/*
 *
 * Copyright 2021 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 <chrono>
#include <condition_variable>
#include <iostream>
#include <memory>
#include <mutex>
#include <random>
#include <string>
#include <thread>

#include <grpc/grpc.h>
#include <grpcpp/alarm.h>
#include <grpcpp/channel.h>
#include <grpcpp/client_context.h>
#include <grpcpp/create_channel.h>
#include <grpcpp/security/credentials.h>
#include "helper.h"
#ifdef BAZEL_BUILD
#include "examples/protos/route_guide.grpc.pb.h"
#else
#include "route_guide.grpc.pb.h"
#endif

using grpc::Channel;
using grpc::ClientContext;
using grpc::Status;
using routeguide::Feature;
using routeguide::Point;
using routeguide::Rectangle;
using routeguide::RouteGuide;
using routeguide::RouteNote;
using routeguide::RouteSummary;

Point MakePoint(long latitude, long longitude) {
  Point p;
  p.set_latitude(latitude);
  p.set_longitude(longitude);
  return p;
}

Feature MakeFeature(const std::string& name, long latitude, long longitude) {
  Feature f;
  f.set_name(name);
  f.mutable_location()->CopyFrom(MakePoint(latitude, longitude));
  return f;
}

RouteNote MakeRouteNote(const std::string& message, long latitude,
                        long longitude) {
  RouteNote n;
  n.set_message(message);
  n.mutable_location()->CopyFrom(MakePoint(latitude, longitude));
  return n;
}

class RouteGuideClient {
 public:
  RouteGuideClient(std::shared_ptr<Channel> channel, const std::string& db)
      : stub_(RouteGuide::NewStub(channel)) {
    routeguide::ParseDb(db, &feature_list_);
  }

  void GetFeature() {
    Point point;
    Feature feature;
    point = MakePoint(409146138, -746188906);
    GetOneFeature(point, &feature);
    point = MakePoint(0, 0);
    GetOneFeature(point, &feature);
  }

  void ListFeatures() {
    routeguide::Rectangle rect;
    Feature feature;

    rect.mutable_lo()->set_latitude(400000000);
    rect.mutable_lo()->set_longitude(-750000000);
    rect.mutable_hi()->set_latitude(420000000);
    rect.mutable_hi()->set_longitude(-730000000);
    std::cout << "Looking for features between 40, -75 and 42, -73"
              << std::endl;

    class Reader : public grpc::ClientReadReactor<Feature> {
     public:
      Reader(RouteGuide::Stub* stub, float coord_factor,
             const routeguide::Rectangle& rect)
          : coord_factor_(coord_factor) {
        stub->async()->ListFeatures(&context_, &rect, this);
        StartRead(&feature_);
        StartCall();
      }
      void OnReadDone(bool ok) override {
        if (ok) {
          std::cout << "Found feature called " << feature_.name() << " at "
                    << feature_.location().latitude() / coord_factor_ << ", "
                    << feature_.location().longitude() / coord_factor_
                    << std::endl;
          StartRead(&feature_);
        }
      }
      void OnDone(const Status& s) override {
        std::unique_lock<std::mutex> l(mu_);
        status_ = s;
        done_ = true;
        cv_.notify_one();
      }
      Status Await() {
        std::unique_lock<std::mutex> l(mu_);
        cv_.wait(l, [this] { return done_; });
        return std::move(status_);
      }

     private:
      ClientContext context_;
      float coord_factor_;
      Feature feature_;
      std::mutex mu_;
      std::condition_variable cv_;
      Status status_;
      bool done_ = false;
    };
    Reader reader(stub_.get(), kCoordFactor_, rect);
    Status status = std::move(reader.Await());
    if (status.ok()) {
      std::cout << "ListFeatures rpc succeeded." << std::endl;
    } else {
      std::cout << "ListFeatures rpc failed." << std::endl;
    }
  }

  void RecordRoute() {
    class Recorder : public grpc::ClientWriteReactor<Point> {
     public:
      Recorder(RouteGuide::Stub* stub, float coord_factor,
               const std::vector<Feature>* feature_list)
          : coord_factor_(coord_factor),
            feature_list_(feature_list),
            generator_(
                std::chrono::system_clock::now().time_since_epoch().count()),
            feature_distribution_(0, feature_list->size() - 1),
            delay_distribution_(500, 1500) {
        stub->async()->RecordRoute(&context_, &stats_, this);
        // Use a hold since some StartWrites are invoked indirectly from a
        // delayed lambda in OnWriteDone rather than directly from the reaction
        // itself
        AddHold();
        NextWrite();
        StartCall();
      }
      void OnWriteDone(bool ok) override {
        // Delay and then do the next write or WritesDone
        alarm_.Set(
            std::chrono::system_clock::now() +
                std::chrono::milliseconds(delay_distribution_(generator_)),
            [this](bool /*ok*/) { NextWrite(); });
      }
      void OnDone(const Status& s) override {
        std::unique_lock<std::mutex> l(mu_);
        status_ = s;
        done_ = true;
        cv_.notify_one();
      }
      Status Await(RouteSummary* stats) {
        std::unique_lock<std::mutex> l(mu_);
        cv_.wait(l, [this] { return done_; });
        *stats = stats_;
        return std::move(status_);
      }

