package Lmo::Types;

use strict;
use warnings qw( FATAL all );

use Carp ();
use Scalar::Util qw(looks_like_number blessed);

# Basic types for isa. If you want a new type, either add it here,
# or give isa a coderef.

our %TYPES = (
   Bool   => sub { !$_[0] || (defined $_[0] && looks_like_number($_[0]) && $_[0] == 1) },
   Num    => sub { defined $_[0] && looks_like_number($_[0]) },
   Int    => sub { defined $_[0] && looks_like_number($_[0]) && $_[0] == int($_[0]) },
   Str    => sub { defined $_[0] },
   Object => sub { defined $_[0] && blessed($_[0]) },
   FileHandle => sub { local $@; require IO::Handle; fileno($_[0]) && $_[0]->opened },

   map {
      my $type = /R/ ? $_ : uc $_;
      $_ . "Ref" => sub { ref $_[0] eq $type }
   } qw(Array Code Hash Regexp Glob Scalar)
);

sub check_type_constaints {
   my ($attribute, $type_check, $check_name, $val) = @_;
   ( ref($type_check) eq 'CODE'
      ? $type_check->($val)
      : (ref $val eq $type_check
         || ($val && $val eq $type_check)
         || (exists $TYPES{$type_check} && $TYPES{$type_check}->($val)))
   )
   || Carp::confess(
        qq<Attribute ($attribute) does not pass the type constraint because: >
      . qq<Validation failed for '$check_name' with value >
      . (defined $val ? Lmo::Dumper($val) : 'undef') )
}

# Nested (or parametized) constraints look like this: ArrayRef[CONSTRAINT] or
# Maybe[CONSTRAINT]. This function returns a coderef that implements one of
# these.
sub _nested_constraints {
   my ($attribute, $aggregate_type, $type) = @_;

   my $inner_types;
   if ( $type =~ /\A(ArrayRef|Maybe)\[(.*)\]\z/ ) {
      # If the inner constraint -- the part within brackets -- is also a parametized
      # constraint, then call this function recursively.
      $inner_types = _nested_constraints($1, $2);
   }
   else {
      # Otherwise, try checking if it's one of the built-in types.
      $inner_types = $TYPES{$type};
   }

   if ( $aggregate_type eq 'ArrayRef' ) {
      return sub {
         my ($val) = @_;
         return unless ref($val) eq ref([]);

         if ($inner_types) {
            for my $value ( @{$val} ) {
               return unless $inner_types->($value)
            }
         }
         else {
            # $inner_types isn't set, we are dealing with a class name.
            for my $value ( @{$val} ) {
               return unless $value && ($value eq $type
                        || (Scalar::Util::blessed($value) && $value->isa($type)));
            }
         }
         return 1;
      };
   }
   elsif ( $aggregate_type eq 'Maybe' ) {
      return sub {
         my ($value) = @_;
         # For Maybe, undef is valid
         return 1 if ! defined($value);
         # Otherwise, defer to the inner type
         if ($inner_types) {
            return unless $inner_types->($value)
         }
         else {
            return unless $value eq $type
                        || (Scalar::Util::blessed($value) && $value->isa($type));
         }
         return 1;
      }
   }
   else {
      Carp::confess("Nested aggregate types are only implemented for ArrayRefs and Maybe");
   }
}

1;