package io;

import com.google.gson.Gson;
import com.google.gson.JsonSyntaxException;
import data.Tweet;
import data.TwitterJsonDeserializer;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

/**
 * Reads tweets from an InputStream.
 *
 * @author Peter Wu
 */
public class TweetReader implements ITweetReader {

    private final InputStream is;
    private final BufferedReader reader;
    private final Gson gson;

    public TweetReader(InputStream is) {
        if (is == null) {
            throw new NullPointerException();
        }
        this.is = is;
        reader = new BufferedReader(new InputStreamReader(is));
        gson = TwitterJsonDeserializer.getGsonBuilder().create();
    }

    @Override
    public Tweet getTweet() throws IOException {
        String line = reader.readLine();
        Tweet tweet = null;
        if (line != null) {
            try {
                tweet = gson.fromJson(line, Tweet.class);
            } catch (JsonSyntaxException ex) {
                debugTweet(line, ex);
                throw ex;
            }
        }
        return tweet;
    }

    @Override
    public void close() {
        try {
            is.close();
        } catch (IOException ex) {
        }
    }

    private void debugTweet(String line, JsonSyntaxException ex) {
        System.err.println("Faulty line: " + line);
        ex.printStackTrace();
    }
}