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| 1 | +/* |
| 2 | + * Copyright 2022 Expedia, Inc |
| 3 | + * |
| 4 | + * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | + * you may not use this file except in compliance with the License. |
| 6 | + * You may obtain a copy of the License at |
| 7 | + * |
| 8 | + * https://www.apache.org/licenses/LICENSE-2.0 |
| 9 | + * |
| 10 | + * Unless required by applicable law or agreed to in writing, software |
| 11 | + * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | + * See the License for the specific language governing permissions and |
| 14 | + * limitations under the License. |
| 15 | + */ |
| 16 | + |
| 17 | +package com.expediagroup.graphql.generator.federation.execution |
| 18 | + |
| 19 | +import com.expediagroup.graphql.generator.federation.exception.InvalidFederatedRequest |
| 20 | +import com.expediagroup.graphql.generator.federation.execution.resolverexecutor.FederatedTypePromiseResolverExecutor |
| 21 | +import com.expediagroup.graphql.generator.federation.execution.resolverexecutor.FederatedTypeSuspendResolverExecutor |
| 22 | +import com.expediagroup.graphql.generator.federation.execution.resolverexecutor.ResolvableEntity |
| 23 | +import com.expediagroup.graphql.generator.federation.extensions.collectAll |
| 24 | +import com.expediagroup.graphql.generator.federation.extensions.toDataFetcherResult |
| 25 | +import graphql.execution.DataFetcherResult |
| 26 | +import graphql.schema.DataFetcher |
| 27 | +import graphql.schema.DataFetchingEnvironment |
| 28 | +import java.util.concurrent.CompletableFuture |
| 29 | + |
| 30 | +private const val TYPENAME_FIELD = "__typename" |
| 31 | +private const val REPRESENTATIONS = "representations" |
| 32 | + |
| 33 | +/** |
| 34 | + * Federated _entities field data fetcher. |
| 35 | + */ |
| 36 | +open class EntitiesDataFetcher( |
| 37 | + resolvers: List<FederatedTypeResolver> |
| 38 | +) : DataFetcher<CompletableFuture<DataFetcherResult<List<Any?>>>> { |
| 39 | + |
| 40 | + constructor(vararg resolvers: FederatedTypeResolver) : this(resolvers.toList()) |
| 41 | + /** |
| 42 | + * Pre-compute resolvers by typename so, we don't have to search on every request |
| 43 | + */ |
| 44 | + private val resolversByType: Map<String, FederatedTypeResolver> = resolvers.associateBy(FederatedTypeResolver::typeName) |
| 45 | + |
| 46 | + /** |
| 47 | + * Resolves entities based on the passed in representations argument. Entities are resolved in the same order |
| 48 | + * they are specified in the list of representations. If target representation cannot be resolved, NULL will |
| 49 | + * be returned instead. |
| 50 | + * |
| 51 | + * Representations are grouped by the underlying typename and each batch is resolved asynchronously before merging |
| 52 | + * the results back into a single list that preserves the original order. |
| 53 | + * |
| 54 | + * @return list of resolved nullable entities |
| 55 | + */ |
| 56 | + override fun get(env: DataFetchingEnvironment): CompletableFuture<DataFetcherResult<List<Any?>>> { |
| 57 | + val representations: List<Map<String, Any>> = env.getArgument(REPRESENTATIONS) |
| 58 | + |
| 59 | + val representationsWithoutResolver = mutableListOf<IndexedValue<Map<String, Any>>>() |
| 60 | + val entitiesWithPromiseResolver = mutableListOf<ResolvableEntity<FederatedTypePromiseResolver<*>>>() |
| 61 | + val entitiesWithSuspendResolver = mutableListOf<ResolvableEntity<FederatedTypeSuspendResolver<*>>>() |
| 62 | + |
| 63 | + representations.withIndex() |
| 64 | + .groupBy { (_, representation) -> representation[TYPENAME_FIELD].toString() } |
| 65 | + .forEach { (typeName, indexedRequests) -> |
| 66 | + when (val resolver = resolversByType[typeName]) { |
| 67 | + is FederatedTypePromiseResolver<*> -> { |
| 68 | + entitiesWithPromiseResolver += ResolvableEntity(typeName, indexedRequests, resolver) |
| 69 | + } |
| 70 | + is FederatedTypeSuspendResolver<*> -> { |
| 71 | + entitiesWithSuspendResolver += ResolvableEntity(typeName, indexedRequests, resolver) |
| 72 | + } |
| 73 | + null -> { |
| 74 | + representationsWithoutResolver += indexedRequests |
| 75 | + } |
| 76 | + } |
| 77 | + } |
| 78 | + |
| 79 | + val noResolverErrors: CompletableFuture<List<Map<Int, Any?>>> = CompletableFuture.completedFuture( |
| 80 | + listOf( |
| 81 | + representationsWithoutResolver.associateBy(IndexedValue<Map<String, Any>>::index) { (_, representation) -> |
| 82 | + InvalidFederatedRequest("Unable to resolve federated type, representation=$representation") |
| 83 | + } |
| 84 | + ) |
| 85 | + ) |
| 86 | + |
| 87 | + val promises: List<CompletableFuture<List<Map<Int, Any?>>>> = listOf( |
| 88 | + FederatedTypePromiseResolverExecutor.execute(entitiesWithPromiseResolver, env), |
| 89 | + FederatedTypeSuspendResolverExecutor.execute(entitiesWithSuspendResolver, env), |
| 90 | + noResolverErrors |
| 91 | + ) |
| 92 | + |
| 93 | + return promises |
| 94 | + .collectAll() |
| 95 | + .thenApply { results -> |
| 96 | + results.asSequence() |
| 97 | + .flatten() |
| 98 | + .map(Map<Int, Any?>::toList) |
| 99 | + .flatten() |
| 100 | + .sortedBy(Pair<Int, Any?>::first) |
| 101 | + .map(Pair<Int, Any?>::second) |
| 102 | + .toDataFetcherResult() |
| 103 | + } |
| 104 | + } |
| 105 | +} |
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