package Error::TypeTiny;

use 5.006001;
use strict;
use warnings;

BEGIN {
	$Error::TypeTiny::AUTHORITY = 'cpan:TOBYINK';
	$Error::TypeTiny::VERSION   = '1.000005';
}

use overload
	q[""]    => sub { $_[0]->to_string },
	q[bool]  => sub { 1 },
	fallback => 1,
;

our %CarpInternal;
$CarpInternal{$_}++ for qw(
	Eval::TypeTiny
	Eval::TypeTiny::Sandbox
	Exporter::Tiny
	Test::TypeTiny
	Type::Coercion
	Type::Coercion::Union
	Error::TypeTiny
	Type::Library
	Type::Params
	Type::Registry
	Types::Standard
	Types::Standard::_Stringable
	Types::TypeTiny
	Type::Tiny
	Type::Tiny::Class
	Type::Tiny::Duck
	Type::Tiny::Enum
	Type::Tiny::Intersection
	Type::Tiny::Role
	Type::Tiny::Union
	Type::Utils
);

sub new
{
	my $class = shift;
	my %params = (@_==1) ? %{$_[0]} : @_;
	return bless \%params, $class;
}

sub throw
{
	my $class = shift;
	
	my ($level, @caller, %ctxt) = 0;
	while (
		defined scalar caller($level) and $CarpInternal{scalar caller($level)}
	) { $level++ };
	if ( ((caller($level - 1))[1]||"") =~ /^parameter validation for '(.+?)'$/ )
	{
		my ($pkg, $func) = ($1 =~ m{^(.+)::(\w+)$});
		$level++ if caller($level) eq ($pkg||"");
	}
	@ctxt{qw/ package file line /} = caller($level);
	
	my $stack = undef;
	if (our $StackTrace)
	{
		require Devel::StackTrace;
		$stack = "Devel::StackTrace"->new(
			ignore_package => [ keys %CarpInternal ],
		);
	}
	
	die(
		our $LastError = $class->new(
			context     => \%ctxt,
			stack_trace => $stack,
			@_,
		)
	);
}

sub message     { $_[0]{message} ||= $_[0]->_build_message };
sub context     { $_[0]{context} };
sub stack_trace { $_[0]{stack_trace} };

sub to_string
{
	my $e = shift;
	my $c = $e->context;
	my $m = $e->message;
	
	$m =~ /\n\z/s ? $m :
	$c            ? sprintf("%s at %s line %s.\n", $m, $c->{file}||'file?', $c->{line}||'NaN') :
	sprintf("%s\n", $m);
}

sub _build_message
{
	return 'An exception has occurred';
}

sub croak
{
	my ($fmt, @args) = @_;
	@_ = (
		__PACKAGE__,
		message => sprintf($fmt, @args),
	);
	goto \&throw;
}

1;

__END__

=pod

=encoding utf-8

=head1 NAME

Error::TypeTiny - exceptions for Type::Tiny and friends

=head1 SYNOPSIS

   use Data::Dumper;
   use Try::Tiny;
   use Types::Standard qw(Str);
   
   try {
      Str->assert_valid(undef);
   }
   catch {
      my $exception = shift;
      warn "Encountered Error: $exception";
      warn Dumper($exception->explain)
         if $exception->isa("Error::TypeTiny::Assertion");
   };

=head1 STATUS

This module is covered by the
L<Type-Tiny stability policy|Type::Tiny::Manual::Policies/"STABILITY">.

=head1 DESCRIPTION

When Type::Tiny and its related modules encounter an error, they throw an
exception object. These exception objects inherit from Error::TypeTiny.

=head2 Constructors

=over

=item C<< new(%attributes) >>

Moose-style constructor function.

=item C<< throw(%attributes) >>

Constructs an exception and passes it to C<die>.

Automatically populates C<context> and C<stack_trace> if appropriate.

=back

=head2 Attributes

=over

=item C<message>

The error message.

=item C<context>

Hashref containing the package, file and line that generated the error.

=item C<stack_trace>

A more complete stack trace. This feature requires L<Devel::StackTrace>;
use the C<< $StackTrace >> package variable to switch it on.

=back

=head2 Methods

=over

=item C<to_string>

Returns the message, followed by the context if it is set.

=back

=head2 Functions

=over

=item C<< Error::TypeTiny::croak($format, @args) >>

Functional-style shortcut to C<throw> method. Takes an C<sprintf>-style
format string and optional arguments to construct the C<message>.

=back

=head2 Overloading

=over

=item *

Stringification is overloaded to call C<to_string>.

=back

=head2 Package Variables

=over

=item C<< %Error::TypeTiny::CarpInternal >>

Serves a similar purpose to C<< %Carp::CarpInternal >>.

=item C<< $Error::TypeTiny::StackTrace >>

Boolean to toggle stack trace generation.

=item C<< $Error::TypeTiny::LastError >>

A reference to the last exception object thrown.

=back

=head1 CAVEATS

Although Error::TypeTiny objects are thrown for errors produced by
Type::Tiny, that doesn't mean every time you use Type::Tiny you'll get
Error::TypeTinys whenever you want.

For example, if you use a Type::Tiny type constraint in a Moose attribute,
Moose will not call the constraint's C<assert_valid> method (which throws
an exception). Instead it will call C<check> and C<get_message> (which do
not), and will C<confess> an error message of its own. (The C<< $LastError >>
package variable may save your bacon.)

=head1 BUGS

Please report any bugs to
L<http://rt.cpan.org/Dist/Display.html?Queue=Type-Tiny>.

=head1 SEE ALSO

L<Error::TypeTiny::Assertion>,
L<Error::TypeTiny::WrongNumberOfParameters>.

L<Try::Tiny>, L<Try::Tiny::ByClass>.

=head1 AUTHOR

Toby Inkster E<lt>tobyink@cpan.orgE<gt>.

=head1 COPYRIGHT AND LICENCE

This software is copyright (c) 2013-2014 by Toby Inkster.

This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.

=head1 DISCLAIMER OF WARRANTIES

THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.

