#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>

#include <unistd.h>
#include <fcntl.h>
#include <netinet/tcp.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>

#define BUF_SZ 1024

struct hostent *hp;
struct sockaddr_in addr; int on = 1;
bool comm_is_open = false;
int comm_sock = -1;
char *server_host = "127.0.0.1";
int server_port = 8005;
char session_id[100]; // session identifier as a string
char success[] = "success";

void open_server_comm(){
    addr.sin_addr.s_addr = inet_addr(server_host);
	addr.sin_port = htons(server_port);
	addr.sin_family = AF_INET;
	comm_sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
    if( comm_sock == -1 ){
        printf("open_server_comm error: create socket for server comm\n");
        return;
    }
    setsockopt(comm_sock, IPPROTO_TCP, TCP_NODELAY, (const char *)&on, sizeof(int));
    if(connect(comm_sock, (struct sockaddr *)&addr, sizeof(struct sockaddr_in)) < 0){
        printf("open_server_comm error: connect\n");fflush(stdout);
        return;
    }
    comm_is_open = true;
    printf("Server communication open\n");fflush(stdout);
}

void close_server_comm(){
    if( comm_is_open == false ) return;
    shutdown(comm_sock, SHUT_RDWR);
    close(comm_sock);
    comm_is_open = false;
    comm_sock = -1;
    printf("Server communication closed\n");fflush(stdout);
}

// functions called by main to interact with server

int session_start(){
    char req_buf[] = "GET /api/session_start\r\n\r\n";
    static char resp_buf[BUF_SZ];
    printf("Session Start\n");
    open_server_comm();
        write(comm_sock, req_buf, sizeof(req_buf)-1);
        bzero( resp_buf, BUF_SZ );
        if( read(comm_sock, resp_buf, BUF_SZ-1) > 0 ){ 
            //printf("Response:\n%s",resp_buf); fflush(stdout);
        }
    close_server_comm();
    char *sp = strstr(resp_buf,success);
    if( sp == NULL ){
        return(EXIT_FAILURE);
    }else{
        // extract and store the session id from the response
        sp += sizeof(success); size_t n = strspn(sp,"0123456789");
        memcpy(session_id,sp,n); session_id[n] = '\0';
        printf("Session Start success %s\n",session_id);fflush(stdout);
        return(EXIT_SUCCESS);
    }
}

void ping(){
    //char req_buf[] = "GET /api/ping?session_id=sid\r\n\r\n";
    char req_buf[] = "GET /api/ping\r\n\r\n";
    static char resp_buf[BUF_SZ];
    printf("ping()\n");
    open_server_comm();
        write(comm_sock, req_buf, sizeof(req_buf)-1);
        bzero( resp_buf, BUF_SZ );
        if( read(comm_sock, resp_buf, BUF_SZ-1) > 0 ){ 
            //printf("Response:\n%s",resp_buf); fflush(stdout);
        }
    close_server_comm();
    if( strstr(resp_buf,success) == NULL ){
        printf("ping failure\n");fflush(stdout);
    }else{
        printf("ping success\n");fflush(stdout);
    }
}

void session_query(char *command){
    char req_buf[BUF_SZ] = "GET /api/session_query?session_id=";
    strcat(req_buf,session_id); strcat(req_buf,"&command=");
    strcat(req_buf,command); strcat(req_buf,"\r\n\r\n");
    size_t req_len = strlen(req_buf);
    static char resp_buf[BUF_SZ];
    printf("Session query\n");
    open_server_comm();
        write(comm_sock, req_buf, req_len);
        bzero( resp_buf, BUF_SZ );
        if( read(comm_sock, resp_buf, BUF_SZ-1) > 0 ){ 
            //printf("Response:\n%s",resp_buf); fflush(stdout);
        }
    close_server_comm();
    char *sp = strstr(resp_buf,success);
    if( sp == NULL ){
        printf("error from query\n"); fflush(stdout);
    }else{
        // extract and store the session response
        sp += sizeof(success); 
        size_t n = strspn(sp,"0123456789"); sp[n] = '\0';
        printf("query success %s\n",sp);fflush(stdout);
    }
}

void session_stop(){
    char req_buf[BUF_SZ] = "GET /api/session_stop?session_id=";
    strcat(req_buf,session_id); strcat(req_buf,"\r\n\r\n");
    size_t req_len = strlen(req_buf);
    static char resp_buf[BUF_SZ];
    printf("Session Stop\n");
    open_server_comm();
        write(comm_sock, req_buf, req_len);
        bzero( resp_buf, BUF_SZ );
        if( read(comm_sock, resp_buf, BUF_SZ-1) > 0 ){ 
            //printf("Response:\n%s",resp_buf); fflush(stdout);
        }
    close_server_comm();
    if( strstr(resp_buf,success) == NULL ){
        printf("error from Session Stop\n"); fflush(stdout);
    }else{
        printf("Session Stop success\n");fflush(stdout);
    }
}

// end of functions called by main

int main(int argc, char *argv[]){
    printf("Client test\n");
    session_start(); // establishes a session with backend instance
    ping(); // does not require the backend
    session_query("sid"); // does require the backend
    session_stop(); // terminates session and backend instance
    printf("end Client test\n");
}