#include <inttypes.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "numberrep.h"

#define MAX_BASE 36

// A number can be interpreted as base N if it only contains characters chosen
// from the first N elements of this string.
//
// Note that this implies that we support numbers up to base 36.
const char allowed_chars[MAX_BASE] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";

// Validates a number given a base. If the number is invalid, this exits the
// program with a relevant error message.
//
// Params
// ------
// char *number :
//     The number we are validating.
// uint32_t base :
//     The base for which we are making sure number is valid. 
//     Must be less than MAX_BASE
//
// Examples
// --------
// validate_number("FFF", 16) // Valid, so nothing happens.
// validate_number( "10",  2) // Valid, so nothing happens.
// validate_number("FFF", 10) // Invalid, so the program exits.
// validate_number("100", 37) // Base is too high, so program exits.
void validate_number(char *number, uint32_t base) {
    if (base > MAX_BASE) {
        fprintf(stderr, "Base %d is too large", base);
        exit(1);
    }
    if (number == NULL) {
        fprintf(stderr, "Number is null");
        exit(1);
    }
    size_t length = strlen(number);
    for (size_t i = 0; i < length; i++) {
        int valid = 0;
        for (int j = 0; j < base; j++) {
            valid = valid || number[i] == allowed_chars[j];
        }
        if (!valid) {
            fprintf(stderr, "Number %s is invalid in base %d", number, base);
            exit(1);
        }
    }
}

// Converts a number to its corresponding unsigned representation in decimal.
//
// Params
// ------
// char *number :
//     The number we are converting to decimal.
//
// Examples
// --------
// convert_to_decimal("11Z", 36) // 1367
// convert_to_decimal("101",  2) // 5
// convert_to_decimal("ABC", 16) // 2748
uint64_t convert_to_decimal(char *number, uint32_t base) {
    validate_number(number, base);

    // YOUR CODE HERE //

    return 0;
}

// Converts an unsigned decimal to the given base.
//
// Params
// ------
// uint64_t number :
//     The unsigned decimal number we are converting.
// uint32_t base :
//     The base we are converting to.
//
// Examples
// --------
// decimal_to_base(1367, 36) // "11Z"
// decimal_to_base(   5,  2) // "101"
// decimal_to_base(2748, 16) // "ABC"
char *decimal_to_base(uint64_t number, uint32_t base) {

    // YOUR CODE HERE //

    return NULL;
}

// Converts an unsigned number from one base to another.
// 
// Params
// ------
// char *number :
//     The number we are converting.
// uint32_t orig_base :
//     The original base for the number.
// uint32_t new_base :
//     The new base for the number.
//
// Examples
// --------
// convert_base("11Z", 36,  2) // "10101010111"
// convert_base("ABC", 16, 36) // "24C"
char *convert_base(char *number, uint32_t orig_base, uint32_t new_base) {
    validate_number(number, orig_base);
    return decimal_to_base(convert_to_decimal(number, orig_base), new_base);
}