//
//  Base64URL.swift
//  AT-IRC
//
//  Base64url helpers used by JWT/DPoP/PKCE encoding.
//

import Foundation

enum Base64URL {
    static func encode(_ data: Data) -> String {
        data.base64EncodedString()
            .replacingOccurrences(of: "+", with: "-")
            .replacingOccurrences(of: "/", with: "_")
            .replacingOccurrences(of: "=", with: "")
    }

    static func decode(_ string: String) -> Data? {
        var s = string
            .replacingOccurrences(of: "-", with: "+")
            .replacingOccurrences(of: "_", with: "/")
        let remainder = s.count % 4
        if remainder > 0 {
            s += String(repeating: "=", count: 4 - remainder)
        }
        return Data(base64Encoded: s)
    }
}

extension Data {
    /// Random bytes from the system CSPRNG.
    static func random(count: Int) -> Data {
        var bytes = [UInt8](repeating: 0, count: count)
        _ = SecRandomCopyBytes(kSecRandomDefault, bytes.count, &bytes)
        return Data(bytes)
    }
}