// MathUtils.swift
// Mathematical utility functions
// Corresponds to MathUtils.kt in Android implementation

import Foundation

public class MathUtils {
    private static let _fibonacciArray: [Int] = [
        1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, 1597, 2584, 4181, 6765, 10946,
        17711, 28657, 46368, 75025, 121393, 196418, 317811, 514229, 832040, 1346269, 2178309, 3524578,
        5702887, 9227465, 14930352, 24157817, 39088169, 63245986, 102334155, 165580141, 267914296,
        433494437, 701408733, 1134903170, 1836311903, 2971215073
    ]
    
    public static func fibonacci(_ n: Int, offset: Int = 0) -> Int64 {
        let len = _fibonacciArray.count
        let idx = n + offset
        
        if idx < len {
            return Int64(_fibonacciArray[idx])
        }
        
        var n1 = Int64(_fibonacciArray[len - 2])
        var n2 = Int64(_fibonacciArray[len - 1])
        var sum: Int64 = 0
        
        for _ in len..<idx {
            sum = n1 + n2
            n1 = n2
            n2 = sum
        }
        
        return sum
    }
}