import { ApiError, toApiError } from "./errors";

const API_BASE_URL = (import.meta.env.VITE_API_BASE_URL as string | undefined)?.trim() || "http://localhost:3001";

function buildUrl(path: string): string {
  const normalizedPath = path.startsWith("/") ? path : `/${path}`;
  return `${API_BASE_URL}${normalizedPath}`;
}

async function parseResponseBody(response: Response): Promise<unknown> {
  const contentType = response.headers.get("content-type") ?? "";
  if (!contentType.includes("application/json")) {
    return null;
  }

  try {
    return await response.json();
  } catch {
    return null;
  }
}

const GATEWAY_RETRY_STATUSES = new Set([502, 503, 504]);

function delay(ms: number): Promise<void> {
  return new Promise((resolve) => {
    setTimeout(resolve, ms);
  });
}

export async function requestJson<T>(path: string, init?: RequestInit): Promise<T> {
  const method = (init?.method ?? "GET").toUpperCase();
  const idempotent = method === "GET" || method === "HEAD";
  const maxAttempts = idempotent ? 3 : 1;

  for (let attempt = 1; attempt <= maxAttempts; attempt += 1) {
    try {
      const response = await fetch(buildUrl(path), {
        ...init,
        headers: {
          "Content-Type": "application/json",
          ...(init?.headers ?? {}),
        },
      });

      if (response.status === 204) {
        return undefined as T;
      }

      const payload = await parseResponseBody(response);

      if (!response.ok) {
        const retryable = idempotent && GATEWAY_RETRY_STATUSES.has(response.status) && attempt < maxAttempts;
        if (retryable) {
          await delay(80 * attempt);
          continue;
        }
        // #region agent log
        fetch("http://127.0.0.1:7488/ingest/a18f912f-72c6-4a58-866b-17810a6b89d2", {
          method: "POST",
          headers: { "Content-Type": "application/json", "X-Debug-Session-Id": "587ee5" },
          body: JSON.stringify({
            sessionId: "587ee5",
            hypothesisId: "H-http-not-ok",
            location: "http.ts:requestJson",
            message: "HTTP error response",
            data: {
              path,
              status: response.status,
              contentType: response.headers.get("content-type"),
              payloadIsObject: payload !== null && typeof payload === "object",
            },
            timestamp: Date.now(),
          }),
        }).catch(() => {});
        // #endregion
        throw toApiError(response.status, payload);
      }

      return payload as T;
    } catch (error) {
      if (error instanceof ApiError) {
        throw error;
      }
      if (error instanceof DOMException && error.name === "AbortError") {
        throw error;
      }
      const retryable = idempotent && attempt < maxAttempts;
      if (retryable) {
        await delay(80 * attempt);
        continue;
      }
      throw new ApiError({
        code: "network_error",
        status: null,
        message: "Не удалось связаться с сервером.",
      });
    }
  }

  throw new ApiError({
    code: "network_error",
    status: null,
    message: "Не удалось связаться с сервером.",
  });
}