#!/bin/bash

# Current version
currentGoVersion=$(go version | cut -f3 -d ' ')
if [ -z "$currentGoVersion" ]; then # Check if it's empty
	echo "Find current Go version: [FAIL]"
	exit 1
else
	echo "Find current Go version: [OK]"
fi

# Find latest version
URL=$(curl -ks https://golang.org/dl/ | grep downloadBox | grep linux-amd64.tar.gz | awk -F 'href="' '{ print $2 }' | cut -f1 -d '"')
if [ -z "$URL" ]; then	# Check if the variable $URL is empty
	echo "Parse latest Go tarball link: [FAIL]"
	exit 1
else
	echo "Parse latest Go tarball link: [OK]"
fi

# Check if the local version is the same as the latest one
if echo "$URL" | grep "$currentGoVersion" &> /dev/null; then
	echo "You have the latest version already installed"
	exit 0
fi

if wget --output-document=latest-go.tar.gz "$URL" &> /dev/null; then
	echo "Download latest Go: [OK]"
else
	echo "Download latest Go: [FAIL]"
	exit 1
fi

# Uninstall the current Go
if sudo rm -rf /usr/local/go &> /dev/null; then
	echo "Uninstall current Go: [OK]"
else
	echo "Uninstall current Go: [FAIL]"
	exit 1
fi

# Install
if sudo tar -C /usr/local -xzf latest-go.tar.gz &> /dev/null; then
	echo "Install latest Go: [OK]"
else
	echo "Install latest Go: [FAIL]"
	exit 1
fi

# Cleanup
if rm latest-go.tar.gz &> /dev/null; then
	echo "Clean temporary files: [OK]"
else
	echo "Clean temporary files: [FAIL]"
	exit 1
fi