#!/bin/bash
## Author: crunchie
## Description: Script to automatically link up certain files in home-directory to pre-built versions.
## 				Backups of currently installed versions are made in a .dtbak-file. 
##				Links the .zshrc, .zshrc-theme and .aliases file to different files depending on whether a linux or mac platform is in use.
##				install routine checks whether .oh-my-zsh exists in users home-folder - and install .oh-my-zsh unattended if not.
##				if .oh-my-zsh is installed the version will be updated to the current version.

# function to check if mac or linux
check_os () {
	which sw_vers > /dev/null 2>&1
	if [ $? == 0 ]; then
		os=mac
	else
		os=linux
	fi
}

# function to unlink symlink or mv original file to dtbak
unlink_mv_file () {
	local file=$1
	if [ -e $file ] || [ -L $file ]; then
		if [ -L $file ]; then
			unlink $file
		fi
		if [ -f $file ]; then
			mv -f $file{,.dtbak}
		fi
	fi
}

# function to check if the file exists in the home directory
# return parameters: 2 = file exists, 3 = file does not exist
check_exist () {
	local file=$1
	if [ -e ~/$file ] || [ -L ~/$file ]; then
		return 2
	else
		return 3
	fi
}

# function to check whether .oh-my-zsh is installed. 
# installation is checked by looking if ~/.oh-my-zsh exists.
check_oh-my-zsh () {
	if [ -d ~/.oh-my-zsh ]; then
		return 2
	else
		return 3
	fi
}

## EXECUTE begins here

# Check whether linux or macos is used
check_os

# Backup dotfiles and link to local versions
for file in $(find ~/dotfiles -maxdepth 1 -name ".*" ! -name ".aliases*" ! -name ".zshrc*" ! -name ".zcompdum*" ! -name ".*history*" -type f  -printf "%f\n" ); do
	check_exist $file
	stat_dot=$?
	if [ $stat_dot == 2 ]; then
		unlink_mv_file ~/$file
		ln -s ~/dotfiles/$file ~/$file
	elif [ $stat_dot == 3 ]; then
		ln -s ~/dotfiles/$file ~/$file
	fi
done

# Unlink or move existing .zshrc config or .zshrc-theme or .aliases file
for file in .zshrc .zshrc-theme .aliases
do
	check_exist $file
	if [ $? == 2 ]; then
		unlink_mv_file ~/$file
	fi
done 

# check if .oh-my-zsh is installed - install if not, update if it is installed.
check_oh-my-zsh
inst=$?
if [ $inst == 3 ]; then
	sh -c "$(curl -fsSL https://raw.githubusercontent.com/ohmyzsh/ohmyzsh/master/tools/install.sh)" "" --unattended
else 
	git -C ~/.oh-my-zsh/ pull
fi

# link the .zshrc-file in home-directory depending on the underlying os
if [ $os == linux ];then
	ln -s ~/dotfiles/.zshrc-linux ~/.zshrc
	ln -s ~/dotfiles/.zshrc-linux-agnoster ~/.zshrc-theme
	ln -s ~/dotfiles/.aliases-linux ~/.aliases
	echo ".zshrc, .zshrc-theme and .aliases linked for linux."
elif [ $os == mac ];then
	ln -s ~/dotfiles/.zshrc-mac ~/.zshrc
	ln -s ~/dotfiles/.zshrc-mac-agnoster ~/.zshrc-theme
	ln -s ~/dotfiles/.aliases-mac ~/.aliases
	echo ".zshrc, .zshrc-theme and .aliases linked for mac"
else
	echo "Unknown OS - no .zshrc, .zshrc-theme or .aliases linked."
fi

echo "Installation done."
touch ~/dotfiles/version.installed
exit 0