// src/pages/DashboardPage/BillingPage/billingExportQuery.ts
// (Billing-Aware Export), Task 9: pure query-string builder for GET /R4/BillingExport, kept
// out of BillingExportService.tsx so the URL-encoding contract is unit-testable with no
// fetch/HttpService/React in the loop. Filters mirror the export dialog's fields; `start`/`end`/
// `format` are the server-required trio, `provider`/`encounterType` are optional narrowing filters
// the handler treats as "no filter" when absent - so a blank string must be OMITTED, not sent as
// `provider=`, or the server would have to special-case an empty value as "no filter" itself.
export type BillingExportFilters = {
    start: string;
    end: string;
    provider?: string;
    encounterType?: string;
    format: 'csv' | 'json';
};

// Built on URLSearchParams (not manual string concatenation) so every value is correctly
// percent-encoded per application/x-www-form-urlencoded rules - this is also why the brief specifies
// "a URLSearchParams string" rather than a hand-rolled one.
export const buildBillingExportQuery = (f: BillingExportFilters): string => {
    const params = new URLSearchParams();
    params.set('start', f.start);
    params.set('end', f.end);
    params.set('format', f.format);
    if (f.provider && f.provider.trim() !== '') {
        params.set('provider', f.provider);
    }
    if (f.encounterType && f.encounterType.trim() !== '') {
        params.set('encounterType', f.encounterType);
    }
    return params.toString();
};

// Client-side download filename - the server sets Content-Disposition too, but the browser download
// (via a Blob + <a download>) needs its own filename, and this keeps it human-readable and stable
// across csv/json without depending on response headers.
export const exportFilename = (f: { start: string; end: string }, format: 'csv' | 'json'): string => {
    return `billing-export_${f.start}_${f.end}.${format}`;
};