in media installation script

install.sh

@@ -7,23 +7,123 @@
 #     type cp file file.bak       #
 ###################################
 
+set -e
+
+VERSION='v0.1.0-beta'
 work_dir=/tmp/bak-old_installation/
+download_url="https://github.com/kevinnls/bak-old/releases/download/${VERSION}/bak-old.sh"
+
+# list of known downloaders and options for download
+declare -A dlers
+dlers[curl]="curl -fsSLO"
+dlers[wget]="wget -q"
+# list of possible destinations for root user
+r_dstdirs=('/usr/local/bin' 
+			'/usr/bin' 
+			'/bin')
+# list of possible destinations for normal user
+u_dstdirs=("$HOME/.local/bin"
+			"$HOME/bin")
+
+declare downloader
+declare dest_dir
 
 debug(){ ### function to call when $DEBUG is set
     set -xv
 }
 
+is_command(){ ### function to check if a command exists
+	{ command -v $1;} >/dev/null && return 0 || return 1
+}
+
+err_no_downloader(){
+	cat <<- EOM
+	$(tput setaf 1; tput bold)ERR: missing dependencies$(tput sgr0)
+
+	required by this installation script:
+	    - wget OR curl
+	install either application using your package manager and try again
+
+	alternatively, you can manually download the file from
+	    $download_url
+	to a directory in your PATH
+
+	EOM
+	exit 1
+}
+err_no_dest_in_path(){
+	cat <<-EOM
+	$(tput setaf 1; tput bold)ERR: no preconfigured destinations are in \
+	your PATH$(tput sgr0)
+	check your PATH variable configuration
+	#or specify the destination with -d
+
+	EOM
+	exit 1
+}
+err_no_home_dir(){
+	cat <<- EOM
+	$(tput setaf 1; tput bold)ERR: user $(whoami) does not have a valid home \
+	directory
+
+	EOM
+	exit 1
+}
+
+find_dler(){
+	for dler in ${!dlers[@]}; do
+		is_command $dler && downloader="${dlers[$dler]}"
+		[[ -n "$downloader" ]] && return
+	done
+
+	[[ -z "$downloader" ]] && err_no_downloader
+}
+
+find_dest_dir(){
+	local user_id=$(id -u)
+	local dirlist
+	if [[ user_id -eq 0 ]]; then
+		dirlist=(${r_dstdirs[@]})
+	elif [[ -d "$HOME" ]]; then
+		dirlist=(${u_dstdirs[@]})
+	else
+		err_no_home_dir
+	fi
+			
+	for dir in ${dirlist[@]}; do
+		if [[ "$PATH" =~ /*:${dir}* ]] || [[ "$PATH" =~ /*${dir}:* ]]; then
+			dest_dir="$dir"
+		fi
+		[[ -n "$dest_dir" ]] && return
+	done
+
+	[[ -z "$dest_dir" ]] && err_no_dest_in_path
+}
+
+setup() {
+	# setup
+	# create temp dir for installation work
+	mkdir -p "$work_dir"
+	cd "$work_dir"
+}
+
+cleanup(){
+	# cleanup
+	cd "$HOME"
+	rm -rf "$work_dir"
+}
+
+install(){
+	setup
+	find_dler
+	echo $downloader
+	find_dest_dir
+	echo $dest_dir
+	cleanup
+}
 
 ### enable debugging if ###
 ${DEBUG+debug}       ###
 ### $DEBUG is set ###
 
-# create dir for installation work
+install
-
-mkdir -p $work_dir
-cd $work_dir
-
-# cleanup
-
-cd $HOME
-rm -rf $work_dir