import type { CreateFlowState } from "../../app/(app)/create/types";
import { CreateFlowUploadValidationError } from "./createFlowUploadValidation";
import {
  clearPendingCommunityAvatarFile,
  readPendingCommunityAvatarFile,
} from "./pendingCommunityAvatarUpload";
import { uploadCreateFlowFile } from "./uploadToServer";

export type FlushPendingCommunityAvatarResult =
  | { status: "none" }
  | { status: "uploaded"; url: string }
  | { status: "invalid" }
  | { status: "failed" };

/**
 * URL from the last successful flush. The IndexedDB file is removed on
 * success, so a second caller (publish, sign-in transfer) can still apply
 * the same URL if React state has not caught up yet.
 * Cleared when anonymous draft storage is wiped.
 */
let lastUploadedUrl: string | null = null;
let inFlight: Promise<FlushPendingCommunityAvatarResult> | null = null;

export function forgetFlushedCommunityAvatarUrl(): void {
  lastUploadedUrl = null;
}

async function runFlush(): Promise<FlushPendingCommunityAvatarResult> {
  let file: File | null;
  try {
    file = await readPendingCommunityAvatarFile();
  } catch {
    return lastUploadedUrl
      ? { status: "uploaded", url: lastUploadedUrl }
      : { status: "none" };
  }
  if (!file) {
    return lastUploadedUrl
      ? { status: "uploaded", url: lastUploadedUrl }
      : { status: "none" };
  }

  try {
    const { url } = await uploadCreateFlowFile(file, "communityAvatar");
    lastUploadedUrl = url;
    await clearPendingCommunityAvatarFile();
    return { status: "uploaded", url };
  } catch (err) {
    if (err instanceof CreateFlowUploadValidationError) {
      await clearPendingCommunityAvatarFile();
      return { status: "invalid" };
    }
    return { status: "failed" };
  }
}

/**
 * Upload the staged community logo, once, even if review and sign-in both ask.
 * A validation failure drops the file. A transient failure leaves it in place.
 */
export function flushPendingCommunityAvatar(): Promise<FlushPendingCommunityAvatarResult> {
  if (!inFlight) {
    inFlight = runFlush().finally(() => {
      inFlight = null;
    });
  }
  return inFlight;
}

/**
 * Copy a staged logo onto `state` as `communityAvatarUrl` when upload works.
 * `upload_failed` means the file is still staged and must not be published over.
 */
export async function stateWithPendingCommunityAvatar(
  state: CreateFlowState,
): Promise<
  | { ok: true; state: CreateFlowState }
  | { ok: false; reason: "upload_failed" }
> {
  const existing =
    typeof state.communityAvatarUrl === "string"
      ? state.communityAvatarUrl.trim()
      : "";
  if (existing.length > 0) return { ok: true, state };

  const flushed = await flushPendingCommunityAvatar();
  if (flushed.status === "uploaded") {
    return {
      ok: true,
      state: { ...state, communityAvatarUrl: flushed.url },
    };
  }
  if (flushed.status === "failed") {
    return { ok: false, reason: "upload_failed" };
  }
  return { ok: true, state };
}