NSDate+Extension.swift

//
//  NSDate+Extension.swift
//  Tasty
//
//  Created by Vitaliy Kuzmenko on 17/10/14.
//  http://github.com/vitkuzmenko
//  Copyright (c) 2014 Vitaliy Kuz'menko. All rights reserved.
//

import Foundation

func NSDateTimeAgoLocalizedStrings(key: String) -> String {
    let resourcePath: String?

    if let frameworkBundle = NSBundle(identifier: "com.kevinlawler.NSDateTimeAgo") {
        // Load from Framework
        resourcePath = frameworkBundle.resourcePath
    } else {
        // Load from Main Bundle
        resourcePath = NSBundle.mainBundle().resourcePath
    }

    if resourcePath == nil {
        return ""
    }

    let path = NSURL(fileURLWithPath: resourcePath!).URLByAppendingPathComponent("NSDateTimeAgo.bundle")
    guard let bundle = NSBundle(URL: path) else {
        return ""
    }

    return NSLocalizedString(key, tableName: "NSDateTimeAgo", bundle: bundle, comment: "")
}

extension NSDate {
    
    // shows 1 or two letter abbreviation for units.
    // does not include 'ago' text ... just {value}{unit-abbreviation}
    // does not include interim summary options such as 'Just now'
    public var timeAgoSimple: String {
        let components = self.dateComponents()

        if components.year > 0 {
            return stringFromFormat("%%d%@yr", withValue: components.year)
        }

        if components.month > 0 {
            return stringFromFormat("%%d%@mo", withValue: components.month)
        }

        // TODO: localize for other calanders
        if components.day >= 7 {
            let value = components.day/7
            return stringFromFormat("%%d%@w", withValue: value)
        }

        if components.day > 0 {
            return stringFromFormat("%%d%@d", withValue: components.day)
        }

        if components.hour > 0 {
            return stringFromFormat("%%d%@h", withValue: components.hour)
        }

        if components.minute > 0 {
            return stringFromFormat("%%d%@m", withValue: components.minute)
        }

        if components.second > 0 {
            return stringFromFormat("%%d%@s", withValue: components.second )
        }

        return ""
    }

    public var timeAgo: String {
        let components = self.dateComponents()

        if components.year > 0 {
            if components.year < 2 {
                return NSDateTimeAgoLocalizedStrings("Last year")
            } else {
                return stringFromFormat("%%d %@years ago", withValue: components.year)
            }
        }

        if components.month > 0 {
            if components.month < 2 {
                return NSDateTimeAgoLocalizedStrings("Last month")
            } else {
                return stringFromFormat("%%d %@months ago", withValue: components.month)
            }
        }

        // TODO: localize for other calanders
        if components.day >= 7 {
            let week = components.day/7
            if week < 2 {
                return NSDateTimeAgoLocalizedStrings("Last week")
            } else {
                return stringFromFormat("%%d %@weeks ago", withValue: week)
            }
        }

        if components.day > 0 {
            if components.day < 2 {
                return NSDateTimeAgoLocalizedStrings("Yesterday")
            } else  {
                return stringFromFormat("%%d %@days ago", withValue: components.day)
            }
        }

        if components.hour > 0 {
            if components.hour < 2 {
                return NSDateTimeAgoLocalizedStrings("An hour ago")
            } else  {
                return stringFromFormat("%%d %@hours ago", withValue: components.hour)
            }
        }

        if components.minute > 0 {
            if components.minute < 2 {
                return NSDateTimeAgoLocalizedStrings("A minute ago")
            } else {
                return stringFromFormat("%%d %@minutes ago", withValue: components.minute)
            }
        }

        if components.second > 0 {
            if components.second < 5 {
                return NSDateTimeAgoLocalizedStrings("Just now")
            } else {
                return stringFromFormat("%%d %@seconds ago", withValue: components.second)
            }
        }
        
        return ""
    }

    private func dateComponents() -> NSDateComponents {
        let calander = NSCalendar.currentCalendar()
        return calander.components([.Second, .Minute, .Hour, .Day, .Month, .Year], fromDate: self, toDate: NSDate(), options: [])
    }

    private func stringFromFormat(format: String, withValue value: Int) -> String {
        let localeFormat = String(format: format, getLocaleFormatUnderscoresWithValue(Double(value)))
        return String(format: NSDateTimeAgoLocalizedStrings(localeFormat), value)
    }
    
    private func getLocaleFormatUnderscoresWithValue(value: Double) -> String {
        guard let localeCode = NSLocale.preferredLanguages().first else {
            return ""
        }
        
        // Russian (ru) and Ukrainian (uk)
        if localeCode == "ru" || localeCode == "uk" {
            let XY = Int(floor(value)) % 100
            let Y = Int(floor(value)) % 10

            if Y == 0 || Y > 4 || (XY > 10 && XY < 15) {
                return ""
            }

            if Y > 1 && Y < 5 && (XY < 10 || XY > 20) {
                return "_"
            }

            if Y == 1 && XY != 11 {
                return "__"
            }
        }
        
        return ""
    }
    
}