#!/usr/local/bin/bash
#
# License: CC0-1.0
#
#  Usage:
#
#    $ tball /path/to/tball-info.txt
#
#

parse_opts() {
    export TBFILE=$1
    if [ -z $TBFILE ]; then
        echo 'Info file not passed! Exiting.'
        exit 1
    fi
    if [ ! -f $TBFILE ]; then
        echo $TBFILE 'does not exist! Exiting.'
        exit 1
    fi
}

parse_src() {
    if [ ! -d $1 ] && [ ! -f $1 ]; then
        echo 'Source "'$1'" does not exists'
        exit 1
    fi

    return 0
}

parse_bdest() {
    if [ ! -d $1 ]; then
        echo 'Making '$1' ...'
        mkdir -p $1
        [[ $? == 1 ]] && exit 1
    fi

    return 0
}

setup_dest() {
    export DEST=$1/$2

    if [ ! -d $DEST ]; then
        echo 'Making '$DEST' ...'
        mkdir -p $DEST
        [[ $? == 1 ]] && exit 1
    fi
}

clean_tmp() {
    echo 'Cleaning up... '$1
    rm -rf $1
}

file_updated() {
    local SRC=$1
    local DEST=$2

    # Get modified time for file
    local FTIME=$(stat -r $SRC | cut -d ' ' -f 10)

    # Get the last time source was tballed.
    local TBALLT=$(find $DEST -type f -name '.suffixes' -exec cat '{}' \; \
                 | tail -n 1)
    [[ -z $TBALLT ]] && return 1 # source not tballed at all.

    # Check if file was updated after the last tball.
    [[ $FTIME -gt $TBALLT ]] && return 1

    return 0
}

dir_updated() {
    local SRC=$1
    local DEST=$2

    # Get file that was last modified in this directory.
    local F=$(find $SRC -type f -exec stat -r '{}' \; \
          | sort -r -k 10 | head -n 1 | cut -d ' ' -f 15);

    return $(file_updated $F $DEST)
}

should_tb() {
    local SRC=$1
    local DEST=$2

    # Get the number of tballs that exists
    local TBALLS=$(find $DEST -type f -name '*.tar.gz' | wc -l)
    [[ $TBALLS == 0 ]] && return 1

    if [ -d $SRC ]; then
        # Check if any files under this directory was modified <= 24hrs
        return $(dir_updated $SRC $DEST)
    else
        return $(file_updated $SRC $DEST)
    fi
}

parse_maxtb() {
    local MAX=$1

    if [ -z $MAX ]; then
        echo 10
    else
        echo $MAX
    fi
}

rm_file() {
    local F=$1

    if [ ! -f $F ]; then
        echo 'File not found: Cannot remove '$F
        return 0
    fi

    # Remove file.
    echo 'Removing '$F'...'
    rm $F && return 0

    return 1 # rm failed
}

clean_ol_tbs() {
    local D=$1
    local S=$1/.suffixes
    local MAX=$2 # TODO: check MAX's value.

    # Check if suffixes file exists.
    if [ ! -f $S ]; then
        echo 'Cannot remove old tballs at '$1 \
             ': .suffixes not found'
        return 0
    fi

    # Get total timestamps.
    local TOTT=$(wc -l $S | sed  -E 's/^ +//' | cut -f 1 -d ' ')

    if [ $TOTT -lt $MAX ]; then
        echo 'No old tballs to clean up [0]'
        return 0
    fi

    # Get number of timestamps to remove.
    local RM=$(($TOTT-$MAX))
    if [ $RM -lt 1 ]; then
        echo 'No old tballs to clean up [1]'
        return 0
    fi

    # Make temp dir.
    local TMP_DIR=$(mktemp -d /tmp/clean_tb.XXXXXX)
    [[ $? == 1 ]] && exit 1

    # Get timestamps to remove.
    local RMT=$TMP_DIR/rmt
    $(head -n $RM $S > $RMT)
    [[ $? == 1 ]] && exit 1

    # Get timestamps to keep.
    local KT=$TMP_DIR/kt
    $(tail -n $MAX $S > $KT)
    [[ $? == 1 ]] && exit 1

    # Get basename.
    local BN=$(basename $D)

    echo 'Removing old tballs...'
    while read -r ts; do
        rm_file $D/$BN.$ts.tar.xz
    done <$RMT

    # Update suffixes
    mv $KT $S
    [[ $? == 1 ]] && exit 1

    # Clean up tmp dir.
    rm -rf $TMP_DIR

    return 0
}

tb() {
    local SRC=${1/#\~/$HOME}
    local BDEST=${2/#\~/$HOME}
    local MAX_TB=$(parse_maxtb $3) # Maximum tballs for a BDEST.

    parse_src $SRC
    parse_bdest $BDEST

    # Get basename.
    local BN=$(basename $SRC)

    # Setup destination dir.
    setup_dest $BDEST $BN

    # Check if source needs to be tballed
    should_tb $SRC $DEST
    [[ $? == 0 ]] && \
        echo $SRC 'is good! Not tballing it' \
        && clean_ol_tbs $DEST $MAX_TB \
        && return 0

    # SUFFIX (current unix time)
    local SUFFIX=$(date '+%s')

    # Make temp dir.
    local TMP_DIR=$(mktemp -d /tmp/tball.XXXXXX)
    [[ $? == 1 ]] && exit 1

    # Make ball name
    local BALL=$TMP_DIR/$BN.$SUFFIX.tar
    local FLIST=$TMP_DIR/files

    # Make ball.
    echo 'Making '$BALL'.xz...'
    if [ ${SRC: -6} == 'tar.xz' ]; then
        cp $SRC $BALL # SRC is already a tar ball
    else
        find $SRC -type f > $FLIST \
            && tar cvf $BALL -I $FLIST && xz $BALL
    fi
    [[ $? == 1 ]] && clean_tmp $TMP_DIR && exit 1

    # Drop ball in destination.
    echo 'rsyncing '$BALL'.xz to '$DEST'...'
    rsync $BALL.xz $DEST
    [[ $? == 1 ]] && clean_tmp $TMP_DIR && exit 1

    # Store suffix
    echo $SUFFIX >> $DEST/.suffixes

    # Clean up ol' tballs.
    clean_ol_tbs $DEST $MAX_TB

    # Clean up
    clean_tmp $TMP_DIR
    unset DEST
}

parse_opts $1

# Tarball 'em all up
while read -r line; do
    tb $line
done <$TBFILE