# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.
#
# This Source Code Form is "Incompatible With Secondary Licenses", as
# defined by the Mozilla Public License, v. 2.0.

=head1 NAME

Bugzilla::DB::Pg - Bugzilla database compatibility layer for PostgreSQL

=head1 DESCRIPTION

This module overrides methods of the Bugzilla::DB module with PostgreSQL
specific implementation. It is instantiated by the Bugzilla::DB module
and should never be used directly.

For interface details see L<Bugzilla::DB> and L<DBI>.

=cut

package Bugzilla::DB::Pg;

use 5.10.1;
use Moo;

use Bugzilla::Error;
use Bugzilla::Version;
use DBD::Pg;

# This module extends the DB interface via inheritance
extends qw(Bugzilla::DB);

use constant BLOB_TYPE => {pg_type => DBD::Pg::PG_BYTEA};

sub BUILDARGS {
  my ($class, $params) = @_;
  my ($user, $pass, $host, $dbname, $port)
    = @$params{qw(db_user db_pass db_host db_name db_port)};

  # The default database name for PostgreSQL. We have
  # to connect to SOME database, even if we have
  # no $dbname parameter.
  $dbname ||= 'template1';

  # construct the DSN from the parameters we got
  my $dsn = "dbi:Pg:dbname=$dbname";
  $dsn .= ";host=$host" if $host;
  $dsn .= ";port=$port" if $port;

  # This stops Pg from printing out lots of "NOTICE" messages when
  # creating tables.
  $dsn .= ";options='-c client_min_messages=warning'";

  my $attrs = {pg_enable_utf8 => Bugzilla->params->{'utf8'}};

  return {dsn => $dsn, user => $user, pass => $pass, attrs => $attrs};
}

# if last_insert_id is supported on PostgreSQL by lowest DBI/DBD version
# supported by Bugzilla, this implementation can be removed.
sub bz_last_key {
  my ($self, $table, $column) = @_;

  my $seq = $table . "_" . $column . "_seq";
  my ($last_insert_id) = $self->selectrow_array("SELECT CURRVAL('$seq')");

  return $last_insert_id;
}

sub sql_group_concat {
  my ($self, $text, $separator, $sort) = @_;
  $sort = 1 if !defined $sort;
  $separator = $self->quote(', ') if !defined $separator;
  my $sql = "array_accum($text)";
  if ($sort) {
    $sql = "array_sort($sql)";
  }
  return "array_to_string($sql, $separator)";
}

sub sql_istring {
  my ($self, $string) = @_;

  return "LOWER(${string}::text)";
}

sub sql_position {
  my ($self, $fragment, $text) = @_;

  return "POSITION(${fragment}::text IN ${text}::text)";
}

sub sql_regexp {
  my ($self, $expr, $pattern, $nocheck, $real_pattern) = @_;
  $real_pattern ||= $pattern;

  $self->bz_check_regexp($real_pattern) if !$nocheck;

  return "${expr}::text ~* $pattern";
}

sub sql_not_regexp {
  my ($self, $expr, $pattern, $nocheck, $real_pattern) = @_;
  $real_pattern ||= $pattern;

  $self->bz_check_regexp($real_pattern) if !$nocheck;

  return "${expr}::text !~* $pattern";
}

sub sql_limit {
  my ($self, $limit, $offset) = @_;

  if (defined($offset)) {
    return "LIMIT $limit OFFSET $offset";
  }
  else {
    return "LIMIT $limit";
  }
}

sub sql_from_days {
  my ($self, $days) = @_;

  return "TO_TIMESTAMP('$days', 'J')::date";
}

sub sql_to_days {
  my ($self, $date) = @_;

  return "TO_CHAR(${date}::date, 'J')::int";
}

sub sql_date_format {
  my ($self, $date, $format) = @_;

  $format = "%Y-%m-%d %H:%i:%s" if !$format;

  $format =~ s/\%Y/YYYY/g;
  $format =~ s/\%y/YY/g;
  $format =~ s/\%m/MM/g;
  $format =~ s/\%d/DD/g;
  $format =~ s/\%a/Dy/g;
  $format =~ s/\%H/HH24/g;
  $format =~ s/\%i/MI/g;
  $format =~ s/\%s/SS/g;

  return "TO_CHAR($date, " . $self->quote($format) . ")";
}

sub sql_date_math {
  my ($self, $date, $operator, $interval, $units) = @_;

  return "$date $operator $interval * INTERVAL '1 $units'";
}

sub sql_string_concat {
  my ($self, @params) = @_;

