Lift emulation

lift.cpp

#include <iostream>
#include <exception>
#include <string>
#include <sstream>
#include <vector>
#include <regex>
#include <thread>
#include <future>
#include <cassert>

using namespace std;

enum EMovingDirection {
    Stop = 1,
    Down = 2,
    Up = 3
};

string DirectionToStr(EMovingDirection direction) {
    if (direction == Stop)
        return "nowhere";
    else if (direction == Down)
        return "down";
    else if (direction == Up)
        return "up";
    else
        return "unknown";
}

struct TLiftStatus {
    int Floor;
    EMovingDirection Direction;
};

struct TLiftSettings {
    int MinFloor;
    int MaxFloor;
    int FloorSpeedMs;
};

typedef std::chrono::system_clock Time;
typedef std::chrono::milliseconds ms;
typedef std::chrono::duration<float> fsec;

class ILift {
public:
    virtual bool IsValidFloor(int floor) const = 0;
    virtual TLiftStatus GetStatus() const = 0;
    virtual TLiftSettings GetSettings() const = 0;
    virtual void ProcessState() = 0;
    virtual bool GoToFloor(int floor) = 0;
};

class TLift: public ILift {
private:
    const int MinFloor = 0;
    const int MaxFloor = 0;
    const int FloorSpeedMs = 0;
    const int NowhereFloor = -1;
    // State must be correct alltimes
    chrono::system_clock::time_point FloorTime = chrono::system_clock::time_point::min();
    int Floor = MinFloor;
    int GoingToFloor = NowhereFloor - 1;
    EMovingDirection Direction = Stop;

private:
    void UpdateSpeedAndPosition() {
        while (true) {
            EMovingDirection oldDirection = Direction;
            if (!IsValidFloor(GoingToFloor))
                Direction = Stop;
            else if (GoingToFloor > Floor)
                Direction = Up;
            else if (GoingToFloor < Floor)
                Direction = Down;
            else {
                GoingToFloor = NowhereFloor;
                Direction = Stop;
            }
            chrono::system_clock::time_point now = chrono::system_clock::now();
            if (Direction != oldDirection)
                FloorTime = now;
            // Not 100% correct model of a real lift
            if (Direction == Stop) {
                FloorTime = chrono::system_clock::time_point::min();
                break;
            }
            assert(IsValidFloor(GoingToFloor));
            chrono::milliseconds elapsed = chrono::duration_cast<chrono::milliseconds>(now - FloorTime);
            if (elapsed.count() < FloorSpeedMs)
                break;
            if (Direction == Up)
                Floor++;
            if (Direction == Down)
                Floor--;
            FloorTime += chrono::milliseconds(FloorSpeedMs);
        }
    }

public:
    virtual bool IsValidFloor(int floor) const {
        return (floor >= MinFloor && floor <= MaxFloor);
    }
    TLift(int minFloor, int maxFloor, int floorSpeedMs)
        : MinFloor(minFloor)
        , MaxFloor(maxFloor)
        , FloorSpeedMs(floorSpeedMs)
        , NowhereFloor(minFloor - 1)
        , Floor(MinFloor)
        , GoingToFloor(NowhereFloor)
        , Direction(EMovingDirection::Stop)
    {
        if (maxFloor <= minFloor)
            throw invalid_argument("TLift:: bad min/max floor parameters");
    }
public:
    virtual TLiftSettings GetSettings() const {
        return { MinFloor, MaxFloor, FloorSpeedMs };
    }
    virtual TLiftStatus GetStatus() const {
        return { Floor, Direction };
    }
    virtual void ProcessState() {
        UpdateSpeedAndPosition();
    }
    virtual bool GoToFloor(int floor) {
        if (Direction != EMovingDirection::Stop)
            return false;
        if (!IsValidFloor(floor))
            return false;
        if (floor == Floor)
            return false;
        GoingToFloor = floor; // If lift is stopped then it's going anywhere yet
        UpdateSpeedAndPosition();
        return true;
    }
};

class TLiftControllerBase {
protected:
    ILift & Lift;
    TLiftSettings Settings;
public:
    TLiftControllerBase(ILift & lift)
        : Lift(lift)
        , Settings(Lift.GetSettings())
    {
    }

    bool IsValidFloor(int floor) {
        return (floor >= Settings.MinFloor && floor <= Settings.MaxFloor);
    }
};

