package controllers;

import auth.CookieConfigs;
import client.AuthServiceClient;
import com.datahub.authentication.Authentication;
import com.linkedin.entity.client.SystemEntityClient;
import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CompletionStage;
import javax.annotation.Nonnull;
import javax.inject.Inject;
import lombok.extern.slf4j.Slf4j;
import org.pac4j.core.config.Config;
import org.pac4j.core.engine.CallbackLogic;
import org.pac4j.core.http.adapter.HttpActionAdapter;
import org.pac4j.play.CallbackController;
import org.pac4j.play.PlayWebContext;
import play.mvc.Http;
import play.mvc.Result;
import auth.sso.oidc.OidcCallbackLogic;
import auth.sso.SsoManager;
import auth.sso.SsoProvider;
import play.mvc.Results;


/**
 * A dedicated Controller for handling redirects to DataHub by 3rd-party Identity Providers after
 * off-platform authentication.
 *
 * Handles a single "callback/{protocol}" route, where the protocol (ie. OIDC / SAML) determines
 * the handling logic to invoke.
 */
@Slf4j
public class SsoCallbackController extends CallbackController {

  private final SsoManager _ssoManager;

  @Inject
  public SsoCallbackController(
      @Nonnull SsoManager ssoManager,
      @Nonnull Authentication systemAuthentication,
      @Nonnull SystemEntityClient entityClient,
      @Nonnull AuthServiceClient authClient,
      @Nonnull com.typesafe.config.Config configs) {
    _ssoManager = ssoManager;
    setDefaultUrl("/"); // By default, redirects to Home Page on log in.
    setSaveInSession(false);
    setCallbackLogic(new SsoCallbackLogic(ssoManager, systemAuthentication, entityClient, authClient, new CookieConfigs(configs)));
  }

  public CompletionStage<Result> handleCallback(String protocol, Http.Request request) {
    if (shouldHandleCallback(protocol)) {
      log.debug(String.format("Handling SSO callback. Protocol: %s", protocol));
      return callback(request).handle((res, e) -> {
        if (e != null) {
          log.error("Caught exception while attempting to handle SSO callback! It's likely that SSO integration is mis-configured.", e);
          return Results.redirect(
              String.format("/login?error_msg=%s",
                  URLEncoder.encode(
                      "Failed to sign in using Single Sign-On provider. Please try again, or contact your DataHub Administrator.",
                      StandardCharsets.UTF_8)))
              .discardingCookie("actor")
              .withNewSession();
        }
        return res;
      });
    }
    return CompletableFuture.completedFuture(Results.internalServerError(
        String.format("Failed to perform SSO callback. SSO is not enabled for protocol: %s", protocol)));
  }


  /**
   * Logic responsible for delegating to protocol-specific callback logic.
   */
  public class SsoCallbackLogic implements CallbackLogic<Result, PlayWebContext> {

    private final OidcCallbackLogic _oidcCallbackLogic;

    SsoCallbackLogic(final SsoManager ssoManager, final Authentication systemAuthentication,
        final SystemEntityClient entityClient, final AuthServiceClient authClient, final CookieConfigs cookieConfigs) {
      _oidcCallbackLogic = new OidcCallbackLogic(ssoManager, systemAuthentication, entityClient, authClient, cookieConfigs);
    }

    @Override
    public Result perform(PlayWebContext context, Config config,
        HttpActionAdapter<Result, PlayWebContext> httpActionAdapter, String defaultUrl, Boolean saveInSession,
        Boolean multiProfile, Boolean renewSession, String defaultClient) {
      if (SsoProvider.SsoProtocol.OIDC.equals(_ssoManager.getSsoProvider().protocol())) {
        return _oidcCallbackLogic.perform(context, config, httpActionAdapter, defaultUrl, saveInSession, multiProfile, renewSession, defaultClient);
      }
      // Should never occur.
      throw new UnsupportedOperationException("Failed to find matching SSO Provider. Only one supported is OIDC.");
    }
  }

  private boolean shouldHandleCallback(final String protocol) {
    return _ssoManager.isSsoEnabled() && _ssoManager.getSsoProvider().protocol().getCommonName().equals(protocol);
  }
}