//Program to add, modify and remove data about workers.
//Do you approve it?

//P.S.: Compile with -lm option if you got a linker error.

#include <stdio.h>
#include <ctype.h>
#include <math.h>


struct data{
    char first_name[255];
    char second_name[255];
    char position[255];
    char data_read[65535];

    int age;
    int days_since_employement;
    int days_until_next_vacation;
    int salary;
    int years_of_experience;
};

void get_string(char[], int);
int get_number();
int save_data(struct data, char[]);
int main(){

    char input[255];

    int i,c;
    int exit = 0;

    struct data worker;

    while(!exit){
        if(c != '1'){
            printf("Workers assignement program.\nThis program is used to add or to remove data about workers.\n\n");
            printf("\t\t-To add a new worker, insert 1\n\t\t-To remove a worker, insert 2\n\t\t-To modify data about a worker, insert 3\n");
            printf("\t\t-To seek help, insert 4\n\t\t-To quit, insert 'q'\n\n");
            printf("\\>");
            c = getchar();
        }
        switch(c){
            case '1':
                while(c == '1'){
        //second getchar to flush stdin.
                    getchar();
                    printf("First name: ");
                    get_string(worker.first_name, 255);
                    printf("Second name: ");
                    get_string(worker.second_name, 255);
                    printf("Position: ");
                    get_string(worker.position, 255);

                    printf("Age: ");
                    worker.age = get_number();
                    printf("Days since employement: ");
                    worker.days_since_employement = get_number();
                    printf("Days until next vacation: ");
                    worker.days_until_next_vacation = get_number();
                    printf("Salary(in USD): ");
                    worker.salary = get_number();
                    printf("Years of experience: ");
                    worker.years_of_experience = get_number();
                    printf("\nWorker's data:\n");

                    printf("\tFirst name: %s\n", worker.first_name);
                    printf("\tSecond name: %s\n", worker.second_name);
                    printf("\tAge: %d\n", worker.age);
                    printf("\tDays since employement: %d\n", worker.days_since_employement);
                    printf("\tDays until next vacation: %d\n", worker.days_until_next_vacation);
                    printf("\tYears of experience: %d\n", worker.years_of_experience);

                    printf("Is this correct?(Y/n)");

                    while((c = getchar()) != 'Y' && c != 'y' && c != 'N' && c != 'n')
                        printf("Is this correct?(Y/n)");
                    if(c == 'Y' || c == 'y'){
                        getchar();
                        printf("Please re-insert the first name of the worker: ");
                        get_string(input, 255);
                        save_data(worker, input);
                        printf("Information saved. Press enter to proceed\n\n");
                        getchar();
                    }
                    else if(c == 'N' || c == 'n'){
                        printf("Operation reset.\n");
                    //this is supposed to make the case start over.
                        c = '1';
                    //again, flushing stdin. Would appreciate an explanation with a solution.
                        getchar();
                    }
                }
                break;
            case '2':
                getchar();
                printf("Please insert the worker's name: ");
                get_string(input, 255);
                printf("\nDo you confirm the deletion of the data of this worker?(Y/n)");

                while((c = getchar()) != 'Y' && c != 'y' && c != 'N' && c != 'n')
                    printf("\nDo you confirm the deletion of the data of this worker?(Y/n)");

                if(c == 'Y' || c == 'y'){
                    if(remove(input))
                        printf("Failed to remove the file\n");
                    else
                        printf("File removed successfully.\n\n");
                    getchar();
                }
                else if(c == 'N' || c == 'n')
                    printf("Operation aborted.\n");
                break;
            case '3':
                FILE *fp;
                getchar();
                printf("Please insert the worker's name: ");
                get_string(input, 255);
                printf("\n\n\n");
                if((fp = fopen(input, "r+")) == NULL){
                    printf("Error while reading data");
                    return -1;
                }
                else
                    while((c = getc(fp)) != EOF)
                        printf("%c",c);
                printf("\nModify this file?(Y/n)");
            //Pretty lazy, isn't?
                while((c = getchar()) != 'Y' && c != 'y' && c != 'N' && c != 'n')
                    printf("\nModify this file?(Y/n)");

                if(c == 'Y' || c == 'y')
                    c = '1';

