#include <stdio.h>
#include <string.h>
#include <stdbool.h>
#include <math.h>
#include <stdlib.h>

// Performs operations listed below
        // Operation Key
        // 1: Addition
        // 2: Subtraction
        // 3: Multiplication
        // 4: Division
        // 5: Exponent
double basic_operation(int operation) {
        double val1, val2, return_val;
        for (int i = 1; i <= 2; i++) {
                double val;
                printf("Please enter value %d: ", i);
                if (i == 1) {
                        scanf("%lf", &val1);
                }
                else {
                        scanf("%lf", &val2);
                }
        }
        switch (operation) {
                case 1:
                        return_val = val1 + val2;
                        break;
                case 2:
                        return_val = val1 - val2;
                        break;
                case 3:
                        return_val = val1 * val2;
                        break;
                case 4:
                        return_val = val1 / val2;
                        break;
                case 5:
                        return_val = 1;
                        for (int i = 0; i < val2; i++) {
                                return_val *= val1;
                        }
                        break;
        }
        return return_val;
}

// Returns the square root of an entered value
double square_root() {
        double val;
        printf("Please enter the value you wish to square root: ");
        scanf("%lf", &val);
        return sqrt(val);
}

void help_text(bool welcome) {
        printf(".... Simple C Calculator ....\n");
        printf("... Written by Liam Keeton ..\n");
        printf("Operations:\n[+] [-] [*] [/]\n[^] [√] [?] [q]\n");
        if (welcome) {
                printf("\n");
        }
}

void select_operation(int iteration) {
        char operation[50];
        int amount_vals;
        printf("Calculation[%d]: Please enter the operation you wish to use: ", iteration);
        scanf("%s", operation);
        if (strcmp(operation, "+") == 0) {
                printf("The sum: %lf\n", basic_operation(1));
        }
        else if (strcmp(operation, "-") == 0) {
                printf("The difference: %lf\n", basic_operation(2));
        }
        else if (strcmp(operation, "*") == 0) {
                printf("The product: %lf\n", basic_operation(3));
        }
        else if (strcmp(operation, "/") == 0) {
                printf("The quotient: %lf\n", basic_operation(4));
        }
        else if (strcmp(operation, "exp") == 0) {
                printf("The power: %lf\n", basic_operation(5));
        }
        else if (strcmp(operation, "sqrt") == 0) {
                printf("The square root: %lf\n", square_root());
        }
        else if (strcmp(operation, "?") == 0) {
                help_text(false);
        }
        else if (strcmp(operation, "q") == 0) {
                exit(0);
        }
        else {
                printf("Unrecognised Operation.\n");
        }
        printf("\n");
        select_operation(iteration + 1);
}

int main() {
        help_text(true);
        select_operation(1);
}