import type { PathWatcherEvent, WebContainer } from '@webcontainer/api';
import { map } from 'nanostores';
import { bufferWatchEvents } from '../../utils/buffer';
import { WORK_DIR } from '../../utils/constants';

const textDecoder = new TextDecoder('utf8', { fatal: true });

interface File {
  type: 'file';
  content: string;
}

interface Folder {
  type: 'folder';
}

type Dirent = File | Folder;

export type FileMap = Record<string, Dirent | undefined>;

export class FilesStore {
  #webcontainer: Promise<WebContainer>;

  files = map<FileMap>({});

  constructor(webcontainerPromise: Promise<WebContainer>) {
    this.#webcontainer = webcontainerPromise;

    this.#init();
  }

  async #init() {
    const webcontainer = await this.#webcontainer;

    webcontainer.watchPaths(
      { include: [`${WORK_DIR}/**`], exclude: ['**/node_modules', '.git'], includeContent: true },
      bufferWatchEvents(100, this.#processEventBuffer.bind(this)),
    );
  }

  #processEventBuffer(events: Array<[events: PathWatcherEvent[]]>) {
    const watchEvents = events.flat(2);

    for (const { type, path, buffer } of watchEvents) {
      // remove any trailing slashes
      const sanitizedPath = path.replace(/\/+$/g, '');

      switch (type) {
        case 'add_dir': {
          // we intentionally add a trailing slash so we can distinguish files from folders in the file tree
          this.files.setKey(sanitizedPath, { type: 'folder' });
          break;
        }
        case 'remove_dir': {
          this.files.setKey(sanitizedPath, undefined);

          for (const [direntPath] of Object.entries(this.files)) {
            if (direntPath.startsWith(sanitizedPath)) {
              this.files.setKey(direntPath, undefined);
            }
          }

          break;
        }
        case 'add_file':
        case 'change': {
          this.files.setKey(sanitizedPath, { type: 'file', content: this.#decodeFileContent(buffer) });
          break;
        }
        case 'remove_file': {
          this.files.setKey(sanitizedPath, undefined);
          break;
        }
        case 'update_directory': {
          // we don't care about these events
          break;
        }
      }
    }
  }

  #decodeFileContent(buffer?: Uint8Array) {
    if (!buffer || buffer.byteLength === 0) {
      return '';
    }

    try {
      return textDecoder.decode(buffer);
    } catch (error) {
      console.log(error);
      return '';
    }
  }
}