#!/usr/bin/perl -w
#
# Update the DAViCal database by repeatedly applying patches to it
# in the correct order.
#

use strict;

use DBI;
use POSIX qw(floor);
use Getopt::Long qw(:config permute);  # allow mixed args.

# Options variables
my $debug  = 0;
my $dbname = "davical";
my $dbport = 5432;
my $dbuser = "";
my $dbpass = "";
my $dbhost = "";
my $appuser = "davical_app";
my $helpmeplease = 0;
my $apply_patches = 1;
my $revoke_list = "";
my $force_owner = "";
my $config_file = "config/administration.yml";

my $dbadir = $0;
$dbadir =~ s#/[^/]*$##;
my $patchdir = $dbadir . "/patches";

#
# We look in a few places for the config file.  First relative to
# where we are, then relative to the code we are running, then we
# start to look in absolute locations.  Then we give up :-)
if ( ! -f $config_file ) {
  $config_file = $0;
  $config_file =~ s{[^/]+/update-[a-z]+-database}{config/administration.yml};
}
if ( ! -f $config_file ) {
  $config_file = "/etc/davical/administration.yml";
}
if ( -f $config_file ) {
  use YAML qw( LoadFile );

  my ($ycfg) = LoadFile($config_file);
  $dbuser  = $ycfg->{'admin_db_user'} if ( defined($ycfg->{'admin_db_user'}));
  $dbpass  = $ycfg->{'admin_db_pass'} if ( defined($ycfg->{'admin_db_pass'}));
  $dbhost  = $ycfg->{'admin_db_host'} if ( defined($ycfg->{'admin_db_host'}));
  $dbname  = $ycfg->{'admin_db_name'} if ( defined($ycfg->{'admin_db_name'}));
  $dbport  = $ycfg->{'admin_db_port'} if ( defined($ycfg->{'admin_db_port'}));
  $appuser = $ycfg->{'app_db_user'}   if ( defined($ycfg->{'app_db_user'}));
}

GetOptions ('debug!'    => \$debug,
            'dbname=s'  => \$dbname,
            'dbuser=s'  => \$dbuser,
            'dbpass=s'  => \$dbpass,
            'dbport=s'  => \$dbport,
            'dbhost=s'  => \$dbhost,
            'appuser=s' => \$appuser,
            'patch!'    => \$apply_patches,
            'owner=s'   => \$force_owner,
            'revoke=s'  => \$revoke_list,
            'help'      => \$helpmeplease  );

show_usage() if ( $helpmeplease );

$revoke_list = ", ". $revoke_list if ( $revoke_list ne "" );


############################################################
# Open database connection. Note that the standard PostgreSQL
# environment variables will also work with DBD::Pg.
############################################################
my $dsn = "dbi:Pg:dbname=$dbname";
$dsn .= ";host=$dbhost" if ( "$dbhost" ne "" );
$dsn .= ";port=$dbport" if ( $dbport != 5432 );

print "Using database: $dbuser".'%'.$dbpass.'@'.$dsn."\n" if ( $debug );

my $pg_version = get_postgresql_version();
my $current_revision;
my $last_results = '';  # Will hold the last SQL result from applying a patch

if ( $apply_patches ) {
  $current_revision = get_current_revision();
  printf( "The database is version %.1lf currently at revision %d.%d.%d.\n", $pg_version, $current_revision->{'schema_major'}, $current_revision->{'schema_minor'}, $current_revision->{'schema_patch'} );

  opendir( PATCHDIR, $patchdir ) or die "Can't open patch directory $patchdir";
  my @patches = grep { /^([0-9]+)\.([0-9]+)\.([0-9]+)([a-z]?)\.sql$/ } readdir(PATCHDIR);
  closedir(PATCHDIR);

  @patches = sort { compare_revisions(revision_hash($a),revision_hash($b), 1); } @patches;

  my $applied = 0;

  for ( my $i=0; $i <= $#patches;  $i++ ) {
    printf( "Looking at patches[%d] (%s)\n", $i, $patches[$i]) if ( $debug );
    if ( compare_revisions(revision_hash($patches[$i]),$current_revision) > 0 ) {
      print "Applying patch $patches[$i] ... ";
      if ( !apply_patch( $patches[$i] ) ) {
        # Skip to the end unless the next patch is an alternate for the same version.
        if ( defined($patches[$i+1]) && compare_revisions(revision_hash($patches[$i]),revision_hash($patches[$i+1])) == 0 ) {
          print "failed.  Attempting next alternative.\n";
          $applied--;
        }
        else {
          print "failed!\n$last_results  ==> No further patches will be attempted!\n";
          last;
        }
      }
      else {
        print "succeeded.\n";
      }
      $applied++;
    }
    else {
      print "Patch $patches[$i] has already been applied.\n" if ( $debug );
    }
  }

  if ( $applied ) {
    print "Successfully applied $applied patches.\n";
  }
  else {
    print "No patches were applied.\n";
  }
}

