/**********************************************************************************************
*
*   raylib Gestures System - Gestures Detection and Usage Functions (Android and HTML5)
*
*   Copyright (c) 2015 Marc Palau and Ramon Santamaria
*
*   This software is provided "as-is", without any express or implied warranty. In no event
*   will the authors be held liable for any damages arising from the use of this software.
*
*   Permission is granted to anyone to use this software for any purpose, including commercial
*   applications, and to alter it and redistribute it freely, subject to the following restrictions:
*
*     1. The origin of this software must not be misrepresented; you must not claim that you
*     wrote the original software. If you use this software in a product, an acknowledgment
*     in the product documentation would be appreciated but is not required.
*
*     2. Altered source versions must be plainly marked as such, and must not be misrepresented
*     as being the original software.
*
*     3. This notice may not be removed or altered from any source distribution.
*
**********************************************************************************************/

//#define GESTURES_STANDALONE     // NOTE: To use the gestures module as standalone lib, just uncomment this line

#if defined(GESTURES_STANDALONE)
    #include "gestures.h"
#else
    #include "raylib.h"         // Required for typedef(s): Vector2, Gestures
#endif

#include <stdlib.h>             // malloc(), free()
#include <stdio.h>              // printf(), fprintf()
#include <math.h>               // Used for ...
#include <stdint.h>             // Defines int32_t, int64_t

#if defined(_WIN32)
    // Functions required to query time on Windows
    int __stdcall QueryPerformanceCounter(unsigned long long int *lpPerformanceCount);
    int __stdcall QueryPerformanceFrequency(unsigned long long int *lpFrequency);
#elif defined(__linux)
    #include <time.h>           // Used for clock functions
#endif

//----------------------------------------------------------------------------------
// Defines and Macros
//----------------------------------------------------------------------------------
#define FORCE_TO_SWIPE          20
#define TAP_TIMEOUT             300
//#define MAX_TOUCH_POINTS        4

//----------------------------------------------------------------------------------
// Types and Structures Definition
//----------------------------------------------------------------------------------
typedef enum {
    TYPE_MOTIONLESS,
    TYPE_DRAG,
    TYPE_DUAL_INPUT
} GestureType;

//----------------------------------------------------------------------------------
// Global Variables Definition
//----------------------------------------------------------------------------------
static GestureType gestureType = TYPE_MOTIONLESS;
static double eventTime = 0;
//static int32_t touchId;               // Not used...

// Tap gesture variables
static Vector2 initialTapPosition = { 0, 0 };

// Double Tap gesture variables
static bool doubleTapping = false;
static bool untap = false;              // Check if recently done a tap

// Drag gesture variables
static Vector2 initialDragPosition = { 0, 0 };
static Vector2 endDragPosition = { 0, 0 };
static Vector2 lastDragPosition = { 0, 0 };
static Vector2 dragVector = { 0, 0 };

static float magnitude = 0;             // Distance traveled dragging
static float angle = 0;                 // Angle direction of the drag
static float intensity = 0;             // How fast we did the drag (pixels per frame)
static int draggingTimeCounter = 0;     // Time that have passed while dragging

// Pinch gesture variables
static Vector2 firstInitialPinchPosition = { 0, 0 };
static Vector2 secondInitialPinchPosition = { 0, 0 };
static Vector2 firstEndPinchPosition = { 0, 0 };
static Vector2 secondEndPinchPosition = { 0, 0 };
static float pinchDelta = 0;            // Pinch delta displacement

// Detected gestures
static int previousGesture = GESTURE_NONE;
static int currentGesture = GESTURE_NONE;

// Enabled gestures flags, all gestures enabled by default 
static unsigned int enabledGestures = 0b0000011111111111;   

//----------------------------------------------------------------------------------
// Module specific Functions Declaration
//----------------------------------------------------------------------------------
static void InitPinchGesture(Vector2 posA, Vector2 posB);
static float CalculateAngle(Vector2 initialPosition, Vector2 actualPosition, float magnitude);
static float VectorDistance(Vector2 v1, Vector2 v2);
static float VectorDotProduct(Vector2 v1, Vector2 v2);
static double GetCurrentTime();

//----------------------------------------------------------------------------------
// Module Functions Definition
//----------------------------------------------------------------------------------

// Process gesture event and translate it into gestures
void ProcessGestureEvent(GestureEvent event)
{
    // Resets
    dragVector = (Vector2){ 0, 0 };
    pinchDelta = 0;
    
    previousGesture = currentGesture;
    
    switch (gestureType)
    {
        case TYPE_MOTIONLESS: // Detect TAP, DOUBLE_TAP and HOLD events
        {
            if (event.touchAction == TOUCH_DOWN)
            {
                if (event.pointCount > 1) InitPinchGesture(event.position[0], event.position[1]);
                else
                {
                    // Set the press position
                    initialTapPosition = event.position[0];
                    
                    // If too much time have passed, we reset the double tap
                    if (GetCurrentTime() - eventTime > TAP_TIMEOUT) untap = false;
                    
