/*
 *
 * Copyright 2017 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.
 *
 */

#include <string.h>

#include <grpc/support/alloc.h>
#include <grpc/support/log.h>
#include <grpc/support/string_util.h>

#include "src/core/ext/filters/client_channel/lb_policy_factory.h"
#include "src/core/ext/filters/client_channel/parse_address.h"
#include "src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h"
#include "src/core/ext/filters/client_channel/resolver_registry.h"
#include "src/core/lib/channel/channel_args.h"
#include "src/core/lib/iomgr/combiner.h"
#include "src/core/lib/security/credentials/fake/fake_credentials.h"

#include "test/core/util/test_config.h"

static grpc_resolver* build_fake_resolver(
    grpc_combiner* combiner,
    grpc_fake_resolver_response_generator* response_generator) {
  grpc_resolver_factory* factory = grpc_resolver_factory_lookup("fake");
  grpc_arg generator_arg =
      grpc_fake_resolver_response_generator_arg(response_generator);
  grpc_resolver_args args;
  memset(&args, 0, sizeof(args));
  grpc_channel_args channel_args = {1, &generator_arg};
  args.args = &channel_args;
  args.combiner = combiner;
  grpc_resolver* resolver =
      grpc_resolver_factory_create_resolver(factory, &args);
  grpc_resolver_factory_unref(factory);
  return resolver;
}

typedef struct on_resolution_arg {
  grpc_channel_args* resolver_result;
  grpc_channel_args* expected_resolver_result;
  gpr_event ev;
} on_resolution_arg;

void on_resolution_cb(void* arg, grpc_error* error) {
  on_resolution_arg* res = static_cast<on_resolution_arg*>(arg);
  // We only check the addresses channel arg because that's the only one
  // explicitly set by the test via
  // grpc_fake_resolver_response_generator_set_response.
  const grpc_lb_addresses* actual_lb_addresses =
      grpc_lb_addresses_find_channel_arg(res->resolver_result);
  const grpc_lb_addresses* expected_lb_addresses =
      grpc_lb_addresses_find_channel_arg(res->expected_resolver_result);
  GPR_ASSERT(
      grpc_lb_addresses_cmp(actual_lb_addresses, expected_lb_addresses) == 0);
  grpc_channel_args_destroy(res->resolver_result);
  grpc_channel_args_destroy(res->expected_resolver_result);
  gpr_event_set(&res->ev, (void*)1);
}

static void test_fake_resolver() {
  grpc_core::ExecCtx exec_ctx;
  grpc_combiner* combiner = grpc_combiner_create();
  // Create resolver.
  grpc_fake_resolver_response_generator* response_generator =
      grpc_fake_resolver_response_generator_create();
  grpc_resolver* resolver = build_fake_resolver(combiner, response_generator);
  GPR_ASSERT(resolver != nullptr);

  // Setup expectations.
  grpc_uri* uris[] = {grpc_uri_parse("ipv4:10.2.1.1:1234", true),
                      grpc_uri_parse("ipv4:127.0.0.1:4321", true)};
  const char* balancer_names[] = {"name1", "name2"};
  const bool is_balancer[] = {true, false};
  grpc_lb_addresses* addresses = grpc_lb_addresses_create(3, nullptr);
  for (size_t i = 0; i < GPR_ARRAY_SIZE(uris); ++i) {
    grpc_lb_addresses_set_address_from_uri(
        addresses, i, uris[i], is_balancer[i], balancer_names[i], nullptr);
    grpc_uri_destroy(uris[i]);
  }
  const grpc_arg addresses_arg =
      grpc_lb_addresses_create_channel_arg(addresses);
  grpc_channel_args* results =
      grpc_channel_args_copy_and_add(nullptr, &addresses_arg, 1);
  grpc_lb_addresses_destroy(addresses);
  on_resolution_arg on_res_arg;
  memset(&on_res_arg, 0, sizeof(on_res_arg));
  on_res_arg.expected_resolver_result = results;
  gpr_event_init(&on_res_arg.ev);
  grpc_closure* on_resolution = GRPC_CLOSURE_CREATE(
      on_resolution_cb, &on_res_arg, grpc_combiner_scheduler(combiner));

  // Set resolver results and trigger first resolution. on_resolution_cb
  // performs the checks.
  grpc_fake_resolver_response_generator_set_response(response_generator,
                                                     results);
  grpc_resolver_next_locked(resolver, &on_res_arg.resolver_result,
                            on_resolution);
  grpc_core::ExecCtx::Get()->Flush();
  GPR_ASSERT(gpr_event_wait(&on_res_arg.ev,
                            grpc_timeout_seconds_to_deadline(5)) != nullptr);

  // Setup update.
  grpc_uri* uris_update[] = {grpc_uri_parse("ipv4:192.168.1.0:31416", true)};
  const char* balancer_names_update[] = {"name3"};
  const bool is_balancer_update[] = {false};
  grpc_lb_addresses* addresses_update = grpc_lb_addresses_create(1, nullptr);
  for (size_t i = 0; i < GPR_ARRAY_SIZE(uris_update); ++i) {
    grpc_lb_addresses_set_address_from_uri(addresses_update, i, uris_update[i],
                                           is_balancer_update[i],
                                           balancer_names_update[i], nullptr);
    grpc_uri_destroy(uris_update[i]);
  }

  grpc_arg addresses_update_arg =
      grpc_lb_addresses_create_channel_arg(addresses_update);
  grpc_channel_args* results_update =
      grpc_channel_args_copy_and_add(nullptr, &addresses_update_arg, 1);
  grpc_lb_addresses_destroy(addresses_update);

  // Setup expectations for the update.
  on_resolution_arg on_res_arg_update;
  memset(&on_res_arg_update, 0, sizeof(on_res_arg_update));
  on_res_arg_update.expected_resolver_result = results_update;
  gpr_event_init(&on_res_arg_update.ev);
  on_resolution = GRPC_CLOSURE_CREATE(on_resolution_cb, &on_res_arg_update,
                                      grpc_combiner_scheduler(combiner));

  // Set updated resolver results and trigger a second resolution.
  grpc_fake_resolver_response_generator_set_response(response_generator,
                                                     results_update);
  grpc_resolver_next_locked(resolver, &on_res_arg_update.resolver_result,
                            on_resolution);
  grpc_core::ExecCtx::Get()->Flush();
  GPR_ASSERT(gpr_event_wait(&on_res_arg_update.ev,
                            grpc_timeout_seconds_to_deadline(5)) != nullptr);

  // Requesting a new resolution without re-senting the response shouldn't
  // trigger the resolution callback.
  memset(&on_res_arg, 0, sizeof(on_res_arg));
  grpc_resolver_next_locked(resolver, &on_res_arg.resolver_result,
                            on_resolution);
  grpc_core::ExecCtx::Get()->Flush();
  GPR_ASSERT(gpr_event_wait(&on_res_arg.ev,
                            grpc_timeout_milliseconds_to_deadline(100)) ==
             nullptr);

  GRPC_COMBINER_UNREF(combiner, "test_fake_resolver");
  GRPC_RESOLVER_UNREF(resolver, "test_fake_resolver");

  grpc_fake_resolver_response_generator_unref(response_generator);
}

int main(int argc, char** argv) {
  grpc_test_init(argc, argv);
  grpc_init();

  test_fake_resolver();

  grpc_shutdown();
  return 0;
}