#
# this file implements index functions using DBI
#

package index_DBI;
use strict qw(vars);
use vars qw($Count);

use DBI;

my %Table;	# index tables which where visited in this run

sub new {
	my $class = shift;
	my $self = {};
	bless($self, $class);

	# FIX: config params
	$self->{dbh} = DBI->connect("DBI:Pg:dbname=webpac","","") || die $DBI::errstr;
	# begin transaction
	$self->{dbh}->begin_work || die $self->{dbh}->errstr();

	$Count++;

	return $self;
}

sub delete_and_create {
	my $self = shift;

	my $field = shift;

	$self->{dbh}->commit;
	$self->{dbh}->begin_work;

	my $sql = "select count(*) from $field";
	my $sth = $self->{dbh}->prepare($sql) || die $self->{dbh}->errstr();
# FIX: this is not a good way to check if table exists!
	if (1 || $sth->execute() && $sth->fetchrow_hashref) {
		my $sql = "drop table $field";
#		my $sth = $self->{dbh}->do($sql) || die "SQL: $sql ".$self->{dbh}->errstr();
	}
	$sql = "create table $field (
			item varchar(255),
			ident varchar(255),
			count int,
			primary key (item,ident)
		)";
#	$sth = $self->{dbh}->do($sql) || die "SQL: $sql ".$self->{dbh}->errstr();
	$sth = $self->{dbh}->do($sql) || warn "SQL: $sql ".$self->{dbh}->errstr();

	$self->{dbh}->commit;
	$self->{dbh}->begin_work;
}

sub insert {
	my $self = shift;

	my $field = shift;
	my $index_data = shift;
	my $ident = shift;	# e.g. Library ID

	if (! $index_data) {
		print STDERR "\$index->insert() -- no value to insert\n";
		return;
	}

	if (! $Table{$field}) {
		$self->delete_and_create($field);
	}
	$Table{$field}++;

	my $sql = "select item from $field where upper(item)=upper(?)";
	my $sth = $self->{dbh}->prepare($sql) || die $self->{dbh}->errstr();
	$sth->execute($index_data) || die "SQL: $sql; ".$self->{dbh}->errstr();
	if (! $sth->fetchrow_hashref) {
		my $sql = "insert into $field (item,ident,count) values (?,?,?)";
		my $sth = $self->{dbh}->prepare($sql) || die $self->{dbh}->errstr();
		$sth->execute($index_data,$ident,1) || die "SQL: $sql; ".$self->{dbh}->errstr();
#print STDERR "in index: $index_data\n";
	} else {
		my $sql = "update $field set count = count + 1 where item = ? and ident = ?";
		my $sth = $self->{dbh}->prepare($sql) || die $self->{dbh}->errstr();
		$sth->execute($index_data,$ident) || die "SQL: $sql; ".$self->{dbh}->errstr();
	}
}

sub close {
	my $self = shift;

	if ($self->{dbh}) {
		$self->{dbh}->commit || die $self->{dbh}->errstr();
		$self->{dbh}->disconnect;
		undef $self->{dbh};
	}
}

END {
	$Count--;
	print STDERR "index_DBI fatal error: \$index->close() not called... $Count references left!\n" if ($Count != 0);
	# FIX: debug output
	print STDERR "usage\ttable\n";
	foreach (keys %Table) {
		print STDERR $Table{$_},"\t$_\n";
	}
}

1;