// In the future refactoring each controller type may have a custom internal
// state and deliver different custom status
class TInLiftController : protected TLiftControllerBase {
public:
    TInLiftController(ILift & lift)
        : TLiftControllerBase(lift)
    {
    }
    bool PushFloorButton(int floor) {
        if (!IsValidFloor(floor))
            return false;
        return Lift.GoToFloor(floor);
    }
    string GetStatusStr() {
        TLiftStatus status = Lift.GetStatus();
        stringstream ss;
        ss << "Welcome to the lift! floor: " << status.Floor << ", going: " << DirectionToStr(status.Direction);
        return ss.str();
    }
};

class TOutLiftController : protected TLiftControllerBase {
private:
    int AtFloor = -1;
public:
    TOutLiftController(ILift & lift, int floor)
        : TLiftControllerBase(lift)
        , AtFloor(floor)
    {
        if (!IsValidFloor(floor))
            throw invalid_argument("TLiftController - Wrong floor number");
    }
public:
    bool PushCallButton() {
        return Lift.GoToFloor(AtFloor);
    }
    string GetStatusStr() {
        TLiftStatus status = Lift.GetStatus();
        stringstream ss;
        ss << "Push button to call the lift. floor: " << status.Floor << ", going: " << DirectionToStr(status.Direction);
        return ss.str();
    }
};

class TBuilding {
private:
    TLift Lift;
    TInLiftController LiftController;
    vector<TOutLiftController> FloorControllers; // don't modify outside constuctor, so pointers do not invalidate
    int controllerOffet = 0;
public:
    TBuilding(int minFloor, int maxFloor, int speedFloorMs) // Let's construct the building ;)
        : Lift(minFloor, maxFloor, speedFloorMs) // Will throw exception on wrong parameters
        , LiftController(Lift)
    {
        controllerOffet = minFloor;
        for (int floor = minFloor; floor <= maxFloor; floor++) {
            FloorControllers.emplace_back(Lift, floor);
        }
    }
    TInLiftController * GetInLiftController() {
        return &LiftController;
    }
    TOutLiftController * GetOutLiftController(int floor) {
        int pos = floor - controllerOffet;
        if (pos < 0 || pos >= FloorControllers.size())
            return nullptr;
        return &FloorControllers[pos];
    }
    string GetStatusStr() {
        stringstream ss;
        ss << "Welcome to the building, we have floors from " << controllerOffet << " to " << controllerOffet + FloorControllers.size() << endl;
        ss << "You are welcome to use our lift! Ask \"help\" to get further assistance" << endl;
        return ss.str();
    }
    void ProcessState() {
        Lift.ProcessState();
    }
};

class TLiftTextController {
private:
    TBuilding & Building;
    ostream & OutStream;
    string LastStatus = "";
    TInLiftController * CurrentInLiftController = nullptr;
    TOutLiftController * CurrentOutLiftController = nullptr;
    string PanelName = "";
    bool ExitBuilding = false;
private:
    void Help() {
        OutStream << "use lift  - start using lift inner panel" << endl;
        OutStream << "use 1     - start using panel on the 1st floor" << endl;
        OutStream << "push 5    - while using lift panel push 5th floor button" << endl;
        OutStream << "push call - while using floor panel call the lift" << endl;
        OutStream << "show this help" << endl;
    }

public:
    TLiftTextController(TBuilding & building, ostream & outStream)
        : Building(building)
        , OutStream(outStream)
        , CurrentInLiftController(nullptr)
        , CurrentOutLiftController(nullptr)
    {
        OutStream << Building.GetStatusStr();
    }