     private:
      void NextWrite() {
        if (points_remaining_ != 0) {
          const Feature& f =
              (*feature_list_)[feature_distribution_(generator_)];
          std::cout << "Visiting point "
                    << f.location().latitude() / coord_factor_ << ", "
                    << f.location().longitude() / coord_factor_ << std::endl;
          StartWrite(&f.location());
          points_remaining_--;
        } else {
          StartWritesDone();
          RemoveHold();
        }
      }
      ClientContext context_;
      float coord_factor_;
      int points_remaining_ = 10;
      Point point_;
      RouteSummary stats_;
      const std::vector<Feature>* feature_list_;
      std::default_random_engine generator_;
      std::uniform_int_distribution<int> feature_distribution_;
      std::uniform_int_distribution<int> delay_distribution_;
      grpc::Alarm alarm_;
      std::mutex mu_;
      std::condition_variable cv_;
      Status status_;
      bool done_ = false;
    };
    Recorder recorder(stub_.get(), kCoordFactor_, &feature_list_);
    RouteSummary stats;
    Status status = std::move(recorder.Await(&stats));
    if (status.ok()) {
      std::cout << "Finished trip with " << stats.point_count() << " points\n"
                << "Passed " << stats.feature_count() << " features\n"
                << "Travelled " << stats.distance() << " meters\n"
                << "It took " << stats.elapsed_time() << " seconds"
                << std::endl;
    } else {
      std::cout << "RecordRoute rpc failed." << std::endl;
    }
  }

  void RouteChat() {
    class Chatter : public grpc::ClientBidiReactor<RouteNote, RouteNote> {
     public:
      explicit Chatter(RouteGuide::Stub* stub)
          : notes_{MakeRouteNote("First message", 0, 0),
                   MakeRouteNote("Second message", 0, 1),
                   MakeRouteNote("Third message", 1, 0),
                   MakeRouteNote("Fourth message", 0, 0)},
            notes_iterator_(notes_.begin()) {
        stub->async()->RouteChat(&context_, this);
        NextWrite();
        StartRead(&server_note_);
        StartCall();
      }
      void OnWriteDone(bool /*ok*/) override { NextWrite(); }
      void OnReadDone(bool ok) override {
        if (ok) {
          std::cout << "Got message " << server_note_.message() << " at "
                    << server_note_.location().latitude() << ", "
                    << server_note_.location().longitude() << std::endl;
          StartRead(&server_note_);
        }
      }
      void OnDone(const Status& s) override {
        std::unique_lock<std::mutex> l(mu_);
        status_ = s;
        done_ = true;
        cv_.notify_one();
      }
      Status Await() {
        std::unique_lock<std::mutex> l(mu_);
        cv_.wait(l, [this] { return done_; });
        return std::move(status_);
      }

     private:
      void NextWrite() {
        if (notes_iterator_ != notes_.end()) {
          const auto& note = *notes_iterator_;
          std::cout << "Sending message " << note.message() << " at "
                    << note.location().latitude() << ", "
                    << note.location().longitude() << std::endl;
          StartWrite(&note);
          notes_iterator_++;
        } else {
          StartWritesDone();
        }
      }
      ClientContext context_;
      const std::vector<RouteNote> notes_;
      std::vector<RouteNote>::const_iterator notes_iterator_;
      RouteNote server_note_;
      std::mutex mu_;
      std::condition_variable cv_;
      Status status_;
      bool done_ = false;
    };

    Chatter chatter(stub_.get());
    Status status = std::move(chatter.Await());
    if (!status.ok()) {
      std::cout << "RouteChat rpc failed." << std::endl;
    }
  }

 private:
  bool GetOneFeature(const Point& point, Feature* feature) {
    ClientContext context;
    bool result;
    std::mutex mu;
    std::condition_variable cv;
    bool done = false;
    stub_->async()->GetFeature(
        &context, &point, feature,
        [&result, &mu, &cv, &done, feature, this](Status status) {
          bool ret;
          if (!status.ok()) {
            std::cout << "GetFeature rpc failed." << std::endl;
            ret = false;
          } else if (!feature->has_location()) {
            std::cout << "Server returns incomplete feature." << std::endl;
            ret = false;
          } else if (feature->name().empty()) {
            std::cout << "Found no feature at "
                      << feature->location().latitude() / kCoordFactor_ << ", "
                      << feature->location().longitude() / kCoordFactor_
                      << std::endl;
            ret = true;
          } else {
            std::cout << "Found feature called " << feature->name() << " at "
                      << feature->location().latitude() / kCoordFactor_ << ", "
                      << feature->location().longitude() / kCoordFactor_
                      << std::endl;
            ret = true;
          }
          std::lock_guard<std::mutex> lock(mu);
          result = ret;
          done = true;
          cv.notify_one();
        });
    std::unique_lock<std::mutex> lock(mu);
    cv.wait(lock, [&done] { return done; });
    return result;
  }

  const float kCoordFactor_ = 10000000.0;
  std::unique_ptr<RouteGuide::Stub> stub_;
  std::vector<Feature> feature_list_;
};

int main(int argc, char** argv) {
  // Expect only arg: --db_path=path/to/route_guide_db.json.
  std::string db = routeguide::GetDbFileContent(argc, argv);
  RouteGuideClient guide(
      grpc::CreateChannel("localhost:50051",
                          grpc::InsecureChannelCredentials()),
      db);

  std::cout << "-------------- GetFeature --------------" << std::endl;
  guide.GetFeature();
  std::cout << "-------------- ListFeatures --------------" << std::endl;
  guide.ListFeatures();
  std::cout << "-------------- RecordRoute --------------" << std::endl;
  guide.RecordRoute();
  std::cout << "-------------- RouteChat --------------" << std::endl;
  guide.RouteChat();

  return 0;
}