Minecraft-Server-Launcher/src/main/java/net/knarcraft/minecraftserverlauncher/utility/CommonFunctions.java

package net.knarcraft.minecraftserverlauncher.utility;

import net.knarcraft.minecraftserverlauncher.Main;
import net.knarcraft.minecraftserverlauncher.userinterface.WebBrowser;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.URL;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.StandardCopyOption;
import java.util.Scanner;

/**
 * A holding class for methods shared between classes
 *
 * @author Kristian Knarvik <kristian.knarvik@knett.no>
 * @version 1.0.0
 * @since 1.0.0
 */
public final class CommonFunctions {

    private static final String filesDirectory = Main.getApplicationWorkDirectory() + File.separator + "files";

    /**
     * Creates all folders necessary for tests and normal operation
     *
     * @throws FileNotFoundException <p>If unable to create a folder</p>
     */
    public static void createAllFolders() throws FileNotFoundException {
        createFolder(new File(filesDirectory));
        createFolder(new File(filesDirectory + File.separator + "Jars"));
    }

    /**
     * Creates a given folder
     *
     * @param folder <p>The folder to create</p>
     * @throws FileNotFoundException <p>If unable to create the folder</p>
     */
    public static void createFolder(File folder) throws FileNotFoundException {
        if (!folder.exists()) {
            if (!folder.mkdirs()) {
                throw new FileNotFoundException("Cannot create necessary directory.");
            }
        }
    }

    /**
     * Gets a resource as an InputStream
     *
     * @param resourceName <p>The name of the resource you want to readFromServer</p>
     * @return <p>An input stream which can be used to access the resource</p>
     */
    public static InputStream getResourceAsStream(String resourceName) {
        ClassLoader classloader = Thread.currentThread().getContextClassLoader();
        return classloader.getResourceAsStream(resourceName);
    }

    /**
     * Gets a resource as a Scanner
     *
     * @param resourceName <p>The name of the resource you want to readFromServer</p>
     * @return <p>A scanner which can be used to readFromServer contents of the resource</p>
     * @throws FileNotFoundException <p>If the resource is not found</p>
     */
    public static Scanner getResourceAsScanner(String resourceName) throws FileNotFoundException {
        InputStream is = getResourceAsStream(resourceName);
        if (is == null) {
            throw new FileNotFoundException("The resource was not found.");
        }
        return new Scanner(is);
    }

    /**
     * Finds a substring between two substrings in a string
     *
     * @param string <p>The string containing the substrings</p>
     * @param start  <p>The substring before the wanted substring</p>
     * @param end    <p>The substring after the wanted substring</p>
     * @return <p>The wanted substring</p>
     */
    public static String stringBetween(String string, String start, String end) {
        int startPos = string.indexOf(start) + start.length();
        if (!string.contains(start) || string.indexOf(end, startPos) < startPos) {
            return "";
        }
        return string.substring(startPos, string.indexOf(end, startPos));
    }

    /**
     * Reads a file from a website
     *
     * <p>This is used to find the newest version of jars and the software.</p>
     *
     * @param path <p>The full url of the file to readFromServer</p>
     * @return <p>True if successful. False otherwise</p>
     * @throws IOException <p>If unable to find or read the file</p>
     */
    public static String readRemoteFile(String path) throws IOException {
        URL url = new URL(path);
        return new Scanner(url.openStream()).useDelimiter("\\Z").next();
    }

    /**
     * Gets a buffered reader for reading a given file
     *
     * @param path <p>The path of the file to read</p>
     * @return <p>A buffered reader for reading the file</p>
     * @throws FileNotFoundException <p>If the file does not exist</p>
     */
    public static BufferedReader getFileReader(String path) throws FileNotFoundException {
        return new BufferedReader(new InputStreamReader(new FileInputStream(path)));
    }

    /**
     * Gets a buffered writer for writing to a given file
     * @param path <p>The path to the file to write to</p>
     * @return <p>A buffered writer for writing to the file</p>
     * @throws FileNotFoundException <p>If the file does not exist</p>
     */
    public static BufferedWriter getFileWriter(String path) throws FileNotFoundException {
        return new BufferedWriter(new OutputStreamWriter(new FileOutputStream(path)));
    }

