#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "student.h"

// Allocate enough memory to store a new student then return a pointer to it
student_t * initialize_student() {
    student_t *student = NULL;
    student = (student_t*)malloc(sizeof(student));
    return student;
}

// Creates a student based on user input and returns a pointer to that student
student_t * create_student() {
    student_t *student = initialize_student();
    if(student) {
        printf("Enter student id:\n\n");
        scanf("%i", &student->id);
        getchar(); // Remove the newline from the buffer

        printf("Enter student name:\n\n");
        fgets(student->name, sizeof(student->name), stdin);
        student->name[(size_t)strlen(student->name) - 1] = '\0'; // Remove the newline from end of the array

        printf("Enter student age:\n\n");
        scanf("%i", &student->age);
        getchar(); // Remove the newline from the buffer 
    } else {
        printf("No student to assign information to, please ensure that the student has been initialized.\n");
    }
    return student;
}

// Reads information from a text file and returns a pointer to a student with that information
student_t * read_student_file() {
    student_t *student = initialize_student();
    if(student) { // Ensure the program was able to allocate memory for the student
        FILE *f = fopen("student_reads.txt", "r");
        if(f) { // Ensure the program was able to find the text file
            fscanf(f, "%i\n", &student->id);
            fgets(student->name, sizeof(student->name), f);
            student->name[strlen(student->name) - 1 ] = '\0';
            fscanf(f, "%i\n", &student->age);
        } else {
            printf("Error opening text file. Please review the file path to ensure it is set correctly.\n");
        }
        fclose(f);
    } else {
        printf("No student to assign information to, please ensure that the student has been initialized.\n");
    }

    return student;
}

// Reads information from a previously created student and writes that information to a text file
void write_student_file( student_t * student ) {
    if(student) { // Ensure the program was able to allocate memory for the student
        FILE *f = fopen("student_write.txt", "w");
        fprintf(f, "%i\n", student->id);
        fprintf(f, "%s\n", student->name);
        fprintf(f, "%i\n", student->age);
        printf("Information has been written to 'student_write.txt'\n\n");
        fclose(f);
    } else {
        printf("No student to assign information to, please ensure that the student has been initialized.\n");
    }
    free(student); // Free the memory previously allocated for that student
}

// Print information about a given student
void print_student( student_t * student ) {
    if(student) { // Ensure the program was able to allocate memory for the student
        printf("Student id: %i\n", student->id);
        printf("Name: %s\n", student->name);
        printf("Age: %i\n\n", student->age); // Extra newline for better formatting
    } else {
        printf("No student to read information from, please ensure that the student has been initialized\n");
    }
    free(student); // Free the memory previously allocated for that student
}

// Prints a menu of options that loops continually until the user chooses to exit the program.
void show_menu() {
    int user_choice;
    do {
        printf("1. Read student information from file\n");
        printf("2. Write student information to file\n");
        printf("3. Exit\n\n"); // Extra newline for better formatting
        scanf("%i", &user_choice);

        switch(user_choice) {
            case 1:
                print_student( read_student_file() );
                break;
            case 2:
                write_student_file( create_student() );
                break;
            case 3:
                printf("You have chosen to exit the program\n");
                break;
            default: // Handle wrong input from the user
                printf("Error, please review that you entered a number between 1 and 3\n");
        }
    } while(user_choice != 3);
}