/**
 * PKCE utilities using Web Crypto API.
 * Works in both Node.js 20+ and browsers.
 */
/**
 * Encode bytes as base64url string.
 */
function base64urlEncode(bytes) {
    let binary = '';
    for (const byte of bytes) {
        binary += String.fromCharCode(byte);
    }
    return btoa(binary).replace(/\+/g, '-').replace(/\//g, '_').replace(/=/g, '');
}
/**
 * Generate PKCE code verifier and challenge.
 * Uses Web Crypto API for cross-platform compatibility.
 */
export async function generatePKCE() {
    // Generate random verifier
    const verifierBytes = new Uint8Array(32);
    crypto.getRandomValues(verifierBytes);
    const verifier = base64urlEncode(verifierBytes);
    // Compute SHA-256 challenge
    const encoder = new TextEncoder();
    const data = encoder.encode(verifier);
    const hashBuffer = await crypto.subtle.digest('SHA-256', data);
    const challenge = base64urlEncode(new Uint8Array(hashBuffer));
    return { verifier, challenge };
}
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