#!/bin/bash
# I, Ian Kelling, follow the GNU license recommendations at
# https://www.gnu.org/licenses/license-recommendations.en.html. They
# recommend that small programs, < 300 lines, be licensed under the
# Apache License 2.0. This file contains or is part of one or more small
# programs. If a small program grows beyond 300 lines, I plan to switch
# its license to GPL.

# Copyright 2024 Ian Kelling

# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at

#     http://www.apache.org/licenses/LICENSE-2.0

# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.


# usage: no args, run to install latest go.

if [ -z "$BASH_VERSION" ]; then echo "error: shell is not bash" >&2; exit 1; fi

shopt -s inherit_errexit 2>/dev/null ||: # ignore fail in bash < 4.4
source /usr/local/lib/bash-bear

force=false
case $1 in
  -f) force=true ;;
esac

m() { printf "$pre %s\n"  "$*"; "$@"; }
e() { printf "$pre %s\n"  "$*"; }
err() { echo "[$(date +'%Y-%m-%d %H:%M:%S%z')]: $0: $*" >&2; }


if [[ ! -d /a/opt/go.git ]]; then
  mkdir -p /a/opt
  cd /a/opt
  git clone --bare https://go.googlesource.com/go
fi

m cd /a/opt/go.git

up=true
install=false

if ! $force; then
  yesterday=$(( $(date +%s) - 60*60*24 ))
  # no need to check for updates on go more than once a day
  if (( $(stat -c %Y FETCH_HEAD) > yesterday )); then
    up=false
  fi

  # update will get overwritten if we dont do it on central host.
  if [[ -e /a/bin/bash_unpublished/source-state ]]; then
    source /a/bin/bash_unpublished/source-state
    if [[ $HOSTNAME != "$HOST2" ]]; then
      up=false
    fi
  fi
fi

shopt -s nullglob

f=$(
  for f in go*.tar.gz; do
    echo $f
  done | sort -Vr | head -n1
 )
if [[ ! $f ]]; then
  up=true
fi

if $up; then
  m git fetch --tags
  mkdir -p ~/.local
  touch ~/.local/gofetch

  vers=($(git tag | sort -Vr | grep -E '^go[0-9.]+$' | head))

  ver=${vers[0]}
  dl() {
    arch=$(dpkg --print-architecture)
    f=${ver}.linux-${arch}.tar.gz
    if [[ -e $f ]]; then
      timestamp=$(stat -c %Y $f)
    else
      timestamp=0
    fi
    m wget -nv -N https://dl.google.com/go/$f || ret=$?
  }
  dl
  # 8 is return code for 404. for a new release, they might not have a binary out yet
  if [[ $ret == 8 ]]; then
    ver=${vers[1]}
    dl
  fi

  new_timestamp=$(stat -c %Y $f)
  if [[ $timestamp != $new_timestamp ]]; then
    install=true
  fi
fi

if $install || [[  ! -e /usr/local/go/bin/go ]]; then
  m sudo rm -rf /usr/local/go
  m sudo tar -C /usr/local -xzf $f
fi

for x in go*.tar.gz; do
  if [[ $x == $f ]]; then continue; fi
  rm -fv $x
done