import { getAccessToken } from "@/lib/auth/auth-storage";
import { expireSessionAndRedirectToLogin } from "@/lib/auth/expire-session";
import { env } from "@/lib/env";
import { resolveApiBaseUrl } from "@/lib/resolve-api-prefix-url";

export interface UploadFormResult {
  ok: boolean;
  status: number;
  data: unknown;
}

export interface UploadFormOptions {
  signal?: AbortSignal;
  onProgress?: (percent: number) => void;
}

function parseJsonBody(text: string): unknown {
  if (!text.trim()) {
    return undefined;
  }

  try {
    return JSON.parse(text) as unknown;
  } catch {
    return undefined;
  }
}

function createAbortError(): DOMException {
  return new DOMException("The upload was aborted.", "AbortError");
}

/**
 * hazard: Ky's `onUploadProgress` turns the body into a ReadableStream, and browsers only accept
 * streamed request bodies over HTTP/2 — on HTTP/1.1 (Vite proxy, plain-HTTP hosts) the request dies
 * as a network error before reaching the API. XHR reports progress on every transport.
 */
export function uploadFormWithProgress(
  path: string,
  body: FormData,
  options?: UploadFormOptions,
): Promise<UploadFormResult> {
  return new Promise((resolve, reject) => {
    if (options?.signal?.aborted) {
      reject(createAbortError());
      return;
    }

    const request = new XMLHttpRequest();
    request.open("POST", `${resolveApiBaseUrl(env.apiUrl)}/${path.replace(/^\/+/, "")}`);
    request.setRequestHeader("Accept", "application/json");

    const token = getAccessToken();
    if (token) {
      request.setRequestHeader("Authorization", token);
    }

    const abortRequest = () => {
      request.abort();
    };
    options?.signal?.addEventListener("abort", abortRequest);

    const detachSignal = () => {
      options?.signal?.removeEventListener("abort", abortRequest);
    };

    const { onProgress } = options ?? {};
    if (onProgress) {
      request.upload.addEventListener("progress", (event) => {
        if (event.lengthComputable && event.total > 0) {
          onProgress(Math.round((event.loaded / event.total) * 100));
        }
      });
    }

    request.addEventListener("load", () => {
      detachSignal();
      const { status } = request;

      if (status === 401) {
        expireSessionAndRedirectToLogin();
      }

      resolve({
        ok: status >= 200 && status < 300,
        status,
        data: parseJsonBody(request.responseText),
      });
    });

    request.addEventListener("error", () => {
      detachSignal();
      reject(new Error("Upload failed. Check your connection and try again."));
    });

    request.addEventListener("abort", () => {
      detachSignal();
      reject(createAbortError());
    });

    request.send(body);
  });
}