=head1 LICENSE

Copyright [1999-2015] Wellcome Trust Sanger Institute and the EMBL-European Bioinformatics Institute
Copyright [2016-2023] EMBL-European Bioinformatics Institute

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

=cut


=head1 CONTACT

  Please email comments or questions to the public Ensembl
  developers list at <http://lists.ensembl.org/mailman/listinfo/dev>.

  Questions may also be sent to the Ensembl help desk at
  <http://www.ensembl.org/Help/Contact>.

=cut

=head1 NAME

Bio::EnsEMBL::DBSQL::CoordSystemAdaptor

=head1 SYNOPSIS

  use Bio::EnsEMBL::Registry;

  Bio::EnsEMBL::Registry->load_registry_from_db(
    -host => 'ensembldb.ensembl.org',
    -user => 'anonymous'
  );

  $csa = Bio::EnsEMBL::Registry->get_adaptor( "human", "core",
    "coordsystem" );

  #
  # Get all coord systems in the database:
  #
  foreach my $cs ( @{ $csa->fetch_all() } ) {
    print $cs->name, ' ', $cs->version, "\n";
  }

  #
  # Fetching by name:
  #

  # use the default version of coord_system 'chromosome' (e.g. NCBI33):
  $cs = $csa->fetch_by_name('chromosome');

  # get an explicit version of coord_system 'chromosome':
  $cs = $csa->fetch_by_name( 'chromsome', 'NCBI34' );

  # get all coord_systems of name 'chromosome':
  foreach $cs ( @{ $csa->fetch_all_by_name('chromosome') } ) {
    print $cs->name, ' ', $cs->version, "\n";
  }

  #
  # Fetching by rank:
  #
  $cs = $csa->fetch_by_rank(2);

  #
  # Fetching the pseudo coord system 'toplevel'
  #

  # Get the default top_level coord system:
  $cs = $csa->fetch_top_level();

  # can also use an alias in fetch_by_name:
  $cs = $csa->fetch_by_name('toplevel');

  # can also request toplevel using rank=0
  $cs = $csa->fetch_by_rank(0);

  #
  # Fetching by sequence level:
  #

  # Get the coord system which is used to store sequence:
  $cs = $csa->fetch_sequence_level();

  # can also use an alias in fetch_by_name:
  $cs = $csa->fetch_by_name('seqlevel');

  #
  # Fetching by id
  #
  $cs = $csa->fetch_by_dbID(1);


=head1 DESCRIPTION

This adaptor allows the querying of information from the coordinate
system adaptor.

Note that many coordinate systems do not have a concept of a version
for the entire coordinate system (though they may have a per-sequence
version).  The 'chromosome' coordinate system usually has a version
(i.e. the assembly version) but the clonal coordinate system does not
(despite having individual sequence versions).  In the case where a
coordinate system does not have a version an empty string ('') is used
instead.

=head1 METHODS

=cut

package Bio::EnsEMBL::DBSQL::CoordSystemAdaptor;

use strict;
use warnings;

use Bio::EnsEMBL::DBSQL::BaseAdaptor;
use Bio::EnsEMBL::Utils::Exception qw(throw warning);
use Bio::EnsEMBL::CoordSystem;

use vars qw(@ISA);

@ISA = qw(Bio::EnsEMBL::DBSQL::BaseAdaptor);


=head2 new

  Arg [1]    : See BaseAdaptor for arguments (none specific to this
               subclass)
  Example    : $cs = $db->get_CoordSystemAdaptor(); #better than new()
  Description: Creates a new CoordSystem adaptor and caches the contents
               of the coord_system table in memory.
  Returntype : Bio::EnsEMBL::DBSQL::CoordSystemAdaptor
  Exceptions : none
  Caller     :
  Status     : Stable

=cut

sub new {
  my ( $proto, @args ) = @_;

  my $class = ref($proto) || $proto;
  my $self = $class->SUPER::new(@args);

  #
  # Cache the entire contents of the coord_system table cross-referenced
  # by dbID and name.
  #

  # keyed on name, list of coord_system value
  $self->{'_name_cache'} = {};

  # keyed on id, coord_system value
  $self->{'_dbID_cache'} = {};

  # keyed on rank
  $self->{'_rank_cache'} = {};

  # keyed on id, 1/undef values
  $self->{'_is_sequence_level'}  = {};
  $self->{'_is_default_version'} = {};

  #cache to store the seq_region_mapping information
  #from internal->external
  $self->{'_internal_seq_region_mapping'} = {};
  #from external->internal
  $self->{'_external_seq_region_mapping'} = {};

  my $sth = $self->prepare(
                  'SELECT `coord_system_id`, `name`, `rank`, `version`, `attrib` '
                    . 'FROM coord_system '
                    . 'WHERE species_id = ?' );

