gitiles-servlet/src/main/java/com/google/gitiles/Renderer.java

// Copyright 2012 Google Inc. All Rights Reserved.
//
// 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.gitiles;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;

import com.google.common.base.Charsets;
import com.google.common.base.Function;
import com.google.common.collect.FluentIterable;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Iterables;
import com.google.common.collect.Maps;
import com.google.template.soy.tofu.SoyTofu;

import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.List;
import java.util.Map;

import javax.servlet.http.HttpServletResponse;

/**
 * Renderer for Soy templates used by Gitiles.
 * <p>
 * Most callers should not use the methods in this class directly, and instead
 * use one of the HTML methods in {@link BaseServlet}.
 */
public abstract class Renderer {
  // Must match .streamingPlaceholder.
  private static final String PLACEHOLDER = "id=\"STREAMED_OUTPUT_BLOCK\"";

  private static final List<String> SOY_FILENAMES = ImmutableList.of(
      "BlameDetail.soy",
      "Common.soy",
      "DiffDetail.soy",
      "HostIndex.soy",
      "LogDetail.soy",
      "ObjectDetail.soy",
      "PathDetail.soy",
      "RefList.soy",
      "RevisionDetail.soy",
      "RepositoryIndex.soy");

  public static final Map<String, String> STATIC_URL_GLOBALS = ImmutableMap.of(
      "gitiles.CSS_URL", "gitiles.css",
      "gitiles.PRETTIFY_CSS_URL", "prettify/prettify.css");

  protected static class FileUrlMapper implements Function<String, URL> {
    private final String prefix;

    protected FileUrlMapper() {
      this("");
    }

    protected FileUrlMapper(String prefix) {
      this.prefix = checkNotNull(prefix, "prefix");
    }

    @Override
    public URL apply(String filename) {
      if (filename == null) {
        return null;
      }
      try {
        return new File(prefix + filename).toURI().toURL();
      } catch (MalformedURLException e) {
        throw new IllegalArgumentException(e);
      }
    }
  }

  protected ImmutableList<URL> templates;
  protected ImmutableMap<String, String> globals;

  protected Renderer(Function<String, URL> resourceMapper, Map<String, String> globals,
      String staticPrefix, Iterable<URL> customTemplates, String siteTitle) {
    checkNotNull(staticPrefix, "staticPrefix");
    Iterable<URL> allTemplates = FluentIterable.from(SOY_FILENAMES).transform(resourceMapper);
    templates = ImmutableList.copyOf(Iterables.concat(allTemplates, customTemplates));

    Map<String, String> allGlobals = Maps.newHashMap();
    for (Map.Entry<String, String> e : STATIC_URL_GLOBALS.entrySet()) {
      allGlobals.put(e.getKey(), staticPrefix + e.getValue());
    }
    allGlobals.put("gitiles.SITE_TITLE", siteTitle);
    allGlobals.putAll(globals);
    this.globals = ImmutableMap.copyOf(allGlobals);
  }

  void render(HttpServletResponse res, String templateName, Map<String, ?> soyData)
      throws IOException {
    res.setContentType("text/html");
    res.setCharacterEncoding("UTF-8");
    byte[] data = newRenderer(templateName).setData(soyData).render().getBytes(Charsets.UTF_8);
    res.setContentLength(data.length);
    res.getOutputStream().write(data);
  }

  OutputStream renderStreaming(HttpServletResponse res, String templateName, Map<String, ?> soyData)
      throws IOException {
    final String html = newRenderer(templateName)
        .setData(soyData)
        .render();
    int id = html.indexOf(PLACEHOLDER);
    checkArgument(id >= 0, "Template must contain %s", PLACEHOLDER);

    int lt = html.lastIndexOf('<', id);
    final int gt = html.indexOf('>', id + PLACEHOLDER.length());
    final OutputStream out = res.getOutputStream();
    out.write(html.substring(0, lt).getBytes(Charsets.UTF_8));
    out.flush();

    return new OutputStream() {
      @Override
      public void write(byte[] b) throws IOException {
        out.write(b);
      }

      @Override
      public void write(byte[] b, int off, int len) throws IOException {
        out.write(b, off, len);
      }

      @Override
      public void write(int b) throws IOException {
        out.write(b);
      }

      @Override
      public void flush() throws IOException {
        out.flush();
      }

      @Override
      public void close() throws IOException {
        out.write(html.substring(gt + 1).getBytes(Charsets.UTF_8));
        out.close();
      }
    };
  }

  SoyTofu.Renderer newRenderer(String templateName) {
    return getTofu().newRenderer(templateName);
  }

  protected abstract SoyTofu getTofu();
}