gistfile1.swift

//
//  WeekCollectionViewController.swift
//  dot
//
//  Created by LOANER on 4/21/15.
//  Copyright (c) 2015 Thomas Degry. All rights reserved.
//

import UIKit

let reuseIdentifier = "weekCollectionViewCell"
class TestCollectionViewController: UICollectionViewController, UICollectionViewDelegateFlowLayout {
    var fromDate:NSDate?
    var toDate:NSDate?
    var dayDate:NSDate = NSDate()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        calculateFromAndToDate()
    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    
    override func viewWillAppear(animated: Bool) {
        self.collectionView?.reloadData()
    }
    
    override func viewWillLayoutSubviews() {
        // Check if we need to append or prepend dates
        if collectionView?.contentOffset.x < 0 {
            // Create date components
            let components = NSDateComponents()
            components.weekOfYear = -2
            
            // Do it!
            self.shiftDatesByComponents(components)
        } else if (collectionView?.contentOffset.x > (collectionView!.contentSize.width - CGRectGetWidth(self.collectionView!.bounds))) {
            // Create date components
            let components = NSDateComponents()
            components.weekOfYear = 2
            
            // Do it!
            self.shiftDatesByComponents(components)
        }
    }
    
    // MARK: - WeekCollectionView methods
    func calculateFromAndToDate() {
        var calendar = NSCalendar.currentCalendar()
        
        // Get first day of this week
        let weekdayComponents = calendar.components(.CalendarUnitWeekday, fromDate: self.dayDate)
        let componentsToSubtract = NSDateComponents()
        componentsToSubtract.day = -(weekdayComponents.weekday - calendar.firstWeekday)
        
        // First day of the week
        let beginningOfTheWeek = calendar.dateByAddingComponents(componentsToSubtract, toDate: self.dayDate, options: .allZeros)
        
        // Till last monday
        let components = NSDateComponents()
        components.weekOfYear = -2
        self.fromDate = calendar.dateByAddingComponents(components, toDate: beginningOfTheWeek!, options: .allZeros)
        
        // Add 14 days, this week monday + 7 is next week monday + that week = 14
        components.weekOfYear = 2
        self.toDate = calendar.dateByAddingComponents(components, toDate: beginningOfTheWeek!, options: .allZeros)
        
        self.collectionView?.reloadData()
    }
    
    func shiftDatesByComponents(components: NSDateComponents) {
        // Get reference to collectionview and it's layout
        let collectionView = self.collectionView!
        let layout = collectionView.collectionViewLayout as? UICollectionViewFlowLayout
        
        // Get the visible cells
        let visibleCells = collectionView.visibleCells()
        
        // Abort if no cells are visible
        if (visibleCells.count == 0) {
            return
        }
        
        // Get the first visible cell
        let firstCell = visibleCells[0] as? WeekCollectionViewCell
        
        // Get it's indexpath
        let fromIndexPath = collectionView.indexPathForCell(firstCell!)
        
        // First day in section
        let dateForFirstSection = self.dateForWeekOfYearInSection(fromIndexPath!.section)
        println("first day in section = \(dateForFirstSection)")
        
        // Get from section origin
        let fromLayoutAttrs = layout?.layoutAttributesForItemAtIndexPath(NSIndexPath(forItem: 0, inSection: fromIndexPath!.section))
        let fromSectionOrigin = self.view.convertPoint(fromLayoutAttrs!.frame.origin, fromView: collectionView)
        
        self.fromDate = NSCalendar.currentCalendar().dateByAddingComponents(components, toDate: self.fromDate!, options: .allZeros)
        self.toDate = NSCalendar.currentCalendar().dateByAddingComponents(components, toDate: self.toDate!, options: .allZeros)
        println("new from date = \(self.fromDate) and new to date = \(self.toDate)")
        
//        collectionView.performBatchUpdates({ () -> Void in
//            
//            if components.weekOfYear < 0 {
//                collectionView.deleteSections(NSIndexSet(indexesInRange: NSRange(location: collectionView.numberOfSections() - abs(components.weekOfYear), length: abs(components.weekOfYear))))
//                collectionView.insertSections(NSIndexSet(indexesInRange: NSRange(location: 0, length: abs(components.weekOfYear))))
//            } else {
//                collectionView.insertSections(NSIndexSet(indexesInRange: NSRange(location: collectionView.numberOfSections(), length: abs(components.weekOfYear))))
//                collectionView.deleteSections(NSIndexSet(indexesInRange: NSRange(location: 0, length: abs(components.weekOfYear))))
//            }
//            
//            }, completion: { (finished) -> Void in
//                println("finished batch update")
//        })
//        
//        for view in collectionView.subviews {
//            view.layer?.removeAllAnimations()
//        }
        
        collectionView.reloadData()
        layout?.invalidateLayout()
        layout?.prepareLayout()
        
        let fromDate = self.dateForWeekOfYearInSection(0)
        let toSection = NSCalendar.currentCalendar().components(NSCalendarUnit.CalendarUnitWeekOfYear, fromDate: fromDate, toDate: dateForFirstSection, options: .allZeros).weekOfYear
        let toLayoutAttrs = layout?.layoutAttributesForItemAtIndexPath(NSIndexPath(forItem: 0, inSection: toSection))
        let toSectionOrigin = self.view.convertPoint(toLayoutAttrs!.frame.origin, fromView: collectionView)
        
        collectionView.setContentOffset(CGPoint(x: collectionView.contentOffset.x + (toSectionOrigin.x - fromSectionOrigin.x), y: collectionView.contentOffset.y), animated: false)
    }
    
    // MARK: UICollectionViewDataSource
    override func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
        let components = NSCalendar.currentCalendar().components(NSCalendarUnit.CalendarUnitWeekOfYear, fromDate: self.fromDate!, toDate: self.toDate!, options: .allZeros)
        return components.weekOfYear
    }
    
    override func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 7
    }
    
    override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifier, forIndexPath: indexPath) as! WeekCollectionViewCell
        
        // Get the cell's date based on the indexpath + components
        let cellDate = self.dateFromStartDateWithIndexpath(indexPath)
        
        // Set the cell's date
        cell.cellDate = cellDate
        
        let hue = (CGFloat(arc4random()) % 256 / 256)
        let saturation = (CGFloat(arc4random()) % 128 / 256) + 0.5
        let brightness = (CGFloat(arc4random()) % 128 / 256) + 0.5
        let color = UIColor(hue: hue, saturation: saturation, brightness: brightness, alpha: 1)
        
        cell.backgroundColor = color
        
        return cell
    }
    
    // MARK: UICollectionViewDelegateFlowLayout
    func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
        return CGSize(width: self.view.frame.width / 7, height: self.view.frame.height)
    }
    
    // MARK: - Helpers
    func dateFromStartDateWithIndexpath(indexPath: NSIndexPath) -> NSDate {
        // Figure out the cell's date
        let components = NSDateComponents()
        components.day = indexPath.row
        components.weekOfYear = indexPath.section
        
        // Calculate the cell date with the components
        return NSCalendar.currentCalendar().dateByAddingComponents(components, toDate: self.fromDate!, options: .allZeros)!
    }
    
    func dateForWeekOfYearInSection(section: Int) -> NSDate {
        let components = NSDateComponents()
        components.weekOfYear = section
        
        return NSCalendar.currentCalendar().dateByAddingComponents(components, toDate: self.fromDate!, options: .allZeros)!
    }
    
}