### -*-bash-*-
###
### Common utilities for rsync-backup scripts
###
### (c) 2014 Mark Wooding
###

###----- Licensing notice ---------------------------------------------------
###
### This file is part of the `rsync-backup' program.
###
### rsync-backup is free software; you can redistribute it and/or modify
### it under the terms of the GNU General Public License as published by
### the Free Software Foundation; either version 2 of the License, or
### (at your option) any later version.
###
### rsync-backup is distributed in the hope that it will be useful,
### but WITHOUT ANY WARRANTY; without even the implied warranty of
### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
### GNU General Public License for more details.
###
### You should have received a copy of the GNU General Public License
### along with rsync-backup; if not, write to the Free Software Foundation,
### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

###--------------------------------------------------------------------------
### Configuration.

VERSION=@VERSION@
pkgdatadir=@pkgdatadir@
mntbkpdir=@mntbkpdir@
logdir=@logdir@
fshashdir=@fshashdir@
conf=@sysconfdir@/rsync-backup.conf

INDEXDB=@pkglocalstatedir@/index.db

SNAPDIR=$mntbkpdir/snap
STOREDIR=$mntbkpdir/store
METADIR=$mntbkpdir/meta

config () {
  echo
  cat <<EOF
conf = $conf
mntbkpdir = $mntbkpdir
fshashdir = $fshashdir
logdir = $logdir
EOF
}

###--------------------------------------------------------------------------
### Date hacking.

parsedate () {
  date=$1
  ## Parse an ISO8601 DATE, and set YEAR, MONTH, DAY appropriately (and
  ## without leading zeros).

  ## Extract the components of the date and trim leading zeros (which will
  ## cause things to be interpreted as octal and fail).
  year=${date%%-*} rest=${date#*-}; month=${rest%%-*} day=${rest#*-}
  year=${year#0} month=${month#0} day=${day#0}
}

julian () {
  date=$1
  ## Convert an ISO8601 DATE to a Julian Day Number.

  parsedate $date

  ## The actual calculation: convert a (proleptic) Gregorian calendar date
  ## into a Julian day number.  This is taken from Wikipedia's page
  ## http://en.wikipedia.org/wiki/Julian_day#Calculation but the commentary
  ## is mine.  The epoch is 4713BC-01-01 (proleptic) Julian, or 4714BC-11-24
  ## proleptic Gregorian.

  ## If the MONTH is January or February then set a = 1, otherwise set a = 0.
  a=$(( (14 - $month)/12 ))

  ## Compute a year offset relative to 4799BC-03-01.  This puts the leap day
  ## as the very last day in a year, which is very convenient.  The offset
  ## here is sufficient to make all y values positive (within the range of
  ## the JDN calendar), and is a multiple of 400, which is the Gregorian
  ## cycle length.
  y=$(( $year + 4800 - $a ))

  ## Compute the offset month number in that year.  These months count from
  ## zero, not one.
  m=$(( $month + 12*$a - 3 ))

  ## Now for the main event.  The (153 m + 2)/5 term is a surprising but
  ## correct trick for obtaining the number of days in the first m months of
  ## the (shifted) year).  The magic offset 32045 is what you get when you
  ## plug the proper JDN epoch (year = -4713, month = 11, day = 24) into the
  ## above machinery.
  jdn=$(( $day + (153*$m + 2)/5 + 365*$y + $y/4 - $y/100 + $y/400 - 32045 ))

  echo $jdn
}

###----- That's all, folks --------------------------------------------------