/**
 Corral, Jesus J
 CSE7359 Lab 2 - BOF
 02/26/2010
 */

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

#define DEBUG 0
#define DEBUG_INFO {\
    printf("\n");\
    printf("\t+---- DEBUG INFO -----+\n");\
    printf("\t| ACL : %s\n", aclFile);\
    printf("\t| KEY : %s\n", keyFile);\
    printf("\t| usr : %s\n", usr);\
    printf("\t| psw : %s\n", psw);\
    printf("\t| nStr: %s\n", newStr);\
    printf("\t| key : %s\n", key);\
    printf("\t| uPsw: %s\n", usrpsw);\
    printf("\t+---------------------+\n");\
    printf("\n");\
}\

#define MAX_BUFFER      8
#define LINE_BUFFER     32
#define READ_LINE       255
#define ENC_MAX_BUFFER (MAX_BUFFER*2)+1
#define ACLFILENAME "acl.txt"
#define KEYFILENAME "key.txt"
#define ALPHA 26

int find(char str[], char c){
    int i;
    for (i = 0; i < strlen(str) && str[i]; i++)
        if(str[i] == c) return i;
    return -1;
}

void concatenate(char newStr[], char str1[], char str2[]){
    strcat(newStr, str1);
    strcat(newStr, ":");
    strcat(newStr, str2);
}

void lowercase(char str[]){
    int i;
    for(i = 0; i < strlen(str) && str[i]; i++)
        str[i] = tolower(str[i]);
}

void uppercase(char str[]){
    int i;
    for(i = 0; i < strlen(str) && str[i]; i++)
        str[i] = toupper(str[i]);
}

void encode(char key[], char str[]){
    lowercase(str);
    int i;
    for(i = 0; i < strlen(str) && str[i]; i++){
        if('a' <= str[i] && str[i] <= 'z'){
            str[i] = find(key, str[i]) + 'a';
        }
    }
    uppercase(str);
}

int validate(char str1[], char str2[]){
    if(strlen(str1) != strlen(str2)) return 0;
    int i;
    for(i = 0; i < strlen(str1) && i < strlen(str2) ; i++){
        if(str1[i] != str2[i]) return 0;
    }
    return 1;
}

int main(char argc[], int argv[]){
    char aclFile[strlen(ACLFILENAME) + 1];
    char usr    [MAX_BUFFER + 1];
    char psw    [MAX_BUFFER + 1];
    char buf    [LINE_BUFFER];
    char key    [ALPHA];
    char line   [LINE_BUFFER];
    char usrpsw [ENC_MAX_BUFFER];
    char newStr [ENC_MAX_BUFFER];
    char keyFile[strlen(KEYFILENAME) + 1];
    int authenticated;

    while(1){
        // Init all variables
        strncpy(aclFile, ACLFILENAME, strlen(ACLFILENAME));
        aclFile[strlen(ACLFILENAME)] = 0;
        usr[0] = 0;
        psw[0] = 0;
        buf[0] = 0;
        key[0] = 0;
        usrpsw[0] = 0;
        newStr[0] = 0;
        strncpy(keyFile, KEYFILENAME, strlen(KEYFILENAME));
        keyFile[strlen(KEYFILENAME)] = 0;
        authenticated = 0;

        // Get user name
        printf("username: ");
        gets(buf);
        strncpy(usr, buf, MAX_BUFFER);
        usr[MAX_BUFFER] = 0;

        // Get password
        printf("password: ");
        gets(buf);
        strncpy(psw, buf, MAX_BUFFER);
        psw[MAX_BUFFER] = 0;

        // create new string
        concatenate(newStr, usr, psw);

    #if DEBUG
        DEBUG_INFO;
    #endif
        // open key file and get key.
        FILE * pFile = fopen(keyFile, "r");
        if(pFile != NULL){
            fgets(key, ALPHA, pFile);
            fclose(pFile);

            // open acl file and get encoded usr:psw.
            pFile = fopen(aclFile, "r");
            if(pFile != NULL){
                fgets(line, READ_LINE, pFile);
                strncpy(usrpsw, line, ENC_MAX_BUFFER);
                usrpsw[ENC_MAX_BUFFER] = 0;
                fclose(pFile);

                // encode string
                encode(key, newStr);

    #if DEBUG
        DEBUG_INFO;
    #endif
                // authenticate user
                authenticated = validate(usrpsw, newStr);
            }
        } // end of if open file key.

        if(authenticated){
            printf("Congratulations!!! You hacked my program!!!\n");
            printf("Please enter your name: ");
            pFile = fopen("log.txt", "a");
            if(pFile != NULL){
                gets(buf);
                fprintf(pFile, "%s\n", buf);
                fclose(pFile);
            }
            return 0;
        } else {
            printf("Login failed...\n");
        }
        printf("\n");
    }

    return 0;
}