/**
 * Copyright (C) 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.inject.grapher.graphviz;

import com.google.common.base.Joiner;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.google.inject.Inject;
import com.google.inject.Key;
import com.google.inject.grapher.AbstractInjectorGrapher;
import com.google.inject.grapher.BindingEdge;
import com.google.inject.grapher.DependencyEdge;
import com.google.inject.grapher.ImplementationNode;
import com.google.inject.grapher.InstanceNode;
import com.google.inject.grapher.InterfaceNode;
import com.google.inject.grapher.NameFactory;
import com.google.inject.grapher.NodeId;
import com.google.inject.spi.InjectionPoint;
import java.io.PrintWriter;
import java.lang.reflect.Member;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

/**
 * {@link com.google.inject.grapher.InjectorGrapher} implementation that writes out a Graphviz DOT
 * file of the graph. Dependencies are bound in {@link GraphvizModule}.
 * <p>
 * Specify the {@link PrintWriter} to output to with {@link #setOut(PrintWriter)}.
 *
 * @author phopkins@gmail.com (Pete Hopkins)
 * @since 4.0
 */
public class GraphvizGrapher extends AbstractInjectorGrapher {
  private final Map<NodeId, GraphvizNode> nodes = Maps.newHashMap();
  private final List<GraphvizEdge> edges = Lists.newArrayList();
  private final NameFactory nameFactory;
  private final PortIdFactory portIdFactory;

  private PrintWriter out;
  private String rankdir = "TB";

  @Inject GraphvizGrapher(@Graphviz NameFactory nameFactory,
      @Graphviz PortIdFactory portIdFactory) {
    this.nameFactory = nameFactory;
    this.portIdFactory = portIdFactory;
  }

  @Override protected void reset() {
    nodes.clear();
    edges.clear();
  }

  public void setOut(PrintWriter out) {
    this.out = out;
  }

  public void setRankdir(String rankdir) {
    this.rankdir = rankdir;
  }

  @Override protected void postProcess() {
    start();
    
    for (GraphvizNode node : nodes.values()) {
      renderNode(node);
    }

    for (GraphvizEdge edge : edges) {
      renderEdge(edge);
    }
    
    finish();
    
    out.flush();
  }

  protected Map<String, String> getGraphAttributes() {
    Map<String, String> attrs = Maps.newHashMap();
    attrs.put("rankdir", rankdir);
    return attrs;
  }

  protected void start() {
    out.println("digraph injector {");
    
    Map<String, String> attrs = getGraphAttributes();
    out.println("graph " + getAttrString(attrs) + ";");
  }

  protected void finish() {
    out.println("}");
  }

  protected void renderNode(GraphvizNode node) {
    Map<String, String> attrs = getNodeAttributes(node);
    out.println(node.getIdentifier() + " " + getAttrString(attrs));
  }
  
  protected Map<String, String> getNodeAttributes(GraphvizNode node) {
    Map<String, String> attrs = Maps.newHashMap();

    attrs.put("label", getNodeLabel(node));
    // remove most of the margin because the table has internal padding
    attrs.put("margin", "\"0.02,0\"");
    attrs.put("shape", node.getShape().toString());
    attrs.put("style", node.getStyle().toString());
    
    return attrs;
  }

  /**
   * Creates the "label" for a node. This is a string of HTML that defines a
   * table with a heading at the top and (in the case of
   * {@link ImplementationNode}s) rows for each of the member fields.
   */
  protected String getNodeLabel(GraphvizNode node) {
    String cellborder = node.getStyle() == NodeStyle.INVISIBLE ? "1" : "0";
    
    StringBuilder html = new StringBuilder();
    html.append("<");
    html.append("<table cellspacing=\"0\" cellpadding=\"5\" cellborder=\"");
    html.append(cellborder).append("\" border=\"0\">");
    
    html.append("<tr>").append("<td align=\"left\" port=\"header\" ");
    html.append("bgcolor=\"" + node.getHeaderBackgroundColor() + "\">");
    
    String subtitle = Joiner.on("<br align=\"left\"/>").join(node.getSubtitles());
    if (subtitle.length() != 0) {
      html.append("<font color=\"").append(node.getHeaderTextColor());
      html.append("\" point-size=\"10\">");
      html.append(subtitle).append("<br align=\"left\"/>").append("</font>");
    }

    html.append("<font color=\"" + node.getHeaderTextColor() + "\">");
    html.append(htmlEscape(node.getTitle())).append("<br align=\"left\"/>");
    html.append("</font>").append("</td>").append("</tr>");

    for (Map.Entry<String, String> field : node.getFields().entrySet()) {
      html.append("<tr>");
      html.append("<td align=\"left\" port=\"").append(htmlEscape(field.getKey())).append("\">");
      html.append(htmlEscape(field.getValue()));
      html.append("</td>").append("</tr>");
    }

    html.append("</table>");
    html.append(">");
    return html.toString();
  }

  protected void renderEdge(GraphvizEdge edge) {
    Map<String, String> attrs = getEdgeAttributes(edge);
    
    String tailId = getEdgeEndPoint(nodes.get(edge.getTailNodeId()).getIdentifier(),
        edge.getTailPortId(), edge.getTailCompassPoint());

