Utility Functions

/**
 * Gets related entities based on relationship type and optional filters
 * @param entity - Base entity to find relations for
 * @param relationType - Type of relationship to look for
 * @param filter - Optional filter for related entity kind
 * @returns Array of related entity references
 */
function getEntityRelations(
  entity: Entity | undefined,
  relationType: string,
  filter?: { kind: string }
): CompoundEntityRef[];

import { getEntityRelations } from '@backstage/plugin-catalog-react';
import { Entity } from '@backstage/catalog-model';

function EntityRelations({ entity }: { entity: Entity }) {
  // Get all API dependencies
  const apiDependencies = getEntityRelations(entity, 'dependsOn', { kind: 'api' });
  
  // Get all systems this component belongs to
  const systems = getEntityRelations(entity, 'partOf', { kind: 'system' });
  
  // Get all components that depend on this API
  const consumers = getEntityRelations(entity, 'providedBy');
  
  return (
    <div>
      <h3>API Dependencies</h3>
      {apiDependencies.map(ref => (
        <EntityRefLink key={ref.name} entityRef={ref} />
      ))}
      
      <h3>Part of Systems</h3>
      {systems.map(ref => (
        <EntityRefLink key={ref.name} entityRef={ref} />
      ))}
      
      <h3>Consumers</h3>
      {consumers.map(ref => (
        <EntityRefLink key={ref.name} entityRef={ref} />
      ))}
    </div>
  );
}

// Find specific relationship types
function ComponentDependencies({ component }: { component: Entity }) {
  const dependencies = getEntityRelations(component, 'dependsOn');
  const provides = getEntityRelations(component, 'providesApi', { kind: 'api' });
  
  return (
    <div>
      <p>Depends on {dependencies.length} entities</p>
      <p>Provides {provides.length} APIs</p>
    </div>
  );
}

/**
 * Gets the source location information for an entity
 * @param entity - Entity to get source location for
 * @param scmIntegrationsApi - SCM integrations API for URL resolution
 * @returns Source location information or undefined if not available
 */
function getEntitySourceLocation(
  entity: Entity,
  scmIntegrationsApi: ScmIntegrationsApi
): EntitySourceLocation | undefined;

/**
 * Information about an entity's source location
 */
interface EntitySourceLocation {
  /** Target URL for the source location */
  locationTargetUrl: string;
  
  /** Type of integration (github, gitlab, etc.) */
  integrationType?: string;
}

import { 
  getEntitySourceLocation, 
  EntitySourceLocation 
} from '@backstage/plugin-catalog-react';
import { useApi } from '@backstage/core-plugin-api';
import { scmIntegrationsApiRef } from '@backstage/integration-react';

function EntitySourceInfo({ entity }: { entity: Entity }) {
  const scmIntegrationsApi = useApi(scmIntegrationsApiRef);
  const sourceLocation = getEntitySourceLocation(entity, scmIntegrationsApi);
  
  if (!sourceLocation) {
    return <p>No source location available</p>;
  }
  
  return (
    <div>
      <h4>Source Location</h4>
      <a 
        href={sourceLocation.locationTargetUrl} 
        target="_blank" 
        rel="noopener noreferrer"
      >
        View Source
        {sourceLocation.integrationType && (
          <span> ({sourceLocation.integrationType})</span>
        )}
      </a>
    </div>
  );
}

// Check if entity has source location
function hasSourceLocation(entity: Entity, scmIntegrationsApi: ScmIntegrationsApi): boolean {
  return getEntitySourceLocation(entity, scmIntegrationsApi) !== undefined;
}

// Get integration type for UI icons
function getIntegrationType(entity: Entity, scmIntegrationsApi: ScmIntegrationsApi): string | undefined {
  const location = getEntitySourceLocation(entity, scmIntegrationsApi);
  return location?.integrationType;
}

