/*
 * 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
 *
 *     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 org.apache.flink.fs.osshadoop;

import org.apache.flink.annotation.VisibleForTesting;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.core.fs.FileSystem;
import org.apache.flink.core.fs.FileSystemFactory;
import org.apache.flink.runtime.fs.hdfs.HadoopFileSystem;

import org.apache.hadoop.fs.aliyun.oss.AliyunOSSFileSystem;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.net.URI;
import java.util.Collections;
import java.util.Set;

/**
 * Simple factory for the OSS file system.
 */
public class OSSFileSystemFactory implements FileSystemFactory {
	private static final Logger LOG = LoggerFactory.getLogger(OSSFileSystemFactory.class);

	private Configuration flinkConfig;

	private org.apache.hadoop.conf.Configuration hadoopConfig;

	private static final Set<String> CONFIG_KEYS_TO_SHADE = Collections.singleton("fs.oss.credentials.provider");

	private static final String FLINK_SHADING_PREFIX = "org.apache.flink.fs.shaded.hadoop3.";

	/**
	 * In order to simplify, we make flink oss configuration keys same with hadoop oss module.
	 * So, we add all configuration key with prefix `fs.oss` in flink conf to hadoop conf
	 */
	private static final String[] FLINK_CONFIG_PREFIXES = { "fs.oss."};

	@Override
	public String getScheme() {
		return "oss";
	}

	@Override
	public void configure(Configuration config) {
		flinkConfig = config;
		hadoopConfig = null;
	}

	@Override
	public FileSystem create(URI fsUri) throws IOException {
		this.hadoopConfig = getHadoopConfiguration();

		final String scheme = fsUri.getScheme();
		final String authority = fsUri.getAuthority();

		if (scheme == null && authority == null) {
			fsUri = org.apache.hadoop.fs.FileSystem.getDefaultUri(hadoopConfig);
		} else if (scheme != null && authority == null) {
			URI defaultUri = org.apache.hadoop.fs.FileSystem.getDefaultUri(hadoopConfig);
			if (scheme.equals(defaultUri.getScheme()) && defaultUri.getAuthority() != null) {
				fsUri = defaultUri;
			}
		}

		final AliyunOSSFileSystem fs = new AliyunOSSFileSystem();
		fs.initialize(fsUri, hadoopConfig);
		return new HadoopFileSystem(fs);
	}

	@VisibleForTesting
	org.apache.hadoop.conf.Configuration getHadoopConfiguration() {
		org.apache.hadoop.conf.Configuration conf = new org.apache.hadoop.conf.Configuration();
		if (flinkConfig == null) {
			return conf;
		}

		// read all configuration with prefix 'FLINK_CONFIG_PREFIXES'
		for (String key : flinkConfig.keySet()) {
			for (String prefix : FLINK_CONFIG_PREFIXES) {
				if (key.startsWith(prefix)) {
					String value = flinkConfig.getString(key, null);
					conf.set(key, value);
					if (CONFIG_KEYS_TO_SHADE.contains(key)) {
						conf.set(key, FLINK_SHADING_PREFIX + value);
					}

					LOG.debug("Adding Flink config entry for {} as {} to Hadoop config", key, conf.get(key));
				}
			}
		}
		return conf;
	}
}