import type { Communication } from "fhir/r4";
import { mayHaveBeenWritten } from "../fetchFailureMessage";

/**
 * One message send, named so the server can tell a retry from a new message. A send whose answer was lost is sent
 * again under the same name, and the server returns the message the first attempt wrote rather than a second copy.
 */
export const SEND_OPERATION_SYSTEM = "https://akashichealthrecords.com/fhir/sid/send-operation";

export interface SendOperation {
    operationId: string;
    /** Throws once whatever began the send is gone; checked at the last moment before it leaves, and on its answer. */
    admit?: (phase?: "answer") => void;
}

export const newSendOperation = (): SendOperation => ({ operationId: crypto.randomUUID() });

/** The message carrying its send's name; without one it is sent as before. */
export const namedSend = <T extends Communication>(communication: T, send?: SendOperation): T =>
    send
        ? {
            ...communication,
            identifier: [
                ...(communication.identifier ?? []).filter((each) => each.system !== SEND_OPERATION_SYSTEM),
                { system: SEND_OPERATION_SYSTEM, value: send.operationId },
            ],
        }
        : communication;

// The server's own words for a send it has not finished or could not confirm: either way it may already be written.
// A conflict or unproved replay refuses this request, not the send that first used the name, which may be written.
const STILL_OPEN = new Set(["SEND_IN_PROGRESS", "AUTHORIZATION_UNRESOLVED", "SEND_OPERATION_CONFLICT", "SEND_OPERATION_UNPROVED"]);

/** A send that may have been written, so the honest answer is "not confirmed", never "not sent". */
export const sendUnconfirmed = (error: unknown): boolean => {
    if (mayHaveBeenWritten(error)) return true;
    const code = (error as { body?: { code?: unknown } } | null | undefined)?.body?.code;
    return typeof code === "string" && STILL_OPEN.has(code);
};