/*
 * Copyright 2023 gRPC authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

import { ClusterLoadAssignment } from "../src/generated/envoy/config/endpoint/v3/ClusterLoadAssignment";
import { Cluster } from "../src/generated/envoy/config/cluster/v3/Cluster";
import { Backend } from "./backend";
import { Locality } from "../src/generated/envoy/config/core/v3/Locality";
import { RouteConfiguration } from "../src/generated/envoy/config/route/v3/RouteConfiguration";
import { Route } from "../src/generated/envoy/config/route/v3/Route";
import { Listener } from "../src/generated/envoy/config/listener/v3/Listener";
import { HttpConnectionManager } from "../src/generated/envoy/extensions/filters/network/http_connection_manager/v3/HttpConnectionManager";
import { AnyExtension } from "@grpc/proto-loader";
import { CLUSTER_CONFIG_TYPE_URL, HTTP_CONNECTION_MANGER_TYPE_URL, UPSTREAM_TLS_CONTEXT_TYPE_URL } from "../src/resources";
import { LocalityLbEndpoints } from "../src/generated/envoy/config/endpoint/v3/LocalityLbEndpoints";
import { LbEndpoint } from "../src/generated/envoy/config/endpoint/v3/LbEndpoint";
import { ClusterConfig } from "../src/generated/envoy/extensions/clusters/aggregate/v3/ClusterConfig";
import { Any } from "../src/generated/google/protobuf/Any";
import { ControlPlaneServer } from "./xds-server";
import { UpstreamTlsContext } from "../src/generated/envoy/extensions/transport_sockets/tls/v3/UpstreamTlsContext";
import { HttpFilter } from "../src/generated/envoy/extensions/filters/network/http_connection_manager/v3/HttpFilter";

interface Endpoint {
  locality: Locality;
  backends: Backend[];
  weight?: number;
  priority?: number;
}

function getLbEndpoint(backend: Backend): LbEndpoint {
  return {
    health_status: "HEALTHY",
    endpoint: {
      address: {
        socket_address: {
          address: '::1',
          port_value: backend.getPort()
        }
      }
    }
  };
}

function getLocalityLbEndpoints(endpoint: Endpoint): LocalityLbEndpoints {
  return {
    lb_endpoints: endpoint.backends.map(getLbEndpoint),
    locality: endpoint.locality,
    load_balancing_weight: {value: endpoint.weight ?? 1},
    priority: endpoint.priority ?? 0
  }
}

export interface FakeCluster {
  getClusterConfig(): Cluster;
  getAllClusterConfigs(): Cluster[];
  getName(): string;
  startAllBackends(controlPlaneServer: ControlPlaneServer): Promise<any>;
  haveAllBackendsReceivedTraffic(): boolean;
  waitForAllBackendsToReceiveTraffic(): Promise<void>;
}

export class FakeEdsCluster implements FakeCluster {
  constructor(
    private clusterName: string,
    private endpointName: string,
    private endpoints: Endpoint[],
    private loadBalancingPolicyOverride?: Any | 'RING_HASH' | undefined,
    private upstreamTlsContext?: UpstreamTlsContext
  ) {}

  getEndpointConfig(): ClusterLoadAssignment {
    return {
      cluster_name: this.endpointName,
      endpoints: this.endpoints.map(getLocalityLbEndpoints)
    };
  }

  getClusterConfig(): Cluster {
    const result: Cluster = {
      name: this.clusterName,
      type: 'EDS',
      eds_cluster_config: {eds_config: {ads: {}}, service_name: this.endpointName},
      lrs_server: {self: {}},
      circuit_breakers: {
        thresholds: [
          {
            priority: 'DEFAULT',
            max_requests: {value: 1000}
          }
        ]
      }
    };
    if (this.loadBalancingPolicyOverride === 'RING_HASH') {
      result.lb_policy = 'RING_HASH';
    } else if (this.loadBalancingPolicyOverride) {
      result.load_balancing_policy = {
        policies: [
          {
            typed_extension_config: {
              'name': 'test',
              typed_config: this.loadBalancingPolicyOverride
            }
          }
        ]
      }
    } else {
      result.lb_policy = 'ROUND_ROBIN';
    }
    if (this.upstreamTlsContext) {
      result.transport_socket = {
        typed_config: {
          '@type': UPSTREAM_TLS_CONTEXT_TYPE_URL,
          ...this.upstreamTlsContext
        }
      }
    }
    return result;
  }

