import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.Collections;

import javax.inject.Inject;

import com.google.api.client.auth.oauth2.AuthorizationCodeRequestUrl;
import com.google.api.client.auth.oauth2.AuthorizationCodeTokenRequest;
import com.google.api.client.auth.oauth2.BearerToken;
import com.google.api.client.auth.oauth2.ClientParametersAuthentication;
import com.google.api.client.auth.oauth2.Credential;
import com.google.api.client.auth.oauth2.CredentialStoreRefreshListener;
import com.google.api.client.auth.oauth2.TokenResponse;
import com.google.api.client.extensions.appengine.auth.oauth2.AppEngineCredentialStore;
import com.google.api.client.extensions.appengine.http.UrlFetchTransport;
import com.google.api.client.http.GenericUrl;
import com.google.api.client.json.jackson2.JacksonFactory;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@SuppressWarnings("deprecation")
public class GoogleOAuth2Utils {
    private final static Logger log = LoggerFactory.getLogger(GoogleOAuth2Utils.class);
    private final GoogleOAuth2Config googleOAuth2Config;

    @Inject
    public GoogleOAuth2Utils(final GoogleOAuth2Config googleOAuth2Config) {
        this.googleOAuth2Config = googleOAuth2Config;
    }

    public Credential blankCredential(final String userId) {
        Credential credential =
            new Credential.Builder(BearerToken.authorizationHeaderAccessMethod())
                .addRefreshListener(new CredentialStoreRefreshListener(userId,
                    new AppEngineCredentialStore()))
                .setJsonFactory(new JacksonFactory())
                .setTokenServerUrl(new GenericUrl("https://accounts.google.com/o/oauth2/token"))
                .setClientAuthentication(
                    new ClientParametersAuthentication(
                        this.googleOAuth2Config.getGoogleApiKey(),
                        this.googleOAuth2Config.getGoogleApiSecret()))
                .setTransport(new UrlFetchTransport())
                .build();

        return (credential);
    }

    public Credential getCredential(String userId, TokenResponse tokenResponse) {
        Credential credential = blankCredential(userId);

        credential.setFromTokenResponse(tokenResponse);

        if (tokenResponse.getRefreshToken() != null) {
            log.debug("setting refresh token from token response");

            credential.setRefreshToken(tokenResponse.getRefreshToken());
        }

        AppEngineCredentialStore appEngineCredentialStore = new AppEngineCredentialStore();

        appEngineCredentialStore.store(userId, credential);

        return (credential);
    }
    public TokenResponse tokenResponse(final String code, final String scheme, final String serverName, final int serverPort) throws IOException, URISyntaxException {
        TokenResponse tokenResponse =
            new AuthorizationCodeTokenRequest(new UrlFetchTransport(),
                new JacksonFactory(),
                new GenericUrl("https://accounts.google.com/o/oauth2/token"),
                code)
            .setRedirectUri(googleOJCCallbackUri(scheme, serverName, serverPort))
            .setClientAuthentication(new ClientParametersAuthentication(
                this.googleOAuth2Config.getGoogleApiKey(),
                this.googleOAuth2Config.getGoogleApiSecret()))
            .execute();

        return (tokenResponse);
    }

    public String callbackUrl(final String scheme, final String serverName, final int serverPort, final String requestUri) throws URISyntaxException {
        String url =
            new AuthorizationCodeRequestUrl("https://accounts.google.com/o/oauth2/auth", this.googleOAuth2Config.getGoogleApiKey())
                .setRedirectUri(googleOJCCallbackUri(scheme, serverName, serverPort))
                .setScopes(Collections.singletonList("https://www.googleapis.com/auth/urlshortener"))
                .setState(requestUri)
                .set("approval_prompt", "force")
                .set("access_type", "offline")
                .build();

        return (url);
    }

    public String googleOJCCallbackUri(String scheme, String serverName, int serverPort) throws URISyntaxException {
        final URI callbackUri = new URI(scheme,
                null,
                serverName,
                serverPort,
                this.googleOAuth2Config.getGoogleOJCCallbackPath(),
                null, null);

        return (callbackUri.normalize().toString());
    }
}