#!/usr/bin/env bash
#
# variables.
#
# Copyright 2015 - 2019 Einhard Leichtfuß
#
# This file is part of rsync-backup.
#
# rsync-backup is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published
# by the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# rsync-backup is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with rsync-backup.  If not, see <https://www.gnu.org/licenses/>.
#


## CONSTANTS
typeset -r CONFIG=/etc/rsync-backup/config

typeset -r RET_TYPES='
	RET_SUCCESS RET_FAILURE RET_BADSYNTAX RET_FILE_ERR RET_ERROR'
typeset -r RET_SUCCESS=0
typeset -r RET_FAILURE=1
typeset -r RET_BADSYNTAX=2
typeset -r RET_FILE_ERR=4
typeset -r RET_ERROR=8

typeset -r DATEFMT='%Y-%m-%d_%H%M%S'

# Shell options:
#   nullglob: In case of a non-matching glob, return nothing.
#   dotglob:  Include dotfiles (except . and ..) in glob matching.
typeset -r SHOPTS='dotglob'
typeset -r SHOPTS_AFTER_GET_ARGS='nullglob'

# Always give these variables and functions to remotely executed commands,
# as they are very commonly used.
# These will not be listed as required.
# Note that $host is given as argument to run_function.
typeset -r REMOTE_DEFAULT_VARS="$RET_TYPES verbose debug host"
typeset -r REMOTE_DEFAULT_FUNS='prefixed_write message debug error
                                debug_error'


## Global program variables.
typeset src  src_path  src_host
typeset dest dest_path dest_host
typeset -a filter_args
typeset -i n


## Variables that may be configured.
typeset RSYNC=rsync

typeset verbose=true
typeset debug=true

# Location to put mirrored trees on the source.
typeset src_mirror_reldir='.backup'

typeset -a rsync_base_args
typeset -a rsync_mirror_args
typeset -a rsync_transfer_args
typeset -A bakpath
typeset -A filter_file
typeset filter_file_all			# Applied after specific filter.

# Base arguments for rsync (-rptogAXlHS, --timeout=, --numeric-ids, --info=).
# These are used both for creation of the source mirror and the transfer of
# that mirror to the destination.  In both cases, attributes may be added.
rsync_args=(
	--recursive
	--perms --times --owner --group
	--acls --xattrs
	--links
	--hard-links
	--sparse
	--numeric-ids
	--timeout=60
	#-vv
	--info=progress2
	)

source "$CONFIG"


# Set the globabl variables $src, $dest_path and $filter_args according to
# command line parameters and the configuration.
#
# $@: command line parameters
#
# requires the shell option nullglob to be _unset_.  (for test -v to work)
#
function get_args
{
	if [ $# -eq 0 ]
	then
		message "Usage: $exec_name <src> [<dest>]" 2>&1
		return $RET_BADSYNTAX
	fi

	local l_src="$1"
	local l_dest

	# Set $src_path, $src_host and $src.
	resolve_host_path src "$l_src" || return $?

	if [ $# -gt 1 ]
	then
		l_dest="$2"
	elif [[ -v bakpath[$src] ]]		# $# -eq 1
	then
		l_dest="${bakpath[$src]}"
	else
		error "Backup path for \"$src\" neither configured" \
			"nor specified on command line."

		return $RET_BADSYNTAX
	fi

	# Set $dest_path, $dest_host and $dest.
	resolve_host_path dest "$l_dest" || return $?

	filter_args=()
	if [[ -v filter_file[$src] && -f "${filter_file[$src]}" ]]
	then
		filter_args+=("--filter=merge ${filter_file[$src]}")
	fi
	if [[ -v filter_file_all && -f "$filter_file_all" ]]
	then
		filter_args+=("--filter=merge ${filter_file_all}")
	fi

	return $RET_SUCCESS
}


# Split host:target like rsync and convert local (!) relative paths to
# absolute ones.  This is needed at least for $src_path which is used as
# key for associative arrays.
#
# The results are written to the global variables $<vtype>, $<vtype>_host
# and $<vtype>_path, where <vtype> is either src or dest.  $<vtype> gets
# set to the original to be resolved string, unless we are local, i.e.
# there is no host.
#
# Note: This is not a place for bash to shine.  Perl for instance would do
#       this much more easily.
#
# Examples:
# - a:b -> (a, b)
# - a/b:c -> ('', a/b:c)
#
# $1: which global variables to set: (src|dest)
# $2: path string potentially containing host prefix
#
# sets: ${$1}_host: host name (may be empty)
#       ${$1}_path: path (absolute, if local, i.e. ${$1}_host='')
#       ${$1}:      ${$1}_path,                   if ${$1}_host='',
#                   ${$1}_host:${$1}_path (= $2), elsewise.
#
function resolve_host_path
{
	local vtype="$1"
	local combined="$2"
	local host path

	# Split host and path.
	host=${combined%%:*}
	if [[ "$host" == "$combined" || "$host" =~ '/' ]]
	then
		host=''
		path="$combined"

		# Resolve to absolute directory.
		# pwd -P avoids symlinks.
		# Do not resolve symlimks in ${path} or test for its existance.
		#  `- realpath could do that.
		if ! [[ "$path" =~ / ]]
		then
			path="$(pwd -P)/${path}"
		fi

		combined="$path"
	else
		path="${combined#*:}"
	fi

	# Set global variables.
	if [[ "$vtype" == 'src' ]]
	then
		src_host="$host"
		src_path="$path"
		src="$combined"
	else # "$vtype" == 'dest'
		dest_host="$host"
		dest_path="$path"
		dest="$combined"
	fi

	return $RET_SUCCESS
}

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