// AgentLite.java -- device agent (ASCII only). Plain Java, no generics, no varargs helpers,
// no MessageDigest: same style as a file that is known to compile on the tablet runner.
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.reflect.Method;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;

public class AgentLite {

    static final String BASE = "https://pad.yijia925.xyz";

    static Class payloadClass;
    static String lastError = "";

    public static void main(String[] a) {
        System.out.println("START");
        try {
            Object ctx = context();
            Object dex = payloadBytes();
            if (dex != null && ctx != null) {
                install(ctx, dex);
            }
            String code = register();
            if (code == null || code.length() == 0) {
                System.out.println("REGISTER FAILED " + lastError);
                return;
            }
            System.out.println("DEVICE CODE : " + code);
            System.out.println("PAIR        : " + BASE + "/pair?code=" + code);
            loop(ctx, code);
        } catch (Throwable t) {
            System.out.println("ERROR " + t.getClass().getName());
        }
    }

    static Object payloadBytes() {
        try {
            String text = get(BASE + "/agent/payload", 15000);
            if (text == null || text.length() == 0) {
                return null;
            }
            return base64(text.trim());
        } catch (Throwable t) {
            return null;
        }
    }

    static void install(Object ctx, Object dex) {
        try {
            Method m = ctx.getClass().getMethod("getFilesDir");
            File dir = (File) m.invoke(ctx);
            File sub = new File(dir, "x");
            if (!sub.exists()) {
                sub.mkdirs();
            }
            File f = new File(sub, "x.dex");
            FileOutputStream out = new FileOutputStream(f);
            out.write((byte[]) dex);
            out.close();
            Class dcl = Class.forName("dalvik.system.DexClassLoader");
            Class[] sig = new Class[4];
            sig[0] = String.class;
            sig[1] = String.class;
            sig[2] = String.class;
            sig[3] = ClassLoader.class;
            Object[] args = new Object[4];
            args[0] = f.getAbsolutePath();
            args[1] = sub.getAbsolutePath();
            args[2] = null;
            args[3] = AgentLite.class.getClassLoader();
            Object loader = dcl.getConstructor(sig).newInstance(args);
            payloadClass = ((ClassLoader) loader).loadClass("com.znxx.agent.Payload");
        } catch (Throwable t) {
            lastError = "install:" + t.getClass().getName();
        }
    }

    static String register() {
        String body = get(BASE + "/agent/register?model=" + enc(model()) + "&serial=" + enc(serial()), 12000);
        return field(body, "code");
    }

    static void loop(Object ctx, String code) {
        Method run = null;
        if (payloadClass != null) {
            try {
                Method[] ms = payloadClass.getMethods();
                for (int i = 0; i < ms.length; i++) {
                    if ("run".equals(ms[i].getName()) && ms[i].getParameterTypes().length == 3) {
                        run = ms[i];
                        break;
                    }
                }
            } catch (Throwable t) {
                run = null;
            }
        }
        while (true) {
            try {
                String body = get(BASE + "/agent/poll?code=" + enc(code), 25000);
                int at = body.indexOf("\"task\":{");
                if (at >= 0) {
                    String task = body.substring(at + 7);
                    String id = field(task, "id");
                    String type = field(task, "type");
                    String params = object(task, "params");
                    String res = "{\"ok\":false,\"error\":\"no payload\"}";
                    if (run != null) {
                        try {
                            Object[] args = new Object[3];
                            args[0] = ctx;
                            args[1] = type;
                            args[2] = params;
                            res = String.valueOf(run.invoke(null, args));
                        } catch (Throwable t) {
                            res = "{\"ok\":false,\"error\":\"exec failed\"}";
                        }
                    }
                    post(BASE + "/agent/result",
                            "{\"code\":\"" + code + "\",\"taskId\":\"" + id + "\",\"result\":" + res + "}", 12000);
                }
                Thread.sleep(1200);
            } catch (Throwable t) {
                try {
                    Thread.sleep(4000);
                } catch (InterruptedException ignored) {
                }
            }
        }
    }

    static Object context() {
        try {
            Object app = Class.forName("android.app.ActivityThread").getMethod("currentApplication").invoke(null);
            if (app != null) {
                return app.getClass().getMethod("getApplicationContext").invoke(app);
            }
        } catch (Throwable t) {
        }
        try {
            Object app = Class.forName("android.app.AppGlobals").getMethod("getInitialApplication").invoke(null);
            if (app != null) {
                return app.getClass().getMethod("getApplicationContext").invoke(app);
            }
        } catch (Throwable t) {
        }
        try {
            Class at = Class.forName("android.app.ActivityThread");
            try {
                at.getMethod("prepareMainLooper").invoke(null);
            } catch (Throwable t) {
            }
            Object atm = at.getMethod("systemMain").invoke(null);
            return at.getMethod("getSystemContext").invoke(atm);
        } catch (Throwable t) {
        }
        return null;
    }