  $sth->bind_param( 1, $self->species_id(), SQL_INTEGER );
  $sth->execute();

  my ( $dbID, $name, $rank, $version, $attrib );
  $sth->bind_columns( \( $dbID, $name, $rank, $version, $attrib ) );

  while ( $sth->fetch() ) {
    my $seq_lvl = 0;
    my $default = 0;

    if ( defined($attrib) ) {
      foreach my $attrib ( split( ',', $attrib ) ) {
        $self->{"_is_$attrib"}->{$dbID} = 1;
        if ( $attrib eq 'sequence_level' ) {
          $seq_lvl = 1;
        } elsif ( $attrib eq 'default_version' ) {
          $default = 1;
        }
      }
    }

    my $cs =
      Bio::EnsEMBL::CoordSystem->new( -DBID           => $dbID,
                                      -ADAPTOR        => $self,
                                      -NAME           => $name,
                                      -VERSION        => $version,
                                      -RANK           => $rank,
                                      -SEQUENCE_LEVEL => $seq_lvl,
                                      -DEFAULT        => $default );

    $self->{'_dbID_cache'}->{$dbID} = $cs;

    $self->{'_name_cache'}->{ lc($name) } ||= [];
    $self->{'_rank_cache'}->{$rank} = $cs;

    push @{ $self->{'_name_cache'}->{ lc($name) } }, $cs;

  } ## end while ( $sth->fetch() )
  $sth->finish();

  $self->_cache_mapping_paths();

  $self->_cache_seq_region_mapping();

  return $self;
} ## end sub new

sub _cache_seq_region_mapping {
  #
  # This cache will load the information from the seq_region_table, if
  # any, to allow mapping between internal and external seq_region_id.
  #

  my ($self) = @_;

  # For a given core database, will return the schema_build information.
  my $schema_build = $self->db->_get_schema_build();

  # Prepare the query to get relation for the current database being
  # used.
  my $sql = qq(
  SELECT    s.internal_seq_region_id,
            s.external_seq_region_id
  FROM      seq_region_mapping s,
            mapping_set ms,
            seq_region sr,
            coord_system cs
  WHERE     ms.mapping_set_id = s.mapping_set_id
    AND     ms.internal_schema_build = ?
    AND     s.internal_seq_region_id = sr.seq_region_id
    AND     sr.coord_system_id = cs.coord_system_id
    AND     cs.species_id = ?);

  my $sth = $self->prepare($sql);

  $sth->bind_param( 1, $schema_build,       SQL_VARCHAR );
  $sth->bind_param( 2, $self->species_id(), SQL_INTEGER );

  $sth->execute();

  # Load the cache:
  foreach my $row ( @{ $sth->fetchall_arrayref() } ) {
    # internal->external
    $self->{'_internal_seq_region_mapping'}->{ $row->[0] } = $row->[1];
    # external->internal
    $self->{'_external_seq_region_mapping'}->{ $row->[1] } = $row->[0];
  }

  $sth->finish();

} ## end sub _cache_seq_region_mapping


sub _cache_mapping_paths {
  # Retrieve a list of available mappings from the meta table.  This
  # may eventually be moved a table of its own if this proves too
  # cumbersome.

  my ($self) = @_;

  my %mapping_paths;
  my $mc = $self->db()->get_MetaContainer();

MAP_PATH:
  foreach
    my $map_path ( @{ $mc->list_value_by_key('assembly.mapping') } )
  {
    my @cs_strings = split( /[|#]/, $map_path );

    if ( scalar(@cs_strings) < 2 ) {
      warning(   "Incorrectly formatted assembly.mapping value in meta "
               . "table: $map_path" );
      next MAP_PATH;
    }

    my @coord_systems;
    foreach my $cs_string (@cs_strings) {
      my ( $name, $version ) = split( /:/, $cs_string );

      my $cs = $self->fetch_by_name( $name, $version );

      if ( !defined($cs) ) {
        warning(   "Unknown coordinate system specified in meta table "
                 . " assembly.mapping:\n  $name:$version" );
        next MAP_PATH;
      }

      push( @coord_systems, $cs );
    }

    # If the delimiter is a '#' we want a special case, multiple parts
    # of the same component map to the same assembly part.  As this
    # looks like the "long" mapping, we just make the path a bit longer
    # :-)

    if ( index( $map_path, '#' ) != -1 && scalar(@coord_systems) == 2 )
    {
      splice( @coord_systems, 1, 0, (undef) );
    }

    my $cs1 = $coord_systems[0];
    my $cs2 = $coord_systems[$#coord_systems];

    my $key1 = $cs1->name();
    $key1 .= ':' . $cs1->version() if $cs1->version();
    my $key2 = $cs2->name();
    $key2 .= ':' . $cs2->version() if $cs2->version();

    if ( exists( $mapping_paths{"$key1|$key2"} ) ) {
      warning(   "Meta table specifies multiple mapping paths between "
               . "coord systems $key1 and $key2.\n"
               . "Choosing shorter path arbitrarily." );

      if ( scalar( @{ $mapping_paths{"$key1|$key2"} } ) <
           scalar(@coord_systems) )
      {
        next MAP_PATH;
      }
    }

    $mapping_paths{"$key1|$key2"} = \@coord_systems;
  } ## end foreach my $map_path ( @{ $mc...

