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# Copyright 2007, 2008, 2009, 2010, 2011 Kevin Ryde

# This file is part of Chart.
#
# Chart is free software; you can redistribute it and/or modify it under the
# terms of the GNU General Public License as published by the Free Software
# Foundation; either version 3, or (at your option) any later version.
#
# Chart is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
# details.
#
# You should have received a copy of the GNU General Public License along
# with Chart.  If not, see <http://www.gnu.org/licenses/>.

package App::Chart::DBI;
use 5.006;
use strict;
use warnings;
use File::Spec;

use App::Chart;

# uncomment this to run the ### lines
#use Smart::Comments;

# See Database/Create.pm for revisions
use constant DATABASE_SCHEMA_VERSION => 2;


# return the database filename ~/Chart/database.sqdb or the notes database
# filename ~/Chart/notes.sqdb, as absolute path in filesystem charset bytes
use constant::defer database_filename => sub {
  return File::Spec->catfile (App::Chart::chart_directory(), 'database.sqdb');
};
use constant::defer notes_filename => sub {
  return File::Spec->catfile(App::Chart::chart_directory(), 'notes.sqdb');
};

use Class::Singleton 1.4;
use base 'Class::Singleton';
our $_instance;

# singleton
sub _new_instance {
  ### Chart-DBI _new_instance()
  my $database_filename = database_filename();
  ### $database_filename

  if (! -e $database_filename) {
    require App::Chart::Database::Create;
    App::Chart::Database::Create::initial_database ($database_filename);
  }

  my $notes_filename = notes_filename();
  ### $notes_filename
  if (! -e $notes_filename) {
    require App::Chart::Database::Create;
    App::Chart::Database::Create::initial_notes ($notes_filename);
  }

  require DBI;
  my $dbh = DBI->connect ("dbi:SQLite:dbname=$database_filename",
                          '', '', {RaiseError=>1});
  $dbh->func(90_000, 'busy_timeout');  # 90 seconds
  $dbh->{'sqlite_unicode'} = 1;
  $dbh->do ('ATTACH DATABASE ' . $dbh->quote($notes_filename)
            . ' AS notesdb');

  my ($dbversion) = do {
    local $dbh->{RaiseError} = undef;
    local $dbh->{PrintError} = undef;
    $dbh->selectrow_array
      ("SELECT value FROM extra WHERE key='database-schema-version'")
    };
  $dbversion ||= 0;
  if ($dbversion < DATABASE_SCHEMA_VERSION) {
    require App::Chart::Database::Create;
    $_instance = $dbh;
    App::Chart::Database::Create::upgrade_database ($dbh, $dbversion);
  }

  return $dbh;
}

sub disconnect {
  my ($class) = @_;
  ### Chart-DBI _disconnect()
  if (my $dbh = $class->has_instance) {

    # Empty cache to suppress warnings about statement handles.
    # Is this supposed to be necessary?