/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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
 *
 *     https://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 org.apache.commons.configuration2.io;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;

import org.apache.commons.configuration2.ex.ConfigurationException;

/**
 * FileSystem that uses java.io.File or HttpClient.
 *
 * @since 1.7
 */
public class DefaultFileSystem extends FileSystem {

    /**
     * Wraps the output stream so errors can be detected in the HTTP response.
     *
     * @since 1.7
     */
    private static final class HttpOutputStream extends VerifiableOutputStream {

        /** The wrapped OutputStream */
        private final OutputStream stream;

        /** The HttpURLConnection */
        private final HttpURLConnection connection;

        public HttpOutputStream(final OutputStream stream, final HttpURLConnection connection) {
            this.stream = stream;
            this.connection = connection;
        }

        @Override
        public void close() throws IOException {
            stream.close();
        }

        @Override
        public void flush() throws IOException {
            stream.flush();
        }

        @Override
        public String toString() {
            return stream.toString();
        }

        @Override
        public void verify() throws IOException {
            if (connection.getResponseCode() >= HttpURLConnection.HTTP_BAD_REQUEST) {
                throw new IOException("HTTP Error " + connection.getResponseCode() + " " + connection.getResponseMessage());
            }
        }

        @Override
        public void write(final byte[] bytes) throws IOException {
            stream.write(bytes);
        }

        @Override
        public void write(final byte[] bytes, final int i, final int i1) throws IOException {
            stream.write(bytes, i, i1);
        }

        @Override
        public void write(final int i) throws IOException {
            stream.write(i);
        }
    }

    /**
     * Constructs a new instance.
     */
    public DefaultFileSystem() {
        // empty
    }

    /**
     * Create the path to the specified file.
     *
     * @param file the target file
     * @throws ConfigurationException if the path cannot be created
     */
    private void createPath(final File file) throws ConfigurationException {
        // create the path to the file if the file doesn't exist
        if (file != null && !file.exists()) {
            final File parent = file.getParentFile();
            if (parent != null && !parent.exists() && !parent.mkdirs()) {
                throw new ConfigurationException("Cannot create path: %s", parent);
            }
        }
    }

    @Override
    public String getBasePath(final String path) {
        final URL url;
        try {
            url = getURL(null, path);
            return FileLocatorUtils.getBasePath(url);
        } catch (final Exception e) {
            return null;
        }
    }

    @Override
    public String getFileName(final String path) {
        final URL url;
        try {
            url = getURL(null, path);
            return FileLocatorUtils.getFileName(url);
        } catch (final Exception e) {
            return null;
        }
    }

    @Override
    public InputStream getInputStream(final URL url) throws ConfigurationException {
        return getInputStream(url, null);
    }

    @Override
    public InputStream getInputStream(final URL url, final URLConnectionOptions urlConnectionOptions) throws ConfigurationException {
        // throw an exception if the target URL is a directory
        final File file = FileLocatorUtils.fileFromURL(url);
        if (file != null && file.isDirectory()) {
            throw new ConfigurationException("Cannot load a configuration from a directory");
        }

        try {
            return urlConnectionOptions == null ? url.openStream() : urlConnectionOptions.openConnection(url).getInputStream();
        } catch (final Exception e) {
            throw new ConfigurationException(e, "Unable to load the configuration from the URL %s", url);
        }
    }

    @Override
    public OutputStream getOutputStream(final File file) throws ConfigurationException {
        try {
            // create the file if necessary
            createPath(file);
            return new FileOutputStream(file);
        } catch (final FileNotFoundException e) {
            throw new ConfigurationException(e, "Unable to save to file %s", file);
        }
    }

    @Override
    public OutputStream getOutputStream(final URL url) throws ConfigurationException {
        // file URLs have to be converted to Files since FileURLConnection is
        // read only (https://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4191800)
        final File file = FileLocatorUtils.fileFromURL(url);
        if (file != null) {
            return getOutputStream(file);
        }
        // for non file URLs save through an URLConnection
        OutputStream out;
        try {
            final URLConnection connection = url.openConnection();
            connection.setDoOutput(true);

            // use the PUT method for http URLs
            if (connection instanceof HttpURLConnection) {
                final HttpURLConnection conn = (HttpURLConnection) connection;
                conn.setRequestMethod("PUT");
            }

            out = connection.getOutputStream();

            // check the response code for http URLs and throw an exception if an error occurred
            if (connection instanceof HttpURLConnection) {
                out = new HttpOutputStream(out, (HttpURLConnection) connection);
            }
            return out;
        } catch (final IOException e) {
            throw new ConfigurationException(e, "Could not save to URL %s", url);
        }
    }

    @Override
    public String getPath(final File file, final URL url, final String basePath, final String fileName) {
        String path = null;
        // if resource was loaded from jar file may be null
        if (file != null) {
            path = file.getAbsolutePath();
        }

        // try to see if file was loaded from a jar
        if (path == null) {
            if (url != null) {
                path = url.getPath();
            } else {
                try {
                    path = getURL(basePath, fileName).getPath();
                } catch (final Exception e) {
                    // simply ignore it and return null
                    if (getLogger().isDebugEnabled()) {
                        getLogger().debug(String.format("Could not determine URL for basePath = %s, fileName = %s: %s", basePath, fileName, e));
                    }
                }
            }
        }

        return path;
    }

    @Override
    public URL getURL(final String basePath, final String file) throws MalformedURLException {
        final File f = new File(file);
        // already absolute?
        if (f.isAbsolute()) {
            return FileLocatorUtils.toURL(f);
        }

        try {
            if (basePath == null) {
                return new URL(file);
            }
            final URL base = new URL(basePath);
            return new URL(base, file);
        } catch (final MalformedURLException uex) {
            return FileLocatorUtils.toURL(FileLocatorUtils.constructFile(basePath, file));
        }
    }

    @Override
    public URL locateFromURL(final String basePath, final String fileName) {
        try {
            final URL url;
            if (basePath == null) {
                return new URL(fileName);
                // url = new URL(name);
            }
            final URL baseURL = new URL(basePath);
            url = new URL(baseURL, fileName);

            // check if the file exists
            try (InputStream in = url.openStream()) {
                // nothing
                in.available();
            }
            return url;
        } catch (final IOException e) {
            if (getLogger().isDebugEnabled()) {
                getLogger().debug("Could not locate file " + fileName + " at " + basePath + ": " + e.getMessage());
            }
            return null;
        }
    }
}
