file_handler.c

#include <stdio.h>
#include "file_handler.h"

int file_exists(const char *path) {
    FILE *f = fopen(path, "rb");
    if (f) { fclose(f); return 1; }
    return 0;
}

void ensure_data_file() {
    if (!file_exists(STUDENT_DATA_FILE)) {
        FILE *f = fopen(STUDENT_DATA_FILE, "wb");
        if (f) fclose(f);
    }
}

int find_student_by_id(int id, Student *out, long *position) {
    ensure_data_file();
    FILE *fp = fopen(STUDENT_DATA_FILE, "rb");
    if (!fp) return 0;
    Student s;
    long pos = 0;
    while(fread(&s, sizeof(Student), 1, fp) == 1) {
        if (s.id == id) {
            if (out) *out = s;
            if (position) *position = pos;
            fclose(fp);
            return 1;
        }
        pos += sizeof(Student);
    }
    fclose(fp);
    return 0;
}

void updateStudentRoomInFile(int id) {
    ensure_data_file();
    FILE *fp = fopen(STUDENT_DATA_FILE, "rb+");
    if (!fp) { printf("Failed to open data file\n"); return; }

    Student s;
    long pos = 0;
    while(fread(&s, sizeof(Student), 1, fp) == 1) {
        if (s.id == id) {
            printf("Current Room: %d\nEnter new room: ", s.room);
            if (scanf("%d", &s.room) != 1) { while(getchar()!='\n'); printf("Invalid room\n"); fclose(fp); return; }
            fseek(fp, pos, SEEK_SET);
            if (fwrite(&s, sizeof(Student), 1, fp) != 1) {
                printf("Failed to update student record\n");
            } else {
                printf("Room updated successfully\n");
            }
            fclose(fp);
            return;
        }
        pos += sizeof(Student);
    }
    printf("Student with ID %d not found\n", id);
    fclose(fp);
}

void increaseMealCount(int id) {
    ensure_data_file();
    FILE *fp = fopen(STUDENT_DATA_FILE, "rb+");
    if (!fp) { printf("Failed to open data file\n"); return; }

    Student s;
    long pos = 0;
    while(fread(&s, sizeof(Student), 1, fp) == 1) {
        if (s.id == id) {
            s.mealCount += 1;
            fseek(fp, pos, SEEK_SET);
            if (fwrite(&s, sizeof(Student), 1, fp) != 1) {
                printf("Failed to update meal count\n");
            } else {
                printf("Meal count increased. Total meals: %d\n", s.mealCount);
            }
            fclose(fp);
            return;
        }
        pos += sizeof(Student);
    }
    printf("Student with ID %d not found\n", id);
    fclose(fp);
}