package DBIx::Class::Schema::Loader::DBI::Pg;

use strict;
use warnings;
use base 'DBIx::Class::Schema::Loader::DBI';
use Carp::Clan qw/^DBIx::Class/;
use Class::C3;

=head1 NAME

DBIx::Class::Schema::Loader::DBI::Pg - DBIx::Class::Schema::Loader::DBI
PostgreSQL Implementation.

=head1 SYNOPSIS

  package My::Schema;
  use base qw/DBIx::Class::Schema::Loader/;

  __PACKAGE__->loader_options(
    relationships => 1,
  );

  1;

=head1 DESCRIPTION

See L<DBIx::Class::Schema::Loader::Base>.

=cut

sub _setup {
    my $self = shift;

    $self->next::method(@_);
    $self->{db_schema} ||= 'public';
}

sub _table_uniq_info {
    my ($self, $table) = @_;

    my @uniqs;
    my $dbh = $self->schema->storage->dbh;

    # Most of the SQL here is mostly based on
    #   Rose::DB::Object::Metadata::Auto::Pg, after some prodding from
    #   John Siracusa to use his superior SQL code :)

    my $attr_sth = $self->{_cache}->{pg_attr_sth} ||= $dbh->prepare(
        q{SELECT attname FROM pg_catalog.pg_attribute
        WHERE attrelid = ? AND attnum = ?}
    );

    my $uniq_sth = $self->{_cache}->{pg_uniq_sth} ||= $dbh->prepare(
        q{SELECT x.indrelid, i.relname, x.indkey
        FROM
          pg_catalog.pg_index x
          JOIN pg_catalog.pg_class c ON c.oid = x.indrelid
          JOIN pg_catalog.pg_class i ON i.oid = x.indexrelid
          JOIN pg_catalog.pg_constraint con ON con.conname = i.relname
          LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
        WHERE
          x.indisunique = 't' AND
          c.relkind     = 'r' AND
          i.relkind     = 'i' AND
          con.contype   = 'u' AND
          n.nspname     = ? AND
          c.relname     = ?}
    );

    $uniq_sth->execute($self->db_schema, $table);
    while(my $row = $uniq_sth->fetchrow_arrayref) {
        my ($tableid, $indexname, $col_nums) = @$row;
        $col_nums =~ s/^\s+//;
        my @col_nums = split(/\s+/, $col_nums);
        my @col_names;

        foreach (@col_nums) {
            $attr_sth->execute($tableid, $_);
            my $name_aref = $attr_sth->fetchrow_arrayref;
            push(@col_names, $name_aref->[0]) if $name_aref;
        }

        if(!@col_names) {
            warn "Failed to parse UNIQUE constraint $indexname on $table";
        }
        else {
            push(@uniqs, [ $indexname => \@col_names ]);
        }
    }

    return \@uniqs;
}

=head1 SEE ALSO

L<DBIx::Class::Schema::Loader>, L<DBIx::Class::Schema::Loader::Base>,
L<DBIx::Class::Schema::Loader::DBI>

=cut

1;
