#ifndef AOS_COMMON_LOGGING_REPLAY_H_
#define AOS_COMMON_LOGGING_REPLAY_H_

#include <unordered_map>
#include <string>
#include <functional>
#include <memory>

#include "aos/common/logging/binary_log_file.h"
#include "aos/common/queue.h"
#include "aos/common/logging/logging.h"
#include "aos/common/macros.h"
#include "aos/linux_code/ipc_lib/queue.h"
#include "aos/common/queue_types.h"

namespace aos {
namespace logging {
namespace linux_code {

// Manages pulling logged queue messages out of log files.
//
// Basic usage:
//   - Use the Add* methods to register handlers for various message sources.
//   - Call OpenFile to open a log file.
//   - Call ProcessMessage repeatedly until it returns true.
//
// This code could do something to adapt similar-but-not-identical
// messages to the current versions, but currently it will LOG(FATAL) if any of
// the messages don't match up exactly.
class LogReplayer {
 public:
  LogReplayer() {}

  // Gets ready to read messages from fd.
  // Does not take ownership of fd.
  void OpenFile(int fd) {
    reader_.reset(new LogFileReader(fd));
  }
  // Closes the currently open file.
  void CloseCurrentFile() { reader_.reset(); }
  // Returns true if we have a file which is currently open.
  bool HasCurrentFile() const { return reader_.get() != nullptr; }

  // Processes a single message from the currently open file.
  // Returns true if there are no more messages in the file.
  // This will not call any of the handlers if the next message either has no
  // registered handlers or is not a queue message.
  bool ProcessMessage();

  // Adds a handler for messages with a certain string from a certain process.
  // T must be a Message with the same format as the messages generated by
  // the .q files.
  // LOG(FATAL)s for duplicate handlers.
  template <class T>
  void AddHandler(const ::std::string &process_name,
                  const ::std::string &log_message,
                  ::std::function<void(const T &message)> handler) {
    CHECK(handlers_.emplace(
        ::std::piecewise_construct,
        ::std::forward_as_tuple(process_name, log_message),
        ::std::forward_as_tuple(::std::unique_ptr<StructHandlerInterface>(
            new TypedStructHandler<T>(handler)))).second);
  }

  // Adds a handler which takes messages and places them directly on a queue.
  // T must be a Message with the same format as the messages generated by
  // the .q files.
  template <class T>
  void AddDirectQueueSender(const ::std::string &process_name,
                            const ::std::string &log_message,
                            const ::aos::Queue<T> &queue) {
    AddHandler(process_name, log_message,
               ::std::function<void(const T &)>(
                   QueueDumpStructHandler<T>(queue.name())));
  }

 private:
  // A generic handler of struct log messages.
  class StructHandlerInterface {
   public:
    virtual ~StructHandlerInterface() {}

    virtual void HandleStruct(::aos::monotonic_clock::time_point log_time,
                              uint32_t type_id, const void *data,
                              size_t data_size) = 0;
  };

  // Converts struct log messages to a message type and passes it to an
  // ::std::function.
  template <class T>
  class TypedStructHandler : public StructHandlerInterface {
   public:
    TypedStructHandler(::std::function<void(const T &message)> handler)
        : handler_(handler) {}

    void HandleStruct(::aos::monotonic_clock::time_point log_time,
                      uint32_t type_id, const void *data,
                      size_t data_size) override {
      CHECK_EQ(type_id, T::GetType()->id);
      T message;
      CHECK_EQ(data_size, T::Size());
      CHECK_EQ(data_size, message.Deserialize(static_cast<const char *>(data)));
      message.sent_time = log_time;
      handler_(message);
    }

   private:
    const ::std::function<void(T message)> handler_;
  };

  // A callable class which dumps messages straight to a queue.
  template <class T>
  class QueueDumpStructHandler {
   public:
    QueueDumpStructHandler(const ::std::string &queue_name)
        : queue_(RawQueue::Fetch(queue_name.c_str(), sizeof(T), T::kHash,
                                 T::kQueueLength)) {}

    void operator()(const T &message) {
      LOG_STRUCT(DEBUG, "re-sending", message);
      void *raw_message = queue_->GetMessage();
      CHECK_NOTNULL(raw_message);
      memcpy(raw_message, &message, sizeof(message));
      CHECK(queue_->WriteMessage(raw_message, RawQueue::kOverride));
    }

   private:
    ::aos::RawQueue *const queue_;
  };

  // A key for specifying log messages to give to a certain handler.
  struct Key {
    Key(const ::std::string &process_name, const ::std::string &log_message)
        : process_name(process_name), log_message(log_message) {}

    ::std::string process_name;
    ::std::string log_message;
  };

  struct KeyHash {
    size_t operator()(const Key &key) const {
      return string_hash(key.process_name) ^
             (string_hash(key.log_message) << 1);
    }

   private:
    const ::std::hash<::std::string> string_hash = ::std::hash<::std::string>();
  };
  struct KeyEqual {
    bool operator()(const Key &a, const Key &b) const {
      return a.process_name == b.process_name && a.log_message == b.log_message;
    }
  };

  ::std::unordered_map<const Key, ::std::unique_ptr<StructHandlerInterface>,
                       KeyHash, KeyEqual> handlers_;
  ::std::unique_ptr<LogFileReader> reader_;

  DISALLOW_COPY_AND_ASSIGN(LogReplayer);
};

}  // namespace linux_code
}  // namespace logging
}  // namespace aos

#endif  // AOS_COMMON_LOGGING_REPLAY_H_