import { ISnippets, SnippetCollection } from '../../interfaces/ISnippets';
import { SiteThemeId } from '../../interfaces/SiteTheme';

export abstract class BaseDocumentationSection {
  snippets: ISnippets;
  theme: SiteThemeId = SiteThemeId.Keppel;

  SiteThemeId = SiteThemeId;

  private _themedSnippetRegex: RegExp;

  constructor(private readonly _context: __WebpackModuleApi.RequireContext) {
    this.snippets = this.getSnippets();
  }

  /** Update the active theme and replace snippets with theme-specific versions if available. */
  onThemeChange(theme: SiteThemeId): void {
    this.theme = theme;
    this.snippets = this.getSnippets();
  }

  private getSnippets(): ISnippets {
    // eslint-disable-next-line no-useless-escape
    this._themedSnippetRegex = new RegExp(`\.${this.theme}`, 'i');

    const compiled: SnippetCollection = {};
    const raw: SnippetCollection = {};

    const keys = this.getContextKeys();

    keys.forEach(key => {
      const snippetName = this.getSnippetNameFromContext(key);
      const codeSnippet: CodeSnippet = this._context(key);

      compiled[snippetName] = codeSnippet.snippet;
      raw[snippetName] = codeSnippet.example;
    });

    return { compiled, raw };
  }

  private getContextKeys(): string[] {
    const allKeys = this._context.keys();

    // Get a list of the keys with the theme-specific keys after the generic keys
    return [
      ...allKeys.filter(key => !this._themedSnippetRegex.test(key)),
      ...allKeys.filter(key => this._themedSnippetRegex.test(key)),
    ];
  }

  private getSnippetNameFromContext(contextKey: string): string {
    return contextKey
      .replace(this._themedSnippetRegex, '')
      .replace('./', '')
      .replace(/\W+(\w)/g, match => match[1].toUpperCase());
  }
}

export function isBaseDocumentationSection(obj: any): obj is BaseDocumentationSection {
  return 'theme' in obj;
}

export interface CodeSnippet {
  snippet?: string;
  example?: string;
}