                    // If we are in time, we detect the double tap
                    if (untap) doubleTapping = true;
                    
                    // Update our event time
                    eventTime = GetCurrentTime();
                    
                    // Set hold
                    if (doubleTapping) currentGesture = GESTURE_DOUBLETAP;
                    else currentGesture = GESTURE_TAP;
                }
            }
            else if (event.touchAction == TOUCH_UP)
            {
			    currentGesture = GESTURE_NONE;

                // Detect that we are tapping instead of holding
                if (GetCurrentTime() - eventTime < TAP_TIMEOUT)
                {
                    if (doubleTapping) untap = false;
                    else untap = true;
                }
                
                // Tap finished
                doubleTapping = false;

                // Update our event time
                eventTime = GetCurrentTime();
            }
            // Begin dragging
            else if (event.touchAction == TOUCH_MOVE)
            {
                if (event.pointCount > 1) InitPinchGesture(event.position[0], event.position[1]);
                else
                {
                    // Set the drag starting position
                    initialDragPosition = initialTapPosition;
                    endDragPosition = initialDragPosition;
                    
                    // Initialize drag
                    draggingTimeCounter = 0;
                    gestureType = TYPE_DRAG;
                    currentGesture = GESTURE_NONE;
                }
            }
        } break;
        case TYPE_DRAG: // Detect DRAG and SWIPE events 
        {
            // end of the drag
            if (event.touchAction == TOUCH_UP)
            {
                // Return Swipe if we have enough sensitivity
                if (intensity > FORCE_TO_SWIPE)
                {
                    if (angle < 30 || angle > 330) currentGesture = GESTURE_SWIPE_RIGHT; // Right
                    else if (angle > 60 && angle < 120) currentGesture = GESTURE_SWIPE_UP; // Up
                    else if (angle > 150 && angle < 210) currentGesture = GESTURE_SWIPE_LEFT; // Left
                    else if (angle > 240 && angle < 300) currentGesture = GESTURE_SWIPE_DOWN; // Down
                }
                
                magnitude = 0;
                angle = 0;
                intensity = 0;
                
                gestureType = TYPE_MOTIONLESS;
            }
            // Update while we are dragging
            else if (event.touchAction == TOUCH_MOVE)
            {
                if (event.pointCount > 1) InitPinchGesture(event.position[0], event.position[1]);
                else
                {
                    lastDragPosition = endDragPosition;
                    endDragPosition = event.position[0];
                    
                    //endDragPosition.x = AMotionEvent_getX(event, 0);
                    //endDragPosition.y = AMotionEvent_getY(event, 0);
                    
                    // Calculate attributes
                    dragVector = (Vector2){ endDragPosition.x - lastDragPosition.x, endDragPosition.y - lastDragPosition.y };
                    magnitude = sqrt(pow(endDragPosition.x - initialDragPosition.x, 2) + pow(endDragPosition.y - initialDragPosition.y, 2));
                    angle = CalculateAngle(initialDragPosition, endDragPosition, magnitude);
                    intensity = magnitude / (float)draggingTimeCounter;
                    
                    currentGesture = GESTURE_DRAG;
                    draggingTimeCounter++;
                }
            }
        } break;
        case TYPE_DUAL_INPUT:
        {
            if (event.touchAction == TOUCH_UP)
            {
                if (event.pointCount == 1)
                {
                    // Set the drag starting position
                    initialTapPosition = event.position[0];
                }
                gestureType = TYPE_MOTIONLESS;
            }
            else if (event.touchAction == TOUCH_MOVE)
            {
                // Adapt the ending position of the inputs
                firstEndPinchPosition = event.position[0];
                secondEndPinchPosition = event.position[1];
                
                // If there is no more than two inputs
                if (event.pointCount == 2)
                {
                    // Calculate distances
                    float initialDistance = VectorDistance(firstInitialPinchPosition, secondInitialPinchPosition);
                    float endDistance = VectorDistance(firstEndPinchPosition, secondEndPinchPosition);

                    // Calculate Vectors
                    Vector2 firstTouchVector = { firstEndPinchPosition.x - firstInitialPinchPosition.x, firstEndPinchPosition.y - firstInitialPinchPosition.y };
                    Vector2 secondTouchVector = { secondEndPinchPosition.x - secondInitialPinchPosition.x, secondEndPinchPosition.y - secondInitialPinchPosition.y };

                    // Detect the pinch gesture
                    if (VectorDotProduct(firstTouchVector, secondTouchVector) < -0.5) pinchDelta = initialDistance - endDistance;
                    else pinchDelta = 0;
                    
                    // Pinch gesture resolution
                    if (pinchDelta != 0)
                    {
                        if (pinchDelta > 0) currentGesture = GESTURE_PINCH_IN;
                        else currentGesture = GESTURE_PINCH_OUT;
                    }
                }
                else
                {
                    // Set the drag starting position
                    initialTapPosition = event.position[0];
                    
                    gestureType = TYPE_MOTIONLESS;
                }
                
                // Readapt the initial position of the inputs
                firstInitialPinchPosition = firstEndPinchPosition;
                secondInitialPinchPosition = secondEndPinchPosition;
            }
        } break;
    }
}

