#!/bin/bash

if [ -z "$1" ]; then
    echo "No filename to archive provided"
    exit 1
elif [ -z "$2" ]; then
    echo "No archive directory path provided"
    exit 2
fi

FILENAME="${1}"
ARCHIVEDIR="${2}"

if [ ! -z "$3" ]; then
    # Alternative archive filename was provided
    FILE="${3}"
fi

if [ ! -e $FILENAME ]; then
    echo "$FILENAME does not exist, exiting"
    exit 3
elif [ ! -e $ARCHIVEDIR ]; then
    mkdir -p $ARCHIVEDIR
    echo "Created $ARCHIVEDIR"
fi

DATETIME=$(stat -c %Y $FILENAME)

if [ -e "$ARCHIVEDIR/timestamp.txt" ]; then
    PREV_DATETIME=$(cat "$ARCHIVEDIR/timestamp.txt")
else
    PREV_DATETIME=0
fi

if [ $DATETIME != $PREV_DATETIME ]; then
    # Archive the file
    if [ -z $FILE ]; then
        FILE=$(basename $FILENAME)
    fi
    TARGETFILE="${ARCHIVEDIR}/${HOSTNAME}_${DATETIME}_${FILE}"
    if [ ! -e "${TARGETFILE}" ] && [ ! -e "${TARGETFILE}.gz" ]; then
        # Only copy if archived version doesn't exist yet
        cp -a $FILENAME "${TARGETFILE}"
        gzip -9 "${TARGETFILE}"
    fi
    echo $DATETIME > "$ARCHIVEDIR/timestamp.txt"
fi