package Local::DB;

=begin # README
================================================================================
wrapper around DBIx::Simple providing overloaded query() and _replace_omniholder()
* dumps query statements to stdout using Term::ANSIColor to colour-code
* logs queries using Local::QueryLogger (switch off with $NO_QUERY_LOGS)
* auto-inflates dates (unless switched off in caller with 
    $Local::DBIx::Simple::Result::NO_AUTO_DATE_INFLATION = 1)
* allows omniplaceholders (??) in same query as placeholders (?)
usage: my $o = Local::DB->dbix(\%args), then call DBIx::Simple methods on $o
================================================================================
=cut

use parent 'DBIx::Simple';
use DBIx::Simple::OO; # allows call to ->objects

use Local::DBIx::Simple::Result; # sub-classes DBIx::Simple::Result to auto-inflate dates
use Module::Runtime qw(use_module);
use Scalar::Util 'looks_like_number';
use Data::Printer alias => 'ddp';
use SQL::Abstract;
use Data::Dumper;
use Modern::Perl;
use Local::Utils;

use Local::QueryLogger;
sub query_logger { $_[0]->{logger} ||= $_[0]->_build_query_logger }
sub _build_query_logger { Local::QueryLogger->new }

sub sqla { $_[0]->{_sqla} ||= $_[0]->_build_sqla }
sub _build_sqla { SQL::Abstract->new }

our %DBIx_Simple_Cache; # so DBIx::Simple object can be shared

sub debug { ddp @_ }

# just returns dsn as array:
sub dsn {
    my ($class, $args) = @_;
    my @dsn = _mysql_connection_params($args); # warn Dumper \@dsn;
    return @dsn;
}

sub query { # inherits from parent, logs query to console and/or log file
    my $self = shift; # ddp $self;
    my ($str, @bind) = @_; # warn $str; warn Dumper \@bind;

    # do querylog functions:
    $self->query_logger->log_query($str, @bind);
    # continue on its original way:
    $self->SUPER::query($str, @bind);
}

sub count {
    my ($self, $table, $where) = @_; # ddp $table; ddp $where;
    my @args = ($table, ['COUNT(*)']);
    push @args, $where if $where;
    my $count = $self->select(@args)->list;
    return $count;
}

sub get_cols {
    my ($self, $tbl) = @_;
    
	my @data = $self->query('SHOW COLUMNS FROM ' . $tbl)->hashes;
	my @cols = map $_->{Field}, @data;
	return wantarray ? @cols : \@cols;
}

sub dbix { # provides overloaded query() & _mysql_connection_params()
    my ($class, $ref) = @_; # href of username & (db or dsn)

    # either db_name or dsn eg (dbi:SQLite:dbname=:memory:)
    my $db = $ref->{dsn} || $ref->{dbname} || die 'no dsn or db name';

    # this doesn't work for long-running dbix objects in case db disconnects:
    # $DBIx_Simple_Cache{$db_name} ||= $class->_new_dbix_simple($args); replaced with:

#=begin # non-debugging version:
    # returned cached object if dbh still active, or create new & return it:
    if ( my $dbix = $DBIx_Simple_Cache{$db} ) {
        return $dbix if $dbix->dbh->ping; # only return cached dbix if dbh still active
    }
    # so either no $DBIx_Simple_Cache{$db_name} or dbh didn't respond to ping so
    # create a new one and return it:
    return $DBIx_Simple_Cache{$db} = $class->_new_dbix_simple($ref);
#=cut

# debugging variant of above ===================================================
    my $time_now = Local::Utils::time_now;
    my @caller   = caller(1); # ddp @caller;
    my $caller   = $caller[3]; # ddp $caller; # needs adjusting if called from a .pl script ??
    if ( my $dbix = $DBIx_Simple_Cache{$db} ) {
        my $id = $dbix->dbh->{mysql_thread_id};
        # return $dbix if $dbix->dbh->ping;
        if ( $dbix->dbh->ping ) { # only return cached dbix if dbh still active:
            say "$time_now active dbh (thread_id=$id) so returning cached dbix for $caller";
            return $dbix;
        }
        say "$time_now have cached dbix for $caller but dbh INACTIVE (thread_id=$id)";
    }
    # so either no $DBIx_Simple_Cache{$db_name} or dbh didn't respond to ping so
    # create a new one and return it:
    my $new_dbix = $class->_new_dbix_simple($ref);
    my $id = $new_dbix->dbh->{mysql_thread_id};
    say "$time_now creating new dbix object for $caller (thread_id=$id)";
    $DBIx_Simple_Cache{$db} = $new_dbix;
    return $new_dbix;
#===============================================================================
}

sub _new_dbix_simple {
    my ($class, $args) = @_;

    my @dsn = _mysql_connection_params($args);
    my $dbix = $class->SUPER::connect(@dsn); # ddp $dbix; # SUPER is DBIx::Simple