  # Create the pseudo coord system 'toplevel' and cache it so that only
  # one of these is created for each database.

  my $toplevel =
    Bio::EnsEMBL::CoordSystem->new( -TOP_LEVEL => 1,
                                    -NAME      => 'toplevel',
                                    -ADAPTOR   => $self );

  $self->{'_top_level'}     = $toplevel;
  $self->{'_mapping_paths'} = \%mapping_paths;

  return 1;
} ## end sub _cache_mapping_paths

=head2 fetch_all

  Arg [1]    : none
  Example    : foreach my $cs (@{$csa->fetch_all()}) {
                 print $cs->name(), ' ', $cs->version(), "\n";
               }
  Description: Retrieves every coordinate system defined in the DB.
               These will be returned in ascending order of rank. I.e.
               The highest coordinate system with rank=1 would be first in the
               array.
  Returntype : listref of Bio::EnsEMBL::CoordSystems
  Exceptions : none
  Caller     : general
  Status     : Stable

=cut

sub fetch_all {
  my $self = shift;

  my @coord_systems;

  #order the array by rank in ascending order
  foreach my $rank (sort {$a <=> $b} keys %{$self->{'_rank_cache'}}) {
    push @coord_systems, $self->{'_rank_cache'}->{$rank};
  }

  return \@coord_systems;
}



=head2 fetch_by_rank

  Arg [1]    : int $rank
  Example    : my $cs = $coord_sys_adaptor->fetch_by_rank(1);
  Description: Retrieves a CoordinateSystem via its rank. 0 is a special
               rank reserved for the pseudo coordinate system 'toplevel'.
               undef is returned if no coordinate system of the specified rank
               exists.
  Returntype : Bio::EnsEMBL::CoordSystem
  Exceptions : none
  Caller     : general
  Status     : Stable

=cut

sub fetch_by_rank {
  my $self = shift;
  my $rank = shift;

  throw("Rank argument must be defined.") if(!defined($rank));
  throw("Rank argument must be a non-negative integer.") if($rank !~ /^\d+$/);

  if($rank == 0) {
    return $self->fetch_top_level();
  }

  return $self->{'_rank_cache'}->{$rank};
}


=head2 fetch_by_name

  Arg [1]    : string $name
               The name of the coordinate system to retrieve.  Alternatively
               this may be an alias for a real coordinate system.  Valid
               aliases are 'toplevel' and 'seqlevel'.
  Arg [2]    : string $version (optional)
               The version of the coordinate system to retrieve.  If not
               specified the default version will be used.
  Example    : $coord_sys = $csa->fetch_by_name('clone');
               $coord_sys = $csa->fetch_by_name('chromosome', 'NCBI33');
               # toplevel is an pseudo coord system representing the highest
               # coord system in a given region
               # such as the chromosome coordinate system
               $coord_sys = $csa->fetch_by_name('toplevel');
               #seqlevel is an alias for the sequence level coordinate system
               #such as the clone or contig coordinate system
               $coord_sys = $csa->fetch_by_name('seqlevel');
  Description: Retrieves a coordinate system by its name
  Returntype : Bio::EnsEMBL::CoordSystem
  Exceptions : throw if no name argument provided
               warning if no version provided and default does not exist
  Caller     : general
  Status     : Stable

=cut

sub fetch_by_name {
  my $self = shift;
  my $name = lc(shift); #case insensitve matching
  my $version = shift;

  throw('Name argument is required.') if(!$name);

  $version = lc($version) if($version);


  if($name eq 'seqlevel') {
    return $self->fetch_sequence_level();
  } elsif($name eq 'toplevel') {
    return $self->fetch_top_level($version);
  }

  if(!exists($self->{'_name_cache'}->{$name})) {
    if($name =~ /top/) {
      warning("Did you mean 'toplevel' coord system instead of '$name'?");
    } elsif($name =~ /seq/) {
      warning("Did you mean 'seqlevel' coord system instead of '$name'?");
    }
    return undef;
  }

  my @coord_systems = @{$self->{'_name_cache'}->{$name}};

  foreach my $cs (@coord_systems) {
    if($version) {
      return $cs if(lc($cs->version()) eq $version);
    } elsif($self->{'_is_default_version'}->{$cs->dbID()}) {
      return $cs;
    }
  }

  if($version) {
    #the specific version we were looking for was not found
    return undef;
  }

