package Mojo::Message;
use Mojo::Base 'Mojo::EventEmitter';

use Carp 'croak';
use Mojo::Asset::Memory;
use Mojo::Content::Single;
use Mojo::DOM;
use Mojo::JSON;
use Mojo::JSON::Pointer;
use Mojo::Parameters;
use Mojo::Upload;
use Mojo::Util 'decode';

has content => sub { Mojo::Content::Single->new };
has default_charset  => 'UTF-8';
has max_line_size    => sub { $ENV{MOJO_MAX_LINE_SIZE} || 10240 };
has max_message_size => sub { $ENV{MOJO_MAX_MESSAGE_SIZE} // 10485760 };
has version          => '1.1';

sub body {
  my $self = shift;

  # Downgrade multipart content
  my $content = $self->content;
  $content = $self->content(Mojo::Content::Single->new)->content
    if $content->is_multipart;

  # Get
  return $content->asset->slurp unless @_;

  # Set
  $content->asset(Mojo::Asset::Memory->new->add_chunk(@_));

  return $self;
}

sub body_params {
  my $self = shift;

  return $self->{body_params} if $self->{body_params};
  my $params = $self->{body_params} = Mojo::Parameters->new;
  $params->charset($self->content->charset || $self->default_charset);

  # "application/x-www-form-urlencoded"
  my $type = $self->headers->content_type // '';
  if ($type =~ m!application/x-www-form-urlencoded!i) {
    $params->parse($self->content->asset->slurp);
  }

  # "multipart/form-data"
  elsif ($type =~ m!multipart/form-data!i) {
    $params->append(@$_[0, 1]) for @{$self->_parse_formdata};
  }

  return $params;
}

sub body_size { shift->content->body_size }

sub build_body       { shift->_build('get_body_chunk') }
sub build_headers    { shift->_build('get_header_chunk') }
sub build_start_line { shift->_build('get_start_line_chunk') }

sub cookie { shift->_cache(cookies => @_) }

sub cookies { croak 'Method "cookies" not implemented by subclass' }

sub dom {
  my $self = shift;
  return undef if $self->content->is_multipart;
  my $dom = $self->{dom} ||= Mojo::DOM->new($self->text);
  return @_ ? $dom->find(@_) : $dom;
}

sub error {
  my $self = shift;

  # Set
  if (@_) {
    $self->{error} = [@_];
    return $self->finish;
  }

  # Get
  return unless my $err = $self->{error};
  return wantarray ? @$err : $err->[0];
}

sub extract_start_line {
  croak 'Method "extract_start_line" not implemented by subclass';
}

sub finish {
  my $self = shift;
  $self->{state} = 'finished';
  return $self->{finished}++ ? $self : $self->emit('finish');
}

sub fix_headers {
  my $self = shift;

  # Content-Length or Connection (unless chunked transfer encoding is used)
  my $content = $self->content;
  return $self if $self->{fix}++ || $content->is_chunked;
  my $headers = $self->headers;
  $content->is_dynamic
    ? $headers->connection('close')
    : $headers->content_length($self->body_size)
    unless $headers->content_length;

  return $self;
}

sub get_body_chunk {
  my ($self, $offset) = @_;

  $self->emit('progress', 'body', $offset);
  my $chunk = $self->content->get_body_chunk($offset);
  return $chunk if !defined $chunk || length $chunk;
  $self->finish;

  return $chunk;
}

sub get_header_chunk {
  my ($self, $offset) = @_;
  $self->emit('progress', 'headers', $offset);
  return $self->fix_headers->content->get_header_chunk($offset);
}

sub get_start_line_chunk {
  croak 'Method "get_start_line_chunk" not implemented by subclass';
}

sub header_size { shift->fix_headers->content->header_size }

sub headers { shift->content->headers }

sub is_finished { (shift->{state} // '') eq 'finished' }

sub is_limit_exceeded { !!shift->{limit} }

sub json {
  my ($self, $pointer) = @_;
  return undef if $self->content->is_multipart;
  my $data = $self->{json} ||= Mojo::JSON->new->decode($self->body);
  return $pointer ? Mojo::JSON::Pointer->new->get($data, $pointer) : $data;
}

sub param { shift->body_params->param(@_) }

sub parse {
  my ($self, $chunk) = @_;

