MDBSwiftUtils.swift

//
//  MDBSwiftUtils.swift
//
//  Created by Akkshay Khoslaa on 4/25/16.
//  Copyright © 2016 Mobile Developers of Berkeley. All rights reserved.
//

import Foundation
import UIKit
import CoreLocation

public class MDBSwiftUtils {
    
    /**
     Returns the time since an NSDate as a properly formatted string.
     
     - returns:
     time passed since oldTime as properly formatted string
     
     - parameters:
        - oldTime: we want to find time elapsed since this time
     */
    static func timeSince(oldDate: NSDate) -> String {
      let currDate = NSDate()
      let dayHourMinuteSecond: NSCalanderUnit = [.Day, .Hour, .Minute, .Second]
      let difference = NSCalandar.currentCalendar().components(dayHourMinuteSecond, fromDate: oldTime, toDate: currDate, options: [])

      if difference.day > 0 {
        if difference.day == 1 {
          return "1 day ago"
        }
        return "\(difference.day) days ago"
      } else if difference.hour > 0 {
        if difference.hour == 1 {
          return "1 hr ago"
        }
        return "\(difference.hour) hrs ago"
      } else if difference.minute > 0 {
        if difference.minute == 1 {
          return "1 min ago"
        }
        return "\(difference.minute) mins ago"
      } else {
        if difference.second == 1 {
          return "1 sec ago"
        }
        return "\(difference.second) secs ago"
      }
    }
    
    /**
     Returns a random number between 2 numbers.
     
     - returns:
     random number as CGFloat
     
     - parameters:
        - firstNum: the returned number must be greater than this
        - secondNum: the returned number must be less than this
     */
    static func randomNumBetween(firstNum: CGFloat, secondNum: CGFloat) -> CGFloat {
        return CGFloat(arc4random()) / CGFloat(UINT32_MAX) * abs(firstNum - secondNum) + min(firstNum, secondNum)
    }
    
    
    /**
     Returns a currency formatted string.
     
     - returns:
     val formatted as a currency string
     
     - parameters:
        - val: value to be converted to currency string
     */
    static func doubleToCurrencyString(val: Double) -> String {
        if (val * 100) % 100 == 0 {
            return "$\(Int(val))"
        } else {
            let currencyFormatter = NSNumberFormatter()
            currencyFormatter.numberStyle = .CurrencyStyle
            return currencyFormatter.stringFromNumber(val)!
        }
    }
    
    /**
     Formats a label to support dynamic content and expand to multiple lines if needed.
     
     - parameters:
        - label: the label to be formatted
     */
    static func formatMultiLineLabel(label: UILabel) {
        label.lineBreakMode = .ByWordWrapping
        label.numberOfLines = 0
    }
    
    /**
     Returns the expected height of the label based on the text. Assumes that label is formatted to support multiple lines and dynamic content.
     
     - returns:
     expected height of the label as CGFloat
     
     - parameters:
        - content: text that will be put in the label
        - maxWidth: the maxWidth the label can be
        - font: the font used by the label
     */
    static func getMultiLineLabelHeight(content: String, maxWidth: Int, font: UIFont) -> CGFloat {
        let contentString = content
        let maximumLabelSize: CGSize = CGSizeMake(CGFloat(maxWidth), 1000)
        let options: NSStringDrawingOptions = [.TruncatesLastVisibleLine, .UsesLineFragmentOrigin]
        let attr : [String: AnyObject] = [NSFontAttributeName:  font]
        let labelBounds: CGRect = contentString.boundingRectWithSize(maximumLabelSize, options: options, attributes: attr, context: nil)
        let labelHeight: CGFloat = labelBounds.size.height
        return labelHeight
    }
    
    /**
     Starts location services by requesting authorization if needed.
     
     - parameters:
        - locationManager: CLLocationManager instance being used in your VC
        - currVC: the VC you are calling this function in. Make sure it includes CLLocationManagerDelegate
     */
    static func startLocationServices(locationManager: CLLocationManager, currVC: CLLocationManagerDelegate) {
        locationManager.delegate = currVC
        locationManager.requestAlwaysAuthorization()
        locationManager.requestWhenInUseAuthorization()
        
        if CLLocationManager.locationServicesEnabled() {
            locationManager.delegate = currVC
            locationManager.desiredAccuracy = kCLLocationAccuracyNearestTenMeters
            locationManager.startUpdatingLocation()
        }
    }
    
    /**
     Check if location services are authorized, and if they are get the current location. Make sure you call startLocationServices() first.
     