  #didn't find a default, just take first one
  my $cs =  shift @coord_systems;
  my $v = $cs->version();
  warning("No default version for coord_system [$name] exists. " .
      "Using version [$v] arbitrarily");

  return $cs;
}


=head2 fetch_all_by_name

  Arg [1]    : string $name
               The name of the coordinate system to retrieve.  This can be
               the name of an actual coordinate system or an alias for a
               coordinate system.  Valid aliases are 'toplevel' and 'seqlevel'.
  Example    : foreach my $cs (@{$csa->fetch_all_by_name('chromosome')}){
                 print $cs->name(), ' ', $cs->version();
               }
  Description: Retrieves all coordinate systems of a particular name
  Returntype : listref of Bio::EnsEMBL::CoordSystem objects
  Exceptions : throw if no name argument provided
  Caller     : general
  Status     : Stable

=cut

sub fetch_all_by_name {
  my $self = shift;
  my $name = lc(shift); #case insensitive matching

  throw('Name argument is required') if(!$name);

  if($name eq 'seqlevel') {
    return [$self->fetch_sequence_level()];
  } elsif($name eq 'toplevel') {
    return [$self->fetch_top_level()];
  }

  return $self->{'_name_cache'}->{$name} || [];
}

=head2 fetch_all_by_version

  Arg [1]    : string $version
               The version of the coordinate systems to retrieve.
  Example    : foreach my $cs (@{$csa->fetch_all_by_version('GRCh37')}){
                 print $cs->name(), ' ', $cs->version();
               }
  Description: Retrieves all coordinate systems of a particular version
  Returntype : ArrayRef of Bio::EnsEMBL::CoordSystem objects
  Exceptions : throw if no name argument provided
  Caller     : general
  Status     : Stable

=cut

sub fetch_all_by_version {
  my ($self, $version) = @_;
  throw "Version argument is required" if ! $version;
  my @coord_systems;

  foreach my $rank (sort {$a <=> $b} keys %{$self->{'_rank_cache'}}) {
    if ($self->{'_rank_cache'}->{$rank}->version()) {
      if ($self->{'_rank_cache'}->{$rank}->version() eq $version) {
        push @coord_systems, $self->{'_rank_cache'}->{$rank};
      }
    } else {
      if (!$version) {
        push @coord_systems, $self->{'_rank_cache'}->{$rank};
      }
    }
  }
  return \@coord_systems;
}

=head2 fetch_by_dbID

  Arg [1]    : int dbID
  Example    : $cs = $csa->fetch_by_dbID(4);
  Description: Retrieves a coord_system via its internal
               identifier, or undef if no coordinate system with the provided
               id exists.
  Returntype : Bio::EnsEMBL::CoordSystem or undef
  Exceptions : thrown if no coord_system exists for specified dbID
  Caller     : general
  Status     : Stable

=cut

sub fetch_by_dbID {
  my $self = shift;
  my $dbID = shift;

  throw('dbID argument is required') if(!$dbID);

  my $cs = $self->{'_dbID_cache'}->{$dbID};

  return undef if(!$cs);

  return $cs;
}



=head2 fetch_top_level

  Arg [1]    : none
  Example    : $cs = $csa->fetch_top_level();
  Description: Retrieves the toplevel pseudo coordinate system.
  Returntype : Bio::EnsEMBL::CoordSystem object
  Exceptions : none
  Caller     : general
  Status     : Stable

=cut

sub fetch_top_level {
  my $self = shift;

  return $self->{'_top_level'};
}


=head2 fetch_sequence_level

  Arg [1]    : none
  Example    : ($id, $name, $version) = $csa->fetch_sequence_level();
  Description: Retrieves the coordinate system at which sequence
               is stored at.
  Returntype : Bio::EnsEMBL::CoordSystem
  Exceptions : throw if no sequence_level coord system exists at all
               throw if multiple sequence_level coord systems exists
  Caller     : general
  Status     : Stable

=cut

sub fetch_sequence_level {
  my $self = shift;

  my @dbIDs = keys %{$self->{'_is_sequence_level'}};

  throw('No sequence_level coord_system is defined') if(!@dbIDs);

  if(@dbIDs > 1) {
    throw('Multiple sequence_level coord_systems are defined.' .
          'Only one is currently supported');
  }

  return $self->{'_dbID_cache'}->{$dbIDs[0]};
}
=head2 get_default_version

  Arg [1]    : none
  Example    : $version = $csa->get_default_version();
  Description: Retrieves the default version of the assembly
  Returntype : String
  Exceptions : throw if no default version is defined
  Caller     : general
  Status     : Stable

=cut

sub get_default_version {
  my $self = shift;

  my $version;
  foreach my $dbID (keys %{$self->{'_is_default_version'}}) {
    if ($self->{'_dbID_cache'}->{$dbID}->version) {
      $version = $self->{'_dbID_cache'}->{$dbID}->version;
      last;
    }
  }

  return $version;
}



=head2 get_all_versions

  Arg [1]    : none
  Example    : @versions = $csa->get_all_versions();
  Description: Retrieves all the available versions of assemblies
  Returntype : Listref of versions (strings)
  Exceptions : throw if no version is defined
  Caller     : general
  Status     : Stable