  # Check message size
  my $max = $self->max_message_size;
  return $self->_limit('Maximum message size exceeded', 413)
    if $max && ($self->{raw_size} += length($chunk //= '')) > $max;

  $self->{buffer} .= $chunk;

  # Start line
  unless ($self->{state}) {

    # Check line size
    my $len = index $self->{buffer}, "\x0a";
    $len = length $self->{buffer} if $len < 0;
    return $self->_limit('Maximum line size exceeded', 431)
      if $len > $self->max_line_size;

    $self->{state} = 'content' if $self->extract_start_line(\$self->{buffer});
  }

  # Content
  my $state = $self->{state} // '';
  $self->content($self->content->parse(delete $self->{buffer}))
    if $state eq 'content' || $state eq 'finished';

  # Check line size
  return $self->_limit('Maximum line size exceeded', 431)
    if $self->headers->is_limit_exceeded;

  # Check buffer size
  return $self->error('Maximum buffer size exceeded', 400)
    if $self->content->is_limit_exceeded;

  return $self->emit('progress')->content->is_finished ? $self->finish : $self;
}

sub start_line_size { length shift->build_start_line }

sub text {
  my $self    = shift;
  my $body    = $self->body;
  my $charset = $self->content->charset;
  return $charset ? decode($charset, $body) // $body : $body;
}

sub to_string {
  my $self = shift;
  return $self->build_start_line . $self->build_headers . $self->build_body;
}

sub upload { shift->_cache(uploads => @_) }

sub uploads {
  my $self = shift;

  my @uploads;
  for my $data (@{$self->_parse_formdata(1)}) {
    my $upload = Mojo::Upload->new(
      name     => $data->[0],
      filename => $data->[2],
      asset    => $data->[1]->asset,
      headers  => $data->[1]->headers
    );
    push @uploads, $upload;
  }

  return \@uploads;
}

sub _build {
  my ($self, $method) = @_;

  my $buffer = '';
  my $offset = 0;
  while (1) {

    # No chunk yet, try again
    next unless defined(my $chunk = $self->$method($offset));

    # End of part
    last unless my $len = length $chunk;

    $offset += $len;
    $buffer .= $chunk;
  }

  return $buffer;
}

sub _cache {
  my ($self, $method, $name) = @_;

  # Cache objects by name
  unless ($self->{$method}) {
    $self->{$method} = {};
    push @{$self->{$method}{$_->name}}, $_ for @{$self->$method};
  }

  return unless my $objects = $self->{$method}{$name};
  return wantarray ? @$objects : $objects->[0];
}

sub _limit {
  my $self = shift;
  $self->{limit} = 1;
  $self->error(@_);
}

sub _parse_formdata {
  my ($self, $upload) = @_;

  my @formdata;
  my $content = $self->content;
  return \@formdata unless $content->is_multipart;
  my $charset = $content->charset || $self->default_charset;

  # Check all parts recursively
  my @parts = ($content);
  while (my $part = shift @parts) {

    if ($part->is_multipart) {
      unshift @parts, @{$part->parts};
      next;
    }

    next unless my $disposition = $part->headers->content_disposition;
    my ($filename) = $disposition =~ /[; ]filename\s*=\s*"?((?:\\"|[^"])*)"?/i;
    next if ($upload && !defined $filename) || (!$upload && defined $filename);
    my ($name) = $disposition =~ /[; ]name\s*=\s*"?((?:\\"|[^";])+)"?/i;
    if ($charset) {
      $name     = decode($charset, $name)     // $name     if $name;
      $filename = decode($charset, $filename) // $filename if $filename;
    }

    unless ($upload) {
      $part = $part->asset->slurp;
      $part = decode($charset, $part) // $part if $charset;
    }

    push @formdata, [$name, $part, $filename];
  }

  return \@formdata;
}

1;

=encoding utf8

=head1 NAME

Mojo::Message - HTTP message base class

=head1 SYNOPSIS

  package Mojo::Message::MyMessage;
  use Mojo::Base 'Mojo::Message';

  sub cookies              {...}
  sub extract_start_line   {...}
  sub get_start_line_chunk {...}

=head1 DESCRIPTION

L<Mojo::Message> is an abstract base class for HTTP messages as described in
RFC 2616 and RFC 2388.

