#!/bin/bash

# Environments
LAPTOP="laptop"
DESKTOP="desk"
ENV_EXT_REGEXP=".*\.${LAPTOP}|.*\.${DESKTOP}"

# Special filename for external config path
DEST_FILENAME="dest"

# Special configuration filename
BASE_CONFIG="config_common"
MERGE_CONFIG_FOLDER="config.d"
FINAL_CONFIG="config"

# Special directories with per-environment configuration merge
I3_CONFIG="i3"
POLYBAR_CONFIG="polybar"
ARCH_PACKAGES="bootstrap"
MERGE_DIRS="${I3_CONFIG} ${POLYBAR_CONFIG} ${ARCH_PACKAGES}"

# Check if a file has been modified and deleted since last commit, if so perform an action
# $1 : path of file
# $2 : command to launch if file has been created of modifed
# $3 : command to launch if file has been deleted
function check_copy() {
	# When initializing, always copy files
	if [ ! -z ${INIT} ]; then
		echo -e "* Running \"$2\"" && eval "$2"
		return
	fi
	echo "$changed_files" | grep --quiet "${1#$HOME/}"
	if [ $? == "0" ]; then
		echo "$changed_files" | cut -f 1 | grep --quiet "D"
		if [ $? == "0" ]; then
			echo "* $1 has been removed"
			echo -e "\t* Running \"$3\"" && eval "$3"
		else
			echo "* Changes detected in $1"
			echo -e "* Running \"$2\"" && eval "$2"
		fi
	else
		echo "$1 not modified, no need to copy"
	fi
}

# Generates a `config` file in $1, by merging a required $1/{MERGE_CONFIG_FOLDER} file
# with an optional `$1/config.d/$2` file. This is useful for having
# a common base for multiple computer, and per-computer stuff.
# $1 : path of the folder 
# $2 : optional current environment
function merge_config() {
	echo -e "\n=== Generate ${m} config file ==="
	rm -f ${CONFIG}/${m}/${FINAL_CONFIG}
	# Copy common config
	cp ${CONFIG}/${m}/${BASE_CONFIG} ${CONFIG}/${m}/${FINAL_CONFIG}
	echo "${CONFIG}/${m}/${FINAL_CONFIG} created"
	# If there is an override folder, merge given env
	if [ ! -z ${2} ] && [ -d ${CONFIG}/${m}/${MERGE_CONFIG_FOLDER} ]; then
		for f in `find ${CONFIG}/${m}/config.d -type f -path "*${2}"`; do
			echo "Found ${f}, add to regular config file"
			cat "${f}" >> ${CONFIG}/${m}/${FINAL_CONFIG}
		done
	fi
}

function usage() {
	echo "${0}: manage package installation, environment divergence and external location for config, see README."
	echo "usage: [WM_RESTART=1] [INIT=1] $0 [${ENVIRONMENTS}]"
	exit 0
}

# Use XDG_CONFIG_HOME if defined, default otherwise
CONFIG=${XDG_CONFIG_HOME:-$HOME/.config}

ENV=${1}

changed_files="$(git --git-dir=$HOME/.cfg/ --work-tree=$HOME diff-tree -r --name-status --no-commit-id HEAD^1 HEAD)"

for m in ${MERGE_DIRS}; do
	merge_config $m ${ENV}
done

if [ ! -z "$INIT" ]; then
	echo -e "* Installing base Arch packages..."
	yay -Syu --needed --noconfirm - < ${CONFIG}/${ARCH_PACKAGES}/${FINAL_CONFIG}
	echo -e "* Changing shell to ZSH..."
	chsh -s $(which zsh)
	# https://man.archlinux.org/man/rofi-dmenu.5
	echo -e "* Symlink dmenu → rofi..."
	sudo ln -s /usr/bin/rofi /usr/bin/dmenu
	echo -e "* Enabling NetworkManager..."
	sudo systemctl enable --now NetworkManager
	# So that "Open in Terminal" works in Nemo
	gsettings set org.cinnamon.desktop.default-applications.terminal exec i3-sensible-terminal
fi

if [ ! -z ${ENV} ]; then
	echo -e "\n=== Create symlink to *.${ENV} regular files ==="
	# Take all specific files and create a symlink pointing to it without the extension
	# This file will be used by applications
	for f in `find ${CONFIG} -type f -name "*.${ENV}"`; do
		echo "${f%.*} → ${f}"
		ln -sf ${f} ${f%.*}
	done
	# Take care of config files at home level, outside ${CONFIG} (e.g. Xresources)
	for f in `find ${HOME} -maxdepth 1 -mindepth 1 -type f -name "*.${ENV}"`; do
		echo "${f%.*} → ${f}"
		ln -sf ${f} ${f%.*}
	done
fi

echo -e "\n=== Copy changed configuration which resides in outer directory ==="
# Destination files are regular files
for f in `find ${CONFIG} -type f -name ${DEST_FILENAME}`; do
	DIR=`dirname "${f}"`
	DEST=`cat ${f}`
	# Get all files, either regular files or symlinks, which are not the destination file nor specific desktop/laptop files
	# This is because if desktop/laptop files exist, they already have a symlink pointing to them at this stage
	for config_file in `find ${DIR} -regextype emacs -mindepth 1 -type f -not \( -regex "*.${ENV_EXT_REGEXP}" -o -name "${DEST_FILENAME}" \)`; do
		# Now copy to destination
                sudo mkdir -p ${DEST}
		check_copy "${config_file}" "sudo cp ${config_file} ${DEST}" "sudo rm ${DEST}/${config_file##*/}"
	done
done

if [ ! -z "${WM_RESTART}" ]; then
	echo -e "\n=== Restart graphical environment ==="
	# Reload i3 configuration
	i3-msg reload

	# Restart picom due to this bug https://github.com/yshui/picom/issues/166
	killall picom; picom &>/dev/null &
fi