package org.handwerkszeug.dns.conf;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStreamReader;
import java.util.List;

import org.handwerkszeug.chain.Chain;
import org.handwerkszeug.chain.ChainResult;
import org.handwerkszeug.chain.impl.SimpleChainResult;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import werkzeugkasten.common.util.Streams;
import werkzeugkasten.common.util.StringUtil;

public
class ResolvConf implements Chain<List<String>, ChainResult> {

    static final Logger LOG = LoggerFactory.getLogger(ResolvConf.class);

    @Override
    public
    ChainResult execute(List<String> context) {
        handle("/etc/resolv.conf", context);
        return SimpleChainResult.Continue;
    }

    protected
    void handle(String path, final List<String> list) {
        final File file = new File(path);
        if (file.exists()) {
            new Streams.using<BufferedReader, Exception>() {
                @Override
                public
                BufferedReader open() throws Exception {
                    return new BufferedReader(new InputStreamReader(new FileInputStream(file)));
                }

                @Override
                public
                void handle(BufferedReader stream) throws Exception {
                    while (stream.ready()) {
                        parse(stream.readLine(), list);
                    }
                }

                @Override
                public
                void happen(Exception e) {
                    LOG.error(e.getLocalizedMessage(), e);
                }
            };
        }
    }

    protected
    void parse(String line, List<String> list) {
        if (StringUtil.isEmpty(line) == false) {
            String[] ary = line.split("\\s");
            if ((1 < ary.length) && ary[0].equalsIgnoreCase("nameserver")) {
                list.add(ary[1]);
            }
        }
    }
}