#
# this file implements index functions using DBI
# and huge amounts of memory for cache speedup
#
# this version doesn't support ident (which sould be location in
# library). But, that functionality is not used anyway...
#

package index_DBI;
use strict qw(vars);
use vars qw($Count);
use HTML::Entities;
use URI::Escape;
use Carp;
use DBI;
use locale;

# bench time
my $bench_time = time();

my $debug = 1;

sub bench {
	my $self = shift;
	my $msg = shift;

	print STDERR "last operation took ",time()-$bench_time," seconds...\n";
	$bench_time=time();
	print STDERR "$msg\n";
}

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->{dbd} = $dbd;

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

	$self->bench("connected to $dbd as $user");

	# force SQLite to support binary 0 in data (which shouldn't
	# happend, but it did to me)
	eval {
		no warnings 'all';
		$self->{dbh}->{sqlite_handle_binary_nulls} = 1;
	};

	return $self;
}

sub delete_and_create {
	my $self = shift;

	my $table = shift || croak "need table name!";
	my $sql = shift || croak "need sql to create table!";

	print STDERR "## delete_and_create($table)\n" if ($debug);

	my $sql_delete = "delete from $table";
	my $sth = $self->{dbh}->prepare($sql_delete);

	if ($sth && $sth->execute()) {
		print STDERR "## deleted rows from table $table\n" if ($debug);
	} else {
		# can't delete from table, assume it doesn't exists!
		$self->{dbh}->rollback;
		$self->{dbh}->do($sql) || confess "SQL: $sql ".$self->{dbh}->errstr();
		print STDERR "## creating table $table\n" if ($debug);
		$self->{dbh}->begin_work;
	}
}

sub insert {
	my $self = shift;

	my $field = shift;
	my $index_data = shift || print STDERR "\$index->insert($field,NULL,...)";
	my $display = shift || $index_data;
	my $filter = shift;

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

	$index_data =~ s#&(\w)(acute|cedil|circ|grave|ring|slash|tilde|uml);#$1#gi;

	# strip spaces
	$index_data =~ s#^\s+##;
	$index_data =~ s#\s+$##;
	$index_data =~ s#\s\s+# #g;

	my $uc = uc($index_data);

	if (! $self->{c}->{$uc}->{$field}) {
#print stderr "in index: $index_data\n";
		$self->{c}->{$uc}->{$field}->{item} = lc($index_data);
		$self->{c}->{$uc}->{$field}->{display} = $display;
	}

	$self->{c}->{$uc}->{$field}->{count}++;
	$self->{c}->{$uc}->{$field}->{filter}->{$filter}++ if ($filter);
}

sub count {
	my $self = shift;

	my $field = shift;
	my $where = shift;

	my $filter = shift;

	my $tables_sql = 'data';
	my $where_sql = '';
	my @sql_args = ( $field, lc($where) );

	if ($filter) {
		$tables_sql .= ",filters";
		$where_sql .= "
			and data.ord = filters.ord
			and filter = ?
		";
		push @sql_args, $filter;
	}

	my $sql = qq{
		select count(*)
		from $tables_sql
		where name = ? and item like ?||'%'
		$where_sql
	};

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

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

	# no results, count all
	if (! $total) {
		my $sql = qq{
			select count(*)
			from $tables_sql
			where data.name = ?
			$where_sql
		};

		@sql_args = ( $field );
		push @sql_args, $filter if ($filter);

		my $sth = $self->{dbh}->prepare($sql) || confess $self->{dbh}->errstr();
		$sth->execute(@sql_args) || confess "sql: $sql; ".$self->{dbh}->errstr();
		$total = $sth->fetchrow_array();

	}

	return $total || '0';
}


sub fetch {
	my $self = shift;

	my $field = shift;
	my $where = shift;

	my $offset = shift || 0;
	my $rows = shift || 10;
	my $filter = shift;

	my $from_ord = 0;

	my $tables_sql = 'data';
	my $where_sql = '';

	my @sql_args = ( $field, lc($where) );

	if ($filter) {
		$tables_sql .= ",filters";
		$where_sql .= "
			and data.ord = filters.ord
			and filter = ?
		";
		push @sql_args, $filter;
	}

	if ($where) {
		my $sql2 = qq{
			select data.ord as ord
			from $tables_sql
			where name = ? and item like ?||'%'
			$where_sql
			order by data.ord
		};
		my $sth = $self->{dbh}->prepare($sql2) || confess "sql2: $sql2; ".$self->{dbh}->errstr();

