#include "common.hh"

#include <unordered_map>

#include "fake_monitor.hh"
#include "looper.hh"
#include "observers.hh"

namespace {

class FakeMonitorImpl : public Monitor {
public:
  explicit FakeMonitorImpl(std::shared_ptr<Looper> const& looper)
    : looper_(looper), timer_(0), host_id_(0), job_id_(0), max_jobs_(0) {
  }

  ~FakeMonitorImpl() override {
    disconnect();
  }

  void connect(std::string const&, std::string const&,
               uint16_t) override {
    disconnect();

    timer_ = looper_->schedule(
        (rand() % 500) / 1000.0,
        std::bind(&FakeMonitorImpl::fake_connect, this,
                  std::placeholders::_1,
                  std::placeholders::_2));
  }

  void disconnect() override {
    if (timer_) {
      looper_->cancel(timer_);
      timer_ = 0;
    }
    machines_.clear();
    auto observer = observers_.first();
    while (observer) {
      observer->state(this, SEARCHING);
      observer = observers_.next();
    }
  }

  size_t machines() const override {
    return machines_.size();
  }

  uint32_t id(size_t index) const override {
    auto it = machines_.begin();
    while (index--) ++it;
    if (it == machines_.end()) {
      assert(false);
      return static_cast<uint32_t>(-1);
    }
    return it->first;
  }

  Machine machine_at(size_t index) const override {
    auto it = machines_.begin();
    while (index--) ++it;
    if (it == machines_.end()) {
      assert(false);
      return Machine();
    }
    return it->second.data;
  }

  Machine machine(uint32_t id) const override {
    auto it = machines_.find(id);
    if (it == machines_.end()) {
      assert(false);
      return Machine();
    }
    return it->second.data;
  }

  void add_observer(Observer* observer) override {
    observers_.add(observer);
  }

  void remove_observer(Observer* observer) override {
    observers_.remove(observer);
  }

private:
  struct Job {
    uint32_t const host;
    uint32_t const worker;

    Job(uint32_t host, uint32_t worker)
      : host(host), worker(worker) {
    }
  };
  struct Entry {
    Machine data;
    unsigned active;
  };

  void fake_connect(Looper*, uint32_t) {
    timer_ = 0;

    auto observer = observers_.first();
    while (observer) {
      observer->state(this, CONNECTED);
      observer = observers_.next();
    }

    add_machine("alice", 4);
    add_machine("bob", 10);
    add_machine("DeuX", 22);
    add_machine("machine1", 4);
    add_machine("machine2", 4);
    add_machine("machine3", 4);
    add_machine("machine4", 4);
    add_machine("machine5", 4);
    add_machine("machine6", 4);
    add_machine("machine7", 4);
    add_machine("machine8", 4);

    schedule_jobs();
  }

  void add_machine(std::string const& name, unsigned max_jobs) {
    auto id = ++host_id_;
    auto& entry = machines_[id];
    entry.data.name = name;
    entry.data.max_jobs = max_jobs;
    entry.active = 0;
    max_jobs_ += max_jobs;

    auto observer = observers_.first();
    while (observer) {
      observer->added_machine(this, id);
      observer = observers_.next();
    }
  }

  void schedule_jobs() {
    assert(timer_ == 0);
    timer_ = looper_->schedule(
        (rand() % 2000) / 1000.0,
        std::bind(&FakeMonitorImpl::fiddle_jobs, this,
                  std::placeholders::_1,
                  std::placeholders::_2));
  }

  void fiddle_jobs(Looper*, uint32_t) {
    timer_ = 0;

    auto remove = !jobs_.empty() ? rand() % jobs_.size() : 0;
    while (remove--) {
      auto it = jobs_.begin();
      auto job = it->second;
      jobs_.erase(it);
      machines_[job.worker].active--;
      auto observer = observers_.first();
      while (observer) {
        observer->removed_job(this, job.host, job.worker);
        observer = observers_.next();
      }
    }

    auto avail = (max_jobs_ * 7) / 8 - jobs_.size();
    auto add = avail ? rand() % avail : 0;
    while (add--) {
      auto id = ++job_id_;
      while (jobs_.count(id)) {
        id = ++job_id_;
      }
      auto host = rand() % machines_.size();
      auto target = rand() % machines_.size();
      do {
        auto tgtid = this->id(target);
        auto& entry = machines_[tgtid];
        if (entry.active < entry.data.max_jobs) {
          entry.active++;
          add_job(id, host != target ? this->id(host) : tgtid, tgtid);
          break;
        }
        target = rand() % machines_.size();
      } while (true);
    }

    schedule_jobs();
  }

  void add_job(uint32_t job_id, uint32_t host, uint32_t worker) {
    jobs_.insert(std::make_pair(job_id, Job(host, worker)));
    auto observer = observers_.first();
    while (observer) {
      observer->added_job(this, host, worker);
      observer = observers_.next();
    }
  }

  std::shared_ptr<Looper> looper_;
  uint32_t timer_;
  uint32_t host_id_;
  uint32_t job_id_;
  size_t max_jobs_;
  std::unordered_map<uint32_t, Entry> machines_;
  Observers<Observer> observers_;
  std::unordered_map<uint32_t, Job> jobs_;
};

}  // namespace

// static
std::unique_ptr<Monitor> FakeMonitor::create(
    std::shared_ptr<Looper> const& looper) {
  return std::make_unique<FakeMonitorImpl>(looper);
}