  # Postgres 7.3 does not support concatenating of different types, so we
  # need to cast both parameters to text. Version 7.4 seems to handle this
  # properly, so when we stop support 7.3, this can be removed.
  return '(CAST(' . join(' AS text) || CAST(', @params) . ' AS text))';
}

# Tell us whether or not a particular sequence exists in the DB.
sub bz_sequence_exists {
  my ($self, $seq_name) = @_;
  my $exists
    = $self->selectrow_array(
    'SELECT 1 FROM pg_statio_user_sequences WHERE relname = ?',
    undef, $seq_name);
  return $exists || 0;
}

sub bz_explain {
  my ($self, $sql) = @_;
  my $explain = $self->selectcol_arrayref("EXPLAIN ANALYZE $sql");
  return join("\n", @$explain);
}

#####################################################################
# Custom Database Setup
#####################################################################

sub bz_check_server_version {
  my $self           = shift;
  my ($db)           = @_;
  my $server_version = $self->SUPER::bz_check_server_version(@_);
  my ($major_version, $minor_version) = $server_version =~ /^0*(\d+)\.0*(\d+)/;

  # Pg 9.0 requires DBD::Pg 2.17.2 in order to properly read bytea values.
  # Pg 9.2 requires DBD::Pg 2.19.3 as spclocation no longer exists.
  if ($major_version >= 9) {
    local $db->{dbd}->{version} = ($minor_version >= 2) ? '2.19.3' : '2.17.2';
    local $db->{name} = $db->{name} . " ${major_version}.$minor_version";
    Bugzilla::DB::_bz_check_dbd(@_);
  }
}

sub bz_setup_database {
  my $self = shift;
  $self->SUPER::bz_setup_database(@_);

  # Custom Functions
  my $function = 'array_accum';
  my $array_accum
    = $self->selectrow_array('SELECT 1 FROM pg_proc WHERE proname = ?',
    undef, $function);
  if (!$array_accum) {
    print "Creating function $function...\n";
    $self->do(
      "CREATE AGGREGATE array_accum (
                       SFUNC = array_append,
                       BASETYPE = anyelement,
                       STYPE = anyarray,
                       INITCOND = '{}'
                   )"
    );
  }

  $self->do(<<'END');
CREATE OR REPLACE FUNCTION array_sort(ANYARRAY)
RETURNS ANYARRAY LANGUAGE SQL
IMMUTABLE STRICT
AS $$
SELECT ARRAY(
    SELECT $1[s.i] AS each_item
    FROM
        generate_series(array_lower($1,1), array_upper($1,1)) AS s(i)
    ORDER BY each_item
);
$$;
END

  # PostgreSQL doesn't like having *any* index on the thetext
  # field, because it can't have index data longer than 2770
  # characters on that field.
  $self->bz_drop_index('longdescs', 'longdescs_thetext_idx');

  # Same for all the comments fields in the fulltext table.
  $self->bz_drop_index('bugs_fulltext', 'bugs_fulltext_comments_idx');
  $self->bz_drop_index('bugs_fulltext', 'bugs_fulltext_comments_noprivate_idx');

  # PostgreSQL also wants an index for calling LOWER on
  # login_name, which we do with sql_istrcmp all over the place.
  $self->bz_add_index(
    'profiles',
    'profiles_login_name_lower_idx',
    {FIELDS => ['LOWER(login_name)'], TYPE => 'UNIQUE'}
  );

  # Now that Bugzilla::Object uses sql_istrcmp, other tables
  # also need a LOWER() index.
  _fix_case_differences('fielddefs', 'name');
  $self->bz_add_index('fielddefs', 'fielddefs_name_lower_idx',
    {FIELDS => ['LOWER(name)'], TYPE => 'UNIQUE'});
  _fix_case_differences('keyworddefs', 'name');
  $self->bz_add_index('keyworddefs', 'keyworddefs_name_lower_idx',
    {FIELDS => ['LOWER(name)'], TYPE => 'UNIQUE'});
  _fix_case_differences('products', 'name');
  $self->bz_add_index('products', 'products_name_lower_idx',
    {FIELDS => ['LOWER(name)'], TYPE => 'UNIQUE'});