# Ensure the locales data is up to date
apply_sql_file( $dbadir, "supported_locales.sql" );
print "Supported locales updated.\n";

# Ensure the functions are up to date
apply_sql_file( $dbadir, "caldav_functions.sql" );
print "CalDAV functions updated.\n";

if ( $pg_version >= 8.3 ) {
  apply_sql_file( $dbadir, "rrule_functions.sql" );
}
else {
  apply_sql_file( $dbadir, "rrule_functions-8.1.sql",  );
}
print "RRULE functions updated.\n";

# Ensure the permissions are up to date
apply_permissions( $dbadir, "appuser_permissions.txt" );
print "Database permissions updated.\n";

# The End!
exit 0;




############################################################
# Revision Hash - we either have a single parameter,
# which is of the form "1.2.3" or we have three parameters.
############################################################
sub revision_hash {
  my $rev = +{ 'schema_major', => 0, 'schema_minor' => 0, 'schema_patch' => 0, 'alternative' => '0' };
  my $first = shift;
  return $rev unless ( defined($first) );
  if ( $first =~ /^([0-9]+)\.([0-9]+)\.([0-9]+)([a-z]?)([^0-9]|$)/ ) {
    $rev->{'schema_major'} = $1;
    $rev->{'schema_minor'} = $2;
    $rev->{'schema_patch'} = $3;
    $rev->{'alternative'} = $4;
  }
  else {
    $rev->{'schema_major'} = $first;
    $rev->{'schema_minor'} = shift;
    $rev->{'schema_patch'} = shift;
    $rev->{'alternative'} = '0';
  }
  return $rev;
}


############################################################
# Compare revisions
############################################################
sub compare_revisions {
  my $a = shift;
  my $b = shift;
  my $test_alt = shift;

  return -1 if ( $a->{'schema_major'} < $b->{'schema_major'} );
  return  1 if ( $a->{'schema_major'} > $b->{'schema_major'} );

  return -1 if ( $a->{'schema_minor'} < $b->{'schema_minor'} );
  return  1 if ( $a->{'schema_minor'} > $b->{'schema_minor'} );

  return -1 if ( $a->{'schema_patch'} < $b->{'schema_patch'} );
  return  1 if ( $a->{'schema_patch'} > $b->{'schema_patch'} );

  if ( defined($test_alt) ) {
    return -1 if ( $a->{'alternative'} lt $b->{'alternative'} );
    return  1 if ( $a->{'alternative'} gt $b->{'alternative'} );
  }

  return 0;

}



############################################################
# Get the current version of PostgreSQL
############################################################
sub get_postgresql_version {

  my $dbh = DBI->connect($dsn, $dbuser, $dbpass, { AutoCommit => 0 } ) or die "Can't connect to database $dbname";

  my $current_version = $dbh->prepare( <<EOQ  ) or die $dbh->errstr;
  SELECT regexp_replace( split_part( version(), ' ', 2), E'\.[0-9]\$', '')
EOQ

  if ( $current_version->execute() ) {
    my $version = $current_version->fetchrow_arrayref();
    undef $current_version;
    $dbh->disconnect;
    $version->[0] =~ s/\D+$//;  # It seems the regex in SQL is broken in 8.1, at least on CentOS 5.3
    return $version->[0];
  }
  else {
    die "ERROR: Cannot read current revision from database.";
  }

}


############################################################
# Get the current revision
############################################################
sub get_current_revision {

  my $dbh = DBI->connect($dsn, $dbuser, $dbpass, { AutoCommit => 0 } ) or die "Can't connect to database $dbname";

  my $current_revision = $dbh->prepare( <<EOQ  ) or die $dbh->errstr;
  SELECT schema_major, schema_minor, schema_patch FROM awl_db_revision ORDER BY schema_id DESC LIMIT 1
EOQ

  if ( $current_revision->execute() ) {
    my $revision = $current_revision->fetchrow_hashref();
    undef $current_revision;
    $dbh->disconnect;
    return $revision;
  }
  else {
    die "ERROR: Cannot read current revision from database.";
  }

