package touch.inject;

import android.app.Service;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.hardware.input.InputManager;
import android.os.IBinder;
import android.os.SystemClock;
import android.util.Log;
import android.view.MotionEvent;

import java.util.LinkedHashMap;
import java.util.Map;

/**
 * Multi-touch gesture injector for the Pad emulator.
 *
 * Runs as a privileged system app (/system/priv-app) so that the
 * signature|privileged INJECT_EVENTS permission is granted; it then injects
 * real MotionEvents through InputManager — the exact path a physical touch
 * screen takes — which is what the adb `input` applet cannot do (it has no
 * multi-touch support).
 *
 * Usage:
 *   adb shell am startservice -n touch.inject/.Injector -e script "SCRIPT"
 *
 * SCRIPT is a whitespace-separated sequence of:
 *   down <finger> <x> <y>   finger (1-based) touches at (x,y) px
 *   move <finger> <x> <y>   finger moves to (x,y) px
 *   up <finger>             finger lifts
 *   wait <ms>               pause
 *
 * Progress is logged to logcat under the "TouchInject" tag.
 */
public class Injector extends Service {
    public static final String TAG = "TouchInject";

    /** Shell-triggerable entry point: works even while the app is stopped
     *  (the shell can broadcast to an explicit component).
     *  KNOWN FLAKE: the process is "cached" while the thread runs and the
     *  1.5GB emulator OOM-killed it once mid-script (during a 200ms wait),
     *  losing the final UP. Service routing is NOT an alternative — Android
     *  12+ blocks background startService from a receiver, and the AVD's
     *  locked bootloader blocks the system-app escalation. The harness
     *  therefore verifies "=== done" in logcat after every script and
     *  re-runs on failure; scripts should stay short. */
    public static class ScriptReceiver extends BroadcastReceiver {
        @Override
        public void onReceive(Context context, Intent intent) {
            String script = intent.getStringExtra("script");
            if (script == null) {
                return;
            }
            InputManager im = (InputManager)
                    context.getSystemService(Context.INPUT_SERVICE);
            new Thread(() -> execute(im, script), "TouchInject").start();
        }
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        String script = intent != null ? intent.getStringExtra("script") : null;
        if (script == null) {
            stopSelf();
            return START_NOT_STICKY;
        }
        InputManager im = (InputManager) getSystemService(INPUT_SERVICE);
        new Thread(() -> execute(im, script), "TouchInject").start();
        return START_NOT_STICKY;
    }

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    private static void execute(InputManager im, String script) {
        Log.i(TAG, "=== script: " + script);
        // finger number (1-based) -> [x, y]; insertion order = pointer index.
        LinkedHashMap<Integer, float[]> fingers = new LinkedHashMap<>();
        long downTime = 0;
        String[] toks = script.split("\\s+");
        int i = 0;
        while (i < toks.length) {
            String cmd = toks[i++];
            try {
                switch (cmd) {
                case "down": {
                    int f = Integer.parseInt(toks[i++]);
                    float x = Float.parseFloat(toks[i++]);
                    float y = Float.parseFloat(toks[i++]);
                    int action = fingers.isEmpty()
                            ? MotionEvent.ACTION_DOWN
                            : MotionEvent.ACTION_POINTER_DOWN;
                    int idx = fingers.size();
                    fingers.put(f, new float[]{x, y});
                    inject(im, action, idx, fingers, downTime);
                    if (downTime == 0) {
                        downTime = SystemClock.uptimeMillis();
                    }
                    break;
                }
                case "move": {
                    int f = Integer.parseInt(toks[i++]);
                    float x = Float.parseFloat(toks[i++]);
                    float y = Float.parseFloat(toks[i++]);
                    float[] p = fingers.get(f);
                    if (p == null) {
                        Log.w(TAG, "move of unknown finger " + f + " (skipped)");
                        break;
                    }
                    p[0] = x;
                    p[1] = y;
                    // Generic ACTION_MOVE for all moves (1 or N pointers):
                    // InputFlinger accepts it and GioView treats every
                    // pointer as a MOVE.
                    inject(im, MotionEvent.ACTION_MOVE, 0, fingers, downTime);
                    break;
                }
                case "up": {
                    int f = Integer.parseInt(toks[i++]);
                    if (!fingers.containsKey(f)) {
                        Log.w(TAG, "up of unknown finger " + f + " (skipped)");
                        break;
                    }
                    boolean last = fingers.size() == 1;
                    int action = last
                            ? MotionEvent.ACTION_UP
                            : MotionEvent.ACTION_POINTER_UP;
                    int idx = indexOf(fingers, f);
                    // The lifted pointer must still be part of the event.
                    inject(im, action, idx, fingers, downTime);
                    fingers.remove(f);
                    if (fingers.isEmpty()) {
                        downTime = 0;
                    }
                    break;
                }
                case "wait": {
                    int ms = Integer.parseInt(toks[i++]);
                    Thread.sleep(ms);
                    break;
                }
                default:
                    Log.e(TAG, "unknown command: " + cmd);
                }
            } catch (Exception e) {
                Log.e(TAG, "script error at '" + cmd + "': " + e);
                break;
            }
        }
        Log.i(TAG, "=== done");
    }

