export class ChangelogViewProvider implements TreeDataProvider<PijulChange> {

export class ChangelogViewProvider implements TreeDataProvider<PijulChange | string> {

  getTreeItem (element: PijulChange): TreeItem | Thenable<TreeItem> {
    const resourceUri = Uri.parse('pijul-change:' + element.hash);

  getTreeItem (element: PijulChange | string): TreeItem | Thenable<TreeItem> {
    if (element instanceof PijulChange) {
      const resourceUri = Uri.parse('pijul-change:' + element.hash);

    return {
      // id: element.hash,
      label: element.message,
      description: `${element.author.name}, ${element.date.toISOString()}`,
      collapsibleState: TreeItemCollapsibleState.Collapsed,
      contextValue: 'pijulChange',
      tooltip: `${element.hash}\nRecorded by ${element.author.fullName ?? element.author.name} at ${element.date.toISOString()}\n\n\t${element.message}\n`,
      command: {
        command: 'vscode.open',
        title: 'Open Change TOML',
        arguments: [resourceUri]
      }
    };

      return {
        label: element.message,
        description: `${element.author.name}, ${element.date.toISOString()}`,
        collapsibleState: TreeItemCollapsibleState.Collapsed,
        contextValue: 'pijulChange',
        tooltip: `${element.hash}\nRecorded by ${element.author.fullName ?? element.author.name} at ${element.date.toISOString()}\n\n\t${element.message}\n`,
        command: {
          command: 'vscode.open',
          title: 'Open Change TOML',
          arguments: [resourceUri]
        }
      };
    } else {
      // It's a string, representing a file path
      // TODO: Use URIs instead of strings
      // TODO: Customize appearance depending on file action (Edit, Replacement, Deletion, etc.)
      const sections = element.split(/\\|\//);
      return {
        label: sections[sections.length - 1],
        description: sections.slice(0, -1).join('/'),
        collapsibleState: TreeItemCollapsibleState.None,
        contextValue: 'pijulChangedFile'
        // TODO: Command and Tooltip
      };
    }

  async getChildren (element?: PijulChange): Promise<PijulChange[] | null | undefined> {

  async getChildren (element?: PijulChange | string): Promise<Array<PijulChange | string> | null | undefined> {

      // Show changes which the current one depends on
      return await this.repository.getChangeDependencies(element);

      if (element instanceof PijulChange) {
        // Show the paths of the files altered by the parent change
        return await this.repository.getChangeFiles(element);
      } else {
        // Paths have no children
        return null;
      }

  }
  /**
   * Gets a list of the files which were altered in a change
   * @param change The change to retrieve the altered files for
   */
  async getChangeFiles (change: PijulChange): Promise<string[]> {
    const changeToml = await this.getChangeToml(change.hash);
    const changePattern = /\d\.\s([A-Za-z]+)\sin\s(.*):/g;
    const files: Set<string> = new Set();
    let match = changePattern.exec(changeToml);
    while (match) {
      files.add(match[2]);
      match = changePattern.exec(changeToml);
    }
    return [...files];