    void ProcessCommand(string command) {
        static regex useLiftRegex("use lift", regex_constants::icase);
        static regex useFloorRegex("use (-?\\d+)", regex_constants::icase);
        static regex pushFloorRegex = regex("push (-?\\d+)", regex_constants::icase);
        static regex pushCallRegex = regex("push call", regex_constants::icase);
        static regex helpRegex = regex("help", regex_constants::icase);
        static regex exitRegex = regex("exit", regex_constants::icase);

        if (command.empty())
            return;
        std::smatch floor_match;
        if (regex_match(command, useLiftRegex)) {
            CurrentInLiftController = Building.GetInLiftController();
            CurrentOutLiftController = nullptr;
            PanelName = "Lift panel";
            OutStream << "Switched to lift panel" << endl;
            return;
        }
        if (regex_match(command, floor_match, useFloorRegex)) {
            if (floor_match.size() == 2) {
                int floor = stoi(floor_match[1].str());
                auto ctl = Building.GetOutLiftController(floor);
                if (ctl != nullptr) {
                    CurrentOutLiftController = ctl;
                    CurrentInLiftController = nullptr;
                    OutStream << "Switched to floor panel at #" << floor << " floor" << endl;
                    stringstream pn;
                    pn << "Floor #" << floor << " panel";
                    PanelName = pn.str();
                }
                else
                    Help();
            }
            return;
        }
        if (regex_match(command, floor_match, pushFloorRegex)) {
            if (CurrentInLiftController != nullptr) {
                int floor = stoi(floor_match[1].str());
                bool result = CurrentInLiftController->PushFloorButton(floor);
                OutStream << "Pushed #" << floor << ", " << (result ? "click" : "nothing happened") << endl;
            }
            else
                Help();
            return;
        }
        if (regex_match(command, pushCallRegex)) {
            if (CurrentOutLiftController != nullptr) {
                bool result = CurrentOutLiftController->PushCallButton();
                OutStream << "Pushed call" << ", " << (result ? "click" : "nothing happened") << endl;
            }
            else
                Help();
            return;
        }
        if (regex_match(command, helpRegex)) {
            Help();
            return;
        }
        if (regex_match(command, exitRegex)) {
            ExitBuilding = true;
            return;
        }
        Help();
    }

    bool UpdateStatus() {
        string status = "";
        if (CurrentInLiftController != nullptr) {
            status = CurrentInLiftController->GetStatusStr();
        } else if (CurrentOutLiftController != nullptr) {
            status = CurrentOutLiftController->GetStatusStr();
        }
        if (status != LastStatus) {
            LastStatus = status;
            OutStream << "[ " << PanelName << " ] " << LastStatus << endl;
            return true;
        }
        return false;
    }

    void ShowPrompt() {
        OutStream << "> ";
    }

    bool DoExitBuilding() const {
        return ExitBuilding;
    }
};

class TAsyncLineReader {
private:
    istream & InStream;
    future<string> asyncReader;

public:
    string ReadLineSync() {
        string s;
        getline(InStream, s);
        return s;
    }

    TAsyncLineReader(istream & inStream)
        : InStream(inStream) {

    }

    void StartReading() {
        asyncReader = async(launch::async, &TAsyncLineReader::ReadLineSync, this);
    }

    string ReadLine()
    {
        string result = "";
        if (!asyncReader.valid())
            StartReading();
        if (asyncReader.wait_for(chrono::seconds(0)) == future_status::ready)
            return asyncReader.get();
        else
            return "";
    }
};

int main() {
    istream & inStream = cin;
    ostream & outStream = cerr;

    TBuilding building(-2, 9, 2500);
    TAsyncLineReader cmdReader(inStream);
    TLiftTextController controller(building, outStream);

    controller.ShowPrompt();
    cmdReader.StartReading();
    while (true) {
        string cmd = cmdReader.ReadLine();
        if (!cmd.empty()) {
            controller.ProcessCommand(cmd);
            if (controller.DoExitBuilding())
                break;
            controller.ShowPrompt();
            cmdReader.StartReading();
        }
        building.ProcessState();
        if (controller.UpdateStatus())
            controller.ShowPrompt();
        this_thread::sleep_for(chrono::milliseconds(100));
    }
    return 0;
}