Add ChannelClosed generation at cooperative/force-close/error processing

When we detect a channel `is_shutdown()` or call on it
`force_shutdown()`, we notify the user with a Event::ChannelClosed
informing about the id and closure reason in a best effort.

Author: Antoine Riard

lightning/src/ln/channelmanager.rs

@@ -779,6 +779,9 @@ macro_rules! handle_error {
 						});
 					}
 				}
+				if let Some(channel_id) = chan_id {
+					$self.pending_events.lock().unwrap().push(events::Event::ChannelClosed { channel_id,  err: format!("Channel processing error") });
+				}
 
 				log_error!($self.logger, "{}", err.err);
 				if let msgs::ErrorAction::IgnoreError = err.action {
@@ -1279,6 +1282,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 				msg: update
 			});
 		}
+		self.pending_events.lock().unwrap().push(events::Event::ChannelClosed { channel_id: *channel_id,  err: format!("") });
 
 		Ok(())
 	}
@@ -1325,6 +1329,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 				msg: update
 			});
 		}
+		self.pending_events.lock().unwrap().push(events::Event::ChannelClosed { channel_id: *channel_id,  err: format!("") });
 
 		Ok(chan.get_counterparty_node_id())
 	}
@@ -2220,6 +2225,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 											if let Some(short_id) = channel.get_short_channel_id() {
 												channel_state.short_to_id.remove(&short_id);
 											}
+											// ChannelClosed event is generated by handle_errors for us.
 											Err(MsgHandleErrInternal::from_finish_shutdown(msg, channel_id, channel.force_shutdown(true), self.get_channel_update_for_broadcast(&channel).ok()))
 										},
 										ChannelError::CloseDelayBroadcast(_) => { panic!("Wait is only generated on receipt of channel_reestablish, which is handled by try_chan_entry, we don't bother to support it here"); }
@@ -3091,6 +3097,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 					msg: update
 				});
 			}
+			self.pending_events.lock().unwrap().push(events::Event::ChannelClosed { channel_id: msg.channel_id,  err: format!("Counterparty-initiated cooper") });
 		}
 		Ok(())
 	}
@@ -3137,6 +3144,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 					msg: update
 				});
 			}
+			self.pending_events.lock().unwrap().push(events::Event::ChannelClosed { channel_id: msg.channel_id,  err: format!("Successful cooperative-close") });
 		}
 		Ok(())
 	}
@@ -3615,6 +3623,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 								msg: update
 							});
 						}
+						self.pending_events.lock().unwrap().push(events::Event::ChannelClosed { channel_id: chan.channel_id(),  err: format!("Channel with commitment transaction broadcasted") });
 						pending_msg_events.push(events::MessageSendEvent::HandleError {
 							node_id: chan.get_counterparty_node_id(),
 							action: msgs::ErrorAction::SendErrorMessage {
@@ -3676,6 +3685,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 					Err(e) => {
 						let (close_channel, res) = convert_chan_err!(self, e, short_to_id, chan, channel_id);
 						handle_errors.push((chan.get_counterparty_node_id(), Err(res)));
+						// ChannelClosed event is generated by handle_error for us
 						!close_channel
 					}
 				}
@@ -4089,6 +4099,7 @@ where
 							msg: update
 						});
 					}
+					self.pending_events.lock().unwrap().push(events::Event::ChannelClosed { channel_id: channel.channel_id(),  err: format!("Channel has been closed onchain!") });
 					pending_msg_events.push(events::MessageSendEvent::HandleError {
 						node_id: channel.get_counterparty_node_id(),
 						action: msgs::ErrorAction::SendErrorMessage { msg: e },
@@ -4279,6 +4290,7 @@ impl<Signer: Sign, M: Deref , T: Deref , K: Deref , F: Deref , L: Deref >
 								msg: update
 							});
 						}
+						self.pending_events.lock().unwrap().push(events::Event::ChannelClosed { channel_id: chan.channel_id(),  err: format!("Peer disconnected with no new connection possible") });
 						false
 					} else {
 						true
@@ -4293,6 +4305,7 @@ impl<Signer: Sign, M: Deref , T: Deref , K: Deref , F: Deref , L: Deref >
 							if let Some(short_id) = chan.get_short_channel_id() {
 								short_to_id.remove(&short_id);
 							}
+							self.pending_events.lock().unwrap().push(events::Event::ChannelClosed { channel_id: chan.channel_id(),  err: format!("Disconnected chan aleady shutdown state!") });
 							return false;
 						} else {
 							no_channels_remain = false;