/**
 * Checks if one entity owns another entity
 * @param owner - Potential owner entity (user or group)
 * @param entity - Entity to check ownership of
 * @returns True if owner owns the entity
 */
function isOwnerOf(owner: Entity, entity: Entity): boolean;

import { isOwnerOf } from '@backstage/plugin-catalog-react';
import { Entity } from '@backstage/catalog-model';

function OwnershipCheck({ 
  user, 
  entities 
}: { 
  user: Entity; 
  entities: Entity[] 
}) {
  const ownedEntities = entities.filter(entity => isOwnerOf(user, entity));
  
  return (
    <div>
      <h3>Entities owned by {user.metadata.name}</h3>
      <p>Owns {ownedEntities.length} of {entities.length} entities</p>
      
      {ownedEntities.map(entity => (
        <EntityRefLink key={entity.metadata.name} entityRef={entity} />
      ))}
    </div>
  );
}

// Check ownership for access control
function EntityActions({ entity, currentUser }: { entity: Entity; currentUser: Entity }) {
  const canEdit = isOwnerOf(currentUser, entity);
  
  return (
    <div>
      {canEdit && (
        <button>Edit Entity</button>
      )}
      <button>View Details</button>
    </div>
  );
}

// Group ownership check
function GroupEntities({ group, allEntities }: { group: Entity; allEntities: Entity[] }) {
  const groupEntities = allEntities.filter(entity => isOwnerOf(group, entity));
  
  return (
    <div>
      <h3>{group.metadata.name} Group Entities</h3>
      <EntityTable
        title={`${group.metadata.name} Portfolio`}
        entities={groupEntities}
        columns={[
          { title: 'Name', field: 'metadata.name' },
          { title: 'Kind', field: 'kind' },
          { title: 'Type', field: 'spec.type' }
        ]}
      />
    </div>
  );
}

/**
 * Route reference for entity pages with parameters
 * Includes parameters: namespace, kind, name
 */
const entityRouteRef: RouteRef<{
  namespace: string;
  kind: string;
  name: string;
}>;

/**
 * Extracts route parameters from an entity
 * @param entity - Entity to extract parameters from
 * @returns Object with kind, namespace, and name parameters
 */
function entityRouteParams(entity: Entity): {
  kind: string;
  namespace: string;
  name: string;
};

import { 
  entityRouteRef, 
  entityRouteParams 
} from '@backstage/plugin-catalog-react';
import { useRouteRef } from '@backstage/core-plugin-api';

function EntityNavigation() {
  const entityRoute = useRouteRef(entityRouteRef);
  
  const navigateToEntity = (entity: Entity) => {
    const params = entityRouteParams(entity);
    const url = entityRoute(params);
    // Navigate to entity page
    window.location.href = url;
  };
  
  return null;
}

// Generate entity URLs
function EntityLink({ entity }: { entity: Entity }) {
  const entityRoute = useRouteRef(entityRouteRef);
  const params = entityRouteParams(entity);
  const entityUrl = entityRoute(params);
  
  return (
    <a href={entityUrl}>
      {entity.metadata.name}
    </a>
  );
}

// Use in breadcrumbs or navigation
function EntityBreadcrumb({ entity }: { entity: Entity }) {
  const params = entityRouteParams(entity);
  
  return (
    <div>
      <span>{params.namespace}</span> /
      <span>{params.kind}</span> /
      <strong>{params.name}</strong>
    </div>
  );
}

// Custom route handling
function EntityRouter({ entities }: { entities: Entity[] }) {
  const entityRoute = useRouteRef(entityRouteRef);
  
  const buildEntityMap = () => {
    const entityMap = new Map();
    
    entities.forEach(entity => {
      const params = entityRouteParams(entity);
      const url = entityRoute(params);
      entityMap.set(url, entity);
    });
    
    return entityMap;
  };
  
  const entityUrlMap = buildEntityMap();
  
  return null; // Router implementation
}

/**
 * Reduces multiple entity filters into a single catalog filter object
 * @param filters - Array of EntityFilter instances to combine
 * @returns Combined filter object for catalog backend queries
 */
function reduceCatalogFilters(
  filters: EntityFilter[]
): Record<string, string | symbol | (string | symbol)[]>;