  getAllClusterConfigs(): Cluster[] {
    return [this.getClusterConfig()];
  }

  getName() {
    return this.clusterName;
  }

  startAllBackends(controlPlaneServer: ControlPlaneServer): Promise<any> {
    return Promise.all(this.endpoints.map(endpoint => Promise.all(endpoint.backends.map(backend => backend.startAsync(controlPlaneServer)))));
  }

  haveAllBackendsReceivedTraffic(): boolean {
    for (const endpoint of this.endpoints) {
      for (const backend of endpoint.backends) {
        if (backend.getCallCount() < 1) {
          return false;
        }
      }
    }
    return true;
  }

  waitForAllBackendsToReceiveTraffic(): Promise<void> {
    for (const endpoint of this.endpoints) {
      for (const backend of endpoint.backends) {
        backend.resetCallCount();
      }
    }
    return new Promise((resolve, reject) => {
      let finishedPromise = false;
      for (const endpoint of this.endpoints) {
        for (const backend of endpoint.backends) {
          backend.onCall(() => {
            if (finishedPromise) {
              return;
            }
            if (this.haveAllBackendsReceivedTraffic()) {
              finishedPromise = true;
              resolve();
            }
          });
        }
      }
    });
  }
}

export class FakeDnsCluster implements FakeCluster {
  constructor(private name: string, private backend: Backend) {}

  getClusterConfig(): Cluster {
    return {
      name: this.name,
      type: 'LOGICAL_DNS',
      lb_policy: 'ROUND_ROBIN',
      load_assignment: {
        endpoints: [{
          lb_endpoints: [{
            endpoint: {
              address: {
                socket_address: {
                  address: 'localhost',
                  port_value: this.backend.getPort()
                }
              }
            }
          }]
        }]
      },
      lrs_server: {self: {}}
    };
  }
  getAllClusterConfigs(): Cluster[] {
    return [this.getClusterConfig()];
  }
  getName(): string {
    return this.name;
  }
  startAllBackends(controlPlaneServer: ControlPlaneServer): Promise<any> {
    return this.backend.startAsync(controlPlaneServer);
  }
  haveAllBackendsReceivedTraffic(): boolean {
    return this.backend.getCallCount() > 0;
  }
  waitForAllBackendsToReceiveTraffic(): Promise<void> {
    return new Promise((resolve, reject) => {
      this.backend.onCall(resolve);
    });
  }
}

export class FakeAggregateCluster implements FakeCluster {
  constructor(private name: string, private children: FakeCluster[]) {}

  getClusterConfig(): Cluster {
    const clusterConfig: ClusterConfig & AnyExtension = {
      '@type': CLUSTER_CONFIG_TYPE_URL,
      clusters: this.children.map(child => child.getName())
    };
    return {
      name: this.name,
      lb_policy: 'ROUND_ROBIN',
      cluster_type: {
        typed_config: clusterConfig
      }
    }
  }
  getAllClusterConfigs(): Cluster[] {
    const allConfigs = [this.getClusterConfig()];
    for (const child of this.children) {
      allConfigs.push(...child.getAllClusterConfigs());
    }
    return allConfigs;
  }
  getName(): string {
    return this.name;
  }
  startAllBackends(controlPlaneServer: ControlPlaneServer): Promise<any> {
    return Promise.all(this.children.map(child => child.startAllBackends(controlPlaneServer)));
  }
  haveAllBackendsReceivedTraffic(): boolean {
    for (const child of this.children) {
      if (!child.haveAllBackendsReceivedTraffic()) {
        return false;
      }
    }
    return true;
  }
  waitForAllBackendsToReceiveTraffic(): Promise<void> {
    return Promise.all(this.children.map(child => child.waitForAllBackendsToReceiveTraffic())).then(() => {});
  }
}

interface FakeRoute {
  cluster?: FakeCluster;
  weightedClusters?: [{cluster: FakeCluster, weight: number}];
}

function createRouteConfig(route: FakeRoute): Route {
  if (route.cluster) {
    return {
      match: {
        prefix: ''
      },
      route: {
        cluster: route.cluster.getName(),
        // Default to consistent hash
        hash_policy: [{
          filter_state: {
            key: 'io.grpc.channel_id'
          }
        }]
      },
    };
  } else {
    return {
      match: {
        prefix: ''
      },
      route: {
        weighted_clusters: {
          clusters: route.weightedClusters!.map(clusterWeight => ({
            name: clusterWeight.cluster.getName(),
            weight: {value: clusterWeight.weight}
          }))
        },
        // Default to consistent hash
        hash_policy: [{
          filter_state: {
            key: 'io.grpc.channel_id'
          }
        }]
      }
    }
  }
}

