import { getWorkspace } from "@/lib/session";
import { parseRequestFilters, REQUESTS_EXPORT_MAX, type SearchParams } from "@/lib/requests-filters";
import { listRequestsBatch, type RequestListRow, type Scope } from "@/lib/queries/dashboard";

export const dynamic = "force-dynamic";

const COLUMNS: Array<[string, (r: RequestListRow) => unknown]> = [
  ["request_id", (r) => r.id],
  ["timestamp", (r) => r.createdAt.toISOString()],
  ["completed_at", (r) => r.completedAt?.toISOString() ?? ""],
  ["status", (r) => r.status],
  ["http_status", (r) => r.httpStatus ?? ""],
  ["error_code", (r) => r.errorCode ?? ""],
  ["method", (r) => r.method],
  ["url", (r) => r.url],
  ["final_url", (r) => r.finalUrl ?? ""],
  ["domain", (r) => r.domain],
  ["source", (r) => r.source],
  ["requested_network", (r) => r.requestedNetwork],
  ["network", (r) => r.network ?? ""],
  ["country", (r) => r.country ?? ""],
  ["region", (r) => r.region ?? ""],
  ["city", (r) => r.city ?? ""],
  ["session_id", (r) => r.sessionId ?? ""],
  ["latency_ms", (r) => r.latencyMs ?? ""],
  ["attempts", (r) => r.attempts],
  ["bytes_in", (r) => r.bytesIn],
  ["bytes_out", (r) => r.bytesOut],
  ["price_usd", (r) => r.priceUsd.toFixed(6)],
  ["cached", (r) => (r.cached ? "true" : "false")],
];

/** RFC 4180 quoting plus a guard against spreadsheet formula injection. */
function cell(v: unknown): string {
  let s = v === null || v === undefined ? "" : String(v);
  if (/^[=+\-@\t\r]/.test(s)) s = `'${s}`;
  return /[",\r\n]/.test(s) ? `"${s.replace(/"/g, '""')}"` : s;
}

const BATCH = 1000;

/**
 * GET /dashboard/requests/export?…filters — streams a CSV of the current filter set (newest first),
 * capped at REQUESTS_EXPORT_MAX rows. Upstream cost is never included; `price_usd` is the billed price.
 */
export async function GET(req: Request) {
  const ws = await getWorkspace();
  const scope: Scope = { organizationId: ws.organization.id, projectId: ws.project.id };
  const url = new URL(req.url);
  const sp: SearchParams = Object.fromEntries(url.searchParams.entries());
  const filters = parseRequestFilters(sp);
  const encoder = new TextEncoder();
  const state = { offset: 0, done: false };

  const stream = new ReadableStream<Uint8Array>({
    async start(controller) {
      controller.enqueue(encoder.encode(`${COLUMNS.map(([name]) => name).join(",")}\r\n`));
    },
    async pull(controller) {
      // Pull-based: each call fetches one batch; state lives in the closure.
      const offset = state.offset;
      if (offset >= REQUESTS_EXPORT_MAX || state.done) {
        controller.close();
        return;
      }
      const limit = Math.min(BATCH, REQUESTS_EXPORT_MAX - offset);
      let rows: RequestListRow[];
      try {
        rows = await listRequestsBatch(scope, filters, offset, limit);
      } catch (e) {
        controller.error(e);
        return;
      }
      if (!rows.length) {
        state.done = true;
        controller.close();
        return;
      }
      const chunk = rows.map((r) => COLUMNS.map(([, get]) => cell(get(r))).join(",")).join("\r\n") + "\r\n";
      controller.enqueue(encoder.encode(chunk));
      state.offset += rows.length;
      if (rows.length < limit) state.done = true;
    },
  });

  const stamp = new Date().toISOString().slice(0, 19).replace(/[:T]/g, "").replace(/(\d{8})(\d{6})/, "$1-$2");
  const slug = ws.project.slug || "project";
  return new Response(stream, {
    headers: {
      "content-type": "text/csv; charset=utf-8",
      "content-disposition": `attachment; filename="fetcha-requests-${slug}-${stamp}.csv"`,
      "cache-control": "no-store",
      "x-content-type-options": "nosniff",
    },
  });
}