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/*
 * 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 tech.tablesaw.io;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.io.StringReader;
import java.net.URL;
import java.net.URLConnection;
import java.nio.charset.Charset;
import java.sql.ResultSet;
import java.sql.SQLException;

import com.google.common.io.Files;

import tech.tablesaw.api.Table;
import tech.tablesaw.io.csv.CsvReadOptions;
import tech.tablesaw.io.csv.CsvReader;
import tech.tablesaw.io.jdbc.SqlResultSetReader;

public class DataFrameReader {

    private final ReaderRegistry registry;

    public DataFrameReader(ReaderRegistry registry) {
	this.registry = registry;
    }

    /**
     * Reads the given URL into a table using default options
     * Uses appropriate converter based on mime-type
     * Use {@link #usingOptions(ReadOptions) usingOptions} to use non-default options
     */
    public Table url(String url) throws IOException {
	return url(new URL(url));
    }

    /**
     * Reads the given URL into a table using default options
     * Uses appropriate converter based on mime-type
     * Use {@link #usingOptions(ReadOptions) usingOptions} to use non-default options
     */
    public Table url(URL url) throws IOException {
	URLConnection connection = url.openConnection();
	String contentType = connection.getContentType();
	String[] pair = contentType.split(";");
	String mimeType = pair[0].trim();
	Charset charset = pair.length == 0 ? Charset.defaultCharset() : Charset.forName(pair[1].split("=")[1].trim());
	DataReader reader = registry.getReaderForMimeType(mimeType);
	return reader.read(new Source(connection.getInputStream(), charset));
    }

    /**
     * Reads the given string contents into a table using default options
     * Uses converter specified based on given file extension
     * Use {@link #usingOptions(ReadOptions) usingOptions} to use non-default options
     */
    public Table string(String s, String fileExtension) {
	DataReader reader = registry.getReaderForExtension(fileExtension);
	try {
            return reader.read(Source.fromString(s));
	} catch (IOException e) {
	    throw new IllegalStateException(e);
	}
    }

    /**
     * Reads the given file into a table using default options
     * Uses converter specified based on given file extension
     * Use {@link #usingOptions(ReadOptions) usingOptions} to use non-default options
     */
    public Table file(String file) throws IOException {
        return file(new File(file));
    }

    /**
     * Reads the given file into a table using default options
     * Uses converter specified based on given file extension
     * Use {@link #usingOptions(ReadOptions) usingOptions} to use non-default options
     */
    public Table file(File file) throws IOException {
	String extension = Files.getFileExtension(file.getCanonicalPath());
	DataReader reader = registry.getReaderForExtension(extension);
	return reader.read(new Source(file));
    }

    public  Table usingOptions(T options) throws IOException {
	DataReader reader = registry.getReaderForOptions(options);
	return reader.read(options);
    }

    public Table usingOptions(ReadOptions.Builder builder) throws IOException {
	return usingOptions(builder.build());
    }

    public Table db(ResultSet resultSet) throws SQLException {
        return SqlResultSetReader.read(resultSet);
    }

    public Table db(ResultSet resultSet, String tableName) throws SQLException {
        Table table = SqlResultSetReader.read(resultSet);
        table.setName(tableName);
        return table;
    }


    // Legacy reader methods for backwards-compatibility
    
    public Table csv(String file) throws IOException {
        return csv(CsvReadOptions.builder(file));
    }

    public Table csv(String contents, String tableName) {
        try {
            return csv(CsvReadOptions.builder(new StringReader(contents)).tableName(tableName));
        } catch (Exception e) {
            throw new IllegalStateException(e);
        }
    }

    public Table csv(File file) throws IOException {
        return csv(CsvReadOptions.builder(file));
    }

    public Table csv(InputStream stream) throws IOException {
        return csv(CsvReadOptions.builder(stream));
    }

    public Table csv(InputStream stream, String name) throws IOException {
        return csv(CsvReadOptions.builder(stream).tableName(name));
    }

    public Table csv(Reader reader) throws IOException {
        return csv(CsvReadOptions.builder(reader));
    }

    public Table csv(CsvReadOptions.Builder options) throws IOException {
        return csv(options.build());
    }

    public Table csv(CsvReadOptions options) throws IOException {
	return new CsvReader().read(options);
    }

}