/*
Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements. See the NOTICE file
distributed with this work for additional information
regarding copyright ownership. The ASF licenses this file
to you 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.
*/

#import "CDVAccelerometer.h"

@interface CDVAccelerometer () {}
@property (readwrite, assign) BOOL isRunning;
@end

@implementation CDVAccelerometer

@synthesize callbackId, isRunning;

// defaults to 10 msec
#define kAccelerometerInterval 40
// g constant: -9.81 m/s^2
#define kGravitationalConstant -9.81

- (CDVAccelerometer*)init
{
self = [super init];
if (self) {
x = 0;
y = 0;
z = 0;
timestamp = 0;
self.callbackId = nil;
self.isRunning = NO;
}
return self;
}

- (void)dealloc
{
[self stop:nil];
}

- (void)start:(CDVInvokedUrlCommand*)command
{
NSString* cbId = command.callbackId;
NSTimeInterval desiredFrequency_num = kAccelerometerInterval;
UIAccelerometer* pAccel = [UIAccelerometer sharedAccelerometer];

// accelerometer expects fractional seconds, but we have msecs
pAccel.updateInterval = desiredFrequency_num / 1000;
self.callbackId = cbId;
if (!self.isRunning) {
pAccel.delegate = self;
self.isRunning = YES;
}
}

- (void)onReset
{
[self stop:nil];
}

- (void)stop:(CDVInvokedUrlCommand*)command
{
UIAccelerometer* theAccelerometer = [UIAccelerometer sharedAccelerometer];

theAccelerometer.delegate = nil;
self.isRunning = NO;
}

/**
* Picks up accel updates from device and stores them in this class
*/
- (void)accelerometer:(UIAccelerometer*)accelerometer didAccelerate:(UIAcceleration*)acceleration
{
if (self.isRunning) {
x = acceleration.x;
y = acceleration.y;
z = acceleration.z;
timestamp = ([[NSDate date] timeIntervalSince1970] * 1000);
[self returnAccelInfo];
}
}

- (void)returnAccelInfo
{
// Create an acceleration object
NSMutableDictionary* accelProps = [NSMutableDictionary dictionaryWithCapacity:4];

[accelProps setValue:[NSNumber numberWithDouble:x * kGravitationalConstant] forKey:@"x"];
[accelProps setValue:[NSNumber numberWithDouble:y * kGravitationalConstant] forKey:@"y"];
[accelProps setValue:[NSNumber numberWithDouble:z * kGravitationalConstant] forKey:@"z"];
[accelProps setValue:[NSNumber numberWithDouble:timestamp] forKey:@"timestamp"];

CDVPluginResult* result = [CDVPluginResult resultWithStatus:CDVCommandStatus_OK messageAsDictionary:accelProps];
[result setKeepCallback:[NSNumber numberWithBool:YES]];
[self.commandDelegate sendPluginResult:result callbackId:self.callbackId];
}

// TODO: Consider using filtering to isolate instantaneous data vs. gravity data -jm

/*
#define kFilteringFactor 0.1

// Use a basic low-pass filter to keep only the gravity component of each axis.
grav_accelX = (acceleration.x * kFilteringFactor) + ( grav_accelX * (1.0 - kFilteringFactor));
grav_accelY = (acceleration.y * kFilteringFactor) + ( grav_accelY * (1.0 - kFilteringFactor));
grav_accelZ = (acceleration.z * kFilteringFactor) + ( grav_accelZ * (1.0 - kFilteringFactor));

// Subtract the low-pass value from the current value to get a simplified high-pass filter
instant_accelX = acceleration.x - ( (acceleration.x * kFilteringFactor) + (instant_accelX * (1.0 - kFilteringFactor)) );
instant_accelY = acceleration.y - ( (acceleration.y * kFilteringFactor) + (instant_accelY * (1.0 - kFilteringFactor)) );
instant_accelZ = acceleration.z - ( (acceleration.z * kFilteringFactor) + (instant_accelZ * (1.0 - kFilteringFactor)) );

*/
@end