  # bz_rename_column and bz_rename_table didn't correctly rename
  # the sequence.
  $self->_fix_bad_sequence('fielddefs', 'id', 'fielddefs_fieldid_seq',
    'fielddefs_id_seq');

  # If the 'tags' table still exists, then bz_rename_table()
  # will fix the sequence for us.
  if (!$self->bz_table_info('tags')) {
    my $res = $self->_fix_bad_sequence('tag', 'id', 'tags_id_seq', 'tag_id_seq');

    # If $res is true, then the sequence has been renamed, meaning that
    # the primary key must be renamed too.
    if ($res) {
      $self->do('ALTER INDEX tags_pkey RENAME TO tag_pkey');
    }
  }

  # Certain sequences got upgraded before we required Pg 8.3, and
  # so they were not properly associated with their columns.
  my @tables = $self->bz_table_list_real;
  foreach my $table (@tables) {
    my @columns = $self->bz_table_columns_real($table);
    foreach my $column (@columns) {

      # All our SERIAL pks have "id" in their name at the end.
      next unless $column =~ /id$/;
      my $sequence = "${table}_${column}_seq";
      if ($self->bz_sequence_exists($sequence)) {
        my $is_associated = $self->selectrow_array('SELECT pg_get_serial_sequence(?,?)',
          undef, $table, $column);
        next if $is_associated;
        print "Fixing $sequence to be associated" . " with $table.$column...\n";
        $self->do("ALTER SEQUENCE $sequence OWNED BY $table.$column");

        # In order to produce an exactly identical schema to what
        # a brand-new checksetup.pl run would produce, we also need
        # to re-set the default on this column.
        $self->do(
          "ALTER TABLE $table
                          ALTER COLUMN $column
                           SET DEFAULT nextval('$sequence')"
        );
      }
    }
  }
}

sub _fix_bad_sequence {
  my ($self, $table, $column, $old_seq, $new_seq) = @_;
  if ( $self->bz_column_info($table, $column)
    && $self->bz_sequence_exists($old_seq))
  {
    print "Fixing $old_seq sequence...\n";
    $self->do("ALTER SEQUENCE $old_seq RENAME TO $new_seq");
    $self->do(
      "ALTER TABLE $table ALTER COLUMN $column
                    SET DEFAULT NEXTVAL('$new_seq')"
    );
    return 1;
  }
  return 0;
}

# Renames things that differ only in case.
sub _fix_case_differences {
  my ($table, $field) = @_;
  my $dbh = Bugzilla->dbh;

  my $duplicates = $dbh->selectcol_arrayref(
    "SELECT DISTINCT LOWER($field) FROM $table
        GROUP BY LOWER($field) HAVING COUNT(LOWER($field)) > 1"
  );

  foreach my $name (@$duplicates) {
    my $dups
      = $dbh->selectcol_arrayref(
      "SELECT $field FROM $table WHERE LOWER($field) = ?",
      undef, $name);
    my $primary = shift @$dups;
    foreach my $dup (@$dups) {
      my $new_name = "${dup}_";

      # Make sure the new name isn't *also* a duplicate.
      while (1) {
        last
          if (!$dbh->selectrow_array(
          "SELECT 1 FROM $table WHERE LOWER($field) = ?",
          undef, lc($new_name)
          ));
        $new_name .= "_";
      }
      print "$table '$primary' and '$dup' have names that differ",
        " only in case.\nRenaming '$dup' to '$new_name'...\n";
      $dbh->do("UPDATE $table SET $field = ? WHERE $field = ?",
        undef, $new_name, $dup);
    }
  }
}

#####################################################################
# Custom Schema Information Functions
#####################################################################

# Pg includes the PostgreSQL system tables in table_list_real, so
# we need to remove those.
sub bz_table_list_real {
  my $self = shift;

  my @full_table_list = $self->SUPER::bz_table_list_real(@_);

  # All PostgreSQL system tables start with "pg_" or "sql_"
  my @table_list = grep(!/(^pg_)|(^sql_)/, @full_table_list);
  return @table_list;
}

1;
