#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <getopt.h>
#include <time.h>

#define ANSWER_AMOUNT 4
#define BUFOR 256

///LIST OF QUESTIONS
typedef struct node {
    int questionNumber;
    int correctAnswer;
    char answers[ANSWER_AMOUNT][BUFOR];
    char questionText[BUFOR];
    struct node * next;
} question;

void push(question * head, int questionNumber, char answers[ANSWER_AMOUNT][BUFOR], char questionText[BUFOR], int correctAnswer) {
    question * current = head;
    while (current->next != NULL) {
        current = current->next;
    }

    current->next = malloc(sizeof(question));
    current->next->questionNumber = questionNumber;
    current->next->correctAnswer = correctAnswer;
    strcpy(current->next->questionText, questionText);

    int i;
    for (i = 0; i < ANSWER_AMOUNT; i++)
        strcpy(current->next->answers[i], answers[i]);

    current->next->next = NULL;
}

void askQuestions(question * head, int questionsAmount, int shuffledQuestionsArr[], int * correctAnswers) {
    int i, j, answer;
    question * current = head;

    for (j = 0; j<questionsAmount; j++) {
        current = head;
        current = current->next;


        while (current->questionNumber != shuffledQuestionsArr[j]) {
            current = current->next;
        }

        printf("%s", current->questionText);
            for (i = 0; i < ANSWER_AMOUNT; i++)
                printf("%d: %s", i,  current->answers[i]);

        printf("twoja odpowiedz: ");
        scanf("%d", &answer);
        if (answer == current->correctAnswer) (*correctAnswers)++;
        printf("\n");
    }
}

///FILE
FILE *Fopen(const char *filename, const char *mode)
{
    FILE *fp;

    if ((fp = fopen(filename, mode)) == NULL) {
        printf("Nie mozna otworzyc pliku: %s", filename);
        strerror("fopen");
        exit(EXIT_FAILURE);
    }
    return fp;
}

///SHUFFLING / RANDOM
void fillArray(int array[], int questionNumber) {
    for (int i = 0; i < questionNumber; i++) {     // fill array
        array[i] = i;
    }
}

void shuffleArray(int array[], int questionNumber) {
    for (int i = 0; i < questionNumber; i++) {    // shuffle array
        int temp = array[i];
        int randomIndex = rand() % questionNumber;

        array[i]           = array[randomIndex];
        array[randomIndex] = temp;
    }
}

///MAIN
int main(int argc, char**argv)
{
    //variables
    FILE *input, *destination;
    char databaseName[BUFOR];
    int questionsAmount = 0,
    questionNumber = 0,
    currentLine = 0,
    correctAnswers = 0,
    switchesAmount = 0;
    char *nick = NULL;
    question * head = NULL;
    char line[BUFOR];
    char answers[ANSWER_AMOUNT][BUFOR];
    char questionText[BUFOR];
    int correctAnswer;
    char anserwsFileName[BUFOR];

    //switches handling
    int opt;
    while ((opt = getopt(argc, argv, "o:n:q:")) != -1) {
        switch (opt) {
        case 'o':
            strcpy(databaseName, optarg);
            switchesAmount++;
            break;
        case 'n':
            nick = optarg;
            switchesAmount++;
            break;
        case 'q':
            questionsAmount = atoi(optarg);
            switchesAmount++;
            break;
        default:
            exit(EXIT_FAILURE);
        }
    }

    if (switchesAmount !=3) {
        printf("Zla ilość przełączników!");
        exit(EXIT_FAILURE);
    }

    //wczytanie pytan do listy
    input = Fopen(databaseName, "r");
    head = malloc(sizeof(question));
    if (head == NULL) {
        return 1;
    }

    while (fgets(line, sizeof(line), input)) {
        //printf("line %d, %s", currentLine, line);

        if (currentLine == 0) strcpy(questionText, line);
        else if (currentLine == 1) correctAnswer = atoi(line);
        else strcpy(answers[currentLine-2], line);

        if (currentLine == 5) {
            push(head, questionNumber, answers, questionText, correctAnswer);
            questionNumber++;
            currentLine = -1;
        }

        currentLine++;
    }
    fclose(input);

    //losowanie pytan
    int *shuffledQuestionsArr = malloc(questionNumber * sizeof(int));
    fillArray(shuffledQuestionsArr, questionNumber);
    shuffleArray(shuffledQuestionsArr, questionNumber);

    //asking questions
    if (questionsAmount>questionNumber) questionsAmount=questionNumber;
    askQuestions(head, questionsAmount, shuffledQuestionsArr, &correctAnswers);

    //writing to file
    time_t t; //reading time
    time(&t);

    strcpy(anserwsFileName, "wyniki-");
    strcat(anserwsFileName, databaseName);
    destination = Fopen(anserwsFileName, "a");
    fprintf(destination, "%s - %d/%d, wykonano: %s\n", nick, correctAnswers, questionsAmount, ctime(&t));
    fclose(destination);

    return 0;
}