Fix PathTemplate matcher to match path with protocol and hostname

src/main/java/com/google/api/pathtemplate/PathTemplate.java

@@ -125,13 +125,17 @@ public class PathTemplate {
 
   /**
    * A constant identifying the special variable used for endpoint bindings in the result of
-   * {@link #matchFromFullName(String)}.
+   * {@link #matchFromFullName(String)}. It may also contain protocol string, if its provided in the
+   * input.
    */
   public static final String HOSTNAME_VAR = "$hostname";
 
   // A regexp to match a custom verb at the end of a path.
   private static final Pattern CUSTOM_VERB_PATTERN = Pattern.compile(":([^/*}{=]+)$");
 
+  // A regex to match a hostname with or without protocol.
+  private static final Pattern HOSTNAME_PATTERN = Pattern.compile("^(\\w+:)?//");
+
   // A splitter on slash.
   private static final Splitter SLASH_SPLITTER = Splitter.on('/').trimResults();
 
@@ -533,10 +537,10 @@ private Map<String, String> match(String path, boolean forceHostName) {
       path = path.substring(0, matcher.start(0));
     }
 
-    // Do full match.
-    boolean withHostName = path.startsWith("//");
+    Matcher matcher = HOSTNAME_PATTERN.matcher(path);
+    boolean withHostName = matcher.find();
     if (withHostName) {
-      path = path.substring(2);
+      path = matcher.replaceFirst("");
     }
     List<String> input = SLASH_SPLITTER.splitToList(path);
     int inPos = 0;
@@ -548,16 +552,42 @@ private Map<String, String> match(String path, boolean forceHostName) {
       String hostName = input.get(inPos++);
       if (withHostName) {
         // Put the // back, so we can distinguish this case from forceHostName.
-        hostName = "//" + hostName;
+        hostName = matcher.group(0) + hostName;
       }
       values.put(HOSTNAME_VAR, hostName);
     }
+    if (withHostName) {
+      inPos = alignInputToAlignableSegment(input, inPos, segments.get(0));
+    }
     if (!match(input, inPos, segments, 0, values)) {
       return null;
     }
     return ImmutableMap.copyOf(values);
   }
 
+  // Aligns input to start of literal value of literal or binding segment if input contains hostname.
+  private int alignInputToAlignableSegment(List<String> input, int inPos, Segment segment) {
+    switch (segment.kind()) {
+      case BINDING:
+        inPos = alignInputPositionToLiteral(input, inPos, segment.value() + "s");
+        return inPos + 1;
+      case LITERAL:
+        return alignInputPositionToLiteral(input, inPos, segment.value());
+    }
+    return inPos;
+  }
+
+  // Aligns input to start of literal value if input contains hostname.
+  private int alignInputPositionToLiteral(
+      List<String> input, int inPos, String literalSegmentValue) {
+    for (; inPos < input.size(); inPos++) {
+      if (literalSegmentValue.equals(input.get(inPos))) {
+        return inPos;
+      }
+    }
+    return inPos;
+  }
+
   // Tries to match the input based on the segments at given positions. Returns a boolean
   // indicating whether the match was successful.
   private boolean match(

src/test/java/com/google/api/pathtemplate/PathTemplateTest.java

@@ -83,6 +83,30 @@ public void matchWithHostName() {
     Truth.assertThat(match.get("$1")).isEqualTo("o");
   }
 
+  @Test
+  public void matchWithHostNameAndProtocol() {
+    PathTemplate template = PathTemplate.create("projects/{project}/zones/{zone}");
+    Map<String, String> match =
+        template.match(
+            "https://www.googleapis.com/compute/v1/projects/project-123/zones/europe-west3-c");
+    Truth.assertThat(match).isNotNull();
+    Truth.assertThat(match.get(PathTemplate.HOSTNAME_VAR)).isEqualTo("https://www.googleapis.com");
+    Truth.assertThat(match.get("project")).isEqualTo("project-123");
+    Truth.assertThat(match.get("zone")).isEqualTo("europe-west3-c");
+  }
+
+  @Test
+  public void matchWithHostNameAndProtocolWithTemplateStartWithBinding() {
+    PathTemplate template = PathTemplate.create("{project}/zones/{zone}");
+    Map<String, String> match =
+        template.match(
+            "https://www.googleapis.com/compute/v1/projects/project-123/zones/europe-west3-c");
+    Truth.assertThat(match).isNotNull();
+    Truth.assertThat(match.get(PathTemplate.HOSTNAME_VAR)).isEqualTo("https://www.googleapis.com");
+    Truth.assertThat(match.get("project")).isEqualTo("project-123");
+    Truth.assertThat(match.get("zone")).isEqualTo("europe-west3-c");
+  }
+
   @Test
   public void matchWithCustomMethod() {
     PathTemplate template = PathTemplate.create("buckets/*/objects/*:custom");