import { chartViewResponseSchema, type ChartViewResponse } from "./chart-view-contract.ts";
import type { ChartViewLayer } from "./chart-view-engine.ts";
import { chartViewFailureResponse } from "./chart-view-failure.ts";

export async function fetchChartView(input: {
  layers?: readonly ChartViewLayer[];
  signal?: AbortSignal;
  subjectId?: string;
}): Promise<{ httpStatus: number; body: ChartViewResponse | null }> {
  const params = new URLSearchParams();
  if (input.layers?.length) params.set("layers", input.layers.join(","));
  if (input.subjectId) params.set("subject", input.subjectId);
  const serialized = params.toString();
  const query = serialized ? `?${serialized}` : "";
  const response = await fetch(`/api/chart-view${query}`, {
    credentials: "same-origin",
    headers: { Accept: "application/json" },
    cache: "no-store",
    signal: input.signal,
  });
  // Authentication is known from the headers; a missing body must not keep
  // a signed-out reader waiting for the JSON deadline.
  if (response.status === 401) return { httpStatus: 401, body: null };
  let json: unknown = null;
  try {
    json = await response.json();
  } catch (error) {
    // Aborting while reading the body is still a timeout, not malformed JSON.
    if (input.signal?.aborted) throw input.signal.reason;
    const errorName = error instanceof Error ? error.name : "Error";
    console.warn("chart_view_client_bad_payload", { errorName, httpStatus: response.status });
    return { httpStatus: response.status, body: chartViewFailureResponse("response_schema_failure") };
  }
  const parsed = chartViewResponseSchema.safeParse(json);
  if (!parsed.success) {
    console.warn("chart_view_client_schema_failed", { httpStatus: response.status });
    return { httpStatus: response.status, body: chartViewFailureResponse("response_schema_failure") };
  }
  return { httpStatus: response.status, body: parsed.data };
}