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

use Carp       qw(croak);
use List::Util qw(any);
use Mojo::Message::Request;
use Mojo::Message::Response;
use Mojo::Util qw(network_contains);

has [qw(kept_alive local_address local_port original_remote_address remote_port)];
has req => sub { Mojo::Message::Request->new };
has res => sub { Mojo::Message::Response->new };

sub client_read  { croak 'Method "client_read" not implemented by subclass' }
sub client_write { croak 'Method "client_write" not implemented by subclass' }

sub closed { shift->completed->emit('finish') }

sub completed { ++$_[0]{completed} and return $_[0] }

sub connection {
  my $self = shift;
  return $self->emit(connection => $self->{connection} = shift) if @_;
  return $self->{connection};
}

sub error { $_[0]->req->error || $_[0]->res->error }

sub is_finished { !!shift->{completed} }

sub is_websocket {undef}

sub remote_address {
  my $self = shift;

  return $self->original_remote_address(@_) if @_;
  return $self->original_remote_address unless $self->req->reverse_proxy;

  # Reverse proxy
  my @addrs   = split /\s*,\s*/, ($self->req->headers->header('X-Forwarded-For') // '');
  my $trusted = $self->req->trusted_proxies;
  return @addrs ? $addrs[-1] : $self->original_remote_address unless @$trusted;

  push @addrs, $self->original_remote_address;
  for my $addr (reverse @addrs) {
    return $addr unless any { network_contains($_, $addr) } @$trusted;
  }
  return $addrs[0];
}

sub result {
  my $self = shift;
  my $err  = $self->error;
  return !$err || $err->{code} ? $self->res : croak $err->{message};
}

sub server_read  { croak 'Method "server_read" not implemented by subclass' }
sub server_write { croak 'Method "server_write" not implemented by subclass' }

1;

=encoding utf8

=head1 NAME

Mojo::Transaction - Transaction base class

=head1 SYNOPSIS

  package Mojo::Transaction::MyTransaction;
  use Mojo::Base 'Mojo::Transaction';

  sub client_read  {...}
  sub client_write {...}
  sub server_read  {...}
  sub server_write {...}

=head1 DESCRIPTION

L<Mojo::Transaction> is an abstract base class for transactions, like L<Mojo::Transaction::HTTP> and
L<Mojo::Transaction::WebSocket>.

=head1 EVENTS

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

=head2 connection

  $tx->on(connection => sub ($tx, $connection) {...});

Emitted when a connection has been assigned to transaction.

=head2 finish

  $tx->on(finish => sub ($tx) {...});

Emitted when transaction is finished.

=head1 ATTRIBUTES

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

=head2 kept_alive

  my $bool = $tx->kept_alive;
  $tx      = $tx->kept_alive($bool);

Connection has been kept alive.

=head2 local_address

  my $address = $tx->local_address;
  $tx         = $tx->local_address('127.0.0.1');

Local interface address.

=head2 local_port

  my $port = $tx->local_port;
  $tx      = $tx->local_port(8080);

Local interface port.

=head2 original_remote_address

  my $address = $tx->original_remote_address;
  $tx         = $tx->original_remote_address('127.0.0.1');

Remote interface address.

=head2 remote_port

  my $port = $tx->remote_port;
  $tx      = $tx->remote_port(8081);

Remote interface port.

=head2 req

  my $req = $tx->req;
  $tx     = $tx->req(Mojo::Message::Request->new);

HTTP request, defaults to a L<Mojo::Message::Request> object.

  # Access request information
  my $method = $tx->req->method;
  my $url    = $tx->req->url->to_abs;
  my $info   = $tx->req->url->to_abs->userinfo;
  my $host   = $tx->req->url->to_abs->host;
  my $agent  = $tx->req->headers->user_agent;
  my $custom = $tx->req->headers->header('Custom-Header');
  my $bytes  = $tx->req->body;
  my $str    = $tx->req->text;
  my $hash   = $tx->req->params->to_hash;
  my $all    = $tx->req->uploads;
  my $value  = $tx->req->json;
  my $foo    = $tx->req->json('/23/foo');
  my $dom    = $tx->req->dom;
  my $bar    = $tx->req->dom('div.bar')->first->text;

=head2 res

  my $res = $tx->res;
  $tx     = $tx->res(Mojo::Message::Response->new);

HTTP response, defaults to a L<Mojo::Message::Response> object.

  # Access response information
  my $code    = $tx->res->code;
  my $message = $tx->res->message;
  my $server  = $tx->res->headers->server;
  my $custom  = $tx->res->headers->header('Custom-Header');
  my $bytes   = $tx->res->body;
  my $str     = $tx->res->text;
  my $value   = $tx->res->json;
  my $foo     = $tx->res->json('/23/foo');
  my $dom     = $tx->res->dom;
  my $bar     = $tx->res->dom('div.bar')->first->text;

=head1 METHODS

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

=head2 client_read

  $tx->client_read($bytes);

Read data client-side, used to implement user agents such as L<Mojo::UserAgent>. Meant to be overloaded in a subclass.

=head2 client_write

  my $bytes = $tx->client_write;

Write data client-side, used to implement user agents such as L<Mojo::UserAgent>. Meant to be overloaded in a subclass.

=head2 closed

  $tx = $tx->closed;

Same as L</"completed">, but also indicates that all transaction data has been sent.

=head2 completed

  $tx = $tx->completed;

Low-level method to finalize transaction.

=head2 connection

  my $id = $tx->connection;
  $tx    = $tx->connection($id);

Connection identifier.

=head2 error

  my $err = $tx->error;

Get request or response error and return C<undef> if there is no error.

  # Longer version
  my $err = $tx->req->error || $tx->res->error;

  # Check for 4xx/5xx response and connection errors
  if (my $err = $tx->error) {
    die "$err->{code} response: $err->{message}" if $err->{code};
    die "Connection error: $err->{message}";
  }

=head2 is_finished

  my $bool = $tx->is_finished;

Check if transaction is finished.

=head2 is_websocket

  my $bool = $tx->is_websocket;

False, this is not a L<Mojo::Transaction::WebSocket> object.

=head2 remote_address

  my $address = $tx->remote_address;
  $tx         = $tx->remote_address('127.0.0.1');

Same as L</"original_remote_address"> unless L</"req"> has been performed via a L<Mojo::Message::Request/reverse_proxy>.
If so then the last value of C<X-Forwarded-For> header is returned. Additionally if
L<Mojo::Message::Request/trusted_proxies> are also provided then the original address must be trusted and any
C<X-Forwarded-For> entries that are trusted are ignored, returning the last untrusted address or the first address if
all are trusted.

=head2 result

  my $res = $tx->result;

Returns the L<Mojo::Message::Response> object from L</"res"> or dies if a connection error has occurred.

  # Fine grained response handling (dies on connection errors)
  my $res = $tx->result;
  if    ($res->is_success)  { say $res->body }
  elsif ($res->is_error)    { say $res->message }
  elsif ($res->code == 301) { say $res->headers->location }
  else                      { say 'Whatever...' }

=head2 server_read

  $tx->server_read($bytes);

Read data server-side, used to implement web servers such as L<Mojo::Server::Daemon>. Meant to be overloaded in a
subclass.

=head2 server_write

  my $bytes = $tx->server_write;

Write data server-side, used to implement web servers such as L<Mojo::Server::Daemon>. Meant to be overloaded in a
subclass.

=head1 SEE ALSO

L<Mojolicious>, L<Mojolicious::Guides>, L<https://mojolicious.org>.

=cut