// cpp-readline library
//
// @author zmij
// @date Nov 30, 2015

#ifndef CONSOLE_CONSOLE_HEADER_FILE
#define CONSOLE_CONSOLE_HEADER_FILE

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

namespace CppReadline {
class Console {
public:
  /**
    * @brief This is the function type that is used to interface with the Console class.
    *
    * These are the functions that are going to get called by Console
    * when the user types in a message. The vector will hold the
    * command elements, and the function needs to return its result.
    * The result can either be Quit (-1), OK (0), or an arbitrary
    * error (>=1).
    */
  using Arguments = std::vector<std::string>;
  using CommandFunction = std::function<int(const Arguments &)>;

  enum ReturnCode {
    Quit = -1,
    Ok = 0,
    Error = 1 // Or greater!
  };

  /**
    * @brief Basic constructor.
    *
    * The Console comes with two predefined commands: "quit" and
    * "exit", which both terminate the console, "help" which prints a
    * list of all registered commands, and "run" which executes script
    * files.
    *
    * These commands can be overridden or unregistered - but remember
    * to leave at least one to quit ;).
    *
    * @param greeting This represents the prompt of the Console.
    */
  explicit Console(std::string const &greeting);

  /**
    * @brief Basic destructor.
    *
    * Frees the history which is been produced by GNU readline.
    */
  ~Console();

  /**
    * @brief This function registers a new command within the Console.
    *
    * If the command already existed, it overwrites the previous entry.
    *
    * @param s The name of the command as inserted by the user.
    * @param f The function that will be called once the user writes the command.
    */
  void registerCommand(const std::string &s, CommandFunction f);

  /**
    * @brief This function returns a list with the currently available commands.
    *
    * @return A vector containing all registered commands names.
    */
  std::vector<std::string> getRegisteredCommands() const;

  /**
    * @brief Sets the prompt for this Console.
    *
    * @param greeting The new greeting.
    */
  void setGreeting(const std::string &greeting);

  /**
    * @brief Gets the current prompt of this Console.
    *
    * @return The currently set greeting.
    */
  std::string getGreeting() const;

  /**
    * @brief This function executes an arbitrary string as if it was inserted via stdin.
    *
    * @param command The command that needs to be executed.
    *
    * @return The result of the operation.
    */
  int executeCommand(const std::string &command);

  /**
    * @brief This function calls an external script and executes all commands inside.
    *
    * This function stops execution as soon as any single command returns something
    * different from 0, be it a quit code or an error code.
    *
    * @param filename The pathname of the script.
    *
    * @return What the last command executed returned.
    */
  int executeFile(const std::string &filename);

  /**
    * @brief This function executes a single command from the user via stdin.
    *
    * @return The result of the operation.
    */
  int readLine();

private:
  Console(const Console &) = delete;
  Console(Console &&) = delete;
  Console &operator=(Console const &) = delete;
  Console &operator=(Console &&) = delete;

  struct Impl;
  using PImpl = ::std::unique_ptr<Impl>;
  PImpl pimpl_;

  /**
    * @brief This function saves the current state so that some other Console can make use of the GNU readline facilities.
    */
  void saveState();
  /**
    * @brief This function reserves the use of the GNU readline facilities to the calling Console instance.
    */
  void reserveConsole();

  // GNU newline interface to our commands.
  using commandCompleterFunction = char **(const char *text, int start,
                                           int end);
  using commandIteratorFunction = char *(const char *text, int state);

  static commandCompleterFunction getCommandCompletions;
  static commandIteratorFunction commandIterator;
};
} // namespace CppReadline

#endif