=cut

sub get_all_versions {
  my $self = shift;

  my %hash_versions;
  my @versions;
  my $version;
  foreach my $dbID (sort {$a <=> $b} keys %{$self->{'_rank_cache'}}) {
    if ($self->{'_rank_cache'}->{$dbID}->version) {
      $version = $self->{'_rank_cache'}->{$dbID}->version;
      if (!$hash_versions{$version}) {
        $hash_versions{$version} = 1;
        push @versions, $version;
      }
    }
  }

  throw('No versions found') if(!scalar(@versions));

  return \@versions;
}


=head2 get_mapping_path

  Arg [1]    : Bio::EnsEMBL::CoordSystem $cs1
  Arg [2]    : Bio::EnsEMBL::CoordSystem $cs2
  Example    : foreach my $cs @{$csa->get_mapping_path($cs1,$cs2);
  Description: Given two coordinate systems this will return a mapping path
               between them if one has been defined.  Allowed Mapping paths are
               explicitly defined in the meta table.  The following is an
               example:

          mysql> select * from meta where meta_key = 'assembly.mapping';
          +---------+------------------+--------------------------------------+
          | meta_id | meta_key         | meta_value                           |
          +---------+------------------+--------------------------------------+
          |      20 | assembly.mapping | chromosome:NCBI34|contig             |
          |      21 | assembly.mapping | clone|contig                         |
          |      22 | assembly.mapping | supercontig|contig                   |
          |      23 | assembly.mapping | chromosome:NCBI34|contig|clone       |
          |      24 | assembly.mapping | chromosome:NCBI34|contig|supercontig |
          |      25 | assembly.mapping | supercontig|contig|clone             |
          +---------+------------------+--------------------------------------+

               For a one-step mapping path to be valid there needs to be
               a relationship between the two coordinate systems defined in
               the assembly table.  Two step mapping paths work by building
               on the one-step mapping paths which are already defined.

               The first coordinate system in a one step mapping path must
               be the assembled coordinate system and the second must be
               the component.

               Example of use:
               my $cs1 = $cs_adaptor->fetch_by_name('contig');
               my $cs2 = $cs_adaptor->fetch_by_name('chromosome');

               my @path = @{$cs_adaptor->get_mapping_path($cs1,$cs2)};

               if(!@path) {
                 print "No mapping path.";
               }
               elsif(@path == 2) {
                 print "2 step mapping path.";
                 print "Assembled = " . $path[0]->name() . "\n";
                 print "Component = " . $path[1]->name() . "\n";
               } else {
                 print "Multi step mapping path\n";
               }

  Returntype : reference to a list of Bio::EnsEMBL::CoordSystem objects

  Exceptions : none
  Caller     : general
  Status     : Stable

=cut

sub get_mapping_path {
  my $self = shift;
  my $cs1 = shift;
  my $cs2 = shift;

  if(!ref($cs1) || !ref($cs2) ||
     !$cs1->isa('Bio::EnsEMBL::CoordSystem') ||
     !$cs2->isa('Bio::EnsEMBL::CoordSystem')) {
    throw('Two Bio::EnsEMBL::CoordSystem arguments expected.');
  }

  my $key1 = $cs1->name();
  $key1 .= ':' . $cs1->version() if ($cs1->version());
  my $key2 = $cs2->name();
  $key2 .= ':' . $cs2->version() if ($cs2->version());

  my $path = $self->{'_mapping_paths'}->{"$key1|$key2"};

  return $path if($path);

  $path = $self->{'_mapping_paths'}->{"$key2|$key1"};

  if(!$path) {
    # No path was explicitly defined, but we might be able to guess a
    # suitable path.  We only guess for missing 2 step paths.

    my %mid1;
    my %mid2;

    foreach my $path (values(%{$self->{'_mapping_paths'}})) {
      next if(@$path != 2);

      my $match = undef;

      if($path->[0]->equals($cs1)) {
        $match = 1;
      } elsif($path->[1]->equals($cs1)) {
        $match = 0;
      }

      if(defined($match)) {
        my $mid = $path->[$match];
        my $midkey = $mid->name() . ':' . $mid->version();

        # is the same cs mapped to by other cs?
        if($mid2{$midkey}) {
          my $path = [$cs1,$mid,$cs2];
          $self->{'_mapping_paths'}->{"$key1|$key2"} = $path;
          $key1 =~ s/\:$//;
          $key2 =~ s/\:$//;
          $midkey =~ s/\:$//;
          warning("Using implicit mapping path between '$key1' and '$key2' " .
                  "coord systems.\n" .
                  "An explicit 'assembly.mapping' entry should be added " .
                  "to the meta table.\nExample: " .
                  "'$key1|$midkey|$key2'\n");
          return $path;
        } else {
          $mid1{$midkey} = $mid;
        }
      }

