# Palm::StdAppInfo.pm
#
# Class for dealing with standard AppInfo blocks in PDBs.
#
#	Copyright (C) 1999, 2000, Andrew Arensburger.
#	You may distribute this file under the terms of the Artistic
#	License, as specified in the README file.

use strict;
package Palm::StdAppInfo;
use Palm::Raw();

# Don't harass me about these variables
use vars qw( $VERSION @ISA $error );
	# $error acts like $! in that it reports the error that occurred

# One liner, to allow MakeMaker to work.
$VERSION = '1.012';

@ISA = qw( Palm::Raw );

=head1 NAME

Palm::StdAppInfo - Handles standard AppInfo block (categories)

=head1 SYNOPSIS

Usually:

    package MyPDBHandler;
    use Palm::StdAppInfo();		# Note the parentheses

    @ISA = qw( Palm::StdAppInfo );

    use constant APPINFO_PADDING = 1;

    sub ParseAppInfoBlock {
	my $self = shift;
	my $data = shift;
	my $appinfo = {};

	&Palm::StdAppInfo::parse_StdAppInfo($appinfo, $data);

	$app_specific_data = $appinfo->{other};
    }

    sub PackAppInfoBlock {
	my $self = shift;
	my $retval;

	$self->{appinfo}{other} = <pack application-specific data>;
	$retval = &Palm::StdAppInfo::pack_StdAppInfo($self->{appinfo});
	return $retval;
    }

Or as a standalone C<PDB> helper class:

    use Palm::StdAppInfo;

=head1 DESCRIPTION

Many Palm applications use a common format for keeping track of categories.
The C<Palm::StdAppInfo> class deals with this common format:

	$pdb = new Palm::PDB;
	$pdb->Load("myfile.pdb");

	@categories   = @{$pdb->{appinfo}{categories}};
	$lastUniqueID =   $pdb->{appinfo}{lastUniqueID};
	$other        =   $pdb->{appinfo}{other};

where:

C<@categories> is an array of references-to-hash:

=over 4

=item C<$cat = $categories[0];>

=item C<$cat-E<gt>{name}>

The name of the category, a string of at most 16 characters.

=item C<$cat-E<gt>{id}>

The category ID, an integer in the range 0-255. Each category has a
unique ID. By convention, 0 is reserved for the "Unfiled" category;
IDs assigned by the Palm are in the range 1-127, and IDs assigned by
the desktop are in the range 128-255.

=item C<$cat-E<gt>{renamed}>

A boolean. This field is true iff the category has been renamed since
the last sync.

=back

C<$lastUniqueID> is (I think) the last category ID that was assigned.

C<$other> is any data that follows the category list in the AppInfo
block. If you're writing a helper class for a PDB that includes a
category list, you should parse this field to get any data that
follows the category list; you should also make sure that this field
is initialized before you call C<&Palm::StdAppInfo::pack_AppInfo>.

=head2 APPINFO_PADDING

Normally, the AppInfo block includes a byte of padding at the end, to
bring its length to an even number. However, some databases use this
byte for data.

If your database uses the padding byte for data, then your
C<&ParseAppInfoBlock> method (see L<"SYNOPSIS">) should call
C<&parse_StdAppInfo> with a true $nopadding argument.

If, for whatever reason, you wish to inherit
C<&StdAppInfo::ParseAppInfoBlock>, then add

    use constant APPINFO_PADDING => 0;

to your handler package, to tell it that the padding byte is really
data.

=head1 FUNCTIONS

=cut
#'

use constant APPINFO_PADDING => 1;	# Whether to add the padding byte at
					# the end of the AppInfo block.
			# Note that this might be considered a hack:
			# this relies on the fact that 'use constant'
			# defines a function with no arguments; that
			# therefore this can be called as an instance
			# method, with full inheritance. That is, if
			# the handler class doesn't define it, Perl
			# will find the constant in the parent. If
			# this ever changes, the code below that uses
			# $self->APPINFO_PADDING will need to be
			# changed.
use constant numCategories => 16;	# Number of categories in AppInfo block
use constant categoryLength => 16;	# Length of category names
use constant stdAppInfoSize =>		# Length of a standard AppInfo block
		2 +	
		(categoryLength * numCategories) +
		numCategories +
		1 + 1;			# The padding byte at the end may
					# be omitted

sub import
{
	&Palm::PDB::RegisterPDBHandlers(__PACKAGE__,
		[ "", "" ],
		);
}

=head2 seed_StdAppInfo

    &Palm::StdAppInfo::seed_StdAppInfo(\%appinfo);

Creates the standard fields in an existing AppInfo hash. Usually used
to ensure that a newly-created AppInfo block contains an initialized
category array:

	my $appinfo = {};

	&Palm::StdAppInfo::seed_StdAppInfo($appinfo);

Note: this is not a method.

