Social Authentication — Integrating Social Login Providers

// Social login state machine
class SocialAuthProvider {
  constructor(config) {
    this.provider = config.provider;
    this.clientId = config.clientId;
    this.clientSecret = config.clientSecret;
    this.authorizeUrl = config.authorizeUrl;
    this.tokenUrl = config.tokenUrl;
    this.userInfoUrl = config.userInfoUrl;
    this.scopes = config.scopes;
  }

  getAuthorizationUrl(state, redirectUri) {
    const params = {
      client_id: this.clientId,
      redirect_uri: redirectUri,
      response_type: 'code',
      scope: this.scopes.join(' '),
      state
    };
    return `${this.authorizeUrl}?${new URLSearchParams(params)}`;
  }

  async exchangeCode(code, redirectUri) {
    const response = await axios.post(this.tokenUrl, {
      code,
      client_id: this.clientId,
      client_secret: this.clientSecret,
      redirect_uri: redirectUri,
      grant_type: 'authorization_code'
    });
    return response.data;
  }

  async getUserProfile(accessToken) {
    const response = await axios.get(this.userInfoUrl, {
      headers: { Authorization: `Bearer ${accessToken}` }
    });
    return this.normalizeProfile(response.data);
  }

  normalizeProfile(profile) {
    // Common profile format regardless of provider
    return {
      provider: this.provider,
      providerId: profile.id || profile.sub,
      email: profile.email,
      name: profile.name || profile.login,
      avatar: profile.picture || profile.avatar_url
    };
  }
}

// Provider mapping
const providers = {
  google: new SocialAuthProvider({
    provider: 'google',
    authorizeUrl: 'https://accounts.google.com/o/oauth2/v2/auth',
    // ... config per provider
  })
};