import type { PKCEChallenge } from "./types.ts";

export class PKCEUtils {
  static generateCodeVerifier(): string {
    const array = new Uint8Array(32);
    crypto.getRandomValues(array);
    return btoa(String.fromCharCode.apply(null, Array.from(array)))
      .replace(/\+/g, "-")
      .replace(/\//g, "_")
      .replace(/=/g, "");
  }

  static async generateCodeChallenge(verifier: string): Promise<string> {
    const encoder = new TextEncoder();
    const data = encoder.encode(verifier);
    const digest = await crypto.subtle.digest("SHA-256", data);
    return btoa(
      String.fromCharCode.apply(null, Array.from(new Uint8Array(digest)))
    )
      .replace(/\+/g, "-")
      .replace(/\//g, "_")
      .replace(/=/g, "");
  }

  static async generatePKCEChallenge(): Promise<PKCEChallenge> {
    const codeVerifier = this.generateCodeVerifier();
    const codeChallenge = await this.generateCodeChallenge(codeVerifier);
    return {
      codeVerifier,
      codeChallenge,
      codeChallengeMethod: "S256",
    };
  }
  
  static generateState(): string {
    const array = new Uint8Array(16);
    crypto.getRandomValues(array);
    return btoa(String.fromCharCode.apply(null, Array.from(array)))
      .replace(/\+/g, "-")
      .replace(/\//g, "_")
      .replace(/=/g, "");
  }
}