=cut

# seed_StdAppInfo
# *** THIS IS NOT A METHOD ***
# Given a reference to an appinfo hash, creates all of the fields for
# a new AppInfo block.
sub seed_StdAppInfo
{
	my $appinfo = shift;
	my $i;

	$appinfo->{categories} = [];	# Create array of categories

	# Initialize the categories
	# Note that all of the IDs are initialized to $i. There's no
	# real good reason for doing it this way, except that that's
	# what the Palm appears to do with new category lists.
	for ($i = 0; $i < numCategories; $i++)
	{
		$appinfo->{categories}[$i] = {};

		$appinfo->{categories}[$i]{renamed} = 0;
		$appinfo->{categories}[$i]{name}    = undef;
		$appinfo->{categories}[$i]{id}      = $i;
	}

	# The only fixed category is "Unfiled". Initialize it now
	$appinfo->{categories}[0]{name} = "Unfiled";
	$appinfo->{categories}[0]{id}   = 0;

	# I'm not sure what this is, but let's initialize it.
	# The Palm appears to initialize this to numCategories - 1.
	$appinfo->{lastUniqueID} = numCategories - 1;
}

=head2 newStdAppInfo

    $appinfo = Palm::StdAppInfo->newStdAppInfo;

Like C<seed_StdAppInfo>, but creates an AppInfo hash and returns a
reference to it.

=cut

sub newStdAppInfo
{
	my $class = shift;
	my $retval = {};

	&seed_StdAppInfo($retval);
	return $retval;
}

=head2 new

    $pdb = new Palm::StdAppInfo;

Create a new PDB, initialized with nothing but a standard AppInfo block.

There are very few reasons to use this, and even fewer good ones. If
you're writing a helper class to parse some PDB format that contains a
category list, then you should make that helper class a subclass of
C<Palm::StdAppInfo>.

=cut
#'

sub new
{
	my $classname	= shift;
	my $self	= $classname->SUPER::new(@_);
			# Create a generic PDB. No need to rebless it,
			# though.

	# Initialize the AppInfo block
	$self->{appinfo} = &newStdAppInfo();

	return $self;
}

=head2 parse_StdAppInfo

    $len = &Palm::StdAppInfo::parse_StdAppInfo(\%appinfo, $data, $nopadding);

This function (this is not a method) is intended to be called from
within a PDB helper class's C<ParseAppInfoBlock> method.

C<parse_StdAppInfo()> parses a standard AppInfo block from the raw
data C<$data> and fills in the fields in C<%appinfo>. It returns the
number of bytes parsed.

C<$nopadding> is optional, and defaults to false. Normally, the
AppInfo block includes a padding byte at the end. If C<$nopadding> is
true, then C<&parse_StdAppInfo> assumes that the padding byte is
application data, and includes it in C<$appinfo{'other'}>, so that the
caller can parse it.

=cut
#'

# parse_StdAppInfo
# *** THIS IS NOT A METHOD ***
#
# Reads the raw data from $data, parses it as a standard AppInfo
# block, and fills in the corresponding fields in %$appinfo. Returns
# the number of bytes parsed.
sub parse_StdAppInfo
{
	my $appinfo = shift;	# A reference to hash, to fill in
	my $data = shift;	# Raw data to read
	my $nopadding = shift;	# Optional: no padding byte at end
	my $unpackstr;		# First argument to unpack()
	my $renamed;		# Bitmap of renamed categories
	my @labels;		# Array of category labels
	my @uniqueIDs;		# Array of category IDs
	my $lastUniqueID;	# Not sure what this is

	return undef
		if length $data < 4+(categoryLength*numCategories)+numCategories;

	if (!defined($nopadding))
	{
		$nopadding = 0;
	}

	# Make sure $appinfo contains all of the requisite fields
	&seed_StdAppInfo($appinfo);

	# The argument to unpack() isn't hard to understand, it's just
	# hard to write in a readable fashion.
	$unpackstr =		# Argument to unpack(), since it's hairy
		"n" .		# Renamed categories
		("a" . categoryLength) x numCategories .
				# Category labels
		"C" x numCategories .
				# Category IDs
		"C" .		# Last unique ID
		"x";

