lightningd/invoice.c: Improve programmatic error reporting for delinvoice.

Changelog-Changed: JSON-RPC: `delinvoice` will now report specific error codes: 905 for failing to find the invoice, 906 for the invoice status not matching the parameter.

common/jsonrpc_errors.h

@@ -59,12 +59,14 @@ static const errcode_t CONNECT_ALL_ADDRESSES_FAILED = 401;
 /* bitcoin-cli plugin errors */
 #define BCLI_ERROR                      400
 
-/* Errors from `invoice` command */
+/* Errors from `invoice` or `delinvoice` commands */
 static const errcode_t INVOICE_LABEL_ALREADY_EXISTS = 900;
 static const errcode_t INVOICE_PREIMAGE_ALREADY_EXISTS = 901;
 static const errcode_t INVOICE_HINTS_GAVE_NO_ROUTES = 902;
 static const errcode_t INVOICE_EXPIRED_DURING_WAIT = 903;
 static const errcode_t INVOICE_WAIT_TIMED_OUT = 904;
+static const errcode_t INVOICE_NOT_FOUND = 905;
+static const errcode_t INVOICE_STATUS_UNEXPECTED = 906;
 
 /* Errors from HSM crypto operations. */
 static const errcode_t HSM_ECDH_FAILED = 800;

doc/lightning-delinvoice.7

@@ -19,6 +19,21 @@ The caller should be particularly aware of the error case caused by the
 On success, an invoice description will be returned as per
 \fBlightning-listinvoice\fR(7)\.
 
+.SH ERRORS
+
+The following errors may be reported:
+
+.RS
+.IP \[bu]
+-1:  Database error\.
+.IP \[bu]
+905:  An invoice with that label does not exist\.
+.IP \[bu]
+906:  The invoice \fIstatus\fR does not match the parameter\.
+An error object will be returned as error \fIdata\fR, containing
+\fIcurrent_status\fR and \fIexpected_status\fR fields\.
+
+.RE
 .SH AUTHOR
 
 Rusty Russell \fI<rusty@rustcorp.com.au\fR> is mainly responsible\.

doc/lightning-delinvoice.7.md

@@ -21,6 +21,19 @@ RETURN VALUE
 On success, an invoice description will be returned as per
 lightning-listinvoice(7).
 
+ERRORS
+------
+
+The following errors may be reported:
+
+- -1:  Database error.
+- 905:  An invoice with that label does not exist.
+- 906:  The invoice *status* does not match the parameter.
+  An error object will be returned as error *data*, containing
+  *current_status* and *expected_status* fields.
+  This is most likely due to the *status* of the invoice
+  changing just before this command is invoked.
+
 AUTHOR
 ------
 

lightningd/invoice.c

@@ -1145,7 +1145,7 @@ static struct command_result *json_delinvoice(struct command *cmd,
 		return command_param_failed();
 
 	if (!wallet_invoice_find_by_label(wallet, &i, label)) {
-		return command_fail(cmd, LIGHTNINGD, "Unknown invoice");
+		return command_fail(cmd, INVOICE_NOT_FOUND, "Unknown invoice");
 	}
 
 	details = wallet_invoice_details(cmd, cmd->ld->wallet, i);
@@ -1154,15 +1154,22 @@ static struct command_result *json_delinvoice(struct command *cmd,
 	 * might not make sense if it changed! */
 	actual_status = invoice_status_str(details);
 	if (!streq(actual_status, status)) {
-		return command_fail(cmd, LIGHTNINGD,
+		struct json_stream *js;
+		js = json_stream_fail(cmd, INVOICE_STATUS_UNEXPECTED,
+				      tal_fmt(tmpctx,
 					      "Invoice status is %s not %s",
-				    actual_status, status);
+					      actual_status, status));
+		json_add_string(js, "current_status", actual_status);
+		json_add_string(js, "expected_status", status);
+		json_object_end(js);
+		return command_failed(cmd, js);
 	}
 
 	if (!wallet_invoice_delete(wallet, i)) {
 		log_broken(cmd->ld->log,
 			   "Error attempting to remove invoice %"PRIu64,
 			   i.id);
+		/* FIXME: allocate a generic DATABASE_ERROR code.  */
 		return command_fail(cmd, LIGHTNINGD, "Database error");
 	}