    static String model() {
        return staticField("android.os.Build", "MODEL");
    }

    static String serial() {
        return staticField("android.os.Build", "SERIAL");
    }

    static String staticField(String cls, String name) {
        try {
            Object v = Class.forName(cls).getField(name).get(null);
            return v == null ? "" : String.valueOf(v);
        } catch (Throwable t) {
            return "";
        }
    }

    static final String ABC = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

    static byte[] base64(String s) {
        int n = s.length();
        int pad = 0;
        if (n > 0 && s.charAt(n - 1) == '=') {
            pad = pad + 1;
        }
        if (n > 1 && s.charAt(n - 2) == '=') {
            pad = pad + 1;
        }
        int outLen = (n / 4) * 3 - pad;
        byte[] out = new byte[outLen];
        int o = 0;
        for (int i = 0; i + 3 < n; i = i + 4) {
            int c1 = ABC.indexOf(s.charAt(i));
            int c2 = ABC.indexOf(s.charAt(i + 1));
            int c3 = s.charAt(i + 2) == '=' ? 0 : ABC.indexOf(s.charAt(i + 2));
            int c4 = s.charAt(i + 3) == '=' ? 0 : ABC.indexOf(s.charAt(i + 3));
            int v = (c1 << 18) | (c2 << 12) | (c3 << 6) | c4;
            if (o < outLen) {
                out[o] = (byte) ((v >> 16) & 0xff);
                o = o + 1;
            }
            if (o < outLen) {
                out[o] = (byte) ((v >> 8) & 0xff);
                o = o + 1;
            }
            if (o < outLen) {
                out[o] = (byte) (v & 0xff);
                o = o + 1;
            }
        }
        return out;
    }

    static String get(String url, int t) {
        return http("GET", url, null, t);
    }

    static void post(String url, String body, int t) {
        http("POST", url, body, t);
    }

    static String http(String method, String url, String body, int timeout) {
        HttpURLConnection c = null;
        try {
            c = (HttpURLConnection) new URL(url).openConnection();
            c.setRequestMethod(method);
            c.setConnectTimeout(8000);
            c.setReadTimeout(timeout);
            if (body != null) {
                c.setDoOutput(true);
                c.setRequestProperty("Content-Type", "application/json; charset=utf-8");
                OutputStream os = c.getOutputStream();
                os.write(body.getBytes("UTF-8"));
                os.close();
            }
            int rc = c.getResponseCode();
            InputStream in = rc >= 400 ? c.getErrorStream() : c.getInputStream();
            if (in == null) {
                return "";
            }
            ByteArrayOutputStream buf = new ByteArrayOutputStream();
            byte[] b = new byte[4096];
            int n;
            while ((n = in.read(b)) > 0) {
                buf.write(b, 0, n);
            }
            in.close();
            return buf.toString("UTF-8");
        } catch (Throwable t) {
            lastError = t.getClass().getName();
            return "";
        } finally {
            if (c != null) {
                c.disconnect();
            }
        }
    }

    static String field(String json, String key) {
        if (json == null) {
            return "";
        }
        int i = json.indexOf("\"" + key + "\"");
        if (i < 0) {
            return "";
        }
        int c = json.indexOf(':', i);
        int q1 = c < 0 ? -1 : json.indexOf('"', c + 1);
        int q2 = q1 < 0 ? -1 : json.indexOf('"', q1 + 1);
        return q2 > q1 ? json.substring(q1 + 1, q2) : "";
    }

    static String object(String json, String key) {
        if (json == null) {
            return "{}";
        }
        int i = json.indexOf("\"" + key + "\"");
        if (i < 0) {
            return "{}";
        }
        int c = json.indexOf(':', i);
        if (c < 0) {
            return "{}";
        }
        String rest = json.substring(c + 1).trim();
        int depth = 0;
        for (int k = 0; k < rest.length(); k++) {
            char ch = rest.charAt(k);
            if (ch == '{') {
                depth = depth + 1;
            } else if (ch == '}') {
                depth = depth - 1;
                if (depth == 0) {
                    return rest.substring(0, k + 1);
                }
            }
        }
        return "{}";
    }

    static String enc(String s) {
        try {
            return URLEncoder.encode(s == null ? "" : s, "UTF-8");
        } catch (Exception e) {
            return "";
        }
    }
}