#include "currentCustomerAccountBalance.h"

float fetchBalanceFromBalanceString(char balance_String[MAX_LENGTH]) {
    float balance = 0;
    char *token = strtok(balance_String, "="); // separates string to two parts
    while (token != NULL) {
        if (atoi(token) != 0) {
            balance = atof(token); // converts string to float
            break;
        }
        token = strtok(NULL, "=");
    }
    return balance;
}

float readFileAndGetAvailableBalance(FILE *file, char stringID[MAX_LENGTH]) {
    float balance = 0;
    bool keep_reading = true;
    char buffer[MAX_LENGTH];
    char balance_String[MAX_LENGTH];

    while(keep_reading) {
        fgets(buffer, MAX_LENGTH, file);
        if (feof(file)) {
            keep_reading = false;
        }
        else if(strstr(buffer, stringID)) {
            for (int i = 0; i < 4; i++) {
                fgets(buffer, MAX_LENGTH, file);
            }
            strcpy(balance_String, buffer);
            balance = fetchBalanceFromBalanceString(balance_String);
            keep_reading = false;
        }

    }
    return balance;
}

float getAvailableAccountBalance(int user_id) {
    float availableBalance = 0;
    char stringID[MAX_LENGTH] = "ID=";
    char user_id_as_string[MAX_LENGTH];

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

    FILE *file = fopen(CUSTOMER_DATA_FILE, "r"); 
    if(file == 0) {
        printf("Error: customer data file cannot be opened!\n");
        return 0;
    }
    else {
        availableBalance = readFileAndGetAvailableBalance(file, stringID);
    }

    
    fclose(file);
    
    return availableBalance;
    
}