#!/bin/bash

if [ -z "$1" ]; then
	echo "Usage: ${0##*/} FILES..."
	exit 1
fi


# mtime threshold in seconds for safety
MTIME_DIFF_MAX=$(( 60 * 60 * 24 ))
DATE_FORMAT="%Y%m%d_%H%M%S"


while [[ -n $1 ]]; do
	fdir=`dirname "$1"`
	fname=`basename "$1"`

	# output from date +"%s" is assumed to be at least 10 digits
	mtime=`echo "$fname" | grep -o '\.[0-9]\{10\}' | cut -b2-`
	[[ -z $mtime ]] && {
		shift && continue
	}
	[[ `echo "$mtime" | wc -l` -gt 1 ]] && {
		echo "${0##*/}: ambigious name: '$1'" >&2
		shift && continue
	}

	mtime_real=`stat -c '%Y' "$1"`
	mtime_diff=$(($mtime - $mtime_real))

	# abs()
	[[ $mtime_diff -lt 0 ]] && mtime_diff=$(( -$mtime_diff ))

	[[ $mtime_diff -gt $MTIME_DIFF_MAX ]] && {
		echo "${0##*/}: real mtime differs too much: '$1'" >&2
		shift && continue
	}

	mdate=`date +"$DATE_FORMAT" -d "@$mtime"`
	# sed may need some escaping here
	fname=`echo "$fname" | sed "s/$mtime/$mdate/"`
	mv "$1" "$fdir/$fname"

	shift
done