		$sth->execute(@sql_args) || confess "sql2: $sql2; ".$self->{dbh}->errstr();
		if (my $row = $sth->fetchrow_hashref) {
			$from_ord = $row->{ord} - 1;
		} else {
			# if no match is found when searching from beginning
			# of word in index, try substring match anywhere
			$sql2 = qq{
				select data.ord as ord
				from $tables_sql
				where name = ? and item like '%'||?||'%'
				$where_sql
				order by data.ord
			};
	
			$sth = $self->{dbh}->prepare($sql2) || confess "sql2: $sql2; ".$self->{dbh}->errstr();
			$sth->execute(@sql_args) || confess "sql2: $sql2; ".$self->{dbh}->errstr();

			if (my $row = $sth->fetchrow_hashref) {
				$from_ord = $row->{ord} - 1;
			}
		}
	}

	@sql_args = ( $field, $from_ord );
	push @sql_args, $filter if ($filter);

	my $sql = qq{
		select item,display,data.count as count
		from $tables_sql
		where name = ?
			and data.ord > ?
		$where_sql
			order by data.ord
	};

	# fix SQLite problem which doesn't allow placeholders in limit and offset
	# http://thread.gmane.org/gmane.comp.db.sqlite.general/9707
	$sql .= "limit $rows offset $offset";

	my $sth = $self->{dbh}->prepare($sql) || confess "prepare: $sql; ".$self->{dbh}->errstr();
	$sth->execute(@sql_args) || confess "execute: $sql; ".join("|",@sql_args)." ".$self->{dbh}->errstr();
	my @arr;
	while (my $row = $sth->fetchrow_hashref) {
		$row->{item} = HTML::Entities::encode($row->{item},' <>&"');
		$row->{display} = HTML::Entities::encode($row->{display},'<>&"');
		$row->{item} =~ s#&amp;(\w)(acute|cedil|circ|grave|ring|slash|tilde|uml);#$1#gi;
		$row->{display} =~ s#&amp;(\w)(acute|cedil|circ|grave|ring|slash|tilde|uml);#&$1$2;#gi;
		push @arr,$row;
	}
	return @arr;
}

sub close {
	my $self = shift;

	return if (! $self->{dbh});

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

	$self->delete_and_create('data', qq{
		create table data (
			name varchar(255),
			ord int,
			item text,
			display text,
			count int,
			primary key (name,ord)
		);
	});

	$self->delete_and_create('filters', qq{
		create table filters (
			filter varchar(255),
			ord int,
			count int,
			primary key (filter,ord)
		);
	});

	$self->bench("getting all entries");
	my @items = keys %{$self->{c}};
	$self->bench("got ".($#items+1)." items, now sorting");
	@items = sort @items;

	my $sql = "insert into data (name,ord,item,display,count) values (?,?,?,?,?)";
	my $sth_index = $self->{dbh}->prepare($sql) || confess "$sql: ".$self->{dbh}->errstr();

	$sql = "insert into filters (filter, ord, count) values (?,?,?)";
	my $sth_filter = $self->{dbh}->prepare($sql) || confess "$sql: ".$self->{dbh}->errstr();

	my $ord = 0;
	foreach my $key (@items) {

		foreach my $field (keys %{$self->{c}->{$key}}) {
			# store items
			$sth_index->execute(
				$field,
				++$ord,
				$self->{c}->{$key}->{$field}->{item},
				$self->{c}->{$key}->{$field}->{display},
				$self->{c}->{$key}->{$field}->{count},
			);

			# store filters
			next unless ($self->{c}->{$key}->{$field}->{filter});

			foreach my $filter (keys %{$self->{c}->{$key}->{$field}->{filter}}) {
				$sth_filter->execute( $filter, $ord, $self->{c}->{$key}->{$field}->{filter}->{$filter} );
			}
		}


	}

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

	$self->bench("vacuuming");

	if ($self->{dbd} =~ m/(Pg|SQLite)/) {
		$self->{dbh}->do(qq{vacuum}) || carp "vacumming failed. It shouldn't if you are using PostgreSQL or SQLite: ".$self->{dbh}->errstr();
	}

	$self->bench("disconnecting from database");

	$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;