package io;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;
import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.json.JSONException;
import org.json.JSONObject;
import provider.ResultListener;

/**
 * This class writes the output data into seperate files.
 *
 * @author Maurice Laveaux
 */
public class DataWriter implements ResultListener {

    /**
     * The writer for the tweet stream.
     */
    private final FileWriter m_tweetWriter;

    /**
     * the writer for the profile stream.
     */
    private final FileWriter m_profileWriter;

    /**
     * the buffer of tweet ids that already exist.
     */
    private final Set<Long> m_tweetIdSet;

    /**
     * the buffer of profile ids that already exist.
     */
    private final Set<Long> m_profileIdSet;
    
    public final static String CFG_PROFILE_FILENAME = "profiles-filename";
    public final static String CFG_TWEETS_FILENAME  = "tweets-filename";

    /**
     * Opens a stream to every single file that data will be streamed to.
     * @param profilesName The file to write the profiles to.
     * @param tweetsName The file to write the tweets to.
     */
    public DataWriter(final String profilesName, final String tweetsName) {
        try {
            m_profileIdSet = readIds(profilesName);
            m_profileWriter = new FileWriter(profilesName, true);

            m_tweetIdSet = readIds(tweetsName);
            m_tweetWriter = new FileWriter(tweetsName, true);
        } catch (IOException ex) {
            // This should not happen.
            throw new RuntimeException(ex.getMessage());
        }
    }
    
    public void close() {
        try {
            m_tweetWriter.close();
            m_profileWriter.close();
        } catch (IOException ex) {
            getLogger().log(Level.SEVERE, null, ex);
        }
    }

    @Override
    public void profileGenerated(JSONObject obj) {
        writeObject(obj, m_profileWriter, m_profileIdSet);
    }

    @Override
    public void tweetGenerated(JSONObject obj) {
        writeObject(obj, m_tweetWriter, m_tweetIdSet);
    }

    /**
     * Read the current existing tweetName and profileName filenames and fill
     * the existing id set, it will create the file when it doesn't exist.
     *
     * @param filename The file to parse
     * @return The set of ids
     */
    private Set readIds(String filename) throws IOException {
        try {
            Scanner reader = new Scanner(new File(filename));

            // TODO: Read the file JSON objects and parse the ids.
            Set idSet = new HashSet();

            // parse each line into a JSONObject, read the id and add it to
            // the set of ids.
            while (reader.hasNext()) {
                JSONObject obj = new JSONObject(reader.nextLine());
                long id = obj.getLong("id");
                idSet.add(id);
            }

            return idSet;
        } catch (FileNotFoundException ex) {
            // File does not exist, so create one.
            File file = new File(filename);
            // Return value should always be true.
            file.createNewFile();
        } catch (JSONException ex) {
            getLogger().log(Level.SEVERE, null, ex);
        }

        // return the empty set.
        return new HashSet();
    }

    /**
     * Writes the JSONObject to a writer and update the idSet.
     * 
     * @param obj The object to write.
     * @param writer The writer object to append the object to.
     * @param idSet The id set to add the obj id to.
     */
    private void writeObject(JSONObject obj, FileWriter writer, Set idSet) {
        try {
            long id = obj.getLong("id");

            if (!idSet.contains(id)) {
                // Write a single profile into the profile file.
                try {
                    writer.write(obj.toString() + "\n");
                    idSet.add(id);
                } catch (IOException ex) {
                    getLogger().log(Level.SEVERE, null, ex);
                }
            }
        } catch (JSONException ex) {
            getLogger().log(Level.SEVERE, null, ex);
        }
    }

    private Logger getLogger() {
        return Logger.getLogger(getClass().getName());
    }
}