=head1 EVENTS

L<Mojo::Message> inherits all events from L<Mojo::EventEmitter> and can emit
the following new ones.

=head2 finish

  $msg->on(finish => sub {
    my $msg = shift;
    ...
  });

Emitted after message building or parsing is finished.

  my $before = time;
  $msg->on(finish => sub {
    my $msg = shift;
    $msg->headers->header('X-Parser-Time' => time - $before);
  });

=head2 progress

  $msg->on(progress => sub {
    my $msg = shift;
    ...
  });

Emitted when message building or parsing makes progress.

  # Building
  $msg->on(progress => sub {
    my ($msg, $state, $offset) = @_;
    say qq{Building "$state" at offset $offset};
  });

  # Parsing
  $msg->on(progress => sub {
    my $msg = shift;
    return unless my $len = $msg->headers->content_length;
    my $size = $msg->content->progress;
    say 'Progress: ', $size == $len ? 100 : int($size / ($len / 100)), '%';
  });

=head1 ATTRIBUTES

L<Mojo::Message> implements the following attributes.

=head2 content

  my $msg = $msg->content;
  $msg    = $msg->content(Mojo::Content::Single->new);

Message content, defaults to a L<Mojo::Content::Single> object.

=head2 default_charset

  my $charset = $msg->default_charset;
  $msg        = $msg->default_charset('UTF-8');

Default charset used for form-data parsing, defaults to C<UTF-8>.

=head2 max_line_size

  my $size = $msg->max_line_size;
  $msg     = $msg->max_line_size(1024);

Maximum start line size in bytes, defaults to the value of the
MOJO_MAX_LINE_SIZE environment variable or C<10240>.

=head2 max_message_size

  my $size = $msg->max_message_size;
  $msg     = $msg->max_message_size(1024);

Maximum message size in bytes, defaults to the value of the
MOJO_MAX_MESSAGE_SIZE environment variable or C<10485760>. Setting the value
to C<0> will allow messages of indefinite size. Note that increasing this
value can also drastically increase memory usage, should you for example
attempt to parse an excessively large message body with the L</"body_params">,
L</"dom"> or L</"json"> methods.

=head2 version

  my $version = $msg->version;
  $msg        = $msg->version('1.1');

HTTP version of message, defaults to C<1.1>.

=head1 METHODS

L<Mojo::Message> inherits all methods from L<Mojo::EventEmitter> and
implements the following new ones.

=head2 body

  my $bytes = $msg->body;
  $msg      = $msg->body('Hello!');

Slurp or replace L</"content">, L<Mojo::Content::MultiPart> will be
automatically downgraded to L<Mojo::Content::Single>.

=head2 body_params

  my $params = $msg->body_params;

POST parameters extracted from C<application/x-www-form-urlencoded> or
C<multipart/form-data> message body, usually a L<Mojo::Parameters> object.
Note that this method caches all data, so it should not be called before the
entire message body has been received. Parts of the message body need to be
loaded into memory to parse POST parameters, so you have to make sure it is
not excessively large.

  # Get POST parameter value
  say $msg->body_params->param('foo');

=head2 body_size

  my $size = $msg->body_size;

Content size in bytes.

=head2 build_body

  my $bytes = $msg->build_body;

Render whole body.

=head2 build_headers

  my $bytes = $msg->build_headers;

Render all headers.

=head2 build_start_line

  my $bytes = $msg->build_start_line;

Render start line.

=head2 cookie

  my $cookie  = $msg->cookie('foo');
  my @cookies = $msg->cookie('foo');

Access message cookies, usually L<Mojo::Cookie::Request> or
L<Mojo::Cookie::Response> objects. Note that this method caches all data, so
it should not be called before all headers have been received.

