// =================================================================================================
// This file is part of the CLBlast project. The project is licensed under Apache Version 2.0. This
// project loosely follows the Google C++ styleguide and uses a tab-size of two spaces and a max-
// width of 100 characters per line.
//
// Author(s):
//   Cedric Nugteren <www.cedricnugteren.nl>
//
// This file implements the Database class, providing a static variable holding the actual database
// information. The class also provides utility functions to search the database and to access a
// found entry by parameter-key. The database itself is filled in the corresponding source-file and
// partially also by the database/xxxxx.h files, in which kernel-specific parameters are found.
//
// =================================================================================================

#ifndef CLBLAST_DATABASE_H_
#define CLBLAST_DATABASE_H_

#include <string>
#include <vector>
#include <unordered_map>

#include "utilities/utilities.hpp"
#include "database/database_structure.hpp"

namespace clblast {
// =================================================================================================

// See comment at top of file for a description of the class
class Database {
 public:

  // The OpenCL device vendors
  static const std::string kDeviceVendorAll;

  // The database consists of separate database entries, stored together in a vector
  static std::vector<database::DatabaseEntry> database;

  // Database for a special case: Apple CPUs support limited number of threads
  static const std::vector<database::DatabaseEntry> apple_cpu_fallback;

  Database() = default;

  // The constructor with a user-provided database overlay (potentially an empty vector)
  explicit Database(const Device &device, const std::string &kernel_name,
                    const Precision precision, const std::vector<database::DatabaseEntry> &overlay);

  // Accessor of values by key
  size_t operator[](const std::string &key) const { return parameters_->find(key)->second; }
  bool exists(const std::string &key) const { return (parameters_->count(key) == 1); }

  // Obtain a list of OpenCL pre-processor defines based on the parameters
  std::string GetDefines() const;

  // Retrieves the values or names of all the parameters
  std::string GetValuesString() const;
  std::vector<std::string> GetParameterNames() const;
  const database::Parameters& GetParameters() const { return *parameters_; }

 private:
  // Search method functions, returning a set of parameters (possibly empty)
  database::Parameters Search(const std::string &this_kernel,
                              const std::string &this_vendor, const std::string &this_type,
                              const std::string &this_device, const std::string &this_architecture,
                              const Precision this_precision,
                              const std::vector<database::DatabaseEntry> &db) const;
  database::Parameters SearchDevice(const std::string &target_device,
                        const std::vector<database::DatabaseDevice> &devices,
                        const std::vector<std::string> &parameter_names) const;
  database::Parameters SearchArchitecture(const std::string &target_architecture,
                                          const std::string &this_device,
                                          const std::vector<database::DatabaseArchitecture> &architectures,
                                          const std::vector<std::string> &parameter_names) const;
  database::Parameters SearchVendorAndType(const std::string &target_vendor,
                                           const std::string &target_type,
                                           const std::string &this_device, const std::string &this_architecture,
                                           const std::vector<database::DatabaseVendor> &vendors,
                                           const std::vector<std::string> &parameter_names) const;

  // Helper to convert from database format to proper types
  std::string CharArrayToString(const database::Name char_array) const;

  // Found parameters suitable for this device/kernel
  std::shared_ptr<database::Parameters> parameters_;
};

// =================================================================================================

// Multiple databases together in a map
class Databases {
 public:

  explicit Databases(const std::vector<std::string> &kernel_names): kernel_names_(kernel_names) { }

  // Database accessor
  Database& operator()(const std::string &kernel_name) { return databases_[kernel_name]; }

  // Retrieves a parameter from the database
  size_t operator[](const std::string &key) const {
    for (const auto &kernel_name : kernel_names_) {
      const auto &kernel_db = databases_.find(kernel_name)->second;
      if (kernel_db.exists(key)) { return kernel_db[key]; }
    }
    throw RuntimeErrorCode(StatusCode::kDatabaseError);
  }

 private:
  const std::vector<std::string> kernel_names_;
  std::unordered_map<std::string, Database> databases_;
};

// =================================================================================================
} // namespace clblast

// CLBLAST_DATABASE_H_
#endif