package Mojo::Asset::File;

use Mojo::Base 'Mojo::Asset';

use Carp 'croak';

use Errno 'EEXIST';

use Fcntl qw(O_CREAT O_EXCL O_RDWR);

use File::Copy 'move';

use File::Spec::Functions 'catfile';

use IO::File;

use Mojo::Util 'md5_sum';

has [qw(cleanup path)];

has handle => sub {

  my $self = shift;

  # Open existing file

  my $handle = IO::File->new;

  my $path   = $self->path;

  if (defined $path && -f $path) {

    $handle->open($path, '<') or croak qq{Can't open file "$path": $!};

    return $handle;

  }

  # Open new or temporary file

  my $base = catfile $self->tmpdir, 'mojo.tmp';

  my $name = $path // $base;

  until ($handle->open($name, O_CREAT | O_EXCL | O_RDWR)) {

    croak qq{Can't open file "$name": $!} if defined $path || $! != $!{EEXIST};

    $name = "$base." . md5_sum(time . $$ . rand 9 x 7);

  }

  $self->path($name);

  # Enable automatic cleanup

  $self->cleanup(1) unless defined $self->cleanup;

  return $handle;

};

has tmpdir => sub { $ENV{MOJO_TMPDIR} || File::Spec::Functions::tmpdir };

sub DESTROY {

  my $self = shift;

  return unless $self->cleanup && defined(my $path = $self->path);

  close $self->handle;

  unlink $path if -w $path;

}

sub add_chunk {

  my ($self, $chunk) = @_;

  my $handle = $self->handle;

  $handle->sysseek(0, SEEK_END);

  $chunk //= '';

  croak "Can't write to asset: $!"

    unless defined $handle->syswrite($chunk, length $chunk);

  return $self;

}

sub contains {

  my ($self, $str) = @_;

  my $handle = $self->handle;

  $handle->sysseek($self->start_range, SEEK_SET);

  # Calculate window size

  my $end  = $self->end_range // $self->size;

  my $len  = length $str;

  my $size = $len > 131072 ? $len : 131072;

  $size = $end - $self->start_range if $size > $end - $self->start_range;

  # Sliding window search

  my $offset = 0;

  my $start = $handle->sysread(my $window, $len);

  while ($offset < $end) {

    # Read as much as possible

    my $diff = $end - ($start + $offset);

    my $read = $handle->sysread(my $buffer, $diff < $size ? $diff : $size);

    $window .= $buffer;

    # Search window

    my $pos = index $window, $str;

    return $offset + $pos if $pos >= 0;

    $offset += $read;

    return -1 if $read == 0 || $offset == $end;

    # Resize window

    substr $window, 0, $read, '';

  }

  return -1;

}

sub get_chunk {

  my ($self, $offset, $max) = @_;

  $max //= 131072;

  $offset += $self->start_range;

  my $handle = $self->handle;

  $handle->sysseek($offset, SEEK_SET);

  my $buffer;

  if (defined(my $end = $self->end_range)) {

    my $chunk = $end + 1 - $offset;

    return '' if $chunk <= 0;

    $handle->sysread($buffer, $chunk > $max ? $max : $chunk);

  }

  else { $handle->sysread($buffer, $max) }

  return $buffer;

}

sub is_file {1}

sub move_to {

  my ($self, $to) = @_;

  # Windows requires that the handle is closed

  close $self->handle;

  delete $self->{handle};

  # Move file and prevent clean up

  my $from = $self->path;

  move($from, $to) or croak qq{Can't move file "$from" to "$to": $!};

  return $self->path($to)->cleanup(0);

}

sub size {

  return 0 unless defined(my $file = shift->path);

  return -s $file;

}

sub slurp {

  my $handle = shift->handle;

  $handle->sysseek(0, SEEK_SET);

  my $content = '';

  while ($handle->sysread(my $buffer, 131072)) { $content .= $buffer }

  return $content;

}

1;

=encoding utf8

=head1 NAME

Mojo::Asset::File - File storage for HTTP content

=head1 SYNOPSIS

  use Mojo::Asset::File;

  # Temporary file

  my $file = Mojo::Asset::File->new;

  $file->add_chunk('foo bar baz');

  say 'File contains "bar"' if $file->contains('bar') >= 0;

  say $file->slurp;

  # Existing file

  my $file = Mojo::Asset::File->new(path => '/home/sri/foo.txt');

  $file->move_to('/yada.txt');

  say $file->slurp;

=head1 DESCRIPTION

L<Mojo::Asset::File> is a file storage backend for HTTP content.

=head1 EVENTS

L<Mojo::Asset::File> inherits all events from L<Mojo::Asset>.

=head1 ATTRIBUTES

L<Mojo::Asset::File> inherits all attributes from L<Mojo::Asset> and

implements the following new ones.

=head2 cleanup

  my $bool = $file->cleanup;

  $file    = $file->cleanup($bool);

Delete file automatically once it's not used anymore.

=head2 handle

  my $handle = $file->handle;

  $file      = $file->handle(IO::File->new);

Filehandle, created on demand.

=head2 path

  my $path = $file->path;

  $file    = $file->path('/home/sri/foo.txt');

File path used to create L</"handle">, can also be automatically generated if

necessary.

=head2 tmpdir

  my $tmpdir = $file->tmpdir;

  $file      = $file->tmpdir('/tmp');

Temporary directory used to generate L</"path">, defaults to the value of the

MOJO_TMPDIR environment variable or auto detection.

=head1 METHODS

L<Mojo::Asset::File> inherits all methods from L<Mojo::Asset> and implements

the following new ones.

=head2 add_chunk

  $file = $file->add_chunk('foo bar baz');

Add chunk of data.

=head2 contains

  my $position = $file->contains('bar');

Check if asset contains a specific string.

=head2 get_chunk

  my $bytes = $file->get_chunk($offset);

  my $bytes = $file->get_chunk($offset, $max);

Get chunk of data starting from a specific position, defaults to a maximum

chunk size of C<131072> bytes.

=head2 is_file

  my $true = $file->is_file;

True.

=head2 move_to

  $file = $file->move_to('/home/sri/bar.txt');

Move asset data into a specific file and disable L</"cleanup">.

=head2 size

  my $size = $file->size;

Size of asset data in bytes.

=head2 slurp

  my $bytes = $file->slurp;

Read all asset data at once.

=head1 SEE ALSO

L<Mojolicious>, L<Mojolicious::Guides>, L<http://mojolicio.us>.

=cut