import { NextResponse, type NextRequest } from "next/server";
import { exportFilename, exportResponseHeaders, toCsv, toXlsx, type ExportColumn } from "@/lib/export";
import { EVENT_TYPE_LABELS, parseEventDateParam, parseEventType, type OrgLookups, type ReportEvent } from "@/lib/reports";
import { loadEventHistory, loadOrgLookups } from "@/lib/reports-data";
import { requireHrUser } from "@/lib/auth/require-hr";
import { withUser } from "@/lib/db";

// Full raw event-log dump — one row per employee_history entry in the
// selected period (default: current year), every event type unless one is
// picked, org columns resolved from each affected employee's current
// placement (see loadEventHistory).
export async function GET(request: NextRequest) {
  const gate = await requireHrUser();
  if ("denied" in gate) return gate.denied;

  const params = request.nextUrl.searchParams;
  const format = params.get("format") === "xlsx" ? "xlsx" : "csv";
  const eventType = parseEventType(params.get("eventType"));

  const { lookups, events } = await withUser(gate.userId, async (tx) => {
    const [{ lookups }, events] = await Promise.all([
      loadOrgLookups(tx),
      loadEventHistory(tx, {
        eventType: eventType ?? undefined,
        division: params.get("division") ?? undefined,
        location: params.get("location") ?? undefined,
        from: parseEventDateParam(params.get("from")),
        to: parseEventDateParam(params.get("to")),
      }),
    ]);
    return { lookups, events };
  });

  const columns = eventExportColumns(lookups);
  const filename = exportFilename(`ereignisse-${eventType ?? "alle"}`, format);
  const body = format === "xlsx" ? await toXlsx(events, columns, "Ereignisse") : toCsv(events, columns);
  // TS 5.9's Uint8Array<ArrayBufferLike> vs DOM's BlobPart/ArrayBuffer<> generic
  // mismatch (microsoft/TypeScript#59417) — a real Uint8Array works fine here.
  return new NextResponse(new Blob([body as BlobPart]), { headers: exportResponseHeaders(filename, format) });
}

function eventExportColumns(lookups: OrgLookups): ExportColumn<ReportEvent>[] {
  return [
    { header: "Datum", get: (e) => e.event_date, kind: "date" },
    { header: "Ereignistyp", get: (e) => EVENT_TYPE_LABELS[e.event_type] ?? e.event_type },
    { header: "Vorname", get: (e) => e.first_name },
    { header: "Nachname", get: (e) => e.last_name },
    { header: "Position", get: (e) => e.job_title },
    { header: "Bereich", get: (e) => (e.org_unit_id ? (lookups.divisionName.get(e.org_unit_id) ?? "") : "") },
    { header: "Abteilung", get: (e) => (e.org_unit_id ? (lookups.departmentName.get(e.org_unit_id) ?? "") : "") },
    { header: "Team", get: (e) => (e.org_unit_id ? (lookups.teamName.get(e.org_unit_id) ?? "") : "") },
    { header: "Standort", get: (e) => lookups.locationName.get(e.location_id) ?? "" },
    { header: "Beschreibung", get: (e) => e.description },
  ];
}