package Alzabo::Create::Index;

use strict;
use vars qw($VERSION);

use Alzabo::Create;
use Alzabo::Exceptions ( abbr => 'params_exception' );
use Alzabo::Utils;

use Params::Validate qw( :all );
Params::Validate::validation_options
    ( on_fail => sub { params_exception join '', @_ } );

use base qw(Alzabo::Index);

$VERSION = 2.0;

1;

sub new
{
    my $proto = shift;
    my $class = ref $proto || $proto;

    validate( @_, { table    => { isa => 'Alzabo::Create::Table' },
                    columns  => { type => ARRAYREF },
                    unique   => { type => BOOLEAN, default => 0 },
                    fulltext => { type => BOOLEAN, default => 0 },
                    function => { type => UNDEF | SCALAR,  default => undef },
                  } );
    my %p = @_;

    my $self = bless {}, $class;

    $self->{table} = $p{table};
    $self->{unique} = $p{unique} || 0;
    $self->{fulltext} = $p{fulltext} || 0;
    $self->{function} = $p{function};

    $self->{columns} = Tie::IxHash->new;

    foreach my $c (@{ $p{columns} })
    {
        my %p = Alzabo::Utils::safe_isa( $c, 'Alzabo::Column' ) ? ( column => $c ) : %$c;
        $self->add_column(%p);
    }

    $self->table->schema->rules->validate_index($self);

    return $self;
}

sub add_column
{
    my $self = shift;

    validate( @_, { column => { isa => 'Alzabo::Create::Column' },
                    prefix => { type => SCALAR,
                                optional => 1 } } );
    my %p = @_;

    my $new_name = $p{column}->name;

    params_exception "Column $new_name already exists in index."
        if $self->{columns}->EXISTS($new_name);

    $self->{columns}->STORE( $new_name, \%p );

    eval { $self->table->schema->rules->validate_index($self); };

    if ($@)
    {
        $self->{columns}->DELETE($new_name);

        rethrow_exception($@);
    }
}

sub delete_column
{
    my $self = shift;

    validate_pos( @_, { isa => 'Alzabo::Create::Column' } );
    my $c = shift;

    params_exception "Column " . $c->name . " is not part of index."
        unless $self->{columns}->EXISTS( $c->name );

    $self->{columns}->DELETE( $c->name );
}

sub set_prefix
{
    my $self = shift;

    validate( @_, { column => { isa => 'Alzabo::Create::Column' },
                    prefix => { type => SCALAR } } );
    my %p = @_;

    params_exception "Column " . $p{column}->name . " is not part of index."
        unless $self->{columns}->EXISTS( $p{column}->name );

    my $col = $self->{columns}->FETCH( $p{column}->name );
    my $old_val = delete $col->{prefix};
    $col->{prefix} = $p{prefix};

    eval { $self->table->schema->rules->validate_index($self); };

    if ($@)
    {
        if ($old_val)
        {
            $col->{prefix} = $old_val;
        }
        else
        {
            delete $col->{prefix};
        }

        rethrow_exception($@);
    }
}

sub set_unique
{
    my $self = shift;

    validate_pos( @_, 1 );
    $self->{unique} = shift;
}

sub set_fulltext
{
    my $self = shift;

    validate_pos( @_, 1 );

    my $old_val = $self->{fulltext};

    $self->{fulltext} = shift;

    eval { $self->table->schema->rules->validate_index($self); };

    if ($@)
    {
        $self->{fulltext} = $old_val;

        rethrow_exception($@);
    }
}

sub register_column_name_change
{
    my $self = shift;

    validate( @_, { column => { isa => 'Alzabo::Create::Column' },
                    old_name => { type => SCALAR } } );
    my %p = @_;

    return unless $self->{columns}->EXISTS( $p{old_name} );

    my $new_name = $p{column}->name;

    my $index = $self->{columns}->Indices( $p{old_name} );
    my $val = $self->{columns}->Values($index);
    $val->{column} = $p{column};
    $self->{columns}->Replace( $index, $val, $new_name );
}

__END__

=head1 NAME

Alzabo::Create::Index - Index objects for schema creation

=head1 SYNOPSIS

  use Alzabo::Create::Index;

=head1 DESCRIPTION

This object represents an index on a table.  Indexes consist of
columns and optional prefixes for each column.  The prefix specifies
how many characters of the columns should be indexes (the first X
chars).  Some RDBMS's do not have a concept of index prefixes.  Not
all column types are likely to allow prefixes though this depends on
the RDBMS.  The order of the columns is significant.

