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

EXEC SQL INCLUDE sqlca;

int state = -1;

struct user
{
    int id;
    char login[32];
    char passwd[32];
    int admin;
    user(char* _login, char* _passwd, int _id)
    {
    id = _id;
    strcpy(login, _login);
    strcpy(passwd, _passwd);
    if (strcmp("admin", login) == 0)
    {
        admin = 1;
    }
    else
    {
        admin = 0;
    }
    }
};

user* u;

static void set_error_handler(void)
{
    EXEC SQL WHENEVER SQLERROR SQLPRINT;
}

static void connect()
{
    EXEC SQL CONNECT TO ikryukov@gagarine USER ikryukov IDENTIFIED BY krukovilya;
    EXEC SQL SET AUTOCOMMIT TO ON;
}

static void disconnect()
{
    EXEC SQL DISCONNECT ALL;
}
void printMenu()
{
    printf("Menu:\n");
    printf("1) view user list\n");
    printf("2) add new user (for admin only)\n");
    printf("3) add new task (for admin only)\n");
    printf("4) take test!\n");
    printf("5) view statistic\n");
    printf("0) exit\n");

}
static user* login()
{
    EXEC SQL BEGIN DECLARE SECTION;
    char login[80];
    char passwd[80];
    int id = -1;
    EXEC SQL END DECLARE SECTION;
    printf("login: ");
    scanf("%s", login);
    printf("password: ");
    scanf("%s", passwd);
    EXEC SQL SELECT users.id INTO :id FROM users WHERE users.login = :login AND users.password = :passwd;
    if (id == -1)
    {
    printf("Sorry, wrong login or password\n");
    return NULL;
    } else
    {
    printf("id : %d\n", id);
    printf("Hello, %s!\n", login);
    return new user(login, passwd, id);
    }
}
static void addUser()
{
    if (u->admin == 0)
    {
    printf("You are not admin, sorry\n");
    return;
    }
    EXEC SQL BEGIN DECLARE SECTION;
    char login[80];
    char passwd[80];
    int uid = -1;
    EXEC SQL END DECLARE SECTION;
    bool finish = false;
    while(!finish)
    {
        printf("Enter new user login: ");
    scanf("%s", login);
        printf("Enter new user password: ");
        scanf("%s", passwd);
        EXEC SQL SELECT users.id INTO :uid FROM users WHERE users.login = :login;
        if (uid == -1) //user doesn't exist
        {
        finish = true;
        } else
        {
            printf("User exist! Please, try again!\n");
            uid = -1;
        }
    }
    EXEC SQL INSERT INTO users (login, password) values (:login, :passwd);
    printf("User added!\n");
    state = -1;
}
void addTask()
{
    if (u->admin == 0)
    {
    printf("You are not admin, sorry\n");
    return;
    }
    EXEC SQL BEGIN DECLARE SECTION;
    char quest[1024];
    int ans;
    EXEC SQL END DECLARE SECTION;
    printf("Enter new question: \n");
    scanf("%s", quest);
    printf("Enter correct answer: ");
    scanf("%d", &ans);
    EXEC SQL INSERT INTO task (question, answer) values (:quest, :ans);
    printf("Task added!\n");
    state = -1;
}
static void takeTest()
{
    int usr_ans;
    EXEC SQL SET AUTOCOMMIT TO OFF;
    EXEC SQL BEGIN DECLARE SECTION;
    char quest[1024];
    int ans;
    int win = 0;
    int fail = 0;
    int userID = u->id;
    EXEC SQL END DECLARE SECTION;
    EXEC SQL DECLARE iter CURSOR FOR
    SELECT question, answer from task;
    EXEC SQL OPEN iter;
    EXEC SQL WHENEVER NOT FOUND DO BREAK;
    for (;;)
    {
    EXEC SQL FETCH NEXT FROM iter INTO
    :quest, :ans;
    printf("quest : %s\n", quest);
    scanf("%d", &usr_ans);
    if (ans == usr_ans)
    {
        ++win;
    } else
    {
        ++fail;
    }
    }
    EXEC SQL CLOSE iter;
    EXEC SQL COMMIT;
    EXEC SQL SET AUTOCOMMIT TO ON;
    EXEC SQL WHENEVER NOT FOUND CONTINUE;
    EXEC SQL INSERT INTO statistic (user_id, pass, fail) values (:userID, :win, :fail);
    state = -1;
}
static void viewStatistic()
{
    EXEC SQL SET AUTOCOMMIT TO OFF;
    EXEC SQL BEGIN DECLARE SECTION;
    int userID = u->id;
    date test_date;
    int wins;
    int fails;
    EXEC SQL END DECLARE SECTION;
    EXEC SQL DECLARE iter1 CURSOR FOR
    SELECT dates, pass, fail FROM statistic WHERE user_id = :userID;
    EXEC SQL OPEN iter1;
    EXEC SQL WHENEVER NOT FOUND DO BREAK;
    printf("Results for user: %s\n", u->login);
    for (;;)
    {
    EXEC SQL FETCH NEXT FROM iter1 INTO
    :test_date, :wins, :fails;
    char* str_date = PGTYPESdate_to_asc(test_date);
    printf("Date: %s, wins: %d, fails: %d\n", str_date, wins, fails);
    }
    EXEC SQL CLOSE iter1;
    EXEC SQL COMMIT;
    EXEC SQL SET AUTOCOMMIT TO ON;
    EXEC SQL WHENEVER NOT FOUND CONTINUE;
    state = -1;
}
int main()
{
    state = -1;
    set_error_handler();
    printf("start connection\n");
    connect();
    u = login();
    if (u == NULL)
    {
    disconnect();
    return 0;
    }
    while (state != 0)
    {
    switch (state)
    {
        case 1:
        {
        break;
        }
        case 2:
        {
        addUser();
        break;
        }
        case 3:
        {
        addTask();
        break;
        }
        case 4:
        {
        takeTest();
        break;
        }
        case 5:
        {
        viewStatistic();
        break;
        }
    }
    printMenu();
    scanf("%d", &state);
    }
    printf("end connection\n");
    disconnect();
    return 0;
}