export class FakeRouteGroup {
  constructor(private listenerName: string, private routeName: string, private routes: FakeRoute[]) {}

  getRouteConfiguration(): RouteConfiguration {
    return {
      name: this.routeName,
      virtual_hosts: [{
        domains: ['*'],
        routes: this.routes.map(createRouteConfig)
      }]
    };
  }

  getListener(): Listener {
    const httpConnectionManager: HttpConnectionManager & AnyExtension = {
      '@type': HTTP_CONNECTION_MANGER_TYPE_URL,
      rds: {
        route_config_name: this.routeName,
        config_source: {ads: {}}
      }
    }
    return {
      name: this.listenerName,
      api_listener: {
        api_listener: httpConnectionManager
      }
    };
  }

  startAllBackends(controlPlaneServer: ControlPlaneServer): Promise<any> {
    return Promise.all(this.routes.map(route => {
      if (route.cluster) {
        return route.cluster.startAllBackends(controlPlaneServer);
      } else if (route.weightedClusters) {
        return Promise.all(route.weightedClusters.map(clusterWeight => clusterWeight.cluster.startAllBackends(controlPlaneServer)));
      } else {
        return Promise.resolve();
      }
    }));
  }

  haveAllBackendsReceivedTraffic(): boolean {
    for (const route of this.routes) {
      if (route.cluster) {
        return route.cluster.haveAllBackendsReceivedTraffic();
      } else if (route.weightedClusters) {
        for (const weightedCluster of route.weightedClusters) {
          if (!weightedCluster.cluster.haveAllBackendsReceivedTraffic()) {
            return false;
          }
        }
      }
    }
    return true;
  }

  waitForAllBackendsToReceiveTraffic(): Promise<any> {
    return Promise.all(this.routes.map(route => {
      if (route.cluster) {
        return route.cluster.waitForAllBackendsToReceiveTraffic();
      } else if (route.weightedClusters) {
        return Promise.all(route.weightedClusters.map(clusterWeight => clusterWeight.cluster.waitForAllBackendsToReceiveTraffic())).then(() => {});
      } else {
        return Promise.resolve();
      }
    }));
  }
}

const DEFAULT_BASE_SERVER_LISTENER: Listener = {
  default_filter_chain: {
    filter_chain_match: {
      source_type: 'SAME_IP_OR_LOOPBACK'
    }
  }
};

const DEFAULT_BASE_SERVER_ROUTE_CONFIG: RouteConfiguration = {
  virtual_hosts: [{
    domains: ['*'],
    routes: [{
      match: {
        prefix: ''
      },
      action: 'non_forwarding_action',
      non_forwarding_action: {}
    }]
  }]
};

export class FakeServerRoute {
  private listener: Listener;
  private routeConfiguration: RouteConfiguration;
  constructor(port: number, routeName: string, baseListener?: Listener | undefined, baseRouteConfiguration?: RouteConfiguration | undefined, httpFilters?: HttpFilter[]) {
    this.listener = baseListener ?? {...DEFAULT_BASE_SERVER_LISTENER};
    this.listener.name = `[::1]:${port}`;
    this.listener.address = {
      socket_address: {
        address: '::1',
        port_value: port
      }
    }
    const httpConnectionManager: HttpConnectionManager & AnyExtension = {
      '@type': HTTP_CONNECTION_MANGER_TYPE_URL,
      rds: {
        route_config_name: routeName,
        config_source: {ads: {}}
      },
      http_filters: httpFilters ?? []
    };
    const filterList = [{
      typed_config: httpConnectionManager
    }];
    if (this.listener.default_filter_chain) {
      this.listener.default_filter_chain.filters = filterList;
    }
    for (const filterChain of this.listener.filter_chains ?? []) {
      filterChain.filters = filterList;
    }

    this.routeConfiguration = baseRouteConfiguration ?? {...DEFAULT_BASE_SERVER_ROUTE_CONFIG};
    this.routeConfiguration.name = routeName;
  }

  getRouteConfiguration(): RouteConfiguration {
    return this.routeConfiguration;
  }

  getListener(): Listener {
    return this.listener;
  }
}