//---------------------------------------------------------------------------
//  Greenplum Database
//  Copyright (C) 2016 Pivotal Software, Inc.
//
//  @filename:
//    pg_func_generator_interface.h
//
//  @doc:
//    Interface for all Greenplum Function generator.
//
//---------------------------------------------------------------------------
#ifndef GPCODEGEN_PG_FUNC_GENERATOR_INTERFACE_H_  // NOLINT(build/header_guard)
#define GPCODEGEN_PG_FUNC_GENERATOR_INTERFACE_H_

#include <string>
#include <vector>
#include <memory>

#include "llvm/IR/Value.h"

#include "codegen/utils/gp_codegen_utils.h"

namespace gpcodegen {

/** \addtogroup gpcodegen
 *  @{
 */

/**
 * @brief Object that holds the information needed for generating the builtin
 *        postgres functions.
 *
 **/
struct PGFuncGeneratorInfo {
  // Convenience members for code generation
  llvm::Function* llvm_main_func;
  llvm::BasicBlock* llvm_error_block;

  // llvm arguments for the function.
  // This can be updated while generating the code.
  std::vector<llvm::Value*> llvm_args;

  // Store whether arguments are NULL or not.
  // This can be updated while generating the code.
  std::vector<llvm::Value*> llvm_args_isNull;

  PGFuncGeneratorInfo(
    llvm::Function* llvm_main_func,
    llvm::BasicBlock* llvm_error_block,
    const std::vector<llvm::Value*>& llvm_args,
    const std::vector<llvm::Value*>& llvm_args_isNull) :
      llvm_main_func(llvm_main_func),
      llvm_error_block(llvm_error_block),
      llvm_args(llvm_args),
      llvm_args_isNull(llvm_args_isNull) {
  }
};

/**
 * @brief Interface for all code generators.
 **/
class PGFuncGeneratorInterface {
 public:
  virtual ~PGFuncGeneratorInterface() = default;

  /**
   * @return Greenplum function name for which it generate code
   **/
  virtual std::string GetName() = 0;

  /**
   * @return Total number of arguments for the function.
   **/
  virtual size_t GetTotalArgCount() = 0;

  /**
   * @return True if function is strict; false otherwise.
   */
  virtual bool IsStrict() = 0;

  /**
   * @brief Generate the code for Greenplum function.
   *
   * @param codegen_utils   Utility to easy code generation.
   * @param pg_gen_info     Information needed for generating the function.
   * @param llvm_out_value  Store the results of function
   * @param llvm_isnull_ptr Set to true if result is null
   *
   * @return true when it generated successfully otherwise it return false.
   **/
  virtual bool GenerateCode(gpcodegen::GpCodegenUtils* codegen_utils,
                            const PGFuncGeneratorInfo& pg_gen_info,
                            llvm::Value** llvm_out_value,
                            llvm::Value* const llvm_isnull_ptr) = 0;
};

/** @} */
}  // namespace gpcodegen

#endif  // GPCODEGEN_PG_FUNC_GENERATOR_INTERFACE_H_