#!/bin/bash
display_error() {
	tput sgr0
	tput setaf 1
	echo "ERROR: $1"
	tput sgr0
	exit 1
}

update_profile() {
	[ -f $1 ] || return 1

	cat $1 | grep "$source_line" > /dev/null 2>&1
	if [ $? -ne 0 ]; then
		echo "$source_line" >> $1
	fi
}

check_existing_go() {
	if [ "$GOROOT" == "" ]; then
		echo "No existing Go versions detected"
		return
	fi
	echo "Created profile for existing install of Go at $GOROOT"
	mkdir -p $GVM_DEST/$GVM_NAME/environments &> /dev/null || display_error "Failed to create environment directory"
	mkdir -p $GVM_DEST/$GVM_NAME/pkgsets/system/global &> /dev/null || display_error "Failed to create new package set"
	mkdir -p $GVM_DEST/$GVM_NAME/gos/system &> /dev/null || display_error "Failed to create new Go folder"
	cat << EOF > $GVM_DEST/$GVM_NAME/environments/system
# Automatically generated file. DO NOT EDIT!
export GVM_ROOT; GVM_ROOT="$GVM_DEST/$GVM_NAME"
export gvm_go_name; gvm_go_name="system"
export gvm_pkgset_name; gvm_pkgset_name="global"
export GOROOT; GOROOT="$GOROOT"
export GOPATH; GOPATH="$GVM_DEST/$GVM_NAME/pkgsets/system/global"
export PATH; PATH="$GVM_DEST/$GVM_NAME/pkgsets/system/global:$GOROOT/bin:$GVM_ROOT/bin:\$PATH"
EOF
}

BRANCH=$1
GVM_DEST=$2
if [ "$GVM_DEST" == "" ]; then
	GVM_DEST="$HOME"
	GVM_NAME=".gvm"
else
	GVM_NAME="gvm"
fi

SRC_REPO=https://github.com/moovweb/gvm.git

[ "$GVM_DEST" == "" ] && display_error "No destination specified!"
[ -d $GVM_DEST/$GVM_NAME ] && display_error "Already installed!"
[ -d $GVM_DEST ] || mkdir -p $GVM_DEST > /dev/null 2>&1 || display_error "Failed to create $GVM_DEST"

cd $GVM_DEST && git clone $SRC_REPO $GVM_NAME > /dev/null 2>&1 || 
	display_error "Failed to clone from $SRC_REPO into $GVM_DEST/$GVM_NAME"

if [ "$BRANCH" != "" ]; then
	cd $GVM_DEST/$GVM_NAME && git checkout $BRANCH > /dev/null 2>&1 ||
		display_error "Failed to checkout $BRANCH branch"
fi

mv $GVM_DEST/$GVM_NAME/.git $GVM_DEST/$GVM_NAME/git.bak

if [ "$GVM_NAME" == ".gvm" ]; then
	source_line="[[ -s \"\$HOME/.gvm/scripts/gvm\" ]] && source \"\$HOME/.gvm/scripts/gvm\""
	source_file="\$HOME/.gvm/scripts/gvm"
else
	source_line="[[ -s \"${GVM_DEST}/gvm/scripts/gvm\" ]] && source \"${GVM_DEST}/gvm/scripts/gvm\""
	source_file="${GVM_DEST}/gvm/scripts/gvm"
fi

if [ "`uname`" == "Linux" ]; then
	update_profile $HOME/.bashrc || update_profile $HOME/.bash_profile
elif [ "`uname`" == "Darwin" ]; then
	update_profile $HOME/.profile || update_profile $HOME/.bash_profile
fi

if [ "$?" != "0" ]; then
	echo 'Unable to locate profile settings file'
	echo
	echo " You will have to manually add the following line:"
	echo
	echo "  $source_line"
	echo
fi
echo "export GVM_ROOT=$GVM_DEST/$GVM_NAME" > $GVM_DEST/$GVM_NAME/scripts/gvm
echo ". \$GVM_ROOT/scripts/gvm-default" >> $GVM_DEST/$GVM_NAME/scripts/gvm
check_existing_go
[[ -s "$GVM_DEST/$GVM_NAME/scripts/gvm" ]] && source "$GVM_DEST/$GVM_NAME/scripts/gvm"
echo "Installed GVM v${GVM_VERSION}"
echo
echo "Please restart your terminal session or to get started right away run"
echo " \`source ${source_file}\`"
echo