}



############################################################
# Apply a DB Patch File
############################################################
sub apply_patch {

  my $patch = shift;

  apply_sql_file( $patchdir, $patch );

  $current_revision = get_current_revision();
  if ( compare_revisions($current_revision,revision_hash($patch)) != 0 ) {
    printf( "Failed to apply revision %s to the database!\n", $patch ) if ( $debug );
    return 0;
  }
  return 1;  # Success
}



############################################################
# Apply SQL File
#  Note that this stuffs the password into an environment
#  variable, which isn't ideal.  If you use a .pgpass you
#  can bypass that issue, but you still need it on the command
#  line for this program until I get a patch from someone.
############################################################
sub apply_sql_file {

  my $sqldir  = shift;
  my $sqlfile = shift;

  my @psql_opts = ( "psql", "-q", "-f", $sqldir."/".$sqlfile );
  push @psql_opts, "-h", $dbhost if ( $dbhost ne "" );
  push @psql_opts, "-p", "$dbport" if ( $dbport != 5432 );
  push @psql_opts, "-U", $dbuser if ( $dbuser ne "" );
  push @psql_opts, $dbname;    # It seems that FreeBSD has a poorer argument parsing library so non-option arguments must be last
  $ENV{'PGPASS'} = $dbpass if ( $dbpass ne "" );

  my $command = join ' ', @psql_opts;
  $last_results = `$command 2>&1 1>/dev/null`;

  $last_results =~ s/^.*WARNING:  there is no transaction in progress\s$//m;
  $last_results =~ s/^.*NOTICE: //m;
}



############################################################
# Apply database permissions from file
############################################################
sub apply_permissions {

  my $sqldir  = shift;
  my $permsfile = shift;

  open PERMS, '<', $sqldir."/".$permsfile;
  my $dbh = DBI->connect($dsn, $dbuser, $dbpass, { AutoCommit => 1 } ) or die "Can't connect to database $dbname";

  my $sql;
  my $current_grant;

  while( <PERMS> ) {
    next if ( /^\s*(#|--)/ );

    /^\s*GRANT\s+(\S.*)\s*$/i && do {
      $current_grant = $1;
    };

    /^\s*ON\s+(\S.*)\s*$/i && do {
      defined($current_grant) or die "No GRANT before ON in $permsfile\n";
      my $doohickey = $1;

      if ( $revoke_list ne "" ) {
        # TODO: we should really loop through the revoke_list so that a single non-existent
        # user doesn't cause this whole statement to fail.
        $sql = sprintf( "REVOKE ALL ON %s FROM %s %s", $doohickey, $appuser, $revoke_list );
        print $sql, "\n" if ( $debug );
        $dbh->do($sql);
      }

      $sql = sprintf( "GRANT %s on %s to %s", $current_grant, $doohickey, $appuser );
      print $sql, "\n" if ( $debug );
      $dbh->do($sql);

      if ( $force_owner ne "" ) {
        if ( $doohickey =~ /_seq$/ ) {
          $sql = sprintf( "GRANT ALL on %s to %s", $doohickey, $force_owner );
        }
        else {
          $sql = sprintf( "ALTER TABLE %s OWNER to %s", $doohickey, $force_owner );
        }
        print $sql, "\n" if ( $debug );
        $dbh->do($sql);
      }
    };

  }
  close(PERMS);
  $dbh->disconnect;
}



############################################################
# Tell the nice user how we do things.  Short and sweet.
############################################################
sub show_usage {
    print <<OPTHELP;

update-davical-database [options]

Options are:
    --debug           Turn on debugging
    --dbname  name    The database to dig into
    --dbuser  name    Connect to the database as this user.
    --dbport  5432    Connect to the database on this port.
    --dbhost  name    Connect to the database on this host.
    --appuser name    The database username which the application uses for it's
                      database connection.
    --owner name      The database username which is used for administrative
                      access to the database.  This option forces the tables
                      to be owned by this user (default: not present).
    --nopatch         Don't try and apply any patches
    --revoke  name    Revoke permissions from this user

The program will apply any patches to the database which have
not yet been applied, run any desired data patch scripts and set
the correct minimum permissions for the web application user.

Rather than providing a password on the command-line it is recommended
that you use a .pgpass file in your home directory to hold the database
password.  This file must be mode 600 to work.

OPTHELP
    exit 0;
}

