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/*
 * Copyright (c) 1998-2018 John Caron and University Corporation for Atmospheric Research/Unidata
 * See LICENSE for license information.
 */
package ucar.nc2.util;

import java.io.IOException;
import thredds.inventory.MFile;
import thredds.inventory.MFiles;
import ucar.unidata.util.StringUtil2;
import java.io.File;
import java.net.URI;

/**
 * Networking utilities.
 * 
 * TODO move to util.net
 */
public class URLnaming {

  /// try to figure out if we need to add file: to the location when writing
  public static String canonicalizeWrite(String location) {
    try {
      URI refURI = URI.create(location);
      if (refURI.isAbsolute())
        return location;
    } catch (Exception e) {
      // return "file:" + location;
    }
    return "file:" + location;
  }

  /**
   * This augments URI.resolve(), by also dealing with file: URIs.
   * If baseURi is not a file: scheme, then URI.resolve is called.
   * Otherwise the last "/" is found in the base, and the ref is appended to it.
   * 
   * For file: baseURLS: only relative URLS not starting with / are supported. This is
   * apparently different from the behavior of URI.resolve(), so may be trouble,
   * but it allows NcML absolute location to be specified without the file: prefix.
   * 

   * Example :
   * 
   * 
   * base:     file://my/guide/collections/designfaq.ncml
   * ref:      sub/my.nc
   * resolved: file://my/guide/collections/sub/my.nc
   * 
   *
   * @param baseUri base URI as a Strng
   * @param relativeUri relative URI, as a String
   * @return the resolved URI as a String
   */
  public static String resolve(String baseUri, String relativeUri) {
    if ((baseUri == null) || (relativeUri == null))
      return relativeUri;

    if (relativeUri.startsWith("file:"))
      return relativeUri;

    // deal with a base file URL
    if (baseUri.startsWith("file:")) {

      // the case where the relativeURL is absolute.
      // unfortunately, we may get an Exception
      try {
        URI uriRelative = URI.create(relativeUri);
        if (uriRelative.isAbsolute())
          return relativeUri;
      } catch (Exception e) {
        // empty
      }

      if ((!relativeUri.isEmpty()) && (relativeUri.charAt(0) == '#'))
        return baseUri + relativeUri;

      if ((!relativeUri.isEmpty()) && (relativeUri.charAt(0) == '/'))
        return relativeUri;

      baseUri = StringUtil2.substitute(baseUri, "\\", "/"); // assumes forward slash
      int pos = baseUri.lastIndexOf('/');
      if (pos > 0) {
        String baseDir = baseUri.substring(0, pos + 1);
        if (relativeUri.equals(".")) {
          return baseDir;
        } else {
          return baseDir + relativeUri;
        }
      }
    }

    if (baseUri.startsWith("cdms3:")) {
      if (relativeUri.startsWith("cdms3:")) {
        return relativeUri;
      } else {
        MFile absoluteMFile;
        try {
          absoluteMFile = MFiles.create(baseUri).getParent().getChild(relativeUri);
        } catch (IOException e) {
          return relativeUri;
        }
        return absoluteMFile == null ? relativeUri : absoluteMFile.getPath();
      }
    }

    // non-file URLs

    // relativeUri = canonicalizeRead(relativeUri);
    try {
      URI relativeURI = URI.create(relativeUri);
      if (relativeURI.isAbsolute())
        return relativeUri;

      // otherwise let the URI class resolve it
      URI baseURI = URI.create(baseUri);
      URI resolvedURI = baseURI.resolve(relativeURI);
      return resolvedURI.toASCIIString();

    } catch (IllegalArgumentException e) {
      return relativeUri;
    }
  }

  public static String resolveFile(String baseDir, String filepath) {
    if (baseDir == null)
      return filepath;
    if (filepath == null)
      return null;
    File file = new File(filepath);
    if (file.isAbsolute())
      return filepath;

    if (baseDir.startsWith("file:"))
      baseDir = baseDir.substring(5);

    MFile base = MFiles.create(baseDir);
    if (!base.isDirectory()) {
      try {
        base = base.getParent();
      } catch (IOException e) {
        return filepath;
      }
    }
    if (base == null)
      return filepath;
    MFile absoluteFile = base.getChild(filepath);
    return absoluteFile == null ? filepath : absoluteFile.getPath();
  }

}