// Copyright (C) 2014 The Android Open Source Project
//
// 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.googlesource.gerrit.plugins.xdocs.formatter;

import static com.googlesource.gerrit.plugins.xdocs.XDocGlobalConfig.KEY_ALLOW_HTML;
import static com.googlesource.gerrit.plugins.xdocs.XDocGlobalConfig.KEY_INCLUDE_TOC;

import com.google.inject.Inject;
import com.google.inject.Singleton;
import com.googlesource.gerrit.plugins.xdocs.ConfigSection;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.StringReader;
import java.util.Properties;
import org.asciidoctor.Asciidoctor;
import org.asciidoctor.AttributesBuilder;
import org.asciidoctor.OptionsBuilder;
import org.asciidoctor.SafeMode;

@Singleton
public class AsciidoctorFormatter implements StringFormatter {
  public static final String NAME = "ASCIIDOCTOR";

  private static final String BACKEND = "html5";
  private static final String DOCTYPE = "article";
  private static final String ERUBY = "erb";

  private final Properties attributes;
  private final FormatterUtil util;
  private final Formatters formatters;

  @Inject
  public AsciidoctorFormatter(FormatterUtil formatterUtil, Formatters formatters)
      throws IOException {
    this.attributes = readAttributes();
    this.util = formatterUtil;
    this.formatters = formatters;
  }

  @Override
  public String format(
      String projectName,
      String path,
      String revision,
      String abbrRev,
      ConfigSection globalCfg,
      String raw)
      throws IOException {
    if (!globalCfg.getBoolean(KEY_ALLOW_HTML, false)) {
      raw = suppressHtml(raw);
    }

    ConfigSection projectCfg = formatters.getFormatterConfig(NAME, projectName);
    String html =
        Asciidoctor.Factory.create(AsciidoctorFormatter.class.getClassLoader())
            .convert(raw, createOptions(projectCfg, abbrRev));
    return util.applyCss(html, NAME, projectName);
  }

  private String suppressHtml(String raw) throws IOException {
    try (BufferedReader br = new BufferedReader(new StringReader(raw))) {
      StringBuilder sb = new StringBuilder();
      boolean embeddedHtml = false;
      String line;
      while ((line = br.readLine()) != null) {
        if (line.startsWith("++++")) {
          embeddedHtml = !embeddedHtml;
        }
        if (!embeddedHtml && !line.startsWith("++++")) {
          sb.append(line);
          sb.append("\n");
        }
      }
      return sb.toString();
    }
  }

  private OptionsBuilder createOptions(ConfigSection cfg, String revision) {
    return OptionsBuilder.options()
        .backend(BACKEND)
        .docType(DOCTYPE)
        .eruby(ERUBY)
        .safe(SafeMode.SECURE)
        .attributes(getAttributes(cfg, revision))
        .mkDirs(true);
  }

  private AttributesBuilder getAttributes(ConfigSection cfg, String revision) {
    AttributesBuilder ab =
        AttributesBuilder.attributes()
            .tableOfContents(cfg.getBoolean(KEY_INCLUDE_TOC, true))
            .sourceHighlighter("prettify");
    for (String name : attributes.stringPropertyNames()) {
      ab.attribute(name, attributes.getProperty(name));
    }
    ab.attribute("last-update-label!");
    ab.attribute("revnumber", revision);
    return ab;
  }

  private static Properties readAttributes() throws IOException {
    Properties attributes = new Properties();
    try (InputStream in =
        AsciidoctorFormatter.class.getResourceAsStream("asciidoctor.properties")) {
      attributes.load(in);
    }
    return attributes;
  }
}