#!/bin/bash

set -e
if [ ${EUID} -ne 0 ]; then
  echo "error: this script must be run as root" 1>&2
  exit 1
fi

INSTALL="/usr/local"
GITHUB="https://github.com/golang/go/archive"

V14="go1.4.3"
bootstrap="${INSTALL}/bootstrap-${V14}"
TGZ14="${V14}.tar.gz"

Vnew="go1.8"
TGZnew="${Vnew}.tar.gz"

rm -rf ${INSTALL}/go*

if [ ! -d "${bootstrap}" ]; then
  wget -q ${GITHUB}/${TGZ14} -O ${INSTALL}/${TGZ14}
  tar xfz ${INSTALL}/${TGZ14} -C ${INSTALL}
  mv ${INSTALL}/go-${V14} ${bootstrap}
fi

wget -q ${GITHUB}/${TGZnew} -O ${INSTALL}/${TGZnew}
tar xfz ${INSTALL}/${TGZnew} -C ${INSTALL}
mv ${INSTALL}/go-${Vnew} ${INSTALL}/${Vnew}

export CGO_ENABLED=0

if [ ! -x "${bootstrap}/bin/go" ]; then
  cd ${bootstrap}/src
  ./make.bash &> /dev/null
fi

export GOROOT_BOOTSTRAP=${bootstrap}

if [ "$(uname -m)" == "x86_64" ]; then
  export GOARCH=amd64
else
  export GOARCH=386
fi

cd ${INSTALL}/${Vnew}/src
./make.bash &> /dev/null

rm -rf ${INSTALL}/go
mv ${INSTALL}/${Vnew} ${INSTALL}/go
#ln -s ${INSTALL}/go ${INSTALL}/${Vnew}

export GOROOT=${INSTALL}/go
export PATH=${PATH}:${GOROOT}/bin:~/go/bin

cat <<EOF
add this to your .bashrc/.profile:

export CGO_ENABLED=${CGO_ENABLED}
export GOPATH=~/go
export GOROOT=${GOROOT}
export PATH=\${PATH}:${GOROOT}:~/go/bin

EOF

go version