OauthAuthorizationHeaderBuilder.java

import static java.nio.charset.StandardCharsets.UTF_8;


import com.google.api.client.auth.oauth.OAuthHmacSigner;
import java.security.GeneralSecurityException;
import java.security.SecureRandom;
import java.time.Instant;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.stream.Collectors;
import lombok.Builder;
import lombok.EqualsAndHashCode;
import lombok.Getter;
import lombok.RequiredArgsConstructor;
import org.apache.commons.codec.binary.Hex;
import org.springframework.lang.NonNull;
import org.springframework.web.util.UriUtils;

/**
 * OAuth2.0の認証ヘッダ作成クラス
 */
@Builder
@EqualsAndHashCode
@RequiredArgsConstructor
@Getter
public class OauthAuthorizationHeaderBuilder {

    private static final String AND_DELIMITER = "&";

    private static final String OAUTH_VERSION = "1.0";

    /**
     * Access Token Secret
     */
    @NonNull
    private final String consumerSecret;

    /**
     * HTTPメソッド
     */
    @NonNull
    private final String method;

    /**
     * クエリパラメータのマップ
     */
    @NonNull
    private final Map<String, String> queryParameters;

    /**
     * API Key Secret
     */
    @NonNull
    private final String tokenSecret;

    /**
     * アクセスするAPIのURL
     */
    @NonNull
    private final String url;

    /**
     * API Key
     */
    @NonNull
    private final String consumerKey;

    /**
     * Access Token
     */
    @NonNull
    private final String accessToken;

    /**
     * Instant
     */
    @NonNull
    private final Instant instant;

    /**
     * SecureRandom
     */
    @NonNull
    private final SecureRandom secureRandom;

    /**
     * OAuthHmacSigner
     */
    @NonNull
    private final OAuthHmacSigner signer;

    /**
     * Replaces any character not specifically unreserved to an equivalent percent sequence.
     *
     * @param text the string to encode
     * @return and encoded string
     */
    @NonNull
    private static String encodeUriComponent(final String text) {
        return UriUtils.encode(text, UTF_8);
    }

    /**
     * OauthHeaderの取得
     *
     * @return OauthHeader
     * @throws NotSuccessGetOauthHmacSignerException GeneralSecurityExceptionが発生した場合の独自例外
     */
    @NonNull
    public String getOauthHeader() throws NotSuccessGetOauthHmacSignerException {
        final Map<String, String> parameters = new LinkedHashMap<>(queryParameters);

        // Boiler plate parameters
        parameters.put("oauth_timestamp", String.valueOf(instant.getEpochSecond()));
        parameters.put("oauth_signature_method", signer.getSignatureMethod());
        parameters.put("oauth_version", OAUTH_VERSION);
        parameters.put("oauth_nonce", generateSecretToken());
        parameters.put("oauth_consumer_key", consumerKey);
        parameters.put("oauth_token", accessToken);

        // Build the parameter string after sorting the keys in lexicographic order per the OAuth v1 spec.
        final String parameterString = parameters.entrySet().stream()
                .sorted(Map.Entry.comparingByKey())
                .map(e -> encodeUriComponent(e.getKey()) + "=" + encodeUriComponent(e.getValue()))
                .collect(Collectors.joining(AND_DELIMITER));

        // Build the signature base string
        final String signatureBaseString = method.toUpperCase()
                + AND_DELIMITER
                + encodeUriComponent(url)
                + AND_DELIMITER
                + encodeUriComponent(parameterString);

        // Sign the Signature Base String
        final String signature = generateSignature(signatureBaseString);

        // Add the signature to be included in the header
        parameters.put("oauth_signature", signature);

        // Build the authorization header value using the order in which the parameters were added
        return "OAuth " + parameters.entrySet().stream()
                .map(e -> encodeUriComponent(e.getKey()) + "=\""
                        + encodeUriComponent(e.getValue()) + "\"")
                .collect(Collectors.joining(", "));
    }

    /**
     * OauthHmacSignerの設定
     */
    @NonNull
    private void setOauthHmacSigner() {
        signer.clientSharedSecret = consumerSecret;
        signer.tokenSharedSecret = tokenSecret;
    }

    /**
     * 鍵を生成する
     *
     * @param message メッセージ
     * @return 鍵
     * @throws NotSuccessGetOauthHmacSignerException 鍵の作成に失敗した場合の例外
     */
    @NonNull
    private String generateSignature(final String message)
            throws NotSuccessGetOauthHmacSignerException {
        setOauthHmacSigner();

        try {
            return signer.computeSignature(message);
        } catch (final GeneralSecurityException generalSecurityException) {
            throw new NotSuccessGetOauthHmacSignerException("OAuth2.0の認証鍵作成に失敗しました");
        }
    }

    /**
     * セキュアなTokenを作成する
     *
     * @return セキュアなトークン
     */
    @NonNull
    private String generateSecretToken() {
        final byte[] result = new byte[32];
        secureRandom.nextBytes(result);
        return Hex.encodeHexString(result);
    }
}