package ExcelPerl;
use warnings;
use strict;
use Carp qw(croak);

our $VERSION = 0.08;

# use Readonly; # better not, since Readonly is no standard module yet
use Win32::OLE;
use Win32::OLE::Const 'Microsoft Excel';
use Win32::OLE::Variant;
Win32::OLE->Option( Warn => 3);

use vars qw( @ObjInterfaceMethods @F );

# which object interface methods shell be available as standard
#Readonly::Array: Readonly is not yet a standard module :-(
@ObjInterfaceMethods =
    qw( excelFile excel workBook worksheet
        worksheetNumber currentRow lastRow changeCount
       );

# install object interface methods at startup
foreach my $method ( @ObjInterfaceMethods ) {
    no strict 'refs'; # Sub::Install is no standard module :-(
    *{ $method } = sub {
        my( $self, @values ) = @_;
        $self->{ $method } = $values[0] if scalar @values;
        return $self->{ $method };
    };
} # foreach

# ============================================================
sub new {
    my( $class, %params ) = @_;

    my $self = bless {}, $class;
    foreach my $param (keys %params) {
        $self->$param( $params{$param} );
    } # foreach

    return $self;
} # new
# ------------------------------------------------------------
sub DESTROY {
#    my $self = shift;
#    print "DESTROY: ", ref $self->excel, "\n";
} # DESTROY
# ------------------------------------------------------------
sub increaseCurrentRow {
    my $self = shift;
    $self->currentRow( 1 + $self->currentRow );
} # increaseCurrentRow
# ------------------------------------------------------------
sub increaseChangeCount {
    my $self = shift;
    no warnings;
    $self->changeCount( 1 + $self->changeCount );
} # increaseChangeCount
# ------------------------------------------------------------
sub open {
    my( $self ) = @_;

    my $filename = $self->excelFile;
    defined $filename or croak "Error: no filename given";
    -f $filename or croak( "Error: filename '$filename' doesn't exist");

    my $excel; # try to re-use running instance of Excel
    eval { $excel = Win32::OLE->GetActiveObject( 'Excel.Application' ) };
    die "Error: no Excel installed\n" if $@;

    unless( defined $excel ) { # if not running, start excel
        $excel = Win32::OLE->new( 'Excel.Application', sub { $_[0]->Quit } )
            or die "Error: can't start Excel\n";
    } # unless
    $self->excel( $excel );

    $self->workBook( $excel->Workbooks->Open( $filename ) );

    $self->worksheet( $self->workBook->Worksheets( $self->worksheetNumber ) );

    my $range = $self->worksheet->UsedRange->{Value};
    $self->lastRow( $#$range + 1 );
    $self->currentRow( 0 );

    return $self;
} # open
# ------------------------------------------------------------
sub getNextRow {
    my( $self, $F ) = @_;

    $self->increaseCurrentRow;

    my $row   = $self->currentRow;
    my $sheet = $self->worksheet;
    return if $row > $self->lastRow;

    my $rowData = $sheet->Range("A$row:IV$row")->{Value}; # dirty
    my $itemsFound = 0;

    tie( @$F, 'ExcelPerl::RowArray', $self );

    foreach my $value ( reverse @{ $rowData->[0] } ) {
        if( defined $value ) { unshift( @$F, $value ); $itemsFound++; }
        else                 { unshift( @$F, ''     ) if scalar @$F; }
    } # foreach

    return 1;
} # getNextRow
# ------------------------------------------------------------

# ============================================================
package ExcelPerl::RowArray;
# ------------------------------------------------------------
use Tie::Array;
use vars qw( @ISA );
@ISA   = qw( Tie::Array );
# ------------------------------------------------------------
sub TIEARRAY {
    my( $class, $excelObj ) = @_;

    my $self = bless( { data => [] }, $class );
    $self->{excelObj} = $excelObj;
    $self->{row} = $excelObj->currentRow;

    return $self;
} # TIEARRAY
# ------------------------------------------------------------
sub FETCH {
    my( $self, $index) = @_;
    return $self->{data}->[ $index ];
} # FETCH
# ------------------------------------------------------------
sub STORE {
    my( $self, $index, $value ) = @_;

    my $excelObj = $self->{excelObj};
    my $sheet    = $excelObj->worksheet;

    my $row = $excelObj->currentRow;
    my $col = $index + 1;

    if( $self->{data}->[$index] ne $value ) {
        $excelObj->increaseChangeCount;
        $sheet   ->Cells($row, $col)->{'Value' } = $value;
        $self    ->{'data'}         ->[ $index ] = $value;
    } # if

} # STORE
# ------------------------------------------------------------
sub FETCHSIZE {
    my $self = shift;
    return $#{ $self->{data} };
} # FETCHSIZE
# ------------------------------------------------------------
sub STORESIZE {
    my( $self, $newLength ) = @_;
    $#{ $self->{data} } = $newLength;
} # STORESIZE
# ------------------------------------------------------------
sub UNSHIFT {
    my $self = shift;
    unshift( @{ $self->{data} }, @_ );
} # UNSHIFT
# ------------------------------------------------------------
sub SHIFT {
    my $self = shift;
    return shift @{ $self->{data} };
} # SHIFT
# ------------------------------------------------------------
sub POP {
    my $self = shift;
    return pop @{ $self->{data} };
} # POP
# ------------------------------------------------------------
sub PUSH {
    my $self = shift;
    push( @{ $self->{data} }, @_ );
} # PUSH
# ------------------------------------------------------------
sub CLEAR {
    my( $self ) = @_;
    # TODO: update excel
    $self->{data} = [];
} # CLEAR
# ------------------------------------------------------------
sub DESTROY {
#    my $self = shift;
} # DESTROY
# ------------------------------------------------------------
# ...
# ------------------------------------------------------------
1; # modules have to return a true value