#! /usr/bin/env perl

# dbs_empty - erases any data from a given SQL database

# Copyright (C) 1999-2012 Stefan Hornburg

# Author: Stefan Hornburg (Racke) <racke@linuxia.de>
# Maintainer: Stefan Hornburg (Racke) <racke@linuxia.de>
# Version: 0.19

# This file 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, or (at your option) any
# later version.

# This file 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 this file; see the file COPYING.  If not, write to the Free
# Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.

use strict;
use warnings;

use DBIx::Easy;
use Getopt::Long;
use Term::ReadKey;

# process commandline parameters
my %opts;
my $whandler = $SIG{__WARN__};
$SIG{__WARN__} = sub {print STDERR "$0: @_";};
unless (GetOptions (\%opts, 'exclude-matching-tables=s', 'tables|t')) {
    exit 1;
}
$SIG{__WARN__} = $whandler;

# sanity check on commandline parameters
if (exists $opts{'exclude-matching-tables'}) {
    eval {'' =~ /$opts{'exclude-matching-tables'}/;};
    if ($@) {
        $@ =~ s%at /.*$%%;
        die "$0: $@";
    }
}

my $dbif;
my $pwdused = 0;

my ($driver, $database, $user) = @ARGV;
$dbif = new DBIx::Easy ($driver, $database, $user);

# handler for DBI error messages and missing password
$dbif -> install_handler (\&fatal);

# we need to explicitly establish the connection
# for the case that a password is needed
$dbif -> connect;

my %fieldmap;

my ($sth, $keyfield, $update);
my ($table, $key, $fieldnames, @values, $headline);
my (@columns, $routine);

for ($dbif->tables) {
    # skip tables preserved by user
    if (exists $opts{'exclude-matching-tables'}) {
        next if $table =~ /$opts{'exclude-matching-tables'}/;
    }

    if ($opts{'tables'}) {
        # remove table from database
        $dbif -> process ("DROP TABLE $_");
    } else {
        # empty table
        $dbif -> process ("DELETE FROM $_ WHERE 1 = 1");
    }    
}

# ensures commit 
undef $dbif;

# -----------------------------------
# FUNCTION: fatal
#
# Error handler called by DBIx::Easy.
# -----------------------------------

sub fatal {
  my ($statement, $err, $msg) = @_;
  my $pwd;

  if ($dbif->is_auth_error ($err)) {
    unless ($pwdused) {
      print "We need a password.\n";
      $pwd = querypwd();
      $pwdused = 1;
    
      # retry the connection
      if (length ($pwd)) {
        $dbif = new DBIx::Easy ($driver, $database, $user, $pwd);
        $dbif -> install_handler (\&fatal);
        $dbif -> connect ();
        return;
      } else {
        die ("$statement: $msg.\n");
      }
    }
  }
  die ("$statement: $msg.\n");
}

# ----------------------------
# FUNCTION: querypwd
#
# Queries user for a password.
# ----------------------------

sub querypwd () {
  my $pwd;

  print "Password: ";
  ReadMode ('noecho');  # turn echo off
  $pwd = ReadLine (0);
  ReadMode ('restore'); # restore terminal
  print "\n";
  chomp ($pwd);
  $pwd;
}

# script documentation (POD style)

=head1 NAME

dbs_empty - Empty SQL Databases

=head1 DESCRIPTION

dbs_empty is an utility that B<completely erases> any data from
a given SQL database.

=head1 COMMAND LINE PARAMETERS

Required command line parameters are the DBI driver
(C<Pg> for Postgres or C<mysql> for MySQL)
and the database name. The third parameter is optionally
and specifies the database user and/or the host where the
database resides (C<racke>, C<racke@linuxia.de> or C<@linuxia.de>).

=head1 COMMAND LINE OPTIONS

=head2 B<--exclude-matching-tables>=REGEXP

Excludes any table matching the regular expression REGEXP from dumping.

=head2 B<-t, --tables>

Remove tables from database too.

=head1 AUTHOR

Stefan Hornburg (Racke), racke@linuxia.de

=head1 SEE ALSO

perl(1), DBIx::Easy(3)

=cut