  # Get cookie value
  say $msg->cookie('foo')->value;

=head2 cookies

  my $cookies = $msg->cookies;

Access message cookies. Meant to be overloaded in a subclass.

=head2 dom

  my $dom        = $msg->dom;
  my $collection = $msg->dom('a[href]');

Turns message body into a L<Mojo::DOM> object and takes an optional selector
to perform a C<find> on it right away, which returns a L<Mojo::Collection>
object. Note that this method caches all data, so it should not be called
before the entire message body has been received. The whole message body needs
to be loaded into memory to parse it, so you have to make sure it is not
excessively large.

  # Perform "find" right away
  say $msg->dom('h1, h2, h3')->text;

  # Use everything else Mojo::DOM has to offer
  say $msg->dom->at('title')->text;
  say $msg->dom->html->body->children->type->uniq;

=head2 error

  my $err          = $msg->error;
  my ($err, $code) = $msg->error;
  $msg             = $msg->error('Parser error');
  $msg             = $msg->error('Parser error', 500);

Error and code.

=head2 extract_start_line

  my $bool = $msg->extract_start_line(\$str);

Extract start line from string. Meant to be overloaded in a subclass.

=head2 finish

  $msg = $msg->finish;

Finish message parser/generator.

=head2 fix_headers

  $msg = $msg->fix_headers;

Make sure message has all required headers.

=head2 get_body_chunk

  my $bytes = $msg->get_body_chunk($offset);

Get a chunk of body data starting from a specific position.

=head2 get_header_chunk

  my $bytes = $msg->get_header_chunk($offset);

Get a chunk of header data, starting from a specific position.

=head2 get_start_line_chunk

  my $bytes = $msg->get_start_line_chunk($offset);

Get a chunk of start line data starting from a specific position. Meant to be
overloaded in a subclass.

=head2 header_size

  my $size = $msg->header_size;

Size of headers in bytes.

=head2 headers

  my $headers = $msg->headers;

Message headers, usually a L<Mojo::Headers> object.

=head2 is_finished

  my $bool = $msg->is_finished;

Check if message parser/generator is finished.

=head2 is_limit_exceeded

  my $bool = $msg->is_limit_exceeded;

Check if message has exceeded L</"max_line_size"> or L</"max_message_size">.

=head2 json

  my $hash  = $msg->json;
  my $array = $msg->json;
  my $value = $msg->json('/foo/bar');

Decode JSON message body directly using L<Mojo::JSON> if possible, returns
C<undef> otherwise. An optional JSON Pointer can be used to extract a specific
value with L<Mojo::JSON::Pointer>. Note that this method caches all data, so
it should not be called before the entire message body has been received.
The whole message body needs to be loaded into memory to parse it, so you have
to make sure it is not excessively large.

  # Extract JSON values
  say $msg->json->{foo}{bar}[23];
  say $msg->json('/foo/bar/23');

=head2 param

  my @names = $msg->param;
  my $foo   = $msg->param('foo');
  my @foo   = $msg->param('foo');

Access POST parameters. Note that this method caches all data, so it should
not be called before the entire message body has been received. Parts of the
message body need to be loaded into memory to parse POST parameters, so you
have to make sure it is not excessively large.

=head2 parse

  $msg = $msg->parse('HTTP/1.1 200 OK...');

Parse message chunk.

=head2 start_line_size

  my $size = $msg->start_line_size;

Size of the start line in bytes.

=head2 text

  my $str = $msg->text;

Retrieve L</"body"> and try to decode it if a charset could be extracted with
L<Mojo::Content/"charset">.

=head2 to_string

  my $str = $msg->to_string;

Render whole message.

=head2 upload

  my $upload  = $msg->upload('foo');
  my @uploads = $msg->upload('foo');

Access C<multipart/form-data> file uploads, usually L<Mojo::Upload> objects.
Note that this method caches all data, so it should not be called before the
entire message body has been received.

  # Get content of uploaded file
  say $msg->upload('foo')->asset->slurp;

=head2 uploads

  my $uploads = $msg->uploads;

All C<multipart/form-data> file uploads, usually L<Mojo::Upload> objects.

=head1 SEE ALSO

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

=cut
