resolve-initial-context.ts

import type { ModulesInstance } from '@equinor/fusion-framework-module';
import type { ContextModule } from '../module';
import type { ContextModuleConfig } from '../ContextModuleConfig';
import { concat, EMPTY, first, of } from 'rxjs';

import { type ContextPathResolveArgs, resolveContextFromPath } from './resolve-context-from-path';
import type { NavigationModule } from '@equinor/fusion-framework-module-navigation';

/**
 * Resolves the initial context from the parent module.
 *
 * @param ref - parent modules.
 * @returns An Observable of the resolved initial context.
 */
export const resolveContextFromParent: ContextModuleConfig['resolveInitialContext'] = ({ ref }) => {
  const parentContext = (ref as ModulesInstance<[ContextModule]>)?.context;
  // check if the parent has context module
  if (!parentContext) {
    throw Error(['resolveContextFromNavigation', 'ref does not support context!'].join('\n'));
  }
  // return the current context from the parent or empty if the parent does not have a context
  return parentContext.currentContext ? of(parentContext.currentContext) : EMPTY;
};

/**
 * Resolves the initial context for a Fusion Framework context module.
 *
 * will try to resolve the initial context from the path, and if that fails, it will try to resolve the context from the parent.
 *
 * @param options - Optional configuration for resolving the context path.
 * @returns A function that accepts the module's reference and modules, and returns an Observable of the resolved initial context.
 */
// Deliberately co-located with resolveContextFromParent, which it composes with
// fusion-lint-disable-next-line single-export-per-file
export const resolveInitialContext =
  (options?: {
    path?: ContextPathResolveArgs;
  }): Required<ContextModuleConfig>['resolveInitialContext'] =>
  ({ ref, modules }) => {
    const { context, navigation } = modules;
    // create a path resolver from the context module
    const pathResolver = resolveContextFromPath(context, options?.path);
    // use the path from the navigation module, or the path from the parent navigation module
    const pathname =
      navigation?.path.pathname ??
      (ref as Partial<ModulesInstance<[NavigationModule]>>).navigation?.path.pathname;
    // try to resolve the context from the path, and if that fails, try to resolve the context from the parent
    return concat(
      pathname ? pathResolver(pathname) : EMPTY,
      resolveContextFromParent({ ref, modules }),
    ).pipe(
      // having no initial context is valid; a default avoids first() throwing EmptyError for it
      first(undefined, undefined),
    );
  };

export default resolveInitialContext;