// Check if a gesture have been detected
bool IsGestureDetected(void)
{
    if (currentGesture != GESTURE_NONE) return true;
    else return false;
}

// Check gesture type
int GetGestureType(void)
{
    // Get current gesture only if enabled
    return (enabledGestures & currentGesture);
}

void SetGesturesEnabled(unsigned int gestureFlags)
{
    enabledGestures = enabledGestures | gestureFlags;
}

// Get drag intensity (pixels per frame)
float GetGestureDragIntensity(void)
{
    return intensity;
}

// Get drag angle
// NOTE: Angle in degrees, horizontal-right is 0, counterclock-wise
float GetGestureDragAngle(void)
{
    return angle;
}

// Get drag vector (between initial and final position)
Vector2 GetGestureDragVector(void)
{
    return dragVector;
}

// Hold time measured in frames
int GetGestureHoldDuration(void)
{
    return 0;
}

// Get magnitude between two pinch points
float GetGesturePinchDelta(void)
{
    return pinchDelta;
}

// Get angle beween two pinch points
// NOTE: Angle in degrees, horizontal-right is 0, counterclock-wise
float GetGesturePinchAngle(void)
{
    return 0;
}

// Update gestures detected (must be called every frame)
void UpdateGestures(void)
{
    // NOTE: Gestures are processed through system callbacks on touch events
    
    if ((previousGesture == GESTURE_TAP) && (currentGesture == GESTURE_TAP)) currentGesture = GESTURE_HOLD;
    else if (currentGesture != GESTURE_HOLD) currentGesture = GESTURE_NONE;
}

//----------------------------------------------------------------------------------
// Module specific Functions Definition
//----------------------------------------------------------------------------------

static float CalculateAngle(Vector2 initialPosition, Vector2 finalPosition, float magnitude)
{
    float angle;
    
    // Calculate arcsinus of the movement
    angle = asin((finalPosition.y - initialPosition.y)/magnitude);
    angle *= RAD2DEG;
    
    // Calculate angle depending on the sector
    if ((finalPosition.x - initialPosition.x) >= 0)
    {
        // Sector 4
        if ((finalPosition.y - initialPosition.y) >= 0)
        {
            angle *= -1;
            angle += 360;
        }
        // Sector 1
        else angle *= -1;
    }
    else
    {
        // Sector 3
        if ((finalPosition.y - initialPosition.y) >= 0) angle += 180;
        // Sector 2
        else
        {
            angle *= -1;
            angle = 180 - angle;
        }
    }
    
    return angle;
}

static void InitPinchGesture(Vector2 posA, Vector2 posB)
{
    initialDragPosition = (Vector2){ 0, 0 };
    endDragPosition = (Vector2){ 0, 0 };
    lastDragPosition = (Vector2){ 0, 0 };

    // Initialize positions
    firstInitialPinchPosition = posA;
    secondInitialPinchPosition = posB;
    
    firstEndPinchPosition = firstInitialPinchPosition;
    secondEndPinchPosition = secondInitialPinchPosition;
    
    // Resets
    magnitude = 0;
    angle = 0;
    intensity = 0;

    gestureType = TYPE_DUAL_INPUT;
}

static float VectorDistance(Vector2 v1, Vector2 v2)
{
    float result;

    float dx = v2.x - v1.x;
    float dy = v2.y - v1.y;

    result = sqrt(dx*dx + dy*dy);

    return result;
}

static float VectorDotProduct(Vector2 v1, Vector2 v2)
{
    float result;

    float v1Module = sqrt(v1.x*v1.x + v1.y*v1.y);
    float v2Module = sqrt(v2.x*v2.x + v2.y*v2.y);
    
    Vector2 v1Normalized = { v1.x / v1Module, v1.y / v1Module };
    Vector2 v2Normalized = { v2.x / v2Module, v2.y / v2Module };
    
    result = v1Normalized.x*v2Normalized.x + v1Normalized.y*v2Normalized.y;

    return result;
}

static double GetCurrentTime()
{
    double time = 0;
    
#if defined(_WIN32)
    unsigned long long int clockFrequency, currentTime;
    
    QueryPerformanceFrequency(&clockFrequency);
    QueryPerformanceCounter(&currentTime);
    
    time = (double)currentTime/clockFrequency*1000.0f;  // time in miliseconds
#endif

#if defined(__linux)
    // NOTE: Only for Linux-based systems
    struct timespec now;
    clock_gettime(CLOCK_MONOTONIC, &now);
    uint64_t nowTime = (uint64_t)now.tv_sec*1000000000LLU + (uint64_t)now.tv_nsec;     // Time provided in nanoseconds
    
    time = ((double)nowTime/1000000.0);     // time in miliseconds
#endif

    return time;
}