// PKCE utilities for OIDC flow
function generateRandomString(length: number): string {
  const possible = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'
  let text = ''
  for (let i = 0; i < length; i++) {
    text += possible.charAt(Math.floor(Math.random() * possible.length))
  }
  return text
}

async function generateCodeChallenge(verifier: string): Promise<string> {
  const encoder = new TextEncoder()
  const data = encoder.encode(verifier)
  const digest = await crypto.subtle.digest('SHA-256', data)
  const base64 = btoa(String.fromCharCode(...new Uint8Array(digest)))
  return base64.replace(/\+/g, '-').replace(/\//g, '_').replace(/=/g, '')
}

export async function createPKCE(): Promise<{ verifier: string; challenge: string }> {
  const verifier = generateRandomString(128)
  const challenge = await generateCodeChallenge(verifier)
  return { verifier, challenge }
}

export function storePKCE(verifier: string): void {
  sessionStorage.setItem('pkce_verifier', verifier)
}

export function getPKCE(): string | null {
  return sessionStorage.getItem('pkce_verifier')
}

export function clearPKCE(): void {
  sessionStorage.removeItem('pkce_verifier')
}

export function storeToken(token: string): void {
  localStorage.setItem('access_token', token)
}

export function getToken(): string | null {
  return localStorage.getItem('access_token')
}

export function clearToken(): void {
  localStorage.removeItem('access_token')
}