package net.knarcraft.serverlauncher.server;

import java.io.*;
import java.net.URL;
import java.util.Scanner;
import java.nio.file.StandardCopyOption;
import java.nio.file.*;
import java.util.ArrayList;


/**
 * Contains all necessary information to create, run and manage a Minecraft server.
 *
 * @author		Kristian Knarvik <kristian.knarvik@knett.no>
 * @version	0.0.0.1
 * @since		0.0.0.1
 */
public class Server {
    /**
     * Available ram sizes. For GUI dropdown
     */
    private static final String[] ramList = {"512M", "1G", "2G", "3G", "4G", "5G", "6G", "7G", "8G", "9G", "10G", "11G", "12G", "13G", "14G", "15G", "16G"};
    private static ArrayList<Server> servers = new ArrayList<>();

    private String name;
    private String path;
    private boolean enabled;
    private ArrayList<String> playerList;
    private ServerType type;
    private String serverVersion;
    private String maxRam;
    private long pid;

    public Server(String name) {
        this.name = name;
        this.path = "";
        this.enabled = false;
        this.playerList = new ArrayList<>();
        this.type = null;
        this.serverVersion = null;
        this.maxRam = ramList[0];
        this.pid = -1;
        servers.add(this);
    }

    public void addPlayer(String name) {
        this.playerList.add(name);
    }

    public void removePlayer(String name) {
        for (int i = 0; i < playerList.size(); i++) {
            if (name.equals(playerList.get(i))) {
                playerList.remove(i);
                return;
            }
        }
    }

    public String getType() {
        return this.type.getName() + this.serverVersion + ".jar";
    }

    public static ArrayList<Server> getServers() {
        return servers;
    }

    public void toggle() {
        this.enabled = !this.enabled;
    }

    public void setPath(String path) {
        this.path = path;
    }

    public void setType(ServerType type) {
        this.type = type;
    }

    /**
     * Sets the server's server version to a valid version, or ignores the request.
     *
     * @param serverVersion Version number.
     */
    public void setServerVersion(String serverVersion) throws IllegalArgumentException {
        String[] versions = this.type.getVersions();
        for (String version : versions) {
            if (version.equals(serverVersion)) {
                this.serverVersion = serverVersion;
                return;
            }
        }
        throw new IllegalArgumentException("Invalid server version.");
    }

    public void setMaxRam(String ram) {
        this.maxRam = ram;
    }

    /**
     * Runs all enabled servers with their settings.
     */
    public static void startServers() {
        System.out.println("Starting servers.");
        for (Server server : servers) {
            server.run();
        }
    }

    /**
     * Runs the Minecraft server.
     */
    private void run() {
        if (this.enabled) {
            try {
                System.out.println("Downloading jar...");
                this.downloadJar();
                System.out.println("File downloaded.");
            } catch (FileNotFoundException e) {
                e.printStackTrace();
                System.out.println("File was not found.");
                return;
            }
            Runtime rt = Runtime.getRuntime();
            try {
                System.out.println("Executing command.");
                Process pr = rt.exec("\"java\" -Xmx" + this.maxRam + " -Xms512M -jar " + "\"" + this.path + "\\" + this.type + "\" nogui", null, new File(this.path));
                this.pid = pr.pid();
                System.out.println("Success");
            } catch (IOException e) {
                System.out.println("Error");
            }
        }
    }

