import { ipcRenderer } from 'electron';
import type { IJsonPatch } from 'mobx-state-tree';
import {
  MainToRendererIpcMessage,
  RendererToMainIpcMessage,
  sharedStore,
  SharedStoreListener,
  SharedStoreSnapshotIn,
  SophieRenderer
} from '@sophie/shared';

export type MessageSender = (channel: RendererToMainIpcMessage, ...args: unknown[]) => void;

export class SophieRendererImpl implements SophieRenderer {
  readonly #send: MessageSender;

  #listener: SharedStoreListener | null = null;

  #snapshot: SharedStoreSnapshotIn | null = null;

  constructor(send: MessageSender) {
    this.#send = send;
  }

  sharedStoreSnapshotReceived(snapshot: unknown): void {
    if (sharedStore.is(snapshot)) {
      if (this.#listener === null) {
        this.#snapshot = snapshot;
      } else {
        this.#listener.onSnapshot(snapshot);
      }
    } else {
      console.error('Received invalid snapshot', snapshot);
      this.#snapshot = null;
    }
  }

  sharedStorePatchReceived(patch: unknown): void {
    if (this.#listener !== null) {
      // `mobx-state-tree` will validate the patch, so we can safely cast here.
      this.#listener.onPatch(patch as IJsonPatch);
    }
  }

  setSharedStoreListener(listener: SharedStoreListener): void {
    this.#listener = listener;
    if (this.#snapshot !== null) {
      listener.onSnapshot(this.#snapshot);
      this.#snapshot = null;
    }
    this.#send(RendererToMainIpcMessage.SharedStoreSnapshotRequest);
  }

  buttonClick(): void {
    this.#send(RendererToMainIpcMessage.ButtonClick);
  }
}

export function createSophieRenderer(): SophieRenderer {
  const impl = new SophieRendererImpl(ipcRenderer.send);

  ipcRenderer.on(MainToRendererIpcMessage.SharedStoreSnapshot, (_event, snapshot) => {
    impl.sharedStoreSnapshotReceived(snapshot);
  });

  ipcRenderer.on(MainToRendererIpcMessage.SharedStorePatch, (_event, patch) => {
    impl.sharedStorePatchReceived(patch);
  });

  return {
    setSharedStoreListener: impl.setSharedStoreListener.bind(impl),
    buttonClick: impl.buttonClick.bind(impl),
  };
}