/*  RetroArch - A frontend for libretro.
 *  Copyright (C) 2010-2014 - Hans-Kristian Arntzen
 *  Copyright (C) 2011-2015 - Daniel De Matteis
 *  Copyright (C) 2012-2015 - Michael Lelli
 * 
 *  RetroArch is free software: you can redistribute it and/or modify it under the terms
 *  of the GNU General Public License as published by the Free Software Found-
 *  ation, either version 3 of the License, or (at your option) any later version.
 *
 *  RetroArch is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 *  without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 *  PURPOSE.  See the GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along with RetroArch.
 *  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

#ifndef _ANDROID_NATIVE_APP_GLUE_H
#define _ANDROID_NATIVE_APP_GLUE_H

#include <poll.h>
#include <rthreads/rthreads.h>
#include <sched.h>

#include <android/configuration.h>
#include <android/looper.h>
#include <android/native_activity.h>

#ifdef __cplusplus
extern "C" {
#endif

/**
 * The native activity interface provided by <android/native_activity.h>
 * is based on a set of application-provided callbacks that will be called
 * by the Activity's main thread when certain events occur.
 *
 * This means that each one of this callbacks _should_ _not_ block, or they
 * risk having the system force-close the application. This programming
 * model is direct, lightweight, but constraining.
 *
 * The 'threaded_native_app' static library is used to provide a different
 * execution model where the application can implement its own main event
 * loop in a different thread instead. Here's how it works:
 *
 * 1/ The application must provide a function named "android_main()" that
 *    will be called when the activity is created, in a new thread that is
 *    distinct from the activity's main thread.
 *
 * 2/ android_main() receives a pointer to a valid "android_app" structure
 *    that contains references to other important objects, e.g. the
 *    ANativeActivity obejct instance the application is running in.
 *
 * 3/ the "android_app" object holds an ALooper instance that already
 *    listens to two important things:
 *
 *      - activity lifecycle events (e.g. "pause", "resume"). See APP_CMD_XXX
 *        declarations below.
 *
 *      - input events coming from the AInputQueue attached to the activity.
 *
 *    Each of these correspond to an ALooper identifier returned by
 *    ALooper_pollOnce with values of LOOPER_ID_MAIN and LOOPER_ID_INPUT,
 *    respectively.
 *
 *    Your application can use the same ALooper to listen to additional
 *    file-descriptors.  They can either be callback based, or with return
 *    identifiers starting with LOOPER_ID_USER.
 *
 * 4/ Whenever you receive a LOOPER_ID_MAIN or LOOPER_ID_INPUT event,
 *    the returned data will point to an android_poll_source structure.  You
 *    can call the process() function on it, and fill in android_app->onAppCmd
 *    and android_app->onInputEvent to be called for your own processing
 *    of the event.
 *
 *    Alternatively, you can call the low-level functions to read and process
 *    the data directly...  look at the process_cmd() and process_input()
 *    implementations in the glue to see how to do this.
 *
 * See the sample named "native-activity" that comes with the NDK with a
 * full usage example.  Also look at the JavaDoc of NativeActivity.
 */

struct android_app;

/**
 * Data associated with an ALooper fd that will be returned as the "outData"
 * when that source has data ready.
 */
struct android_poll_source
{
   /* The identifier of this source. May be LOOPER_ID_MAIN or
    * LOOPER_ID_INPUT. */
   int32_t id;

   /* The android_app this ident is associated with. */
   struct android_app *app;

   /* Function to call to perform the standard processing of data from
    * this source. */
   void (*process)(struct android_app *app, struct android_poll_source *source);
};

/**
 * This is the interface for the standard glue code of a threaded
 * application.  In this model, the application's code is running
 * in its own thread separate from the main thread of the process.
 * It is not required that this thread be associated with the Java
 * VM, although it will need to be in order to make JNI calls any
 * Java objects.
 */
struct android_app
{
   /* The application can place a pointer to its own state object
    * here if it likes. */
   void *userData;

   /* Fill this in with the function to process main app commands (APP_CMD_*) */
   void (*onAppCmd)(struct android_app *app, int32_t cmd);

   /* Fill this in with the function to process input events. At this point
    * the event has already been pre-dispatched, and it will be finished upon
    * return. Return 1 if you have handled the event, 0 for any default
    * dispatching. */
   int32_t (*onInputEvent)(struct android_app *app, AInputEvent *event);


   /* The ANativeActivity object instance that this app is running in. */
   ANativeActivity* activity;

   /* The current configuration the app is running in. */
   AConfiguration *config;

    /* This is the last instance's saved state, as provided at creation time.
     * It is NULL if there was no state.  You can use this as you need; the
     * memory will remain around until you call android_app_exec_cmd() for
     * APP_CMD_RESUME, at which point it will be freed and savedState set to NULL.
     * These variables should only be changed when processing a APP_CMD_SAVE_STATE,
     * at which point they will be initialized to NULL and you can malloc your
     * state and place the information here.  In that case the memory will be
     * freed for you later. */
    void* savedState;
    size_t savedStateSize;