      $match = undef;

      if($path->[0]->equals($cs2)) {
        $match = 1;
      } elsif($path->[1]->equals($cs2)) {
        $match = 0;
      }


      if(defined($match)) {
        my $mid = $path->[$match];
        my $midkey = $mid->name() . ':' . $mid->version();

        # is the same cs mapped to by other cs?
        if($mid1{$midkey}) {
          my $path = [$cs2,$mid,$cs1];
          $self->{'_mapping_paths'}->{"$key2|$key1"} = $path;

          $key1 =~ s/\:$//;
          $key2 =~ s/\:$//;
          $midkey =~ s/\:$//;
          warning("Using implicit mapping path between '$key1' and '$key2' " .
                  "coord systems.\n" .
                  "An explicit 'assembly.mapping' entry should be added " .
                  "to the meta table.\nExample: " .
                  "'$key1|$midkey|$key2'\n");

          return $path;
        } else {
          $mid2{$midkey} = $mid;
        }
      }
    }
  }

  return $path || [];
}

=head2 store_mapping_path

  Arg [1]    : Bio::EnsEMBL::CoordSystem $cs1
  Arg [2]    : Bio::EnsEMBL::CoordSystem $cs2
  Arg [3..n] : Bio::EnsEMBL::CoordSystem $cs3..$csN
  Example    : my $pathref = $csa->store_mapping_path($cs1,$cs2);
  Description: Given two or more coordinate systems this will store 
               mapping paths between them in the database. 

               For example, if $cs1 represents chrs of version
               V1, $cs2 represents contigs, and $cs3 clones then, unless
               they already exist, the following entries will be created 
               in the meta table;
               +------------------+---------------------+ 
               | meta_key         | meta_value          |
               +------------------+---------------------+ 
               | assembly.mapping | chr:V1|clone        |
               | assembly.mapping | clone|contig        |
               | assembly.mapping | chr:V1|clone|contig |
               +------------------+---------------------+


               For a one-step mapping path to be valid there needs to be
               a relationship between the two coordinate systems defined in
               the assembly table.  Two step mapping paths work by building
               on the one-step mapping paths which are already defined.

               The first coordinate system in a one step mapping path must
               be the assembled coordinate system and the second must be
               the component.

  Returntype : reference to a list of lists of new meta_value mapping strings
               created for assembly.mapping
  Exceptions : CoordSystems with no rank/duplicated rank
  Caller     : general
  Status     : Experimental

=cut

sub store_mapping_path{
  my $self = shift;
  my @csystems = @_;

  # Validate and sort the args
  my %seen_ranks;
  @csystems >= 2 or throw('Need two or more CoordSystems');
  my $validate = sub{ 
    ref($_[0]) && $_[0]->isa('Bio::EnsEMBL::CoordSystem') or
        throw('CoordSystem argument expected.');
    my $rank = $_[0]->rank || 
        throw('CoordSystem has no rank: '.$_[0]->name);
    $seen_ranks{$rank} &&
        throw('CoordSystem '.$_[0]->name." shares rank $rank with ".
              $seen_ranks{$rank}->name);
    $seen_ranks{$rank} = $_[0];
  };
  @csystems = map{&{$validate}($_)} @csystems;
  my ($key, @keys);
  foreach my $cs (@csystems) {
    $key = $cs->name();
    if ($cs->version()) {
      $key .= ":" . $cs->version();
    }
    push @keys, $key;
  }

  # For each pair in the sorted list, store in the DB
  my $meta = $self->db->get_MetaContainer;
  my @retlist;
  for( my $i=1; $i<@keys; $i++ ){
    for( my $j=0; $j<(@keys-$i); $j++ ){
      my $mapping = join( "|", @keys );
      
      my $mapping_key = join( "|", @keys );
      # Skip existing
      next if $self->{'_mapping_paths'}->{$mapping_key};
      
      # Update the database
      $meta->store_key_value('assembly.mapping',$mapping);
      push @retlist, $mapping;
    }
  }

  if( @retlist ){
    # Update mapping path cache
    $self->_cache_mapping_paths;
  }

  # Return the mappings that we have just created
  return [@retlist];
}


=head2 store_multiple_mapping_path

  Arg [1]    : Bio::EnsEMBL::CoordSystem $cs1
  Arg [2]    : Bio::EnsEMBL::CoordSystem $cs2
  Arg [3..n] : Bio::EnsEMBL::CoordSystem $cs3..$csN
  Example    : my $pathref = $csa->store_multiple_mapping_path($cs1,$cs2);
  Description: Given two or more coordinate systems this will store 
               multiple mapping paths between them in the database. 

