Add Transport URI constructor without a repository

Let a Transport instance be opened with only a URI, for use in the
upcoming publish-subscribe feature.

Change-Id: I391c60c10d034b5c1c0ef19b1f24a9ba76b17bb5

org.eclipse.jgit/resources/org/eclipse/jgit/internal/JGitText.properties

@@ -450,6 +450,7 @@ transportExceptionEmptyRef=Empty ref: {0}
 transportExceptionInvalid=Invalid {0} {1}:{2}
 transportExceptionMissingAssumed=Missing assumed {0}
 transportExceptionReadRef=read {0}
+transportNeedsRepository=Transport needs repository
 transportProtoAmazonS3=Amazon S3
 transportProtoBundleFile=Git Bundle File
 transportProtoFTP=FTP

org.eclipse.jgit/src/org/eclipse/jgit/internal/JGitText.java

@@ -510,6 +510,7 @@ public class JGitText extends TranslationBundle {
 	/***/ public String transportExceptionInvalid;
 	/***/ public String transportExceptionMissingAssumed;
 	/***/ public String transportExceptionReadRef;
+	/***/ public String transportNeedsRepository;
 	/***/ public String transportProtoAmazonS3;
 	/***/ public String transportProtoBundleFile;
 	/***/ public String transportProtoFTP;

org.eclipse.jgit/src/org/eclipse/jgit/transport/HttpTransport.java

@@ -66,4 +66,13 @@ public abstract class HttpTransport extends Transport {
 	protected HttpTransport(Repository local, URIish uri) {
 		super(local, uri);
 	}
+
+	/**
+	 * Create a minimal HTTP transport instance not tied to a single repository.
+	 *
+	 * @param uri
+	 */
+	protected HttpTransport(URIish uri) {
+		super(uri);
+	}
 }

org.eclipse.jgit/src/org/eclipse/jgit/transport/Transport.java

@@ -556,6 +556,29 @@ public abstract class Transport {
 		throw new NotSupportedException(MessageFormat.format(JGitText.get().URINotSupported, uri));
 	}
 
+	/**
+	 * Open a new transport with no local repository.
+	 *
+	 * @param uri
+	 * @return new Transport instance
+	 * @throws NotSupportedException
+	 * @throws TransportException
+	 */
+	public static Transport open(URIish uri) throws NotSupportedException, TransportException {
+		for (WeakReference<TransportProtocol> ref : protocols) {
+			TransportProtocol proto = ref.get();
+			if (proto == null) {
+				protocols.remove(ref);
+				continue;
+			}
+
+			if (proto.canHandle(uri, null, null))
+				return proto.open(uri);
+		}
+
+		throw new NotSupportedException(MessageFormat.format(JGitText.get().URINotSupported, uri));
+	}
+
 	/**
 	 * Convert push remote refs update specification from {@link RefSpec} form
 	 * to {@link RemoteRefUpdate}. Conversion expands wildcards by matching
@@ -745,6 +768,18 @@ public abstract class Transport {
 		this.credentialsProvider = CredentialsProvider.getDefault();
 	}
 
+	/**
+	 * Create a minimal transport instance not tied to a single repository.
+	 *
+	 * @param uri
+	 */
+	protected Transport(final URIish uri) {
+		this.uri = uri;
+		this.local = null;
+		this.checkFetchedObjects = true;
+		this.credentialsProvider = CredentialsProvider.getDefault();
+	}
+
 	/**
 	 * Get the URI this transport connects to.
 	 * <p>

org.eclipse.jgit/src/org/eclipse/jgit/transport/TransportHttp.java

@@ -167,6 +167,10 @@ public class TransportHttp extends HttpTransport implements WalkTransport,
 				throws NotSupportedException {
 			return new TransportHttp(local, uri);
 		}
+
+		public Transport open(URIish uri) throws NotSupportedException {
+			return new TransportHttp(uri);
+		}
 	};
 
 	static final TransportProtocol PROTO_FTP = new TransportProtocol() {
@@ -224,6 +228,10 @@ public class TransportHttp extends HttpTransport implements WalkTransport,
 			postBuffer = rc.getInt("http", "postbuffer", 1 * 1024 * 1024); //$NON-NLS-1$  //$NON-NLS-2$
 			sslVerify = rc.getBoolean("http", "sslVerify", true);
 		}
+
+		private HttpConfig() {
+			this(new Config());
+		}
 	}
 
 	private final URL baseUrl;
@@ -254,6 +262,27 @@ public class TransportHttp extends HttpTransport implements WalkTransport,
 		proxySelector = ProxySelector.getDefault();
 	}
 
+	/**
+	 * Create a minimal HTTP transport with default configuration values.
+	 *
+	 * @param uri
+	 * @throws NotSupportedException
+	 */
+	TransportHttp(final URIish uri) throws NotSupportedException {
+		super(uri);
+		try {
+			String uriString = uri.toString();
+			if (!uriString.endsWith("/")) //$NON-NLS-1$
+				uriString += "/"; //$NON-NLS-1$
+			baseUrl = new URL(uriString);
+			objectsUrl = new URL(baseUrl, "objects/"); //$NON-NLS-1$
+		} catch (MalformedURLException e) {
+			throw new NotSupportedException(MessageFormat.format(JGitText.get().invalidURL, uri), e);
+		}
+		http = new HttpConfig();
+		proxySelector = ProxySelector.getDefault();
+	}
+
 	/**
 	 * Toggle whether or not smart HTTP transport should be used.
 	 * <p>

org.eclipse.jgit/src/org/eclipse/jgit/transport/TransportProtocol.java

@@ -49,6 +49,7 @@ import java.util.Set;
 
 import org.eclipse.jgit.errors.NotSupportedException;
 import org.eclipse.jgit.errors.TransportException;
+import org.eclipse.jgit.internal.JGitText;
 import org.eclipse.jgit.lib.Repository;
 
 /**
@@ -253,4 +254,19 @@ public abstract class TransportProtocol {
 	public abstract Transport open(URIish uri, Repository local,
 			String remoteName)
 			throws NotSupportedException, TransportException;
+
+	/**
+	 * Open a new transport instance to the remote repository. Use default
+	 * configuration instead of reading from configuration files.
+	 *
+	 * @param uri
+	 * @return new Transport
+	 * @throws NotSupportedException
+	 * @throws TransportException
+	 */
+	public Transport open(URIish uri)
+			throws NotSupportedException, TransportException {
+		throw new NotSupportedException(JGitText
+				.get().transportNeedsRepository);
+	}
 }