/*
 *
 * Copyright 2015 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/grpc.h>
#include <grpc/support/alloc.h>

#include "src/core/ext/filters/client_channel/lb_policy_factory.h"
#include "src/core/ext/filters/client_channel/resolver.h"
#include "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.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/iomgr/resolve_address.h"
#include "src/core/lib/iomgr/timer.h"
#include "test/core/util/test_config.h"

static gpr_mu g_mu;
static bool g_fail_resolution = true;
static grpc_combiner* g_combiner;

static void my_resolve_address(grpc_exec_ctx* exec_ctx, const char* addr,
                               const char* default_port,
                               grpc_pollset_set* interested_parties,
                               grpc_closure* on_done,
                               grpc_resolved_addresses** addrs) {
  gpr_mu_lock(&g_mu);
  GPR_ASSERT(0 == strcmp("test", addr));
  grpc_error* error = GRPC_ERROR_NONE;
  if (g_fail_resolution) {
    g_fail_resolution = false;
    gpr_mu_unlock(&g_mu);
    error = GRPC_ERROR_CREATE_FROM_STATIC_STRING("Forced Failure");
  } else {
    gpr_mu_unlock(&g_mu);
    *addrs = static_cast<grpc_resolved_addresses*>(gpr_malloc(sizeof(**addrs)));
    (*addrs)->naddrs = 1;
    (*addrs)->addrs = static_cast<grpc_resolved_address*>(
        gpr_malloc(sizeof(*(*addrs)->addrs)));
    (*addrs)->addrs[0].len = 123;
  }
  GRPC_CLOSURE_SCHED(exec_ctx, on_done, error);
}

static grpc_ares_request* my_dns_lookup_ares(
    grpc_exec_ctx* exec_ctx, const char* dns_server, const char* addr,
    const char* default_port, grpc_pollset_set* interested_parties,
    grpc_closure* on_done, grpc_lb_addresses** lb_addrs, bool check_grpclb,
    char** service_config_json) {
  gpr_mu_lock(&g_mu);
  GPR_ASSERT(0 == strcmp("test", addr));
  grpc_error* error = GRPC_ERROR_NONE;
  if (g_fail_resolution) {
    g_fail_resolution = false;
    gpr_mu_unlock(&g_mu);
    error = GRPC_ERROR_CREATE_FROM_STATIC_STRING("Forced Failure");
  } else {
    gpr_mu_unlock(&g_mu);
    *lb_addrs = grpc_lb_addresses_create(1, NULL);
    grpc_lb_addresses_set_address(*lb_addrs, 0, NULL, 0, false, NULL, NULL);
  }
  GRPC_CLOSURE_SCHED(exec_ctx, on_done, error);
  return NULL;
}

static grpc_resolver* create_resolver(grpc_exec_ctx* exec_ctx,
                                      const char* name) {
  grpc_resolver_factory* factory = grpc_resolver_factory_lookup("dns");
  grpc_uri* uri = grpc_uri_parse(exec_ctx, name, 0);
  GPR_ASSERT(uri);
  grpc_resolver_args args;
  memset(&args, 0, sizeof(args));
  args.uri = uri;
  args.combiner = g_combiner;
  grpc_resolver* resolver =
      grpc_resolver_factory_create_resolver(exec_ctx, factory, &args);
  grpc_resolver_factory_unref(factory);
  grpc_uri_destroy(uri);
  return resolver;
}

static void on_done(grpc_exec_ctx* exec_ctx, void* ev, grpc_error* error) {
  gpr_event_set((gpr_event*)ev, (void*)1);
}

// interleave waiting for an event with a timer check
static bool wait_loop(int deadline_seconds, gpr_event* ev) {
  while (deadline_seconds) {
    gpr_log(GPR_DEBUG, "Test: waiting for %d more seconds", deadline_seconds);
    if (gpr_event_wait(ev, grpc_timeout_seconds_to_deadline(1))) return true;
    deadline_seconds--;

    grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
    grpc_timer_check(&exec_ctx, NULL);
    grpc_exec_ctx_finish(&exec_ctx);
  }
  return false;
}

typedef struct next_args {
  grpc_resolver* resolver;
  grpc_channel_args** result;
  grpc_closure* on_complete;
} next_args;

static void call_resolver_next_now_lock_taken(grpc_exec_ctx* exec_ctx,
                                              void* arg,
                                              grpc_error* error_unused) {
  next_args* a = static_cast<next_args*>(arg);
  grpc_resolver_next_locked(exec_ctx, a->resolver, a->result, a->on_complete);
  gpr_free(a);
}

static void call_resolver_next_after_locking(grpc_exec_ctx* exec_ctx,
                                             grpc_resolver* resolver,
                                             grpc_channel_args** result,
                                             grpc_closure* on_complete) {
  next_args* a = static_cast<next_args*>(gpr_malloc(sizeof(*a)));
  a->resolver = resolver;
  a->result = result;
  a->on_complete = on_complete;
  GRPC_CLOSURE_SCHED(
      exec_ctx,
      GRPC_CLOSURE_CREATE(call_resolver_next_now_lock_taken, a,
                          grpc_combiner_scheduler(resolver->combiner)),
      GRPC_ERROR_NONE);
}

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

  grpc_init();
  gpr_mu_init(&g_mu);
  g_combiner = grpc_combiner_create();
  grpc_resolve_address = my_resolve_address;
  grpc_dns_lookup_ares = my_dns_lookup_ares;
  grpc_channel_args* result = (grpc_channel_args*)1;

  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
  grpc_resolver* resolver = create_resolver(&exec_ctx, "dns:test");
  gpr_event ev1;
  gpr_event_init(&ev1);
  call_resolver_next_after_locking(
      &exec_ctx, resolver, &result,
      GRPC_CLOSURE_CREATE(on_done, &ev1, grpc_schedule_on_exec_ctx));
  grpc_exec_ctx_flush(&exec_ctx);
  GPR_ASSERT(wait_loop(5, &ev1));
  GPR_ASSERT(result == NULL);

  gpr_event ev2;
  gpr_event_init(&ev2);
  call_resolver_next_after_locking(
      &exec_ctx, resolver, &result,
      GRPC_CLOSURE_CREATE(on_done, &ev2, grpc_schedule_on_exec_ctx));
  grpc_exec_ctx_flush(&exec_ctx);
  GPR_ASSERT(wait_loop(30, &ev2));
  GPR_ASSERT(result != NULL);

  grpc_channel_args_destroy(&exec_ctx, result);
  GRPC_RESOLVER_UNREF(&exec_ctx, resolver, "test");
  GRPC_COMBINER_UNREF(&exec_ctx, g_combiner, "test");
  grpc_exec_ctx_finish(&exec_ctx);

  grpc_shutdown();
  gpr_mu_destroy(&g_mu);
}