     - returns:
     the current location as CLLocation if location services are authorized; else returns nil
     
     - parameters:
        - locationManager: CLLocationManager instance being used in your VC
     */
    static func getCurrentLocation(locationManager: CLLocationManager) -> CLLocation? {
      if (CLLocationManager.authorizationStatus() == CLAuthorizationStatus.AuthorizedWhenInUse
        || CLLocationManager.authorizationStatus() == CLAuthorizationStatus.AuthorizedAlways) {
        return locationManager.location!
      }
      return nil
    }
    
    /**
     Shows a basic alert with an "OK" button to dismiss.
     
     - parameters:
        - title: title to display at the top of the alert
        - content: message to display in alert
        - currVC: the ViewController in which this function is being called
     */
    static func showBasicAlert(title: String, content: String, currVC: UIViewController) {
        let alert = UIAlertController(title: title, message: content, preferredStyle: UIAlertControllerStyle.Alert)
        
        alert.addAction(UIAlertAction(title: "OK", style: .Default) {
          action in
            
          alert.dismissViewControllerAnimated(true, completion: nil)
            
        })
        
        currVC.presentViewController(alert, animated: true, completion: nil)
    }
    
    /**
     Returns a UIImage rendered with a given alpha.
     
     - returns:
     a UIImage with an alpha applied to it
     
     - parameters:
        - alpha: the alpha that you want the new image to have
        - image: the image you are applying the alpha to
     
     */
    static func imageWithAlpha(alpha: CGFloat, image: UIImage) -> UIImage {
        UIGraphicsBeginImageContextWithOptions(image.size, false, 0.0)
        let context = UIGraphicsGetCurrentContext()!
        let area: CGRect = CGRectMake(0, 0, image.size.width, image.size.height)
        CGContextScaleCTM(context, 1, -1)
        CGContextTranslateCTM(context, 0, -area.size.height)
        CGContextSetBlendMode(context, CGBlendMode.Multiply)
        CGContextSetAlpha(context, alpha)
        CGContextDrawImage(context, area, image.CGImage)
        let alphaImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return alphaImage
    }

    /**
     Adds an image to the end of a label.
     
     - parameters:
        - label: label we want to add the image to
        - labelText: the text that the label should have
        - image: the image that we want to add to the label
     */
    static func addImageToLabel(label: UILabel, labelText: String, image: UIImage) {
        let attachment = NSTextAttachment()
        attachment.image = image
        let attachmentString = NSAttributedString(attachment: attachment)
        let textString = NSMutableAttributedString(string: labelText)
        textString.appendAttributedString(attachmentString)
        label.attributedText = textString
    }
  
    /**
      centers a subview within a superview's bounds.
 
      - parameters:
          - subview: view to center.
          - view: view to center in.
    */
    static func centerSubviewInView(subview: UIView, view: UIView) {
      let bounds = view.bounds
      
      subview.bounds = CGRect(x: bounds.width / 2 - subview.bounds.width / 2,
                              y: bounds.height / 2 - subview.bounds.height / 2,
                              width: subview.bounds.width, height: subview.bounds.height)
    }
  
    /**
     Set the image of a UIImageView from a url.
     
     - parameters:
        - urlString: url of the image as a String
        - imageView: imageView that we want to set the image of
     */
    static func setImageViewImageFromUrl(urlString: String, imageView: UIImageView) {
        let url = NSURL(string: urlString)!
        let data = NSData(contentsOfURL: url)
        let image = UIImage(data: data!)!
        imageView.image = image
    }
    
    /**
     Get JSON object as an NSDictionary from a url using HTTP GET request.
     
     - parameters:
        - urlString: url for the request as a String
        - completion: block to be called once JSON object is retrieved
    */
    static func httpJSONGETRequest(urlString: String, completion: (NSDictionary) -> Void) {
      guard let url = NSURL(string: urlString) else {
        NSLog("Invalid URI Scheme")
        return
      }
      let request = NSURLRequest(URL: url)
      let opQueue = NSOperationQueue()
        
      NSURLConnection.sendAsynchronousRequest(request, queue: opQueue) {
        (response: NSURLResponse?, data: NSData?, error: NSError?) -> Void in
          
        do {
          if let result = try NSJSONSerialization.JSONObjectWithData(data!, options: []) as? NSDictionary {
            completion(result)
          }
        } catch let error as NSError {
          NSLog(error.localizedDescription)
        }
      }
    }
    
    
}