#!/usr/bin/env sh 

TARGETDIR=${GO_TARGET_DIR:="/usr/local/"}

lookup_file() {
	curl -sSL "https://go.dev/dl/?mode=json" |
		jq -r '.[0].files[]
       | select(.os == "'"$GOOS"'")
       | select(.arch == "'"$GOARCH"'")
       | .filename'
}

fetch() {
	local filename
	if [ $GO_VERS == "latest" ]; then
	  filename="$(lookup_file)"
  else
	  filename="$GO_VERS.$GOOS-$GOARCH.tar.gz"
	fi
	[[ -z "$filename" ]] && echo "unable to fetch filename" 1>&2 && return 1
	local path="/tmp/$filename"
	[[ -n "$DOWNLOADS" ]] && [[ -d "$DOWNLOADS" ]] && path="$DOWNLOADS/$filename"
	curl -L "https://go.dev/dl/$filename" -o "$path"
	echo "$path"
}

install_latest_go() {
	local dir="$1" path
	[[ -z "$dir" ]] && dir="$TARGETDIR"
	[[ -z "$dir" ]] && dir="$HOME/.local"
	mkdir -p "$dir" 2>/dev/null
	path="$(fetch)"
	[[ -z "$path" ]] && echo "unable to fetch go tarball" 1>&2 && return 1
	rm -rf "$dir/go" && tar -C "$dir" -xzf "$path"
}

install_latest_go "$@"