Teapot lib: Implement ability to delete message in chat

lib/Teapot/Bot/Brain.pm

@@ -254,6 +254,44 @@ sub forwardMessage {
   }
 }
 
+# TODO: Check that message is no older than 48 hrs
+sub deleteMessage {
+  my $self = shift;
+  my $args = shift || {};
+  my $send_args = {};
+
+  unless ($args->{chat_id}) {
+    cluck 'No chat_id supplied in deleteMessage()';
+    return {'error' => 1};
+  }
+
+  $send_args->{chat_id} = $args->{chat_id};
+
+  unless ($args->{message_id}) {
+    cluck 'No message_id supplied in deleteMessage()';
+    return {'error' => 1};
+  }
+
+  $send_args->{message_id} = $args->{message_id};
+
+  my $token = $self->token || croak 'No token supplied to deleteMessage()?';
+
+  if (Teapot::Bot::Object::ChatMember::canDelete($self, $chatid)) {
+    my $url = "https://api.telegram.org/bot${token}/deleteMessage";
+    my $api_response = $self->_post_request($url, $send_args);
+
+    if ($api_response) {
+      return Teapot::Bot::Object::Message->create_from_hash($api_response, $self);
+    }
+    else {
+      return {'error' => 1};
+    }
+  }
+  else {
+    return {'error' => 1};
+  }
+}
+
 
 sub sendPhoto {
   my $self = shift;
@@ -571,6 +609,14 @@ Returns a L<Teapot::Bot::Object::Message> object.
 
 On error returns hash reference with error set to 1
 
+=head2 deleteMessage
+
+See L<https://core.telegram.org/bots/api#deletemessage>.
+
+Returns a L<Teapot::Bot::Object::Message> object.
+
+On error returns hash reference with error set to 1
+
 =head2 sendPhoto
 
 See L<https://core.telegram.org/bots/api#sendphoto>.

lib/Teapot/Bot/Object/ChatMember.pm

@@ -3,6 +3,7 @@ package Teapot::Bot::Object::ChatMember;
 
 use Mojo::Base 'Teapot::Bot::Object::Base';
 use Teapot::Bot::Object::User;
+use Carp qw(cluck);
 
 $Teapot::Bot::Object::ChatMember::VERSION = '0.022';
 
@@ -38,6 +39,59 @@ sub fields {
         };
 }
 
+
+sub canDeleteMessage {
+  my $self = shift;
+  my $chatid = shift;
+
+  my $can_delete = 0;
+
+  if ($chatid < 0) {
+    # group chat
+    my $chatobj = $self->_brain->getChat ({ 'chat_id' => $chatid });
+
+    # on api error, keep silence
+    unless ($chatobj) {
+      cluck "Unable to get chat info for $chatid from telegram API";
+      return 0;
+    }
+
+    my $myObj = $self->_brain->getMe ();
+
+    # on api error, keep silence
+    unless ($chatobj) {
+      cluck "Unable to get chat info for $chatid from telegram API";
+      return 0;
+    }
+
+    my $myid = $myObj->id;
+    my $me = $self->_brain->getChatMember ({ 'chat_id' => $chatid, 'user_id' => $myid });
+
+    # on api error, keep silence
+    unless ($me) {
+      cluck 'Unable to get chat info for bot itself from telegram API';
+      return 0;
+    }
+
+    # bot can delete msg if it is group and it is admin there.
+    if ($chatobj->{'type'} eq 'group') {
+      if ($me->{'status'} eq 'administrator') {
+        $can_delete = 1;
+      }
+    # in supergroup bot must be granted with 
+    } elsif ($chatobj->{'type'} eq 'group') || ($chatobj->{'type'} eq 'channel')
+      if ($me->{'can_delete_messages'}) {
+        $can_delete = 1;
+      }
+    }
+  } else {
+    # 1 on 1 chat with user
+    $can_delete = 1;
+  }
+
+  return $can_delete;
+}
+
 1;
 
 __END__
@@ -60,6 +114,14 @@ The base class for Telegram 'ChatMember' type objects.
 See L<https://core.telegram.org/bots/api#chatmember> for details of the
 attributes available for L<Teapot::Bot::Object::ChatMember> objects.
 
+=head1 METHODS
+
+=head2 canDeleteMessage
+
+A convenience method to check if bot can delete message in given conversation.
+
+Returns true if the bot can delete the message in given conversation, otherwise false.
+
 =head1 AUTHOR
 
 Sergei Fedosov <eleksir@gmail.com>