    String headId = getEdgeEndPoint(nodes.get(edge.getHeadNodeId()).getIdentifier(),
        edge.getHeadPortId(), edge.getHeadCompassPoint());
    
    out.println(tailId + " -> " + headId + " " + getAttrString(attrs));
  }

  protected Map<String, String> getEdgeAttributes(GraphvizEdge edge) {
    Map<String, String> attrs = Maps.newHashMap();
    
    attrs.put("arrowhead", getArrowString(edge.getArrowHead()));
    attrs.put("arrowtail", getArrowString(edge.getArrowTail()));
    attrs.put("style", edge.getStyle().toString());
    
    return attrs;
  }
  
  private String getAttrString(Map<String, String> attrs) {
    List<String> attrList = Lists.newArrayList();
    
    for (Entry<String, String> attr : attrs.entrySet()) {
      String value = attr.getValue();

      if (value != null) {
        attrList.add(attr.getKey() + "=" + value);
      }
    }
    
    return "[" + Joiner.on(", ").join(attrList) + "]";
  }

  /**
   * Turns a {@link List} of {@link ArrowType}s into a {@link String} that
   * represents combining them. With Graphviz, that just means concatenating
   * them.
   */
  protected String getArrowString(List<ArrowType> arrows) {
    return Joiner.on("").join(arrows);
  }

  protected String getEdgeEndPoint(String nodeId, String portId, CompassPoint compassPoint) {
    List<String> portStrings = Lists.newArrayList(nodeId);
    
    if (portId != null) {
      portStrings.add(portId);
    }
    
    if (compassPoint != null) {
      portStrings.add(compassPoint.toString());
    }
    
    return Joiner.on(":").join(portStrings);
  }

  protected String htmlEscape(String str) {
    return str.replace("&", "&amp;").replace("<", "&lt;").replace(">", "&gt;");
  }

  protected List<String> htmlEscape(List<String> elements) {
    List<String> escaped = Lists.newArrayList();
    for (String element : elements) {
      escaped.add(htmlEscape(element));
    }
    return escaped;
  }

  @Override protected void newInterfaceNode(InterfaceNode node) {
    // TODO(phopkins): Show the Module on the graph, which comes from the
    // class name when source is a StackTraceElement.

    NodeId nodeId = node.getId();
    GraphvizNode gnode = new GraphvizNode(nodeId);
    gnode.setStyle(NodeStyle.DASHED);
    Key<?> key = nodeId.getKey();
    gnode.setTitle(nameFactory.getClassName(key));
    gnode.addSubtitle(0, nameFactory.getAnnotationName(key));
    addNode(gnode);
  }

  @Override protected void newImplementationNode(ImplementationNode node) {
    NodeId nodeId = node.getId();
    GraphvizNode gnode = new GraphvizNode(nodeId);
    gnode.setStyle(NodeStyle.SOLID);

    gnode.setHeaderBackgroundColor("#000000");
    gnode.setHeaderTextColor("#ffffff");
    gnode.setTitle(nameFactory.getClassName(nodeId.getKey()));

    for (Member member : node.getMembers()) {
      gnode.addField(portIdFactory.getPortId(member), nameFactory.getMemberName(member));
    }

    addNode(gnode);
  }

  @Override protected void newInstanceNode(InstanceNode node) {
    NodeId nodeId = node.getId();
    GraphvizNode gnode = new GraphvizNode(nodeId);
    gnode.setStyle(NodeStyle.SOLID);

    gnode.setHeaderBackgroundColor("#000000");
    gnode.setHeaderTextColor("#ffffff");
    gnode.setTitle(nameFactory.getClassName(nodeId.getKey()));

    gnode.addSubtitle(0, nameFactory.getSourceName(node.getSource()));

    gnode.setHeaderBackgroundColor("#aaaaaa");
    gnode.setHeaderTextColor("#ffffff");
    gnode.setTitle(nameFactory.getInstanceName(node.getInstance()));

    for (Member member : node.getMembers()) {
      gnode.addField(portIdFactory.getPortId(member), nameFactory.getMemberName(member));
    }

    addNode(gnode);
  }

  @Override protected void newDependencyEdge(DependencyEdge edge) {
    GraphvizEdge gedge = new GraphvizEdge(edge.getFromId(), edge.getToId());
    InjectionPoint fromPoint = edge.getInjectionPoint();
    if (fromPoint == null) {
      gedge.setTailPortId("header");
    } else {
      gedge.setTailPortId(portIdFactory.getPortId(fromPoint.getMember()));
    }
    gedge.setArrowHead(ImmutableList.of(ArrowType.NORMAL));
    gedge.setTailCompassPoint(CompassPoint.EAST);

    edges.add(gedge);
  }

  @Override protected void newBindingEdge(BindingEdge edge) {
    GraphvizEdge gedge = new GraphvizEdge(edge.getFromId(), edge.getToId());
    gedge.setStyle(EdgeStyle.DASHED);
    switch (edge.getType()) {
      case NORMAL:
        gedge.setArrowHead(ImmutableList.of(ArrowType.NORMAL_OPEN));
        break;

      case PROVIDER:
        gedge.setArrowHead(ImmutableList.of(ArrowType.NORMAL_OPEN, ArrowType.NORMAL_OPEN));
        break;

      case CONVERTED_CONSTANT:
        gedge.setArrowHead(ImmutableList.of(ArrowType.NORMAL_OPEN, ArrowType.DOT_OPEN));
        break;
    }

    edges.add(gedge);
  }

  private void addNode(GraphvizNode node) {
    node.setIdentifier("x" + nodes.size());
    nodes.put(node.getNodeId(), node);
  }
}