    private static int indexOf(LinkedHashMap<Integer, float[]> m, int f) {
        int idx = 0;
        for (Integer k : m.keySet()) {
            if (k == f) {
                return idx;
            }
            idx++;
        }
        return 0;
    }

    // INJECT_INPUT_EVENT_MODE_WAIT_FOR_RESULT. The SDK stub jar omits the
    // constant (and injectInputEvent itself), so both go through reflection;
    // the method is a public API at runtime on the device.
    private static final int INJECT_WAIT_FOR_RESULT = 1;

    private static void inject(InputManager im, int action, int actionIndex,
                               Map<Integer, float[]> fingers, long downTime) {
        int n = fingers.size();
        int[] ids = new int[n];
        MotionEvent.PointerCoords[] coords = new MotionEvent.PointerCoords[n];
        int j = 0;
        for (Map.Entry<Integer, float[]> e : fingers.entrySet()) {
            ids[j] = e.getKey() - 1; // pointer id (0-based)
            MotionEvent.PointerCoords c = new MotionEvent.PointerCoords();
            c.x = e.getValue()[0];
            c.y = e.getValue()[1];
            c.pressure = 1f;
            c.size = 1f;
            // TOOL_TYPE_FINGER. The compile-time android.jar lacks
            // PointerCoords.setToolType, but the device runtime (API 24+)
            // has it, so call it reflectively.
            try {
                java.lang.reflect.Method stt = MotionEvent.PointerCoords.class
                        .getMethod("setToolType", int.class);
                stt.invoke(c, 1);
            } catch (Exception ignored) {
            }
            coords[j] = c;
            j++;
        }
        long now = SystemClock.uptimeMillis();
        int fullAction = action == MotionEvent.ACTION_MOVE
                ? action
                : action | (actionIndex << MotionEvent.ACTION_POINTER_INDEX_SHIFT);
        MotionEvent ev = MotionEvent.obtain(downTime, now, fullAction, n, ids, coords,
                0 /*edgeFlags*/, 1f /*xPrecision*/, 1f /*yPrecision*/,
                0 /*metaState*/, 0 /*deviceId*/,
                0x4000003 /*SOURCE_TOUCH|SOURCE_CLASS_MASK*/, 0 /*displayId*/);
        boolean ok = doInject(im, ev);
        Log.i(TAG, String.format("inject action=%d idx=%d n=%d ids=%s ok=%b",
                action, actionIndex, n, java.util.Arrays.toString(ids), ok));
        ev.recycle();
    }

    private static boolean doInject(InputManager im, MotionEvent ev) {
        try {
            java.lang.reflect.Method m = InputManager.class.getMethod(
                    "injectInputEvent", android.view.InputEvent.class, int.class);
            Object r = m.invoke(im, ev, INJECT_WAIT_FOR_RESULT);
            return r instanceof Boolean && (Boolean) r;
        } catch (Exception e) {
            Throwable c = e.getCause() != null ? e.getCause() : e;
            Log.e(TAG, "injectInputEvent failed: " + c);
            return false;
        }
    }
}