    /**
     * Reads a file from disk
     *
     * @param path <p>The path of the file to read</p>
     * @return <p>The contents of the file</p>
     * @throws IOException <p>If unable to find or read the file</p>
     */
    public static String readFile(String path) throws IOException {
        return CommonFunctions.readBufferedReader(getFileReader(path));
    }


    /**
     * Writes text to a file and adds a trailing newline
     *
     * @param path               <p>The path of the file to write to</p>
     * @param text               <p>The text to write</p>
     * @throws IOException <p>If unable to write to the file</p>
     */
    public static void writeFile(String path, String text) throws IOException {
        writeFile(path, text, !text.equals(""));
    }

    /**
     * Writes text to a file
     *
     * @param path               <p>The path of the file to write to</p>
     * @param text               <p>The text to write</p>
     * @param addTrailingNewline <p>Whether to add a new line at the end of the file</p>
     * @throws IOException <p>If unable to write to the file</p>
     */
    public static void writeFile(String path, String text, Boolean addTrailingNewline) throws IOException {
        BufferedWriter writer = getFileWriter(path);
        writer.write(text);
        if (addTrailingNewline) {
            writer.newLine();
        }
        writer.close();
    }

    /**
     * Appends text to a file
     *
     * @param path <p>The path to the file to append to</p>
     * @param text <p>The text to append</p>
     * @throws IOException <p>If unable to append to the file</p>
     */
    public static void appendFile(String path, String text) throws IOException {
        BufferedWriter writer = new BufferedWriter(new FileWriter(path, true));
        writer.write(text);
        writer.newLine();
        writer.close();
    }

    /**
     * Downloads a file from a website and replaces the target file
     *
     * @param path    <p>The full url of the file to download</p>
     * @param outfile <p>The file to save to</p>
     * @return <p>True if successful. False otherwise</p>
     */
    public static boolean downloadFile(String path, Path outfile) {
        try {
            URL url = new URL(path);
            InputStream in = url.openStream();
            Files.copy(in, outfile, StandardCopyOption.REPLACE_EXISTING);
            return true;
        } catch (IOException e) {
            return false;
        }
    }

    /**
     * Opens an url in the user's default application.
     *
     * @param url <p>The URL to open</p>
     */
    public static void goToURL(String url) {
        java.awt.Desktop desktop = java.awt.Desktop.getDesktop();
        try {
            desktop.browse(new URI(url));
        } catch (URISyntaxException | IOException | UnsupportedOperationException e1) {
            WebBrowser.displayPage(url);
        }
    }

    /**
     * Reads all lines from a buffered reader
     *
     * @param reader <p>The buffered reader to read from</p>
     * @return <p>All lines currently readable from the reader, split by the \n character</p>
     * @throws IOException <p>If unable to read from the buffered reader</p>
     */
    public static String readBufferedReader(BufferedReader reader) throws IOException {
        //String line;
        StringBuilder text = new StringBuilder();
        char[] readCharacters = new char[1000];
        while (reader.ready()) {
            if (reader.read(readCharacters) > 0) {
                text.append(readCharacters);
                readCharacters = new char[1000];
            } else {
                return text.toString().trim();
            }
        }
        return text.toString().trim();
    }



    /**
     * Validates that a name is not empty and does not contain invalid characters
     *
     * @param name <p>The name to check</p>
     * @return <p>True if the name is valid</p>
     */
    public static boolean nameIsValid(String name) {
        return name != null && !name.equals("") && name.matches("[^!?;,]+");
    }

    /**
     * Removes all files within a folder
     *
     * @param target <p>The folder to delete from</p>
     */
    static void removeFilesRecursively(File target) {
        File[] oldFiles = target.listFiles();
        if (oldFiles == null) {
            throw new IllegalArgumentException("Unable to list files in directory");
        }
        for (File file : oldFiles) {
            if (file.isFile()) {
                if (!file.delete()) {
                    throw new IllegalArgumentException("Unable to delete a file from the directory");
                }
            }
        }
        for (File file : oldFiles) {
            if (file.isDirectory()) {
                removeFilesRecursively(file);
                if (!file.delete()) {
                    throw new IllegalArgumentException("Unable to delete a file from the directory");
                }
            }
        }
    }

}