2022-2-WS_group_project_bankmanagement-system/src/updateCustomerAccountBalance.c

#include "updateCustomerAccountBalance.h"
#include "currentCustomerAccountBalance.c"
#include "lineReplacer.h"

void troubleShoot(int errorCode){
    printf("Error! The requested operation was terminated because of an issue. Here are some details about the error:\n---------------\n");

    switch(errorCode){
        case 0:
            printf("Requested file could not be opened. Are you sure it exists?");
            break;
        case 1:
            printf("A temporary file could not be generated. Are you sure the bank management system has the required authorization to create new files?");
            break;
        case 2:
            printf("Replacement of the old file failed. Are you sure the bank management system has the required authorization to delete files?");
            break;
        case 3:
            printf("Renaming of a file failed. Are you sure the bank management system has the required authorization to rename files?");
            break;        
        case 4:
            printf("Could not find the customer. Please contact customer support.");
            break;
    }
}

void replaceLineInFile(const char* file_name, int line, const char* new_line){
    FILE* file = fopen(file_name, "r");
    if (file == NULL) {
        troubleShoot(0);
        return;
    }
    char current_string[100];
    int current_line = 1;
    char *temp_file_name = calloc(8+1, sizeof(char));
    temp_file_name = "temp.txt";
    FILE* temp_file = fopen(temp_file_name, "w");
    if (temp_file == NULL) {
        troubleShoot(1);
        fclose(file);
        return;
    }
    while (fgets(current_string, sizeof(current_string),file) != NULL) {
        if (current_line == line) {
            fprintf(temp_file, "%s\n", new_line);
            //fputs("\n", temp_file);
        } else {
            fprintf(temp_file, "%s", current_string);
        }
        current_line++;
    }
    fclose(file);
    fclose(temp_file);
    if(remove(file_name)!=0){
        troubleShoot(2);
    } // Remove the original file
    if(rename(temp_file_name, file_name)!=0){
        troubleShoot(3);
    } // Rename the temp file to the original file
}

void replaceBalanceInString(float replacementBalance, int currentLine) {
    char newBalanceLine[MAX_LENGTH] = "balance=";
    char balance_as_string[MAX_LENGTH];
    sprintf(balance_as_string, "%f", replacementBalance); //converts replacement balance to string
    strcat(newBalanceLine, balance_as_string);
    replaceLineInFile(CUSTOMER_DATA_FILE,currentLine,newBalanceLine);
}

bool updateAvailableAccountBalance(int user_id, float newBalance){

    bool keep_reading = true;
    bool foundCustomer = false;

    char *buffer = malloc(MAX_LENGTH * sizeof(char));
    char *stringID = malloc(MAX_LENGTH * sizeof(char));
    stringID = "ID=";
    char *user_id_as_string =malloc(MAX_LENGTH * sizeof(char));
    char *balance_String = malloc(MAX_LENGTH * sizeof(char));
    int currentLine=0;

    sprintf(user_id_as_string, "%d", user_id); // converts user_id to string
    strcat(stringID, user_id_as_string);

    FILE *file = fopen(CUSTOMER_DATA_FILE, "r");
    //printf(stringID);
    while(keep_reading) {
        fgets(buffer, MAX_LENGTH, file);
        currentLine++;
        if (feof(file)) {
            keep_reading = false;
        }
        else if(strstr(buffer, stringID)) { //found the customer
            for (int i = 0; i < 4; i++) {
                fgets(buffer, MAX_LENGTH, file);
                currentLine++;
            }
            strcpy(balance_String, buffer);
            keep_reading = false;
            foundCustomer=true;
        }

    }
    fclose(file);

    if(foundCustomer){
        replaceBalanceInString(newBalance,currentLine);
    }else{
        troubleShoot(4);
    }
    
    return true;
}