NAC_Blockchain/charter-std/utils/math.ch

pub fn safe_add(a: u256, b: u256) -> u256 {
    let result = a + b;
    require(result >= a, "Addition overflow");
    return result;
}

pub fn safe_sub(a: u256, b: u256) -> u256 {
    require(a >= b, "Subtraction underflow");
    return a - b;
}

pub fn safe_mul(a: u256, b: u256) -> u256 {
    if a == 0 {
        return 0;
    }
    let result = a * b;
    require(result / a == b, "Multiplication overflow");
    return result;
}

pub fn safe_div(a: u256, b: u256) -> u256 {
    require(b > 0, "Division by zero");
    return a / b;
}

pub fn safe_mod(a: u256, b: u256) -> u256 {
    require(b > 0, "Modulo by zero");
    return a % b;
}

pub fn max(a: u256, b: u256) -> u256 {
    return if a >= b { a } else { b };
}

pub fn min(a: u256, b: u256) -> u256 {
    return if a <= b { a } else { b };
}

pub fn abs_diff(a: u256, b: u256) -> u256 {
    return if a >= b { a - b } else { b - a };
}

pub fn percentage(amount: u256, basis_points: u16) -> u256 {
    require(basis_points <= 10000, "Basis points must be <= 10000");
    return safe_mul(amount, basis_points as u256) / 10000;
}

pub fn proportion(amount: u256, numerator: u256, denominator: u256) -> u256 {
    require(denominator > 0, "Denominator cannot be zero");
    return safe_mul(amount, numerator) / denominator;
}

pub fn ceil_div(a: u256, b: u256) -> u256 {
    require(b > 0, "Division by zero");
    if a == 0 {
        return 0;
    }
    return (a - 1) / b + 1;
}

pub fn pow(base: u256, exponent: u256) -> u256 {
    if exponent == 0 {
        return 1;
    }
    if base == 0 {
        return 0;
    }
    let mut result: u256 = 1;
    let mut b = base;
    let mut e = exponent;
    while e > 0 {
        if e % 2 == 1 {
            result = safe_mul(result, b);
        }
        b = safe_mul(b, b);
        e = e / 2;
    }
    return result;
}

pub fn sqrt(x: u256) -> u256 {
    if x == 0 {
        return 0;
    }
    if x <= 3 {
        return 1;
    }
    let mut z = x;
    let mut y = (x + 1) / 2;
    while y < z {
        z = y;
        y = (x / y + y) / 2;
    }
    return z;
}

pub fn average(a: u256, b: u256) -> u256 {
    return (a / 2) + (b / 2) + ((a % 2 + b % 2) / 2);
}

pub fn weighted_average(values: Vec<u256>, weights: Vec<u256>) -> u256 {
    require(values.len() == weights.len(), "Arrays length mismatch");
    require(values.len() > 0, "Arrays cannot be empty");
    let mut sum: u256 = 0;
    let mut weight_sum: u256 = 0;
    for i in 0..values.len() {
        sum = safe_add(sum, safe_mul(values[i], weights[i]));
        weight_sum = safe_add(weight_sum, weights[i]);
    }
    require(weight_sum > 0, "Weight sum cannot be zero");
    return sum / weight_sum;
}

pub fn sum(values: Vec<u256>) -> u256 {
    let mut result: u256 = 0;
    for value in values {
        result = safe_add(result, value);
    }
    return result;
}

pub fn array_max(values: Vec<u256>) -> u256 {
    require(values.len() > 0, "Array cannot be empty");
    let mut max_value = values[0];
    for value in values {
        if value > max_value {
            max_value = value;
        }
    }
    return max_value;
}

pub fn array_min(values: Vec<u256>) -> u256 {
    require(values.len() > 0, "Array cannot be empty");
    let mut min_value = values[0];
    for value in values {
        if value < min_value {
            min_value = value;
        }
    }
    return min_value;
}

pub fn compound_interest(principal: u256, rate_basis_points: u16, periods: u256) -> u256 {
    require(rate_basis_points <= 10000, "Rate must be <= 100%");
    if periods == 0 {
        return principal;
    }
    let rate_factor = 10000 + (rate_basis_points as u256);
    let mut result = principal;
    for _ in 0..periods {
        result = safe_mul(result, rate_factor) / 10000;
    }
    return result;
}

pub fn simple_interest(principal: u256, rate_basis_points: u16, periods: u256) -> u256 {
    require(rate_basis_points <= 10000, "Rate must be <= 100%");
    let interest = safe_mul(safe_mul(principal, rate_basis_points as u256), periods) / 10000;
    return safe_add(principal, interest);
}

pub fn calculate_apy(initial_value: u256, final_value: u256, days: u256) -> u16 {
    require(initial_value > 0, "Initial value must be positive");
    require(days > 0, "Days must be positive");
    if final_value <= initial_value {
        return 0;
    }
    let gain = final_value - initial_value;
    let return_rate = safe_mul(gain, 10000) / initial_value;
    let apy = safe_mul(return_rate, 365) / days;
    return min(apy, 10000) as u16;
}