Product.c

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/*
 * Copyright (c) All Rights Reserved
 * 2025 Oliver Dixon <od641@york.ac.uk>
 */
 
#include "Product.h"
#include <stdio.h>
 
#include <errno.h>
#include <stdlib.h>
#include <string.h>
 
struct Product
{
    unsigned int id; 
    unsigned int quantity; 
    char name[MAX_NAME_LENGTH + 1]; 
};
 
struct Product *product_create(const unsigned int id, const char *const name, const unsigned int quantity)
{
    const size_t name_length = strlen(name);
 
    if (name_length > MAX_NAME_LENGTH) {
        fprintf(stderr, "Name of product \"%s\" exceeds maximum character limit.\n", name);
        return NULL;
    }
 
    errno = 0;
    struct Product *product = malloc(sizeof(struct Product));
 
    if (product == NULL) {
        fprintf(stderr, "Could not create product \"%s\": %s\n", name, strerror(errno));
        return NULL;
    }
 
    product->id = id;
    product->quantity = quantity;
    strncpy(product->name, name, name_length);
    product->name[name_length] = '\0';
 
    return product;
}
 
void product_delete(struct Product **this)
{
    free(*this);
    *this = NULL;
}
 
int product_report_serialise(const struct Product *const this, FILE *const buffer)
{
    return fprintf(buffer, "%-4d | %-" XSTR(MAX_NAME_LENGTH) "s | %-11d\n", this->id, this->name, this->quantity);
}
 
int product_file_serialise(const struct Product *const this, FILE *const buffer)
{
    return fprintf(buffer, "%s\n%d\n", this->name, this->quantity);
}
 
bool product_modify_quantity(struct Product *this, const int modifier)
{
    if (modifier < 0 && (unsigned int) -modifier > this->quantity)
        return false;
 
    this->quantity += modifier;
    return true;
}
 
int product_ptr_compare(const void *const product_lhs, const void *const product_rhs)
{
    const unsigned int lhs_quantity = (*(const struct Product **) product_lhs)->quantity;
    const unsigned int rhs_quantity = (*(const struct Product **) product_rhs)->quantity;
 
    if (lhs_quantity < rhs_quantity)
        return -1;
 
    if (lhs_quantity > rhs_quantity)
        return 1;
 
    return 0;
}