#include "liboath/oath.h"
#include "libpq-fe.h"
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <ctype.h>


// These #defines must be present according to PAM documentation. 
#define PAM_SM_AUTH
//#define PAM_SM_ACCOUNT
//#define PAM_SM_SESSION
//#define PAM_SM_PASSWORD


#include <security/pam_appl.h>
#include <security/pam_modules.h>


// Les fonctions de debug
#define D(x) do {\
    printf("[%s:%s(%d)] ", __FILE__, __FUNCTION__, __LINE__);\
    printf x;\
    printf("\n");\
} while (0)
#define DBG(x) if (cfg.debug) {\
    D(x);\
}

#define PAM_EXTERN extern

// Static options
#define BDD_PASS_FILE "/srv/bdd/pipi-system.pass"
#define BDD_CONN_LENGTH 255
#define MIN_OTP_LEN 6
#define DEFAULT_OTP_LEN 6
#define MAX_OTP_LEN 8
#define OTP_SECRET_LEN 32
#define SSH_AUTH_INFO_LEN 1024



struct cfg {
    int debug;
    int digits;
    int window;
};

static void
parse_cfg(int flags, int argc,
    const char ** argv, struct cfg * cfg) {
    int i;

    cfg -> debug = 0;
    cfg -> digits = 6;
    cfg -> window = 5;

    for (i = 0; i < argc; i++) {
        if (strcmp(argv[i], "debug") == 0)
            cfg -> debug = 1;
        if (strncmp(argv[i], "digits=", 7) == 0)
            cfg -> digits = atoi(argv[i] + 7);
        if (strncmp(argv[i], "window=", 7) == 0)
            cfg -> window = atoi(argv[i] + 7);
    }

    if (MIN_OTP_LEN > cfg -> digits || cfg -> digits > MAX_OTP_LEN) {
        D(("La longueur du code otp doit être entre %i et %i. Valeur invalide: digits=%i",MIN_OTP_LEN,MAX_OTP_LEN, cfg -> digits));
    }

    if (cfg -> debug) {
        D(("called."));
        D(("flags %d argc %d", flags, argc));
        for (i = 0; i < argc; i++)
            D(("argv[%d]=%s", i, argv[i]));
        D(("debug=%d", cfg -> debug));
        D(("digits=%d", cfg -> digits));
        D(("window=%d", cfg -> window));
    }
}

char * strtokk(char * str,const char cutter) {
    
    while((*str != cutter) && (*str != '\0'))
        str++;
    
    bool strEnd = (*str == '\0');
    *str = '\0';
    if(!strEnd)
        str++;
    return str;
}

char hexCharReader(char hex){
    if('0'<=hex && hex<='9')
        return hex-'0';
    else
        return hex-'a'+10;
}

void hexToBytes(char * str, char arr[]){
    int pos = 0;
    while(*str != '\0'){
        char b1 = hexCharReader(*str);
        str++;
        char b0 = hexCharReader(*str);
        str++;
        arr[pos] = b1<<4 | b0;
        pos++;
    }
    return;
}

PAM_EXTERN int
pam_sm_authenticate(pam_handle_t * pamh, int flags, int argc, const char ** argv) {
    
    int retval, rc;
    const char * user = NULL;
    const char * password = NULL;
    char otp[MAX_OTP_LEN + 1];
    int password_len = 0;
    struct pam_conv * conv;
    struct pam_message * pmsg[1], msg[1];
    struct pam_response * resp;
    int nargs = 1;
    struct cfg cfg;
    char * query_prompt = NULL;
    char * onlypasswd = strdup(""); /* empty passwords never match */
    PGconn     *conn;
    PGresult   *res;
    int         nFields;
    char * oathSecret;


    /***** Parsing config *****/
    parse_cfg(flags, argc, argv, & cfg);
    
