#!/bin/sh

root=$( realpath "$( dirname "$0" )" )
direction=$1

ALIAS="$root/alias"
EXCLUDES="$root/excludes"
DOTEXCLUDES="$root/.excludes"
FILES="$root/files"
USERS="$root/users"
RSYNC="rsync -a -s --progress --delete"
LOCAL="storage"

host_name() {
	local host=$1

	local alias_path="$ALIAS/$host"

	if [ -f "$alias_path" ]
	then
		cat "$alias_path"
	else
		echo "$host"
	fi
}

host_prefix() {
	local host=$1

	local hostname=$( hostname )
	local user_path="$USERS/$host.txt"
	local user

	for local in $LOCAL
	do
		if [ "$host" = "$local" ]
		then
			return
		fi
	done

	if [ "$host" = "$hostname" ]
	then
		return
	fi

	if [ -f "$user_path" ]
	then
		user=$( cat "$user_path" )

		echo "$user@$host:"
	else
		echo "$host:"
	fi
}

host_files_list() {
	local host=$1
	local qualifier=$2

	local host_files_path="$FILES/$host.txt"
	local qualifier_host_files_path="$FILES/$qualifier/$host.txt"
	local descriptor

	if [ -f "$host_files_path" ]
	then
		cat "$host_files_path" | while read descriptor
		do
			eval echo "$descriptor"
		done
	fi

	if [ -f "$qualifier_host_files_path" ]
	then
		cat "$qualifier_host_files_path" | while read descriptor
		do
			eval echo "$descriptor"
		done
	fi
}

host_file_path() {
	local host_file_descriptor=$1

	echo "$host_file_descriptor" | sed "s,:.*,,"
}

host_file_name() {
	local host_file_descriptor=$1
	shift

	local host_file_suffix=$( echo "$host_file_descriptor" | sed -n "s,.*:\(.*\)$,\1,p" )
	local host_file_name
	local test=$@

	if [ -z "$host_file_suffix" ]
	then
		host_file_name=$( basename "$host_file_descriptor" )
	else
		host_file_name=$host_file_suffix
	fi

	if [ -z "$test" ]
	then
		echo "$host_file_name"
		return
	fi

	for name in "$@"
	do
		if [ "$host_file_name" = "$name" ]
		then
			echo "$name"
		fi
	done
}

host_file_match() {
	local destination=$1
	local source_file_name=$2

	local descriptor
	local name

	host_files_list "$destination" "destination" | while read descriptor
	do
		name=$( host_file_name "$descriptor" )

		if [ "$source_file_name" = "$name" ]
		then
			echo "$descriptor"
		fi
	done
}

host_excludes() {
	local host=$1
	local name=$2

	local excludes_path="$EXCLUDES/$name.txt"
	local host_excludes_path="$EXCLUDES/$host/$name.txt"

	if [ -f "$excludes_path" ]
	then
		cat "$excludes_path"
	fi

	if [ -f "$host_excludes_path" ]
	then
		cat "$host_excludes_path"
	fi
}

usage() {
	printf "$0 [source] [destination] (names)\n" >&2
}

sync() {
	local source=$1
	shift
	local destination=$1
	shift

	local source_prefix
	local source_path
	local destination_prefix
	local destination_path
	local descriptor
	local name
	local match
	local dry
	local dry_description

	set -e

	if [ -z "$source" ] || [ -z "$destination" ]
	then
		usage
		exit 1
	fi

	source_name=$( host_name "$source" )
	destination_name=$( host_name "$destination" )

	source_prefix=$( host_prefix "$source" )
	destination_prefix=$( host_prefix "$destination" )

	host_files_list "$source_name" "source" | while read descriptor
	do
		name=$( host_file_name "$descriptor" "$@" )
		if [ -z "$name" ]
		then
			continue
		fi

		match=$( host_file_match "$destination_name" "$name" )
		if [ -z "$match" ]
		then
			continue
		fi

		if [ -n "$DRY" ]
		then
			dry="--dry-run"
			dry_description=" \e[1;31m(dry run)\e[0m"
		fi

		source_path=$( host_file_path "$descriptor" )
		destination_path=$( host_file_path "$match" )

		echo -n "" > "$DOTEXCLUDES"
		host_excludes "$destination_name" "$name" >> "$DOTEXCLUDES"
		host_excludes "$source_name" "$name" >> "$DOTEXCLUDES"

		echo -e "Sync \e[1;34m$name\e[0m from \e[1;33m$source\e[0m to \e[1;33m$destination\e[0m$dry_description"

		$RSYNC $dry --exclude-from="$DOTEXCLUDES" "$source_prefix$source_path" "$destination_prefix$destination_path"

		rm "$DOTEXCLUDES"
	done
}

sync "$@"