#include <iostream>
#include <string>
#include <sys/socket.h>
#include <sys/un.h>  // need this for unix domain sockets.
#include <unistd.h> // unlink
#include <stdio.h>
#include <sstream>

using namespace std;

const string PATH{"/tmp/CalcServer"};

void Send(char op, int socket);
void DoMath(char op, int socket);
void DoEqual(int socket);
void GetResult(int socket);

int main() {

     int theSocket;
     struct sockaddr_un address, server;
     string name;

     theSocket = socket(AF_UNIX, SOCK_STREAM, 0);

     if(theSocket == -1) {
        perror("Socket failed: ");
        exit(1);
     }

     memset(&address, 0, sizeof(struct sockaddr_un));
     address.sun_family = AF_UNIX;
     strncpy(address.sun_path, PATH.c_str(), sizeof(address.sun_path)-1);

     // just connect, no bind in this pcase.
     if( -1 == connect(theSocket,reinterpret_cast<struct sockaddr *>( &address),                 sizeof(struct sockaddr_un))) {
         perror("Connect failed: ");
     }

     bool done{false};
     char op;

     while (not done) {
         cout << endl;
         cout << "Enter operation : ";
         cin >> op;
         switch(op) {
             case 'q':
                 Send(op, theSocket);
                 done = true;
                 break;
             case 'd':
                 done = true;
                 break;
             case '+':
             case '-':
             case '*':
             case '/':
                 DoMath(op, theSocket);
                 break;
             case '=':
                 DoEqual(theSocket);
                 break;
             default:
                 cout << "Plese pick one: q,d,+,-,*,/,=" << endl;
                 break;
         }
     }

     close(theSocket);

     return 0;
}

void Send(char op, int socket){
   ssize_t bytes = write(socket, &op, sizeof(op)); 
   if (bytes != sizeof(op) ) {
      cerr << "Write failed" << endl;
      exit(-1);
   }
}

void DoMath(char op, int socket){
    // send the operation
    Send(op, socket);

    // get the operand
    int num{0};
    cout << "Enter a number " ;
    cin >> num;
    cout << endl;

    // send the operand
    ssize_t bytes = write(socket, &num, sizeof(num));
    if (bytes < sizeof(num)) {
        cerr << "Write failed " << endl;
    }

    GetResult(socket);
}

const int MSG_SIZE {101};

void DoEqual(int socket){
    char buf[MSG_SIZE];
    int msg_size;
    int size;

    Send('=', socket);

    read(socket, &size, sizeof(int));
    if (size >= MSG_SIZE) {
       cerr << "Message too large " << endl;
    }

    ssize_t bytes = read(socket, buf, size);
    if (bytes > 0) {
        buf[bytes] = 0;
        cout << buf << endl;
    }

    GetResult(socket);
}

void GetResult(int socket){

    char buf[MSG_SIZE];
    int size;
    int msg_size;

    read(socket, &msg_size, sizeof(msg_size));

    if (msg_size > MSG_SIZE) {
        cerr << "Message too large " << endl;
    } else {

        ssize_t bytes = read(socket, buf, msg_size);
        if (bytes > 0) {
            buf[bytes] = 0;
            cout << "operation ended with " << buf << endl;
        } else {
            cerr << "GetResult failed " << endl;
        }
    }
}