#!/usr/bin/env bash
 
VER="0.10"
DIR=~/wiff
CMD="$(which wdiff) -3" # Show only differences
CURL=$(which curl)
CURLOPT="--globoff"
MD5=$(which md5sum)
INTERACTIVE=true
PAUSE=false
DIFFONLY=false
ISBSD=false
 
# Can't set "-e", diff returns exit code > 0
set +e
 
usage () {
    sed 's/^    //' >&2 << EOF
 
    wiff, version $VER - Save and compare states of web pages.
 
    Usage: $0 [options] file
 
    "file" must contain the list of urls to be compared. When the command runs
    for the first time on an url list, the current state is saved. The following
    runs compare the initial state to the current state.
    The snapshots are stored in $DIR.
 
    Options:
        -c command
            Diff command. Default: $CMD
        -d directory
            Set root directory. Default: $DIR
        -n
            Non-interactive mode. Compares the first snapshot to the latest.
        -o
            Don't download the URLs, just compare two states.
        -p
            Pause (2 sec.) after each download.
        -h
            Show this message.
 
EOF
}
 
ts2date () {
	if $ISBSD; then
		date -j -f "%s" $1 "%a %b %d %T %Z %Y"
	else
		date -d "1970-01-01 $1 sec"
	fi
}
 
while getopts "c:d:noph" OPTION; do
	case $OPTION in
		c)	CMD="$OPTARG"
			;;
		d)	DIR="$OPTARG"
			;;
		n)	INTERACTIVE=false
			;;
		o)	DIFFONLY=true
			;;
		p)	PAUSE=true
			;;
		[h?])
			usage
			exit 1
			;;
	esac
done
 
shift $(($OPTIND - 1))
INPUTFILE=$*
 
# System is BSD?
date --version >/dev/null 2>&1
[ $? -gt 0 ] && ISBSD=true
 
# Check required programs
# md5 for Mac OS X (must run in quiet mode)
[ -z "$MD5" ] && MD5="$(which md5) -q"
if [ -z "$MD5" ] || [ -z "${CMD%% *}" ] || [ -z "${CURL%% *}" ]; then
	echo "Required programs not available" >&2
	exit 4
fi
 
if [ -z "$INPUTFILE" ]; then
	echo "No files specified" >&2
	usage
	exit 2
fi
 
[ ! -d "$DIR" ] && mkdir -p "$DIR"
 
 
if [ ! -r "$INPUTFILE" ]; then
	echo "$INPUTFILE does not exist or is not readable" >&2
	exit 3
fi
FILEHASH=$($MD5 "$INPUTFILE" | tr -d " -") # remove space and dash for OS X md5
FILEHASH=${FILEHASH%%$INPUTFILE} # remove input file name from hash string (md5sum)
HDIR="$DIR/$FILEHASH"
[ ! -d "$HDIR" ] && mkdir "$HDIR"
[ ! -f "$HDIR/$INPUTFILE" ] && cp "$INPUTFILE" "$HDIR"
VERSION=1
while [ -f "$HDIR/$VERSION" ]; do
	VERSION=$(($VERSION + 1))
done
if ! $DIFFONLY; then
	date +%s >"$HDIR/$VERSION"
	for URL in $(cat "$INPUTFILE"); do
		URLHASH=$($MD5 <<<"$URL" | tr -d " -")
		echo "Downloading $URL ..."
		$CURL $CURLOPT "$URL" >"$HDIR/$URLHASH.$VERSION"
		$PAUSE && sleep 2
	done
else
	VERSION=$(($VERSION - 1))
fi
if [ $VERSION -gt 1 ]; then
	if $INTERACTIVE; then
		echo -e "\nSaved versions:\n"
		for ((i=1; i<=${VERSION}; i++)); do
			echo $i  -  $(ts2date $(cat "$HDIR/$i"))
		done
		echo -ne "\nEnter number of version A: [1] "
		read A
		echo -n "Enter number of version B: [${VERSION}] "
		read B
	fi
	[ -z $A ] && A="1";
	[ -z $B ] && B="$VERSION"
	for URL in $(cat "$INPUTFILE"); do
		echo -e "\n$URL\n  - Version A: "$(ts2date $(cat "$HDIR/$A"))"\n  + Version B: "$(ts2date $(cat "$HDIR/$B"))
		URLHASH=$($MD5 <<<"$URL" | tr -d " -")
		$CMD "$HDIR/$URLHASH.$A" "$HDIR/$URLHASH.$B"
	done
fi
 
exit 0