    /***** Getting User *****/
    retval = pam_get_user(pamh, &user, NULL);
    if (retval != PAM_SUCCESS) {
        DBG(("Could not get PAM user: %s", pam_strerror(pamh, retval)));
        goto done;
    }
    DBG(("We got the user: %s", user));

    /****** Getting ssh key ******/
    
    /* Retrieve SSH authentication information. */
    char * ssh_auth_info_ret = (char *)pam_getenv(pamh, "SSH_AUTH_INFO_0");
    char ssh_auth_info [SSH_AUTH_INFO_LEN];
    ssh_auth_info_ret = "pubkey ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIKXQt1YWjKCsjcsFW7o1hdjAB/qxWBwesAeV0RcBeW0I";
    strcpy(ssh_auth_info,ssh_auth_info_ret);
    
    if (!ssh_auth_info || !*ssh_auth_info) {
        DBG(("No SSH auth info, du coup on ignore"));
        return PAM_IGNORE;
    }
    
    const char delim = ' ';
    
    char * authType   = ssh_auth_info;
    char * sshKeyType = strtokk(ssh_auth_info, delim);
    char * sshKeyVal  = strtokk(sshKeyType, delim);
    
    DBG(("Authentification Type: '%s'", authType));
    DBG(("Authentification KeyType: '%s'", sshKeyType));
    DBG(("Authentification KeyVal: '%s'", sshKeyVal));
    
    
    rc = oath_init();
    if (rc != OATH_OK) {
        DBG(("oath_init() failed (%d)", rc));
        retval = PAM_AUTHINFO_UNAVAIL;
        goto done;
    }
      
    /****** Get oath secret from database ******/
    char connInfo[BDD_CONN_LENGTH] = "dbname='pipi-system' user=pipiadmin password='";
    char lastAp = '\'';
    FILE *dbPassFile;
    char ch;
    int pos = strlen(connInfo);
    
    
    dbPassFile = fopen(BDD_PASS_FILE,"r");
    if (dbPassFile == NULL) {
        DBG(("Cannot open file %s, on peut pas se connecter à la base de données\n", BDD_PASS_FILE));
        retval = PAM_AUTHINFO_UNAVAIL;
        goto done;
    }
    while (feof(dbPassFile))
    {
        connInfo[pos] = fgetc(dbPassFile);
        pos++;
    }
    fclose(dbPassFile);
    connInfo[pos] = '\'';
    
    
    
    conn = PQconnectdb(connInfo);

    /* Vérifier que la connexion au backend a été faite avec succès */
    if (PQstatus(conn) != CONNECTION_OK) {
        DBG(("Connection to database failed: %s", PQerrorMessage(conn)));
        retval = PAM_AUTH_ERR;
        goto done;
    }

    res = PQexec(conn,
        "SELECT pg_catalog.set_config('search_path', '', false)");
    if (PQresultStatus(res) != PGRES_TUPLES_OK) {
        DBG(("SET failed: %s", PQerrorMessage(conn)));
        PQclear(res);
        retval = PAM_AUTH_ERR;
        goto done;
    }
    
    DBG(("Initialisation de la base de données efféctuée"));

    PQclear(res);
    
    const char *paramValues[2];
    paramValues[0] = sshKeyType;
    paramValues[1] = sshKeyVal;
    
    res = PQexecParams(conn, "SELECT \"oathPrivate\" FROM login.git WHERE \"sshKeyType\"=$1 AND \"sshPubKey\"=$2",2,NULL,paramValues,NULL,NULL,1);
    if (PQresultStatus(res) != PGRES_TUPLES_OK) {
        DBG(("SET failed: %s", PQerrorMessage(conn)));
        PQclear(res);
        retval = PAM_AUTH_ERR;
        goto done;
    }
    
    nFields = PQntuples(res);
    if(nFields!=1){
        DBG(("Aucun code secret oath trouvé pour la clé '%s'", sshKeyVal));
        PQclear(res);
        retval = PAM_AUTH_ERR;
        goto done;
    }
    
    oathSecret=PQgetvalue(res, 0, 0);
    
