PluginLoader (Load a plugin from spigotmc, or bukkit-dev)

PluginLoader.java

import java.io.BufferedReader;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
import java.io.IOException;
import java.io.OutputStream;
import java.net.URL;
import java.net.URLConnection;
import java.net.HttpURLConnection; 
import java.util.ArrayList;
import java.util.List;

import org.bukkit.plugin.java.JavaPlugin;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser; 

import lombok.*;

/**
 * Loads Dependencies from bukkit, spigot, or a maven repo
 * <p>
 * Only downloading from bukkit compiles with the bukkitdev guidelines.
 * </p>
 * 
 * @author Techcable
 */
@NoArgsConstructor(access=AccessLevel.PRIVATE)
public class PluginLoader {
    
    /**
     * Load dependencies from the annotations specified in the plugin's class
     * 
     * @param jPlugin plugin to download for
     * @throws UnableToDownloadException if unable to donwload a dependency
     */
    public static class loadDependencies(Class<? extends JavaPlugin> jPlugin) throws UnableToDonwloadException {
        for 
    }
    
    private static interface Project {
        /**
         * Return the name of this project as specified in plugin.yml
         * 
         * @return the name of this plugin as specified in plugin.yml
         */
        public String getName();
        
        /**
         * Download this project to the specified location
         * 
         * @param file destination file
         * @throws UnableToDownloadException if unable to download
         */
        public void downloadTo(File file) throws UnableToDownloadException;
    }
    
    private static class UnableToDonwloadException extends Exception {
        public UnableToDownloadException(String msg, Exception cause) {
            super(msg, cause);
        }
    }
    
    //Spigot Methods ()
    public String get
    
    //BukkitDev Methods
    public List<JSONObject> getFiles(int projectId) {
        List<JSONObject> files = new ArrayList<>();
        JSONArray json = getJson("https://api.curseforge.com/servermods/files?projectIds" + projectId)
        for (Object obj : json) {
            JSONObject file = (JSONObject) obj;
            files.add(file);
        }
        return files;
    }
    
    @RequiredArgsConstructor
    @Getter
    private static class BukkitDevProject implements Project {
        private final int id;
        private final String name;
        
        @Override
        public void downloadTo(File destination) throws UnableToDonwloadException {
            try {
                List<JSONObject> files = getFiles(getId());
                JSONObject latestFile = null;
                for (JSONObject file : files) {
                    latestFile = file; //Java iterates from first to last, and the last file is the latest release
                }
                String version = (String) latestFile.get("name"); //Name is really version
                URL downloadURL = new URL((String) latestFile.get("downloadUrl"));
                Bukkit.getLogger().info("[PluginLoader] loading version " + version + " of " + getName());
                if (!destination.exists()) destination.createNewFile();
                
                try {
                    int b;
                    
                } finally {
                    if (in != null) in.close();
                    if (out != null) out.close();
                }
            } catch (Exception e) {
                throw new UnableToDonwloadException("Unable to download " + getName(), e);
            }
        }
    }
    
    //Utils
    
    private static download(URL url, File file) throws IOException {
        InputStream in;
        OutputStream out;
        try {
            in = downloadURL.openStream();
            out = new FileOutputStream(destination);
            final byte data[] = new byte[1024];
            int count;
            while ((count = in.read(data, 0, 1024)) != -1) {
                out.write(data, 0, count);
            }
        } finally {
            if (in != null) in.close()
            if (out != null) out.close();
        }
    }
    
    private static JSONParser PARSER = new JSONParser();
    private static Object getJson(String rawUrl) {
        BufferedReader reader = null;
        try {
            URL url = new URL(rawUrl);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setRequestMethod("GET");
            reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
            StringBuffer result = new StringBuffer();
            String line;
            while ((line = reader.readLine()) != null) result.append(line);
            return PARSER.parse(result.toString());
        } catch (Exception ex) {
            return null;
        } finally {
            try {
            if (reader != null) reader.close();
            } catch (IOException ex) {
                ex.printStackTrace();
                return null;
            }
        }
    }
    private static Object postJson(String url, JSONArray body) {
        String rawResponse = post(url, body.toJSONString());
        if (rawResponse == null) return null;
        try {
            return PARSER.parse(rawResponse);
        } catch (Exception e) {
            return null;
        }
    }
    private static String post(String rawUrl, String body) {
        BufferedReader reader = null;
        OutputStream out = null;
        try {
            URL url = new URL(rawUrl);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setRequestMethod("POST");
            connection.setDoOutput(true);
            connection.setDoInput(true);
            connection.setRequestProperty("Content-Type", "application/json");
            out = connection.getOutputStream();
            out.write(body.getBytes());
            reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
            StringBuffer result = new StringBuffer();
            String line;
            while ((line = reader.readLine()) != null) result.append(line);
            return result.toString();
        } catch (IOException ex) {
            ex.printStackTrace();
            return null;
        } finally {
            try {
                if (out != null) out.close();
                if (reader != null) reader.close();
            } catch (IOException ex) {
                ex.printStackTrace();
                return null;
            }
        }
    } 
    
    //Annotations
    
    public class @interface RequiredLibrary {
        public String groupId();
        public String artifactId();
        public String version();
        public String mavenRepo() default "";
    }
    
    public class @interface RequiredLibraries {
        public RequiredLibrary[] value();
    }
    
    public class @interface RequiredPlugin {
        /**
         * Get the bukkit/spigot project id
         * <p>
         * Return the spigot project id if {@link #source()} returns SPIGOT
         * Return the bukkit project id if {@link #source()} returns BUKKIT_DEV
         * </p>
         * 
         * @return the bukkit/spigot project id
         */
        public int projectId();
        /**
         * Return the plugin name as specified in plugin.yml
         * <p>
         * Used to determine whether the plugin is already installed
         * </p>
         * 
         * @return the plugin name as specified in plugin.yml
         */
        public String name();
        public String version();
        /**
         * Return where to download from
         * <p>
         * Currently only supports SPIGOT and BUKKIT_DEV
         * </p>
         * 
         * @return the download source
         */
        public PluginSource source();
    }
    
    public enum PluginSource {
        SPIGOT,
        BUKKIT_DEV;
    }
}