storybook/code/lib/store/src/StoryIndexStore.ts

import { dedent } from 'ts-dedent';
import type {
  Addon_IndexEntry,
  Path,
  Store_StoryIndex,
  Store_StorySpecifier,
  StoryId,
} from '@storybook/types';
import memoize from 'memoizerific';

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

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

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

  entryFromSpecifier(specifier: Store_StorySpecifier) {
    const entries = Object.values(this.entries);
    if (specifier === '*') {
      // '*' means select the first entry. If there is none, we have no selection.
      return entries[0];
    }

    if (typeof specifier === 'string') {
      // Find the story with the exact id that matches the specifier (see #11571)
      if (this.entries[specifier]) {
        return this.entries[specifier];
      }
      // Fallback to the first story that starts with the specifier
      return entries.find((entry) => entry.id.startsWith(specifier));
    }

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

  storyIdToEntry(storyId: StoryId): Addon_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): Addon_IndexEntry {
    return getImportPathMap(this.entries)[importPath];
  }
}