// Copyright 2010-2011 Google
// 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.

#include "util/graph_export.h"

#include "base/logging.h"
#include "base/macros.h"
#include "base/scoped_ptr.h"
#include "base/stringprintf.h"

namespace operations_research {

GraphExporter::~GraphExporter() {}

namespace {
class GraphSyntax {
 public:
  virtual ~GraphSyntax() {}

  // Node in the right syntax.
  virtual string Node(const string& name,
                      const string& label,
                      const string& shape,
                      const string& color) = 0;
  // Adds one link in the generated graph.
  virtual string Link(const string& source,
                      const string& destination,
                      const string& label) = 0;
  // File header.
  virtual string Header(const string& name) = 0;

  // File footer.
  virtual string Footer() = 0;
};

class DotSyntax : public GraphSyntax {
 public:
  virtual ~DotSyntax() {}

  virtual string Node(const string& name,
                      const string& label,
                      const string& shape,
                      const string& color) {
    return StringPrintf("%s [shape=%s label=\"%s\" color=%s]\n",
                        name.c_str(),
                        shape.c_str(),
                        label.c_str(),
                        color.c_str());
  }

  // Adds one link in the generated graph.
  virtual string Link(const string& source,
                      const string& destination,
                      const string& label) {
    return StringPrintf("%s -> %s [label=%s]\n",
                        source.c_str(),
                        destination.c_str(),
                        label.c_str());
  }

  // File header.
  virtual string Header(const string& name) {
    return StringPrintf("graph %s {\n", name.c_str());
  }

  // File footer.
  virtual string Footer() {
    return "}\n";
  }
};

class GmlSyntax : public GraphSyntax {
 public:
  virtual ~GmlSyntax() {}

  virtual string Node(const string& name,
                      const string& label,
                      const string& shape,
                      const string& color) {
    return StringPrintf("  node [\n"
                        "    name \"%s\"\n"
                        "    label \"%s\"\n"
                        "    graphics [\n"
                        "      type \"%s\"\n"
                        "      fill \"%s\"\n"
                        "    ]\n"
                        "  ]\n",
                        name.c_str(),
                        label.c_str(),
                        shape.c_str(),
                        color.c_str());
  }

  // Adds one link in the generated graph.
  virtual string Link(const string& source,
                      const string& destination,
                      const string& label) {
    return StringPrintf("  edge [\n"
                        "    label \"%s\"\n"
                        "    source \"%s\"\n"
                        "    target \"%s\"\n"
                        "  ]\n",
                        label.c_str(),
                        source.c_str(),
                        destination.c_str());
  }

  // File header.
  virtual string Header(const string& name) {
    return StringPrintf("graph [\n"
                        "  name \"%s\"\n"
                        , name.c_str());
  }

  // File footer.
  virtual string Footer() {
    return "]\n";
  }
};

// Graph exporter that will write to a file with a given format.
// Takes ownership of the GraphSyntax parameter.
class FileGraphExporter : public GraphExporter {
 public:
  FileGraphExporter(File* const file, GraphSyntax* const syntax)
      : file_(file), syntax_(syntax) {}

  virtual ~FileGraphExporter() {}

  // Write node in GML or DOT format.
  virtual void WriteNode(const string& name,
                         const string& label,
                         const string& shape,
                         const string& color) {
    Append(syntax_->Node(name, label, shape, color));
  }

  // Adds one link in the generated graph.
  virtual void WriteLink(const string& source,
                         const string& destination,
                         const string& label) {
    Append(syntax_->Link(source, destination, label));
  }

  virtual void WriteHeader(const string& name) {
    Append(syntax_->Header(name));
  }

  virtual void WriteFooter() {
    Append(syntax_->Footer());
  }

 private:
  void Append(const string& string) {
    file_->Write(string.c_str(), string.size());
  }

  File* const file_;
  scoped_ptr<GraphSyntax> syntax_;
};
}  // namespace

GraphExporter* GraphExporter::MakeFileExporter(
    File* const file,
    GraphExporter::GraphFormat format) {
  GraphSyntax* syntax = NULL;
  switch (format) {
    case GraphExporter::DOT_FORMAT: {
      syntax = new DotSyntax();
      break;
    }
    case GraphExporter::GML_FORMAT: {
      syntax = new GmlSyntax();
      break;
    }
    default:
      LOG(FATAL) << "Unknown graph format";
  }
  CHECK(syntax != NULL);
  return new FileGraphExporter(file, syntax);
}
}  // namespace operations_research