/*
 * Copyright (C) 2007 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 android.webkit;

import android.annotation.Nullable;
import android.text.TextUtils;

import libcore.net.MimeUtils;

import java.util.regex.Pattern;

Two-way map that maps MIME-types to file extensions and vice versa.
See also URLConnection.guessContentTypeFromName and URLConnection.guessContentTypeFromStream. This class and URLConnection share the same MIME-type database. /**
 * Two-way map that maps MIME-types to file extensions and vice versa.
 *
 * <p>See also {@link java.net.URLConnection#guessContentTypeFromName}
 * and {@link java.net.URLConnection#guessContentTypeFromStream}. This
 * class and {@code URLConnection} share the same MIME-type database.
 */
public class MimeTypeMap {
    private static final MimeTypeMap sMimeTypeMap = new MimeTypeMap();

    private MimeTypeMap() {
    }

    
Returns the file extension or an empty string if there is no
extension. This method is a convenience method for obtaining the
extension of a url and has undefined results for other Strings.
Params:
url – 
Returns:
The file extension of the given url./**
     * Returns the file extension or an empty string if there is no
     * extension. This method is a convenience method for obtaining the
     * extension of a url and has undefined results for other Strings.
     * @param url
     * @return The file extension of the given url.
     */
    public static String getFileExtensionFromUrl(String url) {
        if (!TextUtils.isEmpty(url)) {
            int fragment = url.lastIndexOf('#');
            if (fragment > 0) {
                url = url.substring(0, fragment);
            }

            int query = url.lastIndexOf('?');
            if (query > 0) {
                url = url.substring(0, query);
            }

            int filenamePos = url.lastIndexOf('/');
            String filename =
                0 <= filenamePos ? url.substring(filenamePos + 1) : url;

            // if the filename contains special characters, we don't
            // consider it valid for our matching purposes:
            if (!filename.isEmpty() &&
                Pattern.matches("[a-zA-Z_0-9\\.\\-\\(\\)\\%]+", filename)) {
                int dotPos = filename.lastIndexOf('.');
                if (0 <= dotPos) {
                    return filename.substring(dotPos + 1);
                }
            }
        }

        return "";
    }

    
Return true if the given MIME type has an entry in the map. 
Params:
mimeType – A MIME type (i.e. text/plain)
Returns:
true if there is a mimeType entry in the map./**
     * Return {@code true} if the given MIME type has an entry in the map.
     * @param mimeType A MIME type (i.e. text/plain)
     * @return {@code true} if there is a mimeType entry in the map.
     */
    public boolean hasMimeType(String mimeType) {
        return MimeUtils.hasMimeType(mimeType);
    }

    
Return the MIME type for the given extension.
Params:
extension – A file extension without the leading '.'
Returns:
The MIME type for the given extension or null if there is none./**
     * Return the MIME type for the given extension.
     * @param extension A file extension without the leading '.'
     * @return The MIME type for the given extension or {@code null} if there is none.
     */
    @Nullable
    public String getMimeTypeFromExtension(String extension) {
        return MimeUtils.guessMimeTypeFromExtension(extension);
    }

    // Static method called by jni.
    private static String mimeTypeFromExtension(String extension) {
        return MimeUtils.guessMimeTypeFromExtension(extension);
    }

    
Return true if the given extension has a registered MIME type. 
Params:
extension – A file extension without the leading '.'
Returns:
true if there is an extension entry in the map./**
     * Return {@code true} if the given extension has a registered MIME type.
     * @param extension A file extension without the leading '.'
     * @return {@code true} if there is an extension entry in the map.
     */
    public boolean hasExtension(String extension) {
        return MimeUtils.hasExtension(extension);
    }

    
Return the registered extension for the given MIME type. Note that some
MIME types map to multiple extensions. This call will return the most
common extension for the given MIME type.
Params:
mimeType – A MIME type (i.e. text/plain)
Returns:
The extension for the given MIME type or null if there is none./**
     * Return the registered extension for the given MIME type. Note that some
     * MIME types map to multiple extensions. This call will return the most
     * common extension for the given MIME type.
     * @param mimeType A MIME type (i.e. text/plain)
     * @return The extension for the given MIME type or {@code null} if there is none.
     */
    @Nullable
    public String getExtensionFromMimeType(String mimeType) {
        return MimeUtils.guessExtensionFromMimeType(mimeType);
    }

    
If the given MIME type is null, or one of the "generic" types (text/plain or application/octet-stream) map it to a type that Android can deal with. If the given type is not generic, return it unchanged. 
Params:
mimeType – MIME type provided by the server.
url – URL of the data being loaded.
contentDisposition – Content-disposition header given by the server.
Returns:
The MIME type that should be used for this data./**
     * If the given MIME type is {@code null}, or one of the "generic" types (text/plain
     * or application/octet-stream) map it to a type that Android can deal with.
     * If the given type is not generic, return it unchanged.
     *
     * @param mimeType MIME type provided by the server.
     * @param url URL of the data being loaded.
     * @param contentDisposition Content-disposition header given by the server.
     * @return The MIME type that should be used for this data.
     */
    /* package */ String remapGenericMimeType(@Nullable String mimeType, String url,
            String contentDisposition) {
        // If we have one of "generic" MIME types, try to deduce
        // the right MIME type from the file extension (if any):
        if ("text/plain".equals(mimeType) ||
                "application/octet-stream".equals(mimeType)) {

            // for attachment, use the filename in the Content-Disposition
            // to guess the mimetype
            String filename = null;
            if (contentDisposition != null) {
                filename = URLUtil.parseContentDisposition(contentDisposition);
            }
            if (filename != null) {
                url = filename;
            }
            String extension = getFileExtensionFromUrl(url);
            String newMimeType = getMimeTypeFromExtension(extension);
            if (newMimeType != null) {
                mimeType = newMimeType;
            }
        } else if ("text/vnd.wap.wml".equals(mimeType)) {
            // As we don't support wml, render it as plain text
            mimeType = "text/plain";
        } else {
            // It seems that xhtml+xml and vnd.wap.xhtml+xml mime
            // subtypes are used interchangeably. So treat them the same.
            if ("application/vnd.wap.xhtml+xml".equals(mimeType)) {
                mimeType = "application/xhtml+xml";
            }
        }
        return mimeType;
    }

    
Get the singleton instance of MimeTypeMap.
Returns:
The singleton instance of the MIME-type map./**
     * Get the singleton instance of MimeTypeMap.
     * @return The singleton instance of the MIME-type map.
     */
    public static MimeTypeMap getSingleton() {
        return sMimeTypeMap;
    }
}