import { Notice } from "obsidian";

import EventListener from "../../../event-listener";
import { DocumentChanges } from "../../../render-plugin/document-changes-listener";
import Context from "../context-detection";

import State from "./state";

class PredictingState extends State {
  private predictionPromise: Promise<void> | null = null;
  private isStillNeeded = true;
  private readonly prefix: string;
  private readonly suffix: string;

  constructor(context: EventListener, prefix: string, suffix: string) {
    super(context);
    this.prefix = prefix;
    this.suffix = suffix;
  }

  static createAndStartPredicting(
    context: EventListener,
    prefix: string,
    suffix: string
  ): PredictingState {
    const predictingState = new PredictingState(context, prefix, suffix);
    predictingState.startPredicting();
    context.setContext(Context.getContext(prefix, suffix));
    return predictingState;
  }

  handleCancelKeyPressed(): boolean {
    this.cancelPrediction();
    return true;
  }

  async handleDocumentChange(
    documentChanges: DocumentChanges
  ): Promise<void> {
    if (
      documentChanges.hasCursorMoved() ||
      documentChanges.hasUserTyped() ||
      documentChanges.hasUserDeleted() ||
      documentChanges.isTextAdded()
    ) {
      this.cancelPrediction();
    }
  }

  private cancelPrediction(): void {
    this.isStillNeeded = false;
    this.context.transitionToIdleState();
  }

  startPredicting(): void {
    this.predictionPromise = this.predict();
  }

  private async predict(): Promise<void> {

    const result =
      await this.context.autocomplete?.fetchPredictions(
        this.prefix,
        this.suffix
      );

    if (!this.isStillNeeded) {
      return;
    }

    if (result.isErr()) {
      new Notice(
        `Copilot: Something went wrong cannot make a prediction. Full error is available in the dev console. Please check your settings. `
      );
      console.error(result.error);
      this.context.transitionToIdleState();
    }

    const prediction = result.unwrapOr("");

    if (prediction === "") {
      this.context.transitionToIdleState();
      return;
    }
    this.context.transitionToSuggestingState(prediction, this.prefix, this.suffix);
  }


  getStatusBarText(): string {
    return `Predicting for ${this.context.context}`;
  }
}

export default PredictingState;