storybook/lib/store/src/StoryIndexStore.ts

import { dedent } from 'ts-dedent';
import type { StoryId } from '@storybook/csf';
import memoize from 'memoizerific';

import type { StorySpecifier, StoryIndex, IndexEntry, Path } from './types';

const getImportPathMap = memoize(1)((entries: StoryIndex['entries']) =>
  Object.values(entries).reduce((acc, entry) => {
    acc[entry.importPath] = acc[entry.importPath] || entry;
    return acc;
  }, {} as Record<Path, IndexEntry>)
);

export class StoryIndexStore {
  entries: StoryIndex['entries'];

  constructor({ entries }: StoryIndex = { v: 4, entries: {} }) {
    this.entries = entries;
  }

  storyIdFromSpecifier(specifier: StorySpecifier) {
    const storyIds = Object.keys(this.entries);
    if (specifier === '*') {
      // '*' means select the first story. If there is none, we have no selection.
      return storyIds[0];
    }

    if (typeof specifier === 'string') {
      // Find the story with the exact id that matches the specifier (see #11571)
      if (storyIds.indexOf(specifier) >= 0) {
        return specifier;
      }
      // Fallback to the first story that starts with the specifier
      return storyIds.find((storyId) => storyId.startsWith(specifier));
    }

    // Try and find a story matching the name/kind, setting no selection if they don't exist.
    const { name, title } = specifier;
    const match = Object.entries(this.entries).find(
      ([id, story]) => story.name === name && story.title === title
    );

    return match && match[0];
  }

  storyIdToEntry(storyId: StoryId): IndexEntry {
    const storyEntry = this.entries[storyId];
    if (!storyEntry) {
      throw new Error(dedent`Couldn't find story matching '${storyId}' after HMR.
      - Did you remove it from your CSF file?
      - Are you sure a story with that id exists?
      - Please check your entries field of your main.js config.
      - Also check the browser console and terminal for error messages.`);
    }

    return storyEntry;
  }

  importPathToEntry(importPath: Path): IndexEntry {
    return getImportPathMap(this.entries)[importPath];
  }
}