import type { Organization } from 'fhir/r4';

/**
 * /611 - WHETHER THIS PRACTICE CAN ACTUALLY SEND A FAX.
 *
 * THE FAX TAB'S WHOLE DESIGN TURNS ON THIS ANSWER, and states the control: *"the fax option
 * must be VISIBLY UNAVAILABLE rather than broken. A button that silently does nothing is worse than one
 * that says why - a coordinator will click it, believe the referral was sent, and stop chasing it. That
 * is a patient not getting to a specialist."* The button exists only when this returns settings that
 * can actually send.
 *
 * IT MIRRORS THE SERVER'S `getFaxVendorPublic` DELIBERATELY, INCLUDING THE VENDOR ALLOW-LIST. A stored
 * id we no longer have an adapter for is not "some vendor" - it is a practice whose fax button would
 * resolve to nothing at the far end, and it must read as unconfigured here so they are told to choose
 * again rather than shown a button the server will refuse.
 *
 * THE TWO COPIES CAN DRIFT, and that is the honest cost of the client knowing this at all. The
 * alternative - a read endpoint - is a round trip for a fact the Organization already carries, and the
 * server refuses independently either way: this decides whether to OFFER the button, never whether the
 * send is allowed.
 */
export const ORGANIZATION_FAX_VENDOR_EXTENSION_URL =
    'https://akashichealthrecords.com/fhir/StructureDefinition/organization-fax-vendor';

/** Kept in step with `FAX_VENDORS` in the api's `faxVendor.ts`. */
export const FAX_VENDOR_IDS = ['phaxio', 'documo', 'sinch'] as const;

export type FaxVendorId = (typeof FAX_VENDOR_IDS)[number];

export interface OrganizationFaxSettings {
    vendorId: FaxVendorId;
    fromNumber?: string;
    credentialsConfigured: boolean;
}

const isFaxVendorId = (value: unknown): value is FaxVendorId =>
    typeof value === 'string' && (FAX_VENDOR_IDS as readonly string[]).includes(value);

export const readOrganizationFaxSettings = (
    organization?: Organization | null,
): OrganizationFaxSettings | undefined => {
    const extension = organization?.extension?.find(
        (entry) => entry.url === ORGANIZATION_FAX_VENDOR_EXTENSION_URL,
    );
    if (!extension) return undefined;

    const vendorId = extension.extension?.find((entry) => entry.url === 'vendorId')?.valueString;
    if (!isFaxVendorId(vendorId)) return undefined;

    return {
        vendorId,
        fromNumber: extension.extension?.find((entry) => entry.url === 'fromNumber')?.valueString,
        credentialsConfigured:
            extension.extension?.find((entry) => entry.url === 'credentialsConfigured')?.valueBoolean ?? false,
    };
};

/**
 * CHOSEN IS NOT THE SAME AS READY, and conflating them is how the "visibly unavailable" control gets
 * broken by accident. A practice can pick a vendor and never save the account details - the settings
 * screen writes those in two steps - and the server refuses that case by name. Offering a send button
 * to a half-configured practice produces exactly the click-and-stop-chasing this design forbids.
 */
export const canSendFax = (organization?: Organization | null): boolean =>
    readOrganizationFaxSettings(organization)?.credentialsConfigured === true;