                else if(c == 'N' || c == 'n'){
                    printf("Operation aborted.\n");
                    getchar();
                }
                break;
            case '4':
                getchar();
                printf("This program is used to create, modify and delete info about the workers.\n");
                printf("When data is created, it will be saved in a file with a desired name, it is preferred that the name of the file matches the first name of the employee for easier access.\n\n\n");
                break;
            case 'q':
                exit++;
                break;
            default:
                printf("Unknown selection.\n");
                break;
        }
    }
    return 0;
}

void get_string(char string[], int max){
    int c, i;
    for(c = i = 0; (c = getchar()) != EOF && c != '\n' && i < max;)
        string[i++] = c;
    string[i] = 0;
    if(i >= max)
        printf("Notice from get_string(): max amount of characters reached.\n");
    return;
}

int get_number(){
    int c, i, j, k;
    char inputted_number_in_char[255];

    for(c = i = 0; (c = getchar()) != EOF && c != '\n' && i < 255;)
        if(isdigit(c))
            inputted_number_in_char[i++] = c;
        else{
            printf("Notice from get_number(): input contains a non-digit character\n.");
            return 0;
        }
    inputted_number_in_char[i--] = 0;
    j = k = 0;
    while(i >= 0)
        j += ((inputted_number_in_char[i--] - '0') * pow(10,k++));
    return j;
}

int save_data(struct data employee, char file_name[]){
    FILE *fp;
    char part0[] = "\t EMPLOYEE INFORMATION \n\n\0";
    char part1[] = "\t\tFirst name: \0";
    char part2[] = "\t\tSecond name: \0";
    char part3[] = "\t\tPosition: \0";
    char part4[] = "\t\tAge: \0";
    char part5[] = "\t\tDays since employement: \0";
    char part6[] = "\t\tDays until next vacation: \0";
    char part7[] = "\t\tSalary: \0";
    char part8[] = "\t\tYears of experience: \0";

    char input[255];

    if((fp = fopen(file_name, "w")) == NULL){
        printf("Error: can't create file %s", file_name);
        return -1;
    }

    int i = 0;
    while(part0[i] != '\0'){
        putc(part0[i++], fp);
    }
    i = 0;
    while(part1[i] != '\0'){
        putc(part1[i++], fp);
    }
    i = 0;
    while(employee.first_name[i] != '\0'){
        putc(employee.first_name[i++], fp);
    }
    putc('\n', fp);
    i = 0;
    while(part2[i] != '\0'){
        putc(part2[i++], fp);
    }
    i = 0;
    while(employee.second_name[i] != '\0'){
        putc(employee.second_name[i++], fp);
    }
    putc('\n', fp);
    i = 0;
    while(part3[i] != '\0'){
        putc(part3[i++], fp);
    }
    i = 0;
    while(employee.position[i] != '\0'){
        putc(employee.position[i++], fp);
    }
    putc('\n', fp);
    i = 0;
    while(part4[i] != '\0'){
        putc(part4[i++], fp);
    }
    //Thanks, Dave Jarvis and cnicutar from Stack Overflow
    sprintf(input, "%d", employee.age);
    i = 0;
    while(input[i] != '\0'){
        putc(input[i++], fp);
    }
    putc('\n', fp);
    i = 0;
    while(part5[i] != '\0'){
        putc(part5[i++], fp);
    }
    sprintf(input, "%d", employee.days_since_employement);
    i = 0;
    while(input[i] != '\0'){
        putc(input[i++], fp);
    }
    putc('\n', fp);
    i = 0;
    while(part6[i] != '\0'){
        putc(part6[i++], fp);
    }
    sprintf(input, "%d", employee.days_until_next_vacation);
    i = 0;
    while(input[i] != '\0'){
        putc(input[i++], fp);
    }
    putc('\n', fp);
    i = 0;
    while(part7[i] != '\0'){
        putc(part7[i++], fp);
    }
    sprintf(input, "%d", employee.salary);
    i = 0;
    while(input[i] != '\0'){
        putc(input[i++], fp);
    }
    putc('\n', fp);
    i = 0;
    while(part8[i] != '\0'){
        putc(part8[i++], fp);
    }
    sprintf(input, "%d", employee.years_of_experience);
    i = 0;
    while(input[i] != '\0'){
        putc(input[i++], fp);
    }
    putc('\n', fp);

    fclose(fp);
    return 0;
}