    DBG(("On a récupéré le code secret : %s",oathSecret));
    
    PQclear(res);
    PQfinish(conn);
    
    
    /*** Parsing hex to byte array ***/
    
    char oathSecretBin[OTP_SECRET_LEN];
    int oathSecretBinLen = OTP_SECRET_LEN+1;
    oath_hex2bin(oathSecret,oathSecretBin,&oathSecretBinLen);
        
    
    
    
     /****** Asking for password ******/
    retval = pam_get_item(pamh, PAM_CONV, (const void ** ) & conv);
    if (retval != PAM_SUCCESS) {
        DBG(("get conv returned error: %s", pam_strerror(pamh, retval)));
        goto done;
    }

    pmsg[0] = & msg[0];
    {
        const char * query_template = "One-time password (OATH) for `%s': ";
        size_t len = strlen(query_template) + strlen(user);
        size_t wrote;

        query_prompt = malloc(len);
        if (!query_prompt) {
            retval = PAM_BUF_ERR;
            goto done;
        }

        wrote = snprintf(query_prompt, len, query_template, user);
        if (wrote < 0 || wrote >= len) {
            retval = PAM_BUF_ERR;
            goto done;
        }

        msg[0].msg = query_prompt;
    }
    
    msg[0].msg_style = PAM_PROMPT_ECHO_OFF;
    resp = NULL;

    retval = conv -> conv(nargs, (const struct pam_message ** ) pmsg, &
        resp, conv -> appdata_ptr);

    free(query_prompt);
    query_prompt = NULL;

    if (retval != PAM_SUCCESS) {
        DBG(("conv returned error: %s", pam_strerror(pamh, retval)));
        goto done;
    }

    DBG(("conv returned: %s", resp -> resp));

    password = resp -> resp;

    if (password)
        password_len = strlen(password);
    else {
        DBG(("Could not read password"));
        retval = PAM_AUTH_ERR;
        goto done;
    }

    if (password_len < MIN_OTP_LEN) {
        DBG(("OTP too short: %s", password));
        retval = PAM_AUTH_ERR;
        goto done;
    } else if (password_len < cfg.digits) {
        DBG(("OTP shorter than digits=%d: %s", cfg.digits, password));
        retval = PAM_AUTH_ERR;
        goto done;
    } else if (password_len > MAX_OTP_LEN) {
        DBG(("OTP too long (and no digits=): %s", password));
        retval = PAM_AUTH_ERR;
        goto done;
    } else {
        strcpy(otp, password);
        password = NULL;
    }
    
    DBG(("Pouf ! OTP: %s", otp ? otp : "(null)"));
    
    
    
    
    /****** Validation du mot de passe oath ******/
    {
        time_t last_otp;
        time_t jetzt = 0;
        time(&jetzt);
        int timeStep = 30;
        DBG(("Validating oath secret %s of length %i at time %ld",oathSecret,oathSecretBinLen, jetzt));
        char cdex[32];
        rc = oath_totp_validate(oathSecretBin, oathSecretBinLen, jetzt, timeStep, 0, cfg.window, otp);
    }
    
    if (rc == OATH_INVALID_OTP) {
        DBG(("One-time password not authorized to login as user '%s'", user));
        retval = PAM_AUTH_ERR;
        goto done;
    }

    retval = PAM_SUCCESS;
    
    
    
    
    /****** Terminé ! ******/
    done:
    
    oath_done();
    free(query_prompt);
    free(onlypasswd);
    
    DBG(("Terminé ! [%s]", pam_strerror(pamh, retval)));
    
    return retval;
}


PAM_EXTERN
int pam_sm_setcred(pam_handle_t *pamh,int flags,int argc
		   ,const char **argv)
{
     return PAM_SUCCESS;
}