#! /bin/bash
set -euf -o pipefail
: ${DIR_DLAGENT_DEBUG:=0}

usage() {
	>&2 echo "Usage: $0 dir://dir-spec/path/to/file.txt <output>"
	>&2 echo "Usage: $0 %u %o"
	exit 1
}

debug() {
	if [[ "$DIR_DLAGENT_DEBUG" -gt 0 ]]; then
		>&2 echo "DEBUG: $@"
	fi
}

# TODO: also use other XDG_CONFIG_DIRS
: ${XDG_CONFIG_HOME:=$HOME/.config}
CONFIG=$XDG_CONFIG_HOME/dir-dlagent.conf
if [[ -e "$CONFIG" ]]; then
	source "$CONFIG"
fi

# TODO: check that `dir=()` exists
# TODO: validate ${dir[@]}

if [[ $# -ne 2 ]]; then
	>&2 echo "Error: got $# arguments instead of 2"
	usage
fi

url="$1"
out="$2"
case "$url" in
dir://*)
	base_uri="${url##dir://}"
	debug "base_uri=$base_uri"
	;;
*)
	>&2 echo "Error: url does not start with dir:// : $url"
	exit 1
	;;
esac

case "$base_uri" in
*/*)
	dir_spec="${base_uri%%/*}"
	subpath="${base_uri:${#dir_spec}}"
	subpath="${subpath:1}"
	debug "dir_spec=$dir_spec"
	debug "subpath=$subpath"
	;;
*)
	>&2 echo "Error: url does not contain a dir-spec : $url"
	exit 1
	;;
esac

for e in "${dirs[@]}"; do
	this_base="${e%%::*}"
	this_path="${e:${#this_base}}"
	this_path="${this_path:2}"
	debug "checking map '$e' => '$this_base' :: '$this_path'"
	if [[ "${this_base}" = "${dir_spec}" ]]; then
		src="${this_path}/${subpath}"
		debug "Copying file: '${src}' to '${out}'"
		cp --no-preserve=all "${src}" "${out}" || {
			echo "Error: could not copy file from '${src}' to '${out}'"
			exit 1
		}
		exit 0
	fi
done

>&2 echo "Error: no map found for dir-spec $dir_spec in url $url"
>&2 echo "Note: add 'dirs+=(\"$dir_spec::/my/path/here\")' to $CONFIG to fix"
exit 1