import { ExtractRequestBody } from "@noya-app/noya-multiplayer-react";
import { uuid } from "@noya-app/noya-utils";
import { Observable } from "@noya-app/observable";
import { RPCManager } from "./rpcManager";

export type FilePropertyManagerOptions = {
  initialName?: string;
};

type UpdateNameResponse = {
  name: string;
};

type PendingChange = {
  id: string;
  name: string;
};

/**
 * Manages synchronization of the file name between the local client and
 * the multiplayer durable object.
 */
export class FilePropertyManager {
  name$ = new Observable<string | undefined>(undefined);

  private pendingChanges$ = new Observable<PendingChange[]>([]);

  optimisticValue$ = Observable.combine(
    [
      this.name$,
      this.pendingChanges$.map((pending) => pending.at(-1)?.name),
    ],
    ([name, optimistic]) => optimistic ?? name
  );

  isInitialized$ = new Observable<boolean>(false);
  isUpdating$ = this.pendingChanges$.map(
    (pending) => pending.length > 0
  );

  constructor(
    private rpcManager: RPCManager,
    options: FilePropertyManagerOptions = {}
  ) {
    if (options.initialName !== undefined) {
      this.setName(options.initialName);
    }
  }

  setName(name: string) {
    this.name$.set(name);
    this.isInitialized$.set(true);
  }

  applyServerUpdate({ name, changeId }: { name: string; changeId?: string }) {
    this.setName(name);

    if (changeId) {
      this.removePendingChange(changeId);
    }
  }

  /**
   * Optimistically update the file name and persist the change through the
   * durable object.
   */
  updateName = async (name: string): Promise<string> => {
    if (!name) {
      name = "";
    }

    const changeId = uuid();
    const pending = this.pendingChanges$.get();
    this.pendingChanges$.set([...pending, { id: changeId, name }]);

    try {
      const payload: ExtractRequestBody<"PUT /api/file"> = { name, changeId };

      const response = await this.rpcManager.requestRoute("PUT /api/file", {
        body: JSON.stringify(payload),
        headers: { "Content-Type": "application/json" },
      });

      const parsed = this.rpcManager.getResponseBody(response) as
        | UpdateNameResponse
        | undefined;
      const resolvedName =
        typeof parsed?.name === "string" && parsed.name.length > 0
          ? parsed.name
          : name;

      this.setName(resolvedName);

      return resolvedName;
    } catch (error) {
      this.removePendingChange(changeId);
      throw error;
    }
  };

  acknowledgeNameChange(changeId: string) {
    this.removePendingChange(changeId);
  }

  private removePendingChange(changeId: string) {
    const pending = this.pendingChanges$.get();
    const next = pending.filter((change) => change.id !== changeId);

    if (next.length !== pending.length) {
      this.pendingChanges$.set(next);
    }
  }
}