               Works similarly to the store_mapping_path method
               But will presume every coord system can be mapped in multiple
               ways to the other coord systems
               This is represented by the use of '#' instead of '|'
               in the mapping key

  Returntype : reference to a list of lists of new meta_value mapping strings
               created for assembly.mapping
  Exceptions : CoordSystems with no rank/duplicated rank
  Caller     : general
  Status     : Experimental

=cut

sub store_multiple_mapping_path{
  my $self = shift;
  my @csystems = @_;

  # Validate and sort the args
  my %seen_ranks;
  @csystems >= 2 or throw('Need two or more CoordSystems');
  my $validate = sub{
    ref($_[0]) && $_[0]->isa('Bio::EnsEMBL::CoordSystem') or
        throw('CoordSystem argument expected.');
    my $rank = $_[0]->rank ||
        throw('CoordSystem has no rank: '.$_[0]->name);
    $seen_ranks{$rank} &&
        throw('CoordSystem '.$_[0]->name." shares rank $rank with ".
              $seen_ranks{$rank}->name);
    $seen_ranks{$rank} = $_[0];
  };
  @csystems = map{&{$validate}($_)} @csystems;
  my ($key, @keys);
  foreach my $cs (@csystems) {
    $key = $cs->name();
    if ($cs->version()) {
      $key .= ":" . $cs->version();
    }
    push @keys, $key;
  }
  # For each pair in the sorted list, store in the DB
  my $meta = $self->db->get_MetaContainer;
  my @retlist;
  for( my $i=1; $i<@keys; $i++ ){
    for( my $j=0; $j<(@keys-$i); $j++ ){
      my $mapping = join( "#", @keys );

      my $mapping_key = join( "#", @keys );
      # Skip existing
      next if $self->{'_mapping_paths'}->{$mapping_key};

      # Update the database
      $meta->store_key_value('assembly.mapping',$mapping) unless $meta->key_value_exists('assembly.mapping',$mapping);
      push @retlist, $mapping;
    }
  }

  if( @retlist ){
    # Update mapping path cache
    $self->_cache_mapping_paths;
  }

  # Return the mappings that we have just created
  return [@retlist];
}



=head2 fetch_by_attrib

  Arg [1]    : string attrib
  Arg [2]    : (optional) string version
  Example    : $csa->fetch_by_attrib('default_version','NCBIM37');
  Description: Retrieves a CoordSystem object from the database that have the specified
               attrib and version, if no version is specified, returns the default version
  Returntype : Bio::EnsEMBL::CoordSystem object
  Exceptions : throw when attrib not present
  Caller     : general
  Status     : Stable

=cut

sub fetch_by_attrib {
  my $self = shift;
  my $attrib = shift;
  my $version = shift;

  $version = lc($version) if($version);

  my @dbIDs = keys %{$self->{"_is_$attrib"}};

  throw("No $attrib coordinate system defined") if(!@dbIDs);

  foreach my $dbID (@dbIDs) {
    my $cs = $self->{'_dbID_cache'}->{$dbID};
    if($version) {
      return $cs if(lc($version) eq $cs->version());
    } elsif($self->{'_is_default_version'}->{$dbID}) {
      return $cs;
    }
  }

  #specifically requested attrib system was not found
  if($version) {
    throw("$attrib coord_system with version [$version] does not exist");
  }

  #coordsystem with attrib exists but no default is defined:
  my $dbID = shift @dbIDs;
  my $cs = $self->{'_dbID_cache'}->{$dbID};
  my $v = $cs->version();
  warning("No default version for $attrib coord_system exists. " .
          "Using version [$v] arbitrarily");

  return $cs;
}


=head2 fetch_all_by_attrib

  Arg [1]    : string attrib
  Example    : $csa->fetch_all_by_attrib('default_version');
  Description: Retrieves all CoordSystem object from the database that have the specified
               attrib.
  Returntype : reference to a list of Bio::EnsEMBL::CoordSystem objects
  Exceptions : throw when attrib not present
  Caller     : general
  Status     : Stable

=cut

sub fetch_all_by_attrib {
  my $self = shift;
  my $attrib = shift;

  my @coord_systems = ();
  foreach my $dbID (keys %{$self->{"_is_$attrib"}}) {
    push @coord_systems, $self->{"_dbID_cache"}->{$dbID};
  }

  return \@coord_systems;
}

=head2 store

  Arg [1]    : Bio::EnsEMBL::CoordSystem
  Example    : $csa->store($coord_system);
  Description: Stores a CoordSystem object in the database.
  Returntype : none
  Exceptions : Warning if CoordSystem is already stored in this database.
  Caller     : none
  Status     : Stable

