#!/bin/sh

# Comments on coding style:
#  * shift mandatory function arguments: Provokes error if missing
#  * quote variables: We want to support oddities like spaces in paths

function preserveolderfile() {
	## DESC: Preserve copy of file, unless one exists already
	# File to tweak
	file="$1"; shift
	# Extension used for new backup
	newext="$1"
	# Space-delimited list of possible extensions, default last
	extensions="orig old"
	for ext in $extensions; do
		backupfile="$file.$ext"
		[ "$ext" = "$newext" ] && newext_valid="yes"
		if [ -f "$backupfile" ]; then
			[ -n "$DEBUG" ] && echo "DEBUG: Backup file \"$backupfile\" not found - continuing." >&2
			continue
		elif [ -e "$backupfile" ]; then
			echo "ERROR: Backup file \"$backupfile\" is not a regular file." >&2
			return 1
		else
			[ -n "$DEBUG" ] && echo "DEBUG: Backup file \"$backupfile\" found - exit silently." >&2
			return 0
		fi
	done
	if [ -n "$newext" ];then
		if [ "$newext_valid" = "yes" ]; then
			backupfile="$file.$newext"
		else
			echo "WARNING: Backup extension \"$newext\" is invalid - using default instead" >&2
		fi
	fi
	if [ -f "$file" ]; then
		cp -p "file" "$backupfile"
	elif [ -e "$file" ]; then
		echo "ERROR: Backup of file \"$file\" failed - not a regular file." >&2
		return 1
	else
		touch "$backupfile"
	fi
	return 0
}

function enableoraddlines() {
	## DESC: Add lines to file, or replace if similar exist already
	# File to tweak
	file="$1"; shift
	# Word number in line to search for and replace if found
	# FIXME: This is broken - wordno unconditionally becomes firstword later on
	wordno="$1"; shift
	[ -e "$file" ] || touch "$file"
	for line; do
		[ -z "$line" ] && continue
		firstword=$(echo "$line" | awk "{print \$$wordno}")
		# FIXME: Why doesn't it work to print ARGVOUT in END block?
		linemissing=$(perl -i -pe "END { print \"$line\\n\" unless \$seen } s¡^[#;\s]*($firstword)\s.*¡$line\\n¡ and \$seen++" "$file")
#"This stray quote is only to please buggy mc (cooledit) code hiliting
		[ -n "$linemissing" ] && echo $linemissing >> "$file"
	done
	# FIXME: Figure out what exits non-zero above
	return 0
}

function preserveandaddlines() {
	## DESC: Backup older file and add lines to it
	# File to tweak
	file="$1"; shift
	# Extension of backup file
	ext="$1"; shift
	# Word number in line to search for and replace if found
	# FIXME: This is broken - wordno unconditionally becomes firstword later on
	wordno="$1"; shift
	preserveolderfile "$file" "$ext"
#	enableoraddlines "$file" "$wordno" $@
	# FIXME: Somehow avoid expansion, to avoid having to duplicate the whole enableoraddlines()
	[ -e "$file" ] || touch "$file"
	for line; do
		[ -z "$line" ] && continue
		firstword=$(echo "$line" | awk "{print \$$wordno}")
		# FIXME: Why doesn't it work to print ARGVOUT in END block?
		linemissing=$(perl -i -pe "END { print \"$line\\n\" unless \$seen } s¡^[#;\s]*($firstword)\s.*¡$line\\n¡ and \$seen++" "$file")
#"This stray quote is only to please buggy mc (cooledit) code hiliting
		[ -n "$linemissing" ] && echo $linemissing >> "$file"
	done
	# FIXME: Figure out what exits non-zero above
	return 0
}

function preserveandhashdisablelines() {
	## DESC: Backup older file and disable lines in it
	# File to tweak
	file="$1"; shift
	# Extension of backup file
	ext="$1"; shift
	# Word number in line to search for and replace if found
	# FIXME: This is broken - wordno unconditionally becomes firstword later on
	wordno="$1"; shift
	preserveolderfile "$file" "$ext"
#	disablelines "$file" "$wordno" "#" $@
	# FIXME: Somehow avoid expansion, to make possibe a separate disablelines()
	[ -e "$file" ] || touch "$file"
	for line; do
		[ -z "$line" ] && continue
		firstword=$(echo "$line" | awk "{print \$$wordno}")
		# FIXME: Why doesn't it work to print ARGVOUT in END block?
		linemissing=$(perl -i -pe "END { print \"$line\\n\" unless \$seen } s¡^(\s*$firstword)\s.*¡#$line\\n¡ and \$seen++" "$file")
#"This stray quote is only to please buggy mc (cooledit) code hiliting
		[ -n "$linemissing" ] && echo >2 "Line \"$linemissing\" not found to disable in $file"
	done
	# FIXME: Figure out what exits non-zero above
	return 0
}

function perlrelines() {
	## DESC: Apply perl regex to lines of a single file
	# File to tweak
	file=$1; shift
	backupfile="`savebackupfile "$file"`"
	for regexp; do
		perl -pi -e "$regexp" "$file"
	done
	cleanbackupfile "$file" "$backupfile"

	# FIXME: Figure out what exits non-zero above
	return 0
}

function mkgrubdevmap() {
	## DESC: Spit out GRUB config used for /boot/grub/devices.map
	device="$1"; shift
	cat <<EOF
(fd0) /dev/fd0
(hd0) $device
EOF
}

function addaddons() {
	context="$1"; shift
	addon_context="$1"; shift
	for addon in $@; do
		context_here="$(eval echo \$\{${addon_context}_$addon\})"
		if [ -n "$context_here" ]; then
			eval ${context}=\"\$${context} \$context_here\"
		else
			echo "Warning: Variable \"${addon_context}_${addon}\" empty or undefined!"
		fi
done
}