#include <stdlib.h>
#include <netdb.h>
#include <netinet/in.h>
#include <string.h>
#include <unistd.h>
#include <time.h>

int doprocessing (int sock);
int authtest(char *username, char *password);
int runcode();
void controlgate(int action);
int countlines(char *filename);

int runcode() {
    /*
     * Dead Code.  Just a stub for now in case this is useful later.
     */
    system("/opt/local/bin/secret");
}

#define RESPLINES 56
int authtest(char *username, char *password) {
    FILE *fppass, *fpresp;
    int randline;
    char grampass[16] = "grampass.txt";
    char gramresp[16] = "gramresp.txt";
    char userpass[16];
    char validpass[16];
    char *response;

    /* The only username allowed is "admin" */
    if (strcmp(username, "admin") != 0) return 0;

    strcpy(userpass, password);

    /* Get the password for authentication from the file */
    fppass = fopen(grampass, "r");
    if (fppass == NULL) {
        perror("Cannot open grampass file");
        return 0;
    }
    if (fgets(validpass, sizeof(validpass), fppass)==NULL) {
        perror("Cannot read from grampass file");
        return 0;
    }
    fclose(fppass);

    validpass[strlen(validpass)-1] = 0; /* Remove newline */
    if (strcmp(userpass, validpass) == 0) {
        /* Success */
        return 1;
    } else {
        /* Return custom message, selected at random from gramresp file */
        srand(time(NULL));
        randline=rand()%countlines(gramresp);

        fpresp = fopen(gramresp, "r");
        if (fpresp == NULL) {
            perror("Cannot open gramresp file");
            return 0;
        }

        /*
         * Allocate memory for response text, then skip to that line in the
         * response file.
         */
        response=malloc(128);
        for (int i=0; i < randline; i++) {
            fgets(response, 128, fpresp);
        }

        fclose(fpresp);
        response[strlen(response)-1] = 0; /* Remove newline */
        printf("ERR \"%s\"\n",response);
        free(response);
        return 0;
    }
    return 0;
}

int countlines(char *filename) {
    FILE *fp;
    unsigned int lines=0;

    fp = fopen(filename, "r");
    if (fp == NULL) {
        return 0;
    }
    while (EOF != (fscanf(fp, "%*[^\n]"), fscanf(fp, "%*c"))) {
        ++lines;
    }
    fclose(fp);
    return lines;
}

#define OPENGATE 1
#define CLOSEGATE 1
void controlgate(int action) {
    FILE *gpio, *export, *direction;

    export = fopen("/sys/class/gpio/export", "wb");
    if (export != NULL) {
        fwrite("11\n", 1, 3, export);
        fclose(export);
    }

    direction = fopen("/sys/class/gpio/gpio11", "wb");
    if (direction != NULL) {
        fwrite("out\n", 1, 4, direction);
        fclose(direction);
    }

    gpio = fopen("/sys/class/gpio/gpio11", "wb");
    if (gpio != NULL) {
        if (action == OPENGATE) {
            fwrite("1\n", 1, 2, gpio);
        } else {
            fwrite("0\n", 1, 2, gpio);
            fclose(gpio);
        }
    }
}

int doprocessing (int sock) {
    int n, gotuser=0, gotpass=0;
    char buffer[1024], strchr[2] = "\n\x00", *token;
    char username[256], password[256];

    memset(buffer, 0, 256);
    chdir("/opt/local/sbin");

    /* Send stdout and stderr to socket client */
    dup2(sock, STDOUT_FILENO);
    dup2(sock, STDERR_FILENO);

    printf("OK GRAMGATE ready. Send USER command.\n"); fflush(stdout);

    while(1) {
        n = read(sock, buffer, 1024);

        if (n < 0) {
            perror("ERROR reading from socket");
            return 0;
        }

        /* Tolkeinize the received string, parsing combined commands delineated with \n */
        token = strtok(buffer, strchr);
        while (token != NULL) {

            /* Got everything we need, don't parse the rest of the buffer */
            if (gotuser == 1 && gotpass == 1) {
                break;
            }

            if (strncmp(token, "USER ", 5) == 0) {
                strncpy(username, token+5, sizeof(username));
                gotuser=1;
                if (gotpass == 0) {
                    printf("OK Send PASS command.\n"); fflush(stdout);
                }
            } else if (strncmp(token, "PASS ", 5) == 0) {
                strncpy(password, token+5, sizeof(password));
                gotpass=1;
                if (gotuser == 0) {
                    printf("OK Send USER command.\n"); fflush(stdout);
                }
            }
            token = strtok(NULL, strchr);
        }

        if (gotuser==1 && gotpass==1) {
            break;
        }
    }

    if (authtest(username, password)) {
        printf("OK Authentication Success. Send OPEN or CLOSE command.\n"); fflush(stdout);
        n = read(sock, buffer, 1024);

        if (n < 0) {
            perror("ERROR reading from socket");
            return 0;
        }

        if (strncmp(buffer, "OPEN", 4) == 0) {
            controlgate(OPENGATE);
        } else if (strncmp(buffer, "CLOSE", 5) == 0) {
            controlgate(CLOSEGATE);
        } else {
            printf("ERR Command Unrecognized.\n"); fflush(stdout);
            return 1;
        }
    } else {
        printf("ERR Authentication Failed.\n"); fflush(stdout);
        return 0;
    }

    return 0;
}

int main( int argc, char *argv[] ) {
    int sockfd, newsockfd, portno, clilen;
    char buffer[256];
    struct sockaddr_in serv_addr, cli_addr;
    int  n, pid, sockyes=1;

    /* First call to socket() function */
    sockfd = socket(AF_INET, SOCK_STREAM, 0);

    if (sockfd < 0) {
        perror("ERROR opening socket");
        exit(1);
    }
    if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &sockyes, sizeof(int)) == -1) {
        perror("ERROR setting socket options");
        exit(1);
    }

    /* Initialize socket structure */
    memset((char *) &serv_addr, 0, sizeof(serv_addr));
    portno = 5001;

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = INADDR_ANY;
    serv_addr.sin_port = htons(portno);

    /* Now bind the host address using bind() call.*/
    if (bind(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0) {
        perror("ERROR on binding");
        exit(1);
    }

    /* Now start listening for the clients, here
    * process will go in sleep mode and will wait
    * for the incoming connection
    */

    listen(sockfd,5);
    clilen = sizeof(cli_addr);

    while (1) {
        newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr, &clilen);
        if (newsockfd < 0) {
            perror("ERROR on accept");
            exit(1);
        }

        /* Create child process */
        pid = fork();
        if (pid < 0) {
            perror("ERROR on fork");
            exit(1);
        }

        if (pid == 0) {
            /* This is the client process */
            close(sockfd);
            exit(doprocessing(newsockfd));
        } else {
            close(newsockfd);
        }
    } /* end of while */
}