/**
 * Reduces entity filters to backend-compatible filters only
 * @param filters - Array of EntityFilter instances
 * @returns Filter object containing only backend-compatible filters
 */
function reduceBackendCatalogFilters(
  filters: EntityFilter[]
): Record<string, string | symbol | (string | symbol)[]>;

/**
 * Creates a composite filter function from multiple entity filters
 * @param filters - Array of EntityFilter instances with filterEntity methods
 * @returns Combined filter function that applies all filters
 */
function reduceEntityFilters(
  filters: EntityFilter[]
): (entity: Entity) => boolean;

import { 
  reduceCatalogFilters,
  reduceBackendCatalogFilters,
  reduceEntityFilters,
  EntityKindFilter,
  EntityTypeFilter,
  EntityTagFilter
} from '@backstage/plugin-catalog-react';

// Combine multiple filters for backend queries
function CombinedFiltersExample() {
  const filters = [
    new EntityKindFilter('component'),
    new EntityTypeFilter(['service', 'website']),
    new EntityTagFilter(['database', 'web'])
  ];
  
  // Get combined catalog filters for backend
  const catalogFilters = reduceCatalogFilters(filters);
  // Result: { kind: 'component', 'spec.type': ['service', 'website'], ... }
  
  // Get only backend-compatible filters
  const backendFilters = reduceBackendCatalogFilters(filters);
  
  // Create frontend filter function
  const filterFunction = reduceEntityFilters(filters);
  
  // Apply to entity list
  const filteredEntities = allEntities.filter(filterFunction);
  
  return (
    <div>
      <p>Applied {filters.length} filters</p>
      <p>Found {filteredEntities.length} matching entities</p>
    </div>
  );
}

// Advanced filter composition
function AdvancedFilterComposition() {
  const baseFilters = [
    new EntityKindFilter('component'),
    new EntityTypeFilter('service')
  ];
  
  const userFilters = [
    new EntityTagFilter(['production']),
    // Custom filters that only work frontend-side
  ];
  
  // Separate backend and frontend filters
  const backendQuery = reduceBackendCatalogFilters(baseFilters);
  const frontendFilter = reduceEntityFilters([...baseFilters, ...userFilters]);
  
  return { backendQuery, frontendFilter };
}

import {
  getEntityRelations,
  getEntitySourceLocation,
  isOwnerOf,
  entityRouteParams
} from '@backstage/plugin-catalog-react';
import { useApi } from '@backstage/core-plugin-api';
import { scmIntegrationsApiRef } from '@backstage/integration-react';

function EntityDetailsPage({ 
  entity, 
  currentUser 
}: { 
  entity: Entity; 
  currentUser: Entity 
}) {
  const scmIntegrationsApi = useApi(scmIntegrationsApiRef);
  
  // Get various entity information
  const sourceLocation = getEntitySourceLocation(entity, scmIntegrationsApi);
  const dependencies = getEntityRelations(entity, 'dependsOn');
  const consumers = getEntityRelations(entity, 'dependsOn').filter(
    ref => ref.kind === 'component'
  );
  const canEdit = isOwnerOf(currentUser, entity);
  const routeParams = entityRouteParams(entity);
  
  return (
    <div>
      <h1>{entity.metadata.name}</h1>
      
      {/* Route information */}
      <p>
        {routeParams.namespace}/{routeParams.kind}/{routeParams.name}
      </p>
      
      {/* Source location */}
      {sourceLocation && (
        <a href={sourceLocation.locationTargetUrl} target="_blank">
          View Source ({sourceLocation.integrationType})
        </a>
      )}
      
      {/* Relationships */}
      <h3>Dependencies ({dependencies.length})</h3>
      {dependencies.map(dep => (
        <EntityRefLink key={dep.name} entityRef={dep} />
      ))}
      
      <h3>Consumers ({consumers.length})</h3>
      {consumers.map(consumer => (
        <EntityRefLink key={consumer.name} entityRef={consumer} />
      ))}
      
      {/* Actions based on ownership */}
      {canEdit && (
        <div>
          <button>Edit Entity</button>
          <button>Delete Entity</button>
        </div>
      )}
    </div>
  );
}