	# Unpack the data
	($renamed,
	 @labels[0..(numCategories-1)],
	 @uniqueIDs[0..(numCategories-1)],
	 $lastUniqueID) =
		unpack $unpackstr, $data;

	# Clean this stuff up a bit
	for (@labels)
	{
		s/\0.*$//;	# Trim at NUL
	}

	# Now put the data into $appinfo
	my $i;

	for ($i = 0; $i < numCategories; $i++)
	{
		$appinfo->{categories}[$i]{renamed} =
			($renamed & (1 << $i) ? 1 : 0);
		$appinfo->{categories}[$i]{name} = $labels[$i];
		$appinfo->{categories}[$i]{id}   = $uniqueIDs[$i];
	}
	$appinfo->{lastUniqueID} = $lastUniqueID;

	# There might be other stuff in the AppInfo block other than
	# the standard categories. Put everything else in
	# $appinfo->{other}.
	$appinfo->{other} = substr($data,
				   stdAppInfoSize - ($nopadding ? 1 : 0));

	return ($nopadding ? stdAppInfoSize - 1 : stdAppInfoSize);
}

=head2 ParseAppInfoBlock

    $pdb = new Palm::StdAppInfo;
    $pdb->ParseAppInfoBlock($data);

If your application's AppInfo block contains standard category support
and nothing else, you may choose to just inherit this method instead
of writing your own C<ParseAppInfoBlock> method. Otherwise, see the
example in L<"SYNOPSIS">.

=cut
#'

sub ParseAppInfoBlock
{
	my $self = shift;
	my $data = shift;

	my $appinfo = {};

	&parse_StdAppInfo($appinfo, $data, $self->APPINFO_PADDING);
	return $appinfo;
}

=head2 pack_StdAppInfo

    $data = &Palm::StdAppInfo::pack_StdAppInfo(\%appinfo);

This function (this is not a method) is intended to be called from
within a PDB helper class's C<PackAppInfoBlock> method.

C<pack_StdAppInfo> takes an AppInfo hash and packs it as a string of
raw data that can be written to a PDB.

Note that if you're using this inside a helper class's
C<PackAppInfoBlock> method, you should make sure that
C<$appinfo{other}> is properly initialized before you call
C<&Palm::StdAppInfo::pack_StdAppInfo>.

C<$nopadding> is optional, and defaults to false. Normally, the
AppInfo block includes a byte of padding at the end. If C<$nopadding>
is true, then C<&pack_StdAppInfo> doesn't include this byte of
padding, so that the application can use it.

=cut
#'

# pack_StdAppInfo
# *** THIS IS NOT A METHOD ***
#
# Given a reference to a hash containing an AppInfo block (such as
# that initialized by parse_StdAppInfo()), returns a packed string
# that can be written to the PDB file.
sub pack_StdAppInfo
{
	my $appinfo = shift;
	my $nopadding = shift;
	my $retval;
	my $i;

	$nopadding = 0 if !defined($nopadding);

	# Create the bitfield of renamed categories
	my $renamed;

	$renamed = 0;
	for ($i = 0; $i < numCategories; $i++)
	{
		if ($appinfo->{categories}[$i]{renamed})
		{
			$renamed |= (1 << $i);
		}
	}
	$retval = pack("n", $renamed);

	# There have to be exactly 16 categories in the AppInfo block,
	# even though $appinfo->{categories} may have been mangled
	# by a naive (or clever) user or broken program.
	for ($i = 0; $i < numCategories; $i++)
	{
		my $name;		# Category name

		# This is mainly to stop Perl 5.6 from complaining if
		# the category name is undefined.
		if ((!defined($appinfo->{categories}[$i]{name})) ||
		    $appinfo->{categories}[$i]{name} eq "")
		{
			$name = "";
		} else {
			$name = $appinfo->{categories}[$i]{name};
		}

		$retval .= pack("a" . categoryLength, $name);
	}

	# Ditto for category IDs
	for ($i = 0; $i < numCategories; $i++)
	{
		$retval .= pack("C", $appinfo->{categories}[$i]{id});
	}

	# Last unique ID, and alignment padding
	$retval .= pack("Cx", $appinfo->{lastUniqueID});

	$retval .= $appinfo->{other} if defined($appinfo->{other});

	return $retval;
}

=head2 PackAppInfoBlock

    $pdb = new Palm::StdAppInfo;
    $data = $pdb->PackAppInfoBlock();

If your application's AppInfo block contains standard category support
and nothing else, you may choose to just inherit this method instead
of writing your own C<PackAppInfoBlock> method. Otherwise, see the
example in L<"SYNOPSIS">.

