id -u) != "0" ]]; then
  echo "Usage: run ${0##*/} as root" 1>&2
  exit 1
fi

echo "Installing Go in \"$DESTDIR\"..."

set -e

/bin/mkdir -p "$DESTDIR"

SYSTEM_ARCH=$("$(/usr/bin/dirname "$0")/arch.sh")
DESTARCH=${2:-$SYSTEM_ARCH}

set -eux;

if [[ $DESTARCH == "amd64" ]]; then
    URL="https://go.dev/dl/go${GOLANG_VERSION}.linux-amd64.tar.gz"
    CHECKSUM="e85278e98f57cdb150fe8409e6e5df5343ecb13cebf03a5d5ff12bd55a80264f *go.tgz"
elif [[ $DESTARCH == "arm64" ]]; then
    URL="https://go.dev/dl/go${GOLANG_VERSION}.linux-arm64.tar.gz"
    CHECKSUM="7ac7b396a691e588c5fb57687759e6c4db84a2a3bbebb0765f4b38e5b1c5b00e *go.tgz"
elif [[ $DESTARCH == "arm" ]]; then
    URL="https://go.dev/dl/go${GOLANG_VERSION}.linux-armv6l.tar.gz"
    CHECKSUM="a80fa43d1f4575fb030adbfbaa94acd860c6847820764eecb06c63b7c103612b *go.tgz"
else
    echo "Unsupported Machine Architecture: $DESTARCH" 1>&2
    exit 1
fi

echo "Downloading Go from \"$URL\". Please wait."

/usr/bin/wget -O go.tgz $URL
echo "$CHECKSUM" | /usr/bin/sha256sum -c -
/bin/rm -rf /usr/local/go
/bin/tar -C /usr/local -xzf go.tgz
/bin/rm go.tgz

/usr/local/go/bin/go version

echo "Done."