    /**
     * Downloads necessary .jar file for the server.
     * This is unfortunately hardcoded since there is no golden standard, and we only host some jars ourselves.
     *
     * @throws FileNotFoundException if the file was not found and could not be acquired.
     */
    public void downloadJar() throws FileNotFoundException {
        AdvancedServerType type;
        File file = new File(this.path + "\\" + this.getType());
        Path filePath = Paths.get(this.path + "\\" + this.getType());
        String versionText;
        String newestVersion;
        boolean success;
        switch (this.type.getName()) {
            case "Custom":
                //TODO: Change Custom to use path as serverdir + input.
                if (!file.isFile()) {
                    throw new FileNotFoundException("Specified custom jar was not found.");
                }
                break;
            case "Spigot":
            case "Craftbukkit":
            case "MCPCplus":
                if (!file.isFile()) {
                    success = downloadFile(this.type.getDownloadURL() + this.type.getName() + this.serverVersion + ".jar", filePath);
                    System.out.println(this.type.getDownloadURL() + this.type.getName() + this.serverVersion + ".jar");
                    if (!success) {
                        throw new FileNotFoundException("Jar file could not be downloaded.");
                    }
                }
                break;
            case "Vanilla":
            case "Snapshot":
                type = (AdvancedServerType) this.type;
                if (this.serverVersion.equals("Latest")) {
                    try {
                        versionText = readFile(type.getVersionURL());
                    } catch (IOException e) {
                        throw new FileNotFoundException("Version file could not be downloaded.");
                    }
                    newestVersion = stringBetween(versionText, type.getSrcStart(), type.getSrcEnd());
                    success = downloadFile(this.type.getDownloadURL() + newestVersion + type.getDownloadURLPart() + newestVersion + ".jar", filePath);
                    //TODO: Register the new version number, and only download if version mismatch or missing file.
                    if (!success) {
                        throw new FileNotFoundException("Jar file could not be downloaded.");
                    }
                } else {
                    if (!file.isFile()) {
                        success = downloadFile(this.type.getDownloadURL() + this.serverVersion + type.getDownloadURLPart() + this.serverVersion + ".jar", filePath);
                        if (!success) {
                            throw new FileNotFoundException("Jar file could not be downloaded.");
                        }
                    }
                }
                break;
            case "SpongeVanilla":
                type = (AdvancedServerType) this.type;
                try {
                    versionText = readFile(type.getVersionURL() + this.serverVersion);
                } catch (IOException e) {
                    throw new FileNotFoundException("Version file could not be downloaded.");
                }
                newestVersion = stringBetween(versionText, type.getSrcStart(), type.getSrcEnd());
                success = downloadFile(this.type.getDownloadURL() + newestVersion + type.getDownloadURLPart() + newestVersion + ".jar", filePath);
                //TODO: Register the new version number, and only download if version mismatch or missing file.
                if (!success) {
                    throw new FileNotFoundException("Jar file could not be downloaded.");
                }
                break;
            case "Bungee":
                /*type = (AdvancedServerType) this.type;
                try {
                    versionText = readFile(this.type.getVersionURL());
                } catch (IOException e) {
                    throw new FileNotFoundException("Version file could not be downloaded.");
                }
                newestVersion = stringBetween(versionText, type.getSrcStart(), type.getSrcEnd());*/
                success = downloadFile(this.type.getDownloadURL(), filePath);
                //TODO: Register the new version number, and only download if version mismatch or missing file.
                if (!success) {
                    throw new FileNotFoundException("Jar file could not be downloaded.");
                }
        }
    }

    /**
     * Reads a file from a website.
     * This is used to find the newest version of the software.
     *
     * @param path The full url of the file to read.
     * @return True if successfull. False otherwise.
     */
    private static String readFile(String path) throws IOException {
        URL url = new URL(path);
        return new Scanner(url.openStream()).useDelimiter("\\Z").next();
    }

    /**
     * Downloads a file from a website.
     *
     * @param path    The full url of the file to download.
     * @param outfile The file to save to.
     * @return True if successful. False otherwise.
     */
    private 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;
        }
    }

    /**
     * Finds a substring between two substrings in a string.
     *
     * @param string The string containing the substrings.
     * @param start  The substring before the wanted substring.
     * @param end    The substring after the wanted substring.
     * @return The wanted substring.
     */
    private String stringBetween(String string, String start, String end) {
        int startPos = string.indexOf(start) + start.length();
        return string.substring(startPos, string.indexOf(end, startPos));
    }
}