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

#include "updateCustomerAccountBalance.h"
#include "lineReplacer.h"
#include "_file_information.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 or that the program has the required permissions?");
            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[1024];
    int current_line = 1;
    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", 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, "%g", 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 customer_found=false;
    char buffer[MAX_LENGTH];
    char stringID[MAX_LENGTH] = "ID=";
    char user_id_as_string[MAX_LENGTH];
    char balance_String[MAX_LENGTH];
    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+"); 
    if (file == NULL) {
        troubleShoot(0);
        return false;
    }
    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);
            }

            strcpy(balance_String, buffer);
            currentLine+=4;
            keep_reading = false;
            customer_found=true;
        }

    }
    
    fclose(file);;
    if(customer_found){
        replaceBalanceInString(newBalance,currentLine);
        return true;
    }else{
        troubleShoot(4);
    }
    return false;
    
}
bool checkCustomerExists(int customerID){
    bool keep_reading = true;
    bool customer_found=false;
    char buffer[MAX_LENGTH];
    char stringID[MAX_LENGTH] = "ID=";
    char user_id_as_string[MAX_LENGTH];
    char balance_String[MAX_LENGTH];
    int currentLine=0;
    
    sprintf(user_id_as_string, "%d", customerID); // converts user_id to string
    strcat(stringID, user_id_as_string);

    FILE *file = fopen(CUSTOMER_DATA_FILE, "r+"); 
    if (file == NULL) {
        return false;
    }
    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);
            }

            strcpy(balance_String, buffer);
            currentLine+=4;
            keep_reading = false;
            customer_found=true;
        }

    }
    
    fclose(file);;
    if(customer_found){
        return true;
    }else{
        return false;
    }
    return false;
    
}

//traditional testing section
/*
int main(int argc, char *argv[])
{
    updateAvailableAccountBalance(1327,70);
    return 0;
}
*/