=cut

sub store {
  my $self = shift;
  my $cs = shift;

  if(!$cs || !ref($cs) || !$cs->isa('Bio::EnsEMBL::CoordSystem')) {
    throw('CoordSystem argument expected.');
  }

  my $db = $self->db();
  my $name = $cs->name();
  my $version = $cs->version();
  my $rank    = $cs->rank();

  my $seqlevel = $cs->is_sequence_level();
  my $default  = $cs->is_default();

  my $toplevel = $cs->is_top_level();

  if($toplevel) {
    throw("The toplevel CoordSystem cannot be stored");
  }

  #
  # Do lots of sanity checking to prevent bad data from being entered
  #

  if($cs->is_stored($db)) {
    warning("CoordSystem $name $version is already in db.\n");
    return;
  }

  if($name eq 'toplevel' || $name eq 'seqlevel' || !$name) {
    throw("[$name] is not a valid name for a CoordSystem.");
  }

  if($seqlevel && keys(%{$self->{'_is_sequence_level'}})) {
    throw("There can only be one sequence level CoordSystem.");
  }

  if(exists $self->{'_name_cache'}->{lc($name)}) {
    my @coord_systems = @{$self->{'_name_cache'}->{lc($name)}};
    foreach my $c (@coord_systems) {
      if(lc($c->version()) eq lc($version)) {
        warning("CoordSystem $name $version is already in db.\n");
        return;
      }
      if($default && $self->{'_is_default_version'}->{$c->dbID()}) {
        throw("There can only be one default version of CoordSystem $name");
      }
    }
  }

  if($rank !~ /^\d+$/) {
    throw("Rank attribute must be a positive integer not [$rank]");
  }
  if($rank == 0) {
    throw("Only toplevel CoordSystem may have rank of 0.");
  }

  if(defined($self->{'_rank_cache'}->{$rank})) {
    throw("CoordSystem with rank [$rank] already exists.");
  }

  my @attrib;

  push @attrib, 'default_version' if($default);
  push @attrib, 'sequence_level' if($seqlevel);

  my $attrib_str = (@attrib) ? join(',', @attrib) : undef;

  #
  # store the coordinate system in the database
  #

  my $sth =
    $db->dbc->prepare(   'INSERT INTO coord_system '
                       . '( `name`, `version`, `attrib`, `rank`, `species_id` ) '
                         . 'VALUES ( ?, ?, ?, ?, ? )' );

  $sth->bind_param( 1, $name,               SQL_VARCHAR );
  $sth->bind_param( 2, $version,            SQL_VARCHAR );
  $sth->bind_param( 3, $attrib_str,         SQL_VARCHAR );
  $sth->bind_param( 4, $rank,               SQL_INTEGER );
  $sth->bind_param( 5, $self->species_id(), SQL_INTEGER );

  $sth->execute();
  my $dbID = $self->last_insert_id('coord_system_id', undef, 'coord_system');
  $sth->finish();

  if(!$dbID) {
    throw("Did not get dbID from store of CoordSystem.");
  }

  $cs->dbID($dbID);
  $cs->adaptor($self);

  #
  # update the internal caches that are used for fetching
  #
  $self->{'_is_default_version'}->{$dbID} = 1 if($default);
  $self->{'_is_sequence_level'}->{$dbID} = 1 if($seqlevel);

  $self->{'_name_cache'}->{lc($name)} ||= [];
  push @{$self->{'_name_cache'}->{lc($name)}}, $cs;

  $self->{'_dbID_cache'}->{$dbID} = $cs;
  $self->{'_rank_cache'}->{$rank} = $cs;

  return $cs;
}

=head2 remove

  Arg [1]    : Bio::EnsEMBL::CoordSystem
  Example    : $csa->remove($coord_system);
  Description: Removes a CoordSystem object from the database.
  Returntype : none
  Exceptions : Warning if CoordSystem is not stored in this database.
  Caller     : none
  Status     : Stable

=cut

sub remove {
  my $self = shift;
  my $cs = shift;

  if(!$cs || !ref($cs) || !$cs->isa('Bio::EnsEMBL::CoordSystem')) {
    throw('CoordSystem argument expected.');
  }

  my $db = $self->db();
  my $name = $cs->name();
  my $version = $cs->version();
  my $dbID = $cs->dbID();
  my $rank = $cs->rank(); 

  #
  # Do lots of sanity checking to prevent bad data from being entered
  #

  if(!$cs->is_stored($db)) {
    warning("CoordSystem $name $version does not exist in db.\n");
    return;
  }

  if($name eq 'toplevel' || $name eq 'seqlevel' || !$name) {
    throw("[$name] is not a valid name for a CoordSystem.");
  }

  #
  # remove the coordinate system from in the database
  #

  my $sql = "DELETE FROM coord_system WHERE name = ?";
  if ($version) {
    $sql .= " AND version = ?";
  }
  
  my $sth = $db->dbc->prepare($sql);

  $sth->bind_param( 1, $name,               SQL_VARCHAR );
  $sth->bind_param( 2, $version,            SQL_VARCHAR ) if $version;

  $sth->execute();
  $sth->finish();

  delete $self->{'_name_cache'}->{lc($name)};

  delete $self->{'_dbID_cache'}->{$dbID};
  delete $self->{'_rank_cache'}->{$rank};
  delete $self->{'_is_sequence_level'}->{$dbID};
  delete $self->{'_is_default_version'}->{$dbID};
  $cs->dbID(undef);
  $cs->adaptor(undef);

  return $cs;
}

1;