    # replace default dbix result_class (DBIx::Simple::Result) with
    # Local::DBIx::Simple::Result (provides auto-date-inflation):
    $dbix->{result_class} = use_module('Local::DBIx::Simple::Result');

=begin # generates mysql gone away error:
    use DBIx::Connector;
    my $dbc = DBIx::Connector->new(@dsn); # ddp $dbc;
    my $dbix = $class->SUPER::new($dbc->dbh); # ddp $dbix; # SUPER is DBIx::Simple
=cut
=begin # integrated Log4perl dbh:
    my $dbh = _log4perl_dbh(@dsn);
    my $dbix = $class->SUPER::new($dbh); # ddp $dbix; # SUPER is DBIx::Simple
=cut
    return $dbix;
}

=begin # integrated Log4perl dbh:
sub _log4perl_dbh { # uncomment dbix_l4p_logmask in _mysql_connection_params()
    use Log::Log4perl;
    use DBIx::Log4perl qw(:masks);
    Log::Log4perl->init("/path/to/mylog4perl.conf");
    return DBIx::Log4perl->connect(@_); # dbh;
}
=cut

sub _mysql_connection_params {
    my $args = shift; # href of username & (db or dsn eg dbi:SQLite:dbname=<db>)

    # just return dsn if configured (eg SQLite doesn't need username/pwd)
    return $args->{dsn} if $args->{dsn};

    my $cnf = '/home/raj/.local/mysql.cnf';
    -f $cnf || die 'no mysql.cnf file found';

    my %attr = (
        PrintError => 0,
        RaiseError => 1,
        mysql_auto_reconnect => 0, # used in conjunction with testing for ping
        # uncomment if using log4perl dbh:
        # dbix_l4p_logmask => DBIX_L4P_LOG_SQL|DBIX_L4P_LOG_DELAYBINDPARAM,
    );
    my $dsn = join ';', (
        'dbi:mysql:host=localhost',
        'database='.$args->{dbname},
        'mysql_read_default_file='.$cnf
    );
    return ( $dsn, undef, undef, \%attr );
}

sub _replace_omniholder {
    my ($self, $query, $binds) = @_; # ddp [$query, $binds]; # scalarref, arrayref
    return if $$query !~ /\(\?\?\)/;

#-------------------------------------------------------------------------------
    # count how many individual placeholders in query for subtraction from @$binds:
    my $re = qr{\s\?}; # ie individual placeholders - WHERE foo = ? AND bar = ?

    # $placeholders_count++ while $$query =~ /$re/g; # warn $placeholders_count;
    my $placeholders_count = () = $$query =~ /$re/g; # warn $placeholders_count; # perlfaq4
    my $omniholders_count = scalar(@$binds) - $placeholders_count;
#-------------------------------------------------------------------------------

    my $omniholders = 0;

#-------------------------------------------------------------------------------
    # global vars copied from DBIx::Simple - only used in this sub anyway:
    my $quoted         = qr/(?:'[^']*'|"[^"]*")*/;  # 'foo''bar' simply matches the (?:) twice
    my $quoted_mysql   = qr/(?:(?:[^\\']*(?:\\.[^\\']*)*)'|"(?:[^\\"]*(?:\\.[^\\"]*)*)")*/;
#-------------------------------------------------------------------------------

    my $q = $self->{dbd} =~ /mysql/ ? $quoted_mysql : $quoted; # ddp $q;
    $$query =~ s[($q|\(\?\?\))] {
        $1 eq '(??)'
        ? do {
            Carp::croak('There can be only one omniholder') if $omniholders++; # ddp $1;
#-------------------------------------------------------------------------------
#           '(' . join(', ', ('?') x @$binds) . ')'
            '(' . join(', ', ('?') x $omniholders_count) . ')' # adjusted bind count
#-------------------------------------------------------------------------------
        }
        : $1
    }eg; # ddp $query;
}

sub dump_query { Local::Utils::dump_query(@_) }

sub update_or_insert {
    my ($self, $table, $data) = @_; # str, href
    my $odku = $_[3] # aref
        or die 'require a list of cols to provide to ON DUPLICATE KEY UPDATE';
	my ($sql, @bind) = $self->sqla->insert($table, $data); # ddp @bind;
	$sql .= ' ON DUPLICATE KEY UPDATE ' 
		. join ', ', map { "`$_`=VALUES(`$_`)" } @$odku; # say $sql; return;
    my $result = $self->query($sql, @bind);
	return $result;    
}

sub insert_or_update_if_greater {
    my ($self, $table, $data) = @_; # str, href
    my $col = $_[3]
        or die 'require one column to provide to ON DUPLICATE KEY UPDATE';
	my ($sql, @bind) = $self->sqla->insert($table, $data); # ddp @bind;
	$sql .= qq! ON DUPLICATE KEY UPDATE $col
        = IF(VALUES($col) > $col, VALUES($col), $col)!; # say $sql; return;
    my $result = $self->query($sql, @bind);
	return $result;    
}

1;