   /* The ALooper associated with the app's thread. */
   ALooper* looper;

   /* When non-NULL, this is the input queue from which the app will
    * receive user input events. */
   AInputQueue* inputQueue;

   /* When non-NULL, this is the window surface that the app can draw in. */
   ANativeWindow* window;

   /* Current content rectangle of the window; this is the area where the
    * window's content should be placed to be seen by the user. */
   ARect contentRect;

   /* Current state of the app's activity. May be either APP_CMD_START,
    * APP_CMD_RESUME, APP_CMD_PAUSE, or APP_CMD_STOP; see below. */
   int activityState;

   /* This is non-zero when the application's NativeActivity is being
    * destroyed and waiting for the app thread to complete. */
   int destroyRequested;

   /* Below are "private" implementation variables of the glue code. */

   slock_t *mutex;
   scond_t *cond;

   int msgread;
   int msgwrite;

   sthread_t *thread;

   struct android_poll_source cmdPollSource;
   struct android_poll_source inputPollSource;

   int running;
   int stateSaved;
   int destroyed;
   int redrawNeeded;
   AInputQueue* pendingInputQueue;
   ANativeWindow* pendingWindow;
   ARect pendingContentRect;
};

enum
{
   /**
    * Looper data ID of commands coming from the app's main thread, which
    * is returned as an identifier from ALooper_pollOnce().  The data for this
    * identifier is a pointer to an android_poll_source structure.
    * These can be retrieved and processed with android_app_read_cmd()
    * and android_app_exec_cmd().
    */
   LOOPER_ID_MAIN   = 1,

   /**
    * Looper data ID of events coming from the AInputQueue of the
    * application's window, which is returned as an identifier from
    * ALooper_pollOnce().  The data for this identifier is a pointer to an
    * android_poll_source structure.  These can be read via the inputQueue
    * object of android_app.
    */
   LOOPER_ID_INPUT  = 2,

   /**
    * Start of user-defined ALooper identifiers.
    */
   LOOPER_ID_USER   = 3,
};

enum
{
   /**
    * Command from main thread: the AInputQueue has changed.  Upon processing
    * this command, android_app->inputQueue will be updated to the new queue
    * (or NULL).
    */
   APP_CMD_INPUT_CHANGED,

   /**
    * Command from main thread: a new ANativeWindow is ready for use.  Upon
    * receiving this command, android_app->window will contain the new window
    * surface.
    */
   APP_CMD_INIT_WINDOW,

   /**
    * Command from main thread: the existing ANativeWindow needs to be
    * terminated.  Upon receiving this command, android_app->window still
    * contains the existing window; after calling android_app_exec_cmd
    * it will be set to NULL.
    */
   APP_CMD_TERM_WINDOW,

   /**
    * Command from main thread: the current ANativeWindow has been resized.
    * Please redraw with its new size.
    */
   APP_CMD_WINDOW_RESIZED,

   /**
    * Command from main thread: the system needs that the current ANativeWindow
    * be redrawn.  You should redraw the window before handing this to
    * android_app_exec_cmd() in order to avoid transient drawing glitches.
    */
   APP_CMD_WINDOW_REDRAW_NEEDED,

   /**
    * Command from main thread: the content area of the window has changed,
    * such as from the soft input window being shown or hidden.  You can
    * find the new content rect in android_app::contentRect.
    */
   APP_CMD_CONTENT_RECT_CHANGED,

   /**
    * Command from main thread: the app's activity window has gained
    * input focus.
    */
   APP_CMD_GAINED_FOCUS,

   /**
    * Command from main thread: the app's activity window has lost
    * input focus.
    */
   APP_CMD_LOST_FOCUS,

   /**
    * Command from main thread: the current device configuration has changed.
    */
   APP_CMD_CONFIG_CHANGED,

   /**
    * Command from main thread: the system is running low on memory.
    * Try to reduce your memory use.
    */
   APP_CMD_LOW_MEMORY,

   /**
    * Command from main thread: the app's activity has been started.
    */
   APP_CMD_START,

   /**
    * Command from main thread: the app's activity has been resumed.
    */
   APP_CMD_RESUME,

   /**
    * Command from main thread: the app should generate a new saved state
    * for itself, to restore from later if needed.  
    */
   APP_CMD_SAVE_STATE,

   /**
    * Command from main thread: the app's activity has been paused.
    */
   APP_CMD_PAUSE,

   /**
    * Command from main thread: the app's activity has been stopped.
    */
   APP_CMD_STOP,

   /**
    * Command from main thread: the app's activity is being destroyed,
    * and waiting for the app thread to clean up and exit before proceeding.
    */
   APP_CMD_DESTROY,

   // Set by thread when it will no longer reply to commands.
   APP_CMD_DEAD,
};

void android_app_write_cmd(struct android_app *android_app, int8_t cmd);

int8_t android_app_read_cmd(struct android_app *android_app);

#ifdef __cplusplus
}
#endif

#endif