Copy SqlTimestampDeserializer from gwtjsonrpc

Keep package-private in the json package so it can be used by all Gson
instances created by OutputFormat. Also copy in JavaSqlTimestampHelper,
which is a dependency.

Change-Id: Ib9d31d346dbf2fd28b8fc78e425c0bf81a2fe9a6

java/com/google/gerrit/json/JavaSqlTimestampHelper.java

@@ -0,0 +1,108 @@
+// Copyright 2008 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.json;
+
+import java.sql.Timestamp;
+import java.util.Date;
+
+/** Utility to parse Timestamp from a string. */
+public class JavaSqlTimestampHelper {
+  /**
+   * Parse a string into a timestamp.
+   *
+   * <p>Note that {@link Timestamp}s have no timezone, so the result is relative to the UTC epoch.
+   *
+   * <p>Supports the format {@code yyyy-MM-dd[ HH:mm:ss[.SSS][ Z]]} where {@code Z} is a 4-digit
+   * offset with sign, e.g. {@code -0500}.
+   *
+   * @param s input string.
+   * @return resulting timestamp.
+   */
+  public static Timestamp parseTimestamp(String s) {
+    String[] components = s.split(" ");
+    if (components.length < 1 || components.length > 3) {
+      throw new IllegalArgumentException("Expected date and optional time: " + s);
+    }
+    String date = components[0];
+    String time = components.length >= 2 ? components[1] : null;
+    int off = components.length == 3 ? parseTimeZone(components[2]) : 0;
+    String[] dSplit = date.split("-");
+    if (dSplit.length != 3) {
+      throw new IllegalArgumentException("Invalid date format: " + date);
+    }
+    int yy, mm, dd;
+    try {
+      yy = Integer.parseInt(dSplit[0]) - 1900;
+      mm = Integer.parseInt(dSplit[1]) - 1;
+      dd = Integer.parseInt(dSplit[2]);
+    } catch (NumberFormatException e) {
+      throw new IllegalArgumentException("Invalid date format: " + date, e);
+    }
+
+    int hh, mi, ss, ns;
+    if (time != null) {
+      int p = time.indexOf('.');
+      String t;
+      double f;
+      try {
+        if (p >= 0) {
+          t = time.substring(0, p);
+          f = Double.parseDouble("0." + time.substring(p + 1));
+        } else {
+          t = time;
+          f = 0;
+        }
+        String[] tSplit = t.split(":");
+        if (tSplit.length != 3) {
+          throw new IllegalArgumentException("Invalid time format: " + time);
+        }
+        hh = Integer.parseInt(tSplit[0]);
+        mi = Integer.parseInt(tSplit[1]);
+        ss = Integer.parseInt(tSplit[2]);
+        ns = (int) Math.round(f * 1e9);
+      } catch (NumberFormatException e) {
+        throw new IllegalArgumentException("Invalid time format: " + time, e);
+      }
+    } else {
+      hh = 0;
+      mi = 0;
+      ss = 0;
+      ns = 0;
+    }
+    @SuppressWarnings("deprecation")
+    Timestamp result = new Timestamp(Date.UTC(yy, mm, dd, hh, mi, ss) - off);
+    result.setNanos(ns);
+    return result;
+  }
+
+  private static int parseTimeZone(String s) {
+    if (s.length() != 5 || (s.charAt(0) != '-' && s.charAt(0) != '+')) {
+      throw new IllegalArgumentException("Invalid time zone: " + s);
+    }
+    for (int i = 1; i < s.length(); i++) {
+      if (s.charAt(i) < '0' || s.charAt(i) > '9') {
+        throw new IllegalArgumentException("Invalid time zone: " + s);
+      }
+    }
+    int off =
+        (s.charAt(0) == '-' ? -1 : 1)
+            * 60
+            * 1000
+            * ((60 * Integer.parseInt(s.substring(1, 3))) + Integer.parseInt(s.substring(3, 5)));
+    return off;
+  }
+
+  private JavaSqlTimestampHelper() {}
+}