#
# this file implements index functions using DBI
#

package index_DBI;
use strict qw(vars);
use vars qw($Count);
use HTML::Entities;

use DBI;

my %Table;	# index tables which where visited in this run
my %sth_cache;	# cache prepared statements

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

	my $dbd = shift || die "need dbi_dbd= in [global] section of configuration file";
	my $dsn = shift || die "need dbi_dsn= in [global] section of configuration file";
	my $user = shift || die "need dbi_user= in [global] section of configuration file";
	my $passwd = shift || die "need dbi_passwd= in [global] section of configuration file";

	$self->{dbh} = DBI->connect("DBI:$dbd:$dsn",$user,$passwd) || 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;

#print "#### delete_and_create($field)\n";

	$self->{dbh}->commit;

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

	$self->{dbh}->begin_work;
	$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 $index_data = shift || print STDERR "\$index->insert($field,NULL,...)";
	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);

		my $sql = "select item from $field where upper(item)=upper(?)";
		$sth_cache{$field."select"} = $self->{dbh}->prepare($sql) || die $self->{dbh}->errstr();

		$sql = "insert into $field (item,ident,count) values (?,?,?)";
		$sth_cache{$field."insert"} = $self->{dbh}->prepare($sql) || die $self->{dbh}->errstr();

		$sql = "update $field set count = count + 1 where item = ? and ident = ?";
		$sth_cache{$field."update"} = $self->{dbh}->prepare($sql) || die $self->{dbh}->errstr();
	}
	$Table{$field}++;

	$sth_cache{$field."select"}->execute($index_data) || die "cache: $field select; ".$self->{dbh}->errstr();
	if (! $sth_cache{$field."select"}->fetchrow_hashref) {
		$index_data = substr($index_data,0,255);
		$sth_cache{$field."insert"}->execute($index_data,$ident,1) || die "cache: $field insert; ".$self->{dbh}->errstr();
#print stderr "in index: $index_data\n";
	} else {
		$sth_cache{$field."update"}->execute($index_data,$ident) || die "cache: $field update; ".$self->{dbh}->errstr();
	}
}

sub check {
	my $self = shift;

	my $field = shift;

	my $sql = "select count(*) from $field";

	my $sth = $self->{dbh}->prepare($sql) || die $self->{dbh}->errstr();
	$sth->execute() || die "sql: $sql; ".$self->{dbh}->errstr();

	my ($total) = $sth->fetchrow_array();

	return $total;
}


sub fetch {
	my $self = shift;

	my $field = shift;
	my $what = shift || 'item';	# 'item,ident'
	my $where = shift;

	my $from_ord = shift || 0;
	my $rows = shift || 10;

	my @sql_args;

	my $sql = "select $what,ord from $field";

	if ($where) {
		my $sql2 = " select ord from $field where upper($what) like upper(?)||'%'";
		my $sth = $self->{dbh}->prepare($sql2) || die "sql2: $sql2; ".$self->{dbh}->errstr();

		$sth->execute($where) || die "sql2: $sql2; ".$self->{dbh}->errstr();
		if (my $row = $sth->fetchrow_hashref) {
			$from_ord += $row->{ord} - 1;
		}
	}
	$sql .= " order by ord limit $rows offset $from_ord";

	my $sth = $self->{dbh}->prepare($sql) || die "prepare: $sql; ".$self->{dbh}->errstr();
	$sth->execute() || die "execute: $sql; ".$self->{dbh}->errstr();
	my @arr;
	while (my $row = $sth->fetchrow_hashref) {
		$row->{item} = HTML::Entities::encode($row->{item},'<>&"');
		push @arr,$row;
	}
	return @arr;
}

sub close {
	my $self = shift;


	# re-create ord column (sorted order) in table
	sub create_ord {

		my $table = shift;

		$self->{dbh}->begin_work || die $self->{dbh}->errstr();

		my $sql = "select oid from $table order by upper(item)";
		my $sth = $self->{dbh}->prepare($sql) || die "sql: $sql; ".$self->{dbh}->errstr();
		$sql = "update $table set ord=? where oid=?";
		my $sth_update = $self->{dbh}->prepare($sql) || die "sql: $sql; ".$self->{dbh}->errstr();
		$sth->execute() || die "sql: $sql; ".$self->{dbh}->errstr();
		my $ord = 1;
		while (my $row = $sth->fetchrow_hashref) {
			$sth_update->execute($ord++,$row->{oid});
		}

		$self->{dbh}->commit || die $self->{dbh}->errstr();
	}
	#--- end of sub

	if ($self->{dbh}) {

		# commit
		$self->{dbh}->commit || die $self->{dbh}->errstr();

		foreach my $table (keys %Table) {
# FIX
print STDERR "creating ord for $table...\n";
			create_ord($table);
			undef $sth_cache{$table."select"};
			undef $sth_cache{$table."insert"};
			undef $sth_cache{$table."update"};
		}

		$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;