import { h, Component } from 'preact';

import { bind, linkRef, Fileish } from '../../lib/initial-util';
import * as style from './style.scss';
import { FileDropEvent } from 'file-drop-element';
import 'file-drop-element';
import SnackBarElement, { SnackOptions } from '../../lib/SnackBar';
import '../../lib/SnackBar';
import Intro from '../intro';
import '../custom-els/LoadingSpinner';

const ROUTE_EDITOR = '/editor';

const compressPromise = import(
  /* webpackChunkName: "main-app" */
  '../compress');
const offlinerPromise = import(
  /* webpackChunkName: "offliner" */
  '../../lib/offliner');

function back() {
  window.history.back();
}

interface Props {}

interface State {
  file?: File | Fileish;
  isEditorOpen: Boolean;
  Compress?: typeof import('../compress').default;
}

export default class App extends Component<Props, State> {
  state: State = {
    isEditorOpen: false,
    file: undefined,
    Compress: undefined,
  };
  private compressInstance?: import('../compress').default;

  snackbar?: SnackBarElement;

  constructor() {
    super();

    compressPromise.then((module) => {
      this.setState({ Compress: module.default });
    }).catch(() => {
      this.showSnack('Failed to load app');
    });

    offlinerPromise.then(({ offliner }) => offliner(this.showSnack));

    // In development, persist application state across hot reloads:
    if (process.env.NODE_ENV === 'development') {
      this.setState(window.STATE);
      const oldCDU = this.componentDidUpdate;
      this.componentDidUpdate = (props, state, prev) => {
        if (oldCDU) oldCDU.call(this, props, state, prev);
        window.STATE = this.state;
      };
    }

    // Since iOS 10, Apple tries to prevent disabling pinch-zoom. This is great in theory, but
    // really breaks things on Squoosh, as you can easily end up zooming the UI when you mean to
    // zoom the image. Once you've done this, it's really difficult to undo. Anyway, this seems to
    // prevent it.
    document.body.addEventListener('gesturestart', (event) => {
      event.preventDefault();
    });

    window.addEventListener('popstate', this.onPopState);
    this.exposeAPI();
  }

  @bind
  private onFileDrop({ files }: FileDropEvent) {
    if (!files || files.length === 0) return;
    const file = files[0];
    this.openEditor();
    this.setState({ file });
  }

  @bind
  private onIntroPickFile(file: File | Fileish) {
    this.openEditor();
    this.setState({ file });
  }

  @bind
  private showSnack(message: string, options: SnackOptions = {}): Promise<string> {
    if (!this.snackbar) throw Error('Snackbar missing');
    return this.snackbar.showSnackbar(message, options);
  }

  @bind
  private onPopState() {
    this.setState({ isEditorOpen: location.pathname === ROUTE_EDITOR });
  }

  @bind
  private openEditor() {
    if (this.state.isEditorOpen) return;
    history.pushState(null, '', ROUTE_EDITOR);
    this.setState({ isEditorOpen: true });
  }

  private exposeAPI() {
    const api = {
      setFile: (blob: Blob, name: string) => {
        return new Promise((resolve) => {
          this.setState({ file: new File([blob], name) });
          document.addEventListener('squooshingdone', () => resolve(), { once: true });
        });
      },
      getBlob: async (side: 0 | 1) => {
        if (!this.state.file || !this.compressInstance) {
          throw new Error('No file has been loaded');
        }
        await this.compressInstance.compressionJobs[side];
        return this.compressInstance.state.images[side].file;
      },
    };
    expose(api, self.parent);
  }

  render({}: Props, { file, isEditorOpen, Compress }: State) {
    return (
      <div id="app" class={style.app}>
        <file-drop accept="image/*" onfiledrop={this.onFileDrop} class={style.drop}>
          {!isEditorOpen
            ? <Intro onFile={this.onIntroPickFile} showSnack={this.showSnack} />
            : (Compress)
              ? <Compress
                  ref={i => this.compressInstance = i}
                  file={file!}
                  showSnack={this.showSnack}
                  onBack={this.onBack}
              />
              : <loading-spinner class={style.appLoader}/>
          }
          <snack-bar ref={linkRef(this, 'snackbar')} />
        </file-drop>
      </div>
    );
  }
}