=cut
#'

sub PackAppInfoBlock
{
	my $self = shift;

	return &pack_StdAppInfo($self->{appinfo}, $self->{APPINFO_PADDING});
}

=head2 addCategory

    $pdb->addCategory($name [, $id [, $renamed]]);

Adds a category to $pdb.

The $name argument specifies the new category's name.

The optional $id argument specifies the new category's numeric ID; if
omitted or undefined, &addCategory will pick one.

The optional $renamed argument is a boolean value indicating whether
the new category should be marked as having been modified. This
defaults to true since, conceptually, &addCategory doesn't really add
a category: it finds one whose name happens to be empty, and renames
it.

Returns a true value if successful, false otherwise. In case of
failure, &addCategory sets $Palm::StdAppInfo::error to an error
message.

=cut
#'
# XXX - When choosing a new category ID, should pick them from the
# range 128-255.
sub addCategory
{
	my $self = shift;	# PDB
	my $name = shift;	# Category name
	my $id = shift;		# Category ID (optional)
	my $renamed = $#_ >= 0 ? $_[0] : 1;
				# Flag: was the category renamed (optional)
				# This initialization may look weird,
				# but it's this way so that it'll
				# default to true if omitted.
	my $categories = $self->{appinfo}{categories};
	my $i;
	my %used;		# Category IDs in use

	# Collect all the IDs in the current list
	for (@{$categories})
	{
		next if !defined($_->{name}) || $_->{name} eq "";
		$used{$_->{id}} = 1;
	}

	if (defined($id))
	{
		# Sanity check: make sure this ID isn't already in use
		if (defined($used{$id}))
		{
			$error = "Category ID already in use";
			return undef;
		}
	} else {
		# Find an unused category number, if none was specified
		for ($id = 128; $id < 256; $id++)
		{
			last if !defined($used{$id});
		}
	}

	# Go through the list of categories, looking for an unused slot
	for ($i = 0; $i < numCategories; $i++)
	{
		# Ignore named categories
		next unless !defined($categories->[$i]{name}) or
			$categories->[$i]{name} eq "";

		# Found an empty slot
		$categories->[$i]{name}    = $name;
		$categories->[$i]{id}      = $id;
		$categories->[$i]{renamed} = $renamed;
		return 1;
	}

	# If we get this far, there are no empty category slots
	$error = "No unused categories";
	return undef;
}

=head2 deleteCategory

    $pdb->deleteCategory($name);

Deletes the category with name $name. Actually, though, it doesn't
delete the category: it just changes its name to the empty string, and
marks the category as renamed.

=cut
#'
sub deleteCategory
{
	my $self = shift;
	my $name = shift;		# Category name

	for (@{$self->{appinfo}{categories}})
	{
		# Find the category named $name
		next if $_->{name} ne $name;

		# Erase this category
		$_->{name} = "";

		# You'd think it would make sense to set the "renamed"
		# field here, but the Palm doesn't do that.
	}
}

=head2 renameCategory

    $pdb->renameCategory($oldname, $newname);

Renames the category named $oldname to $newname.

If successful, returns a true value. If there is no category named
$oldname, returns a false value and sets $Palm::StdAppInfo::error to
an error message.

=cut
#'
# XXX - This doesn't behave the same way as the Palm: the Palm also
# picks a new category ID.
sub renameCategory
{
	my $self = shift;
	my $oldname = shift;
	my $newname = shift;

	for (@{$self->{appinfo}{categories}})
	{
		# Look for a category named $oldname
		next if !defined($_->{name}) || $_->{name} ne $oldname;

		# Found it. Rename it and mark it as renamed.
		$_->{name} = $newname;
		$_->{renamed} = 1;
		return 1;
	}

	$error = "No such category";
	return undef;
}

1;
__END__

=head1 SOURCE CONTROL

The source is in Github:

	http://github.com/briandfoy/p5-Palm/tree/master
	
=head1 AUTHOR

Alessandro Zummo, C<< <a.zummo@towertech.it> >>

Currently maintained by brian d foy, C<< <bdfoy@cpan.org> >>

=head1 SEE ALSO

Palm::PDB(3)

=cut
