/*
 * FTPConnector
 *
 * This class is used to connect to and interact with an
 * FTP server. The methods allow you to download and upload
 * files to and from the server.
 *
 * @author - Joseph Shufflebotham
 *
 * © Copyright 2016
 */
package me.JoeShuff.SkyBasers.FTP;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLEncoder;
import java.util.ArrayList;
import java.util.List;

public class FTPClient {

    private static String host = null;
    private static String user = null;
    private static String pass = null;

    /*
     * This method sets the default static values for the server informations
     *
     * @param host - The host IP or url as a String
     * @param pass - The password for the FTP server
     * @param username - The username for the FTP server
     */
    public static void bootup(String host, String username, String pass)
    {
        FTPClient.host = host;
        FTPClient.user = username;
        FTPClient.pass = pass;
    }

    /*
     * This method sets the default static values for the server informations
     *
     * @param host - The host IP or url as a String
     * @param pass - The password for the FTP server
     * @param username - The username for the FTP server
     */
    public static void changeServerInfo(String host, String username, String pass)
    {
        FTPClient.host = host;
        FTPClient.user = username;
        FTPClient.pass = pass;
    }

    /*
     * This method gets the URL connection to the specified file with default mode
     *
     * @param filePath - The path of the file on the server to be found
     */
    public static URLConnection getConnection(String filePath)
    {
        return getConnection(filePath, "i");
    }

    /*
     * This method gets the URL connection to the specified file with default mode
     *
     * @param filePath - The path of the file on the server to be found
     * @param mode - The mode of which the FTP request needs to be sent in.
     */
    public static URLConnection getConnection(String filePath, String mode)
    {
        try {
            URL url = new URL("ftp://" + URLEncoder.encode(user, "UTF-8") + ":" + URLEncoder.encode(pass, "UTF-8") + "@" + host + "/" + URLEncoder.encode(filePath, "UTF-8") + ";type=" + mode);

            URLConnection conn = url.openConnection();

            return conn;

        } catch (IOException ex) {
            ex.printStackTrace();

            return null;
        }
    }

    /*
     * This method checks the connection to the specified file.
     *
     * It tests that it can both be read from but not written to, as
     * it will create the file and there is no way to delete it.
     *
     * @param filePath - The file that you want to check the connection to
     * @returns boolean - true if it can connect to the file, false if not.
     */
    public static boolean testConnectionToFile(String filePath)
    {
        try
        {
            URLConnection conn = getConnection(filePath);
            InputStream inputStream = conn.getInputStream();
            BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));

            inputStream.close();

            return true;

        } catch (FileNotFoundException e)
        {
            System.out.println("Could not find file " + filePath + " on FTP server!");

            return false;

        } catch (IOException ex)
        {
            ex.printStackTrace();

            return false;
        }
    }

    /*
     * This method gets all the strings that are in a file and
     * returns them in a list. For the developers manipulation.
     *
     * @param filePath - The path to the file they wish to download
     *
     * @returns List<String> - returns the list of all strings in the file.
     *                         can return null if the file doesn't exist, or
     *                         there is another error.
     */
    public static List<String> getFileStrings(String filePath)
    {
        List<String> results = new ArrayList<String>();

        try
        {
            URLConnection conn = getConnection(filePath);
            InputStream inputStream = conn.getInputStream();
            BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));

            String line = null;

            while ((line = reader.readLine()) != null) {
                results.add(line);
            }

            inputStream.close();

        } catch (FileNotFoundException e)
        {
            System.out.println("Could not find file " + filePath + " on FTP server!");

            return null;
        }
        catch (IOException ex)
        {
            ex.printStackTrace();

            return null;
        }

        return results;
    }

    /*
     * This method writes a list of strings to the specified file.
     * It also CLEARS the existing file so make sure to first FETCH
     * everything from the file if you wish to append it.
     *
     * @param filePath - The file location where we are uploading to
     * @param strings - The list of strings that are to be written to the file
     *                  each string will be seperated by a new line.
     */
    public static void writeAllStrings(String filePath, List<String> strings)
    {
        try
        {
            URLConnection conn = getConnection(filePath);

            OutputStream outputStream = conn.getOutputStream();
            BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(outputStream));

            for (String s : strings)
            {
                writer.write(s + "\n");
            }

            writer.close();
            outputStream.close();

        } catch (IOException e)
        {
            e.printStackTrace();
        }
    }

    /*
     * This method provides the ability to append more strings to the end of a file
     *
     * @param filePath - The path of the file on the FTP server to be appended
     * @param strings - The list of strings that are to be appended on the file.
     *                  Each string will be seperated by a new line.
     *
     */
    public static void appendToFile(String filePath, List<String> strings)
    {
        List<String> current = getFileStrings(filePath);

        if (current == null)
        {
            current = strings;
        }
        else
        {
            current.addAll(strings);
        }

        writeAllStrings(filePath, current);
    }

    /*
     * This method downloads text from a file on the FTP server and saves it locally.
     *
     * @param fromFile - The path of the file to be downloaded
     * @param toFile - The path of the file to be outputted to
     */
    public static void downloadTextToLocalFile(String fromFile, String toFile)
    {
        List<String> fileData = getFileStrings(fromFile);

        try
        {
            PrintWriter out = new PrintWriter(toFile);

            for (String line : fileData)
            {
                out.println(line);
            }

            out.close();

            System.out.println("Successfully downloaded file");

        } catch (FileNotFoundException e)
        {
            System.out.println("Unable to find the file " + toFile);
        }
    }

    /*
     * This method downloads the file in bytes from the FTP server.
     *
     * @param fromFile - The path of the file to download on the FTP server
     * @param toFile - The path of the file to store the file from the FTP
     *
     */
    public static void downloadBytesToLocalFile(String fromFile, String toFile)
    {
        try
        {
            URLConnection conn = getConnection(fromFile);

            InputStream inputSteam = conn.getInputStream();
            BufferedInputStream bis = new BufferedInputStream(inputSteam);

            OutputStream outputStream = new FileOutputStream(toFile);
            BufferedOutputStream bos = new BufferedOutputStream(outputStream);

            byte[] buffer = new byte[1024];

            int count;

            while ((count = bis.read(buffer)) > 0)
            {
                bos.write(buffer, 0, count);
            }

            bos.close();
            inputSteam.close();

            System.out.println("Successfully downloaded File");


        } catch (FileNotFoundException e)
        {
            System.out.println("Unable to find the file " + toFile);
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
    }
}