=head1 INHERITS FROM

C<Alzabo::Index>


Note: all relevant documentation from the superclass has been merged into this document.

=head1 METHODS

=head2 new

The constructor takes the following parameters:

=over 4

=item * table => C<Alzabo::Create::Table> object

The table that this index is indexing.

=item * columns => [ C<Alzabo::Create::Column> object, .. ]

=item * columns => [ { column => C<Alzabo::Create::Column> object,
                       prefix => $prefix },
                      repeat as needed ...
                   ]

This parameter indicates which columns that are being indexed.  It can
either be an array reference of column objects, or an array reference
of hash references, each with a key called column and one called
prefix.

The prefix key is optional.

=item * unique => $boolean

Indicates whether or not this is a unique index.

=item * fulltext => $boolean

Indicates whether or not this is a fulltext index.

=item * function => $string

This can be used to create a function index where supported. The value
of this parameter should be the full function, with column names, such
as C<LCASE( username )>.

The "columns" parameter should include all the columns used in the
function.

=back

Returns a new C<Alzabo::Create::Index> object.

Throws: L<C<Alzabo::Exception::Params>|Alzabo::Exceptions>,
L<C<Alzabo::Exception::RDBMSRules>|Alzabo::Exceptions>

=head2 table

Returns the L<C<Alzabo::Create::Table>|Alzabo::Create::Table> object to which the
index belongs.

=head2 columns

Returns an ordered list of the L<C<Alzabo::Create::Column>|Alzabo::Create::Column>
objects that are being indexed.

=head2 add_column

Adds a column to the index.

This method takes the following parameters:

=over 4

=item * column => C<Alzabo::Create::Column> object

=item * prefix => $prefix (optional)

=back

Throws: L<C<Alzabo::Exception::Params>|Alzabo::Exceptions>,
L<C<Alzabo::Exception::RDBMSRules>|Alzabo::Exceptions>

=head2 delete_column (C<Alzabo::Create::Column> object)

Deletes the given column from the index.

Throws: L<C<Alzabo::Exception::Params>|Alzabo::Exceptions>,
L<C<Alzabo::Exception::RDBMSRules>|Alzabo::Exceptions>

=head2 prefix (C<Alzabo::Create::Column> object)

A column prefix is, to the best of my knowledge, a MySQL specific
concept, and as such cannot be set when using an RDBMSRules module for
a different RDBMS.  However, it is important enough for MySQL to have
the functionality be present.  It allows you to specify that the index
should only look at a certain portion of a field (the first N
characters).  This prefix is required to index any sort of BLOB column
in MySQL.

This method returns the prefix for the column in the index.  If there
is no prefix for this column in the index, then it returns undef.

=head2 set_prefix

This method takes the following parameters:

=over 4

=item * column => C<Alzabo::Create::Column> object

=item * prefix => $prefix

=back

Throws: L<C<Alzabo::Exception::Params>|Alzabo::Exceptions>,
L<C<Alzabo::Exception::RDBMSRules>|Alzabo::Exceptions>

=head2 unique

Returns a boolean value indicating whether the index is a unique
index.

=head2 set_unique ($boolean)

Sets whether or not the index is a unique index.

=head2 fulltext

Returns a boolean value indicating whether the index is a fulltext
index.

=head2 set_fulltext ($boolean)

Set whether or not the index is a fulltext index.

Throws: L<C<Alzabo::Exception::Params>|Alzabo::Exceptions>,
L<C<Alzabo::Exception::RDBMSRules>|Alzabo::Exceptions>

=head2 register_column_name_change

This method takes the following parameters:

=over 4

=item * column => C<Alzabo::Create::Column> object

The column (with the new name already set).

=item * old_name => $old_name

=back

This method is called by the table object which owns the index when a
column name changes.  You should never need to call this yourself.

Throws: L<C<Alzabo::Exception::Params>|Alzabo::Exceptions>

=head2 id

The id is generated from the table, column and prefix information for
the index.  This is useful as a canonical name for a hash key, for
example.

Returns a string that is the id which uniquely identifies the index in
this schema.

=head1 AUTHOR

Dave Rolsky, <autarch@urth.org>

=cut