//
//  OrderedDictionary.swift
//  SwiftDataStructures
//
//  Created by Tim Ekl on 6/2/14.
//  Copyright (c) 2014 Tim Ekl. Available under MIT License. See LICENSE.md.
//

import Foundation

struct OrderedDictionary<Tk: Hashable, Tv> {
	var keys: Array<Tk> = []
	var values: Dictionary<Tk,Tv> = [:]
	
	var count: Int {
		assert(keys.count == values.count, "Keys and values array out of sync")
		return self.keys.count;
	}
	
	// Explicitly define an empty initializer to prevent the default memberwise initializer from being generated
	init() {}
	
	subscript(index: Int) -> Tv? {
		get {
			let key = self.keys[index]
			return self.values[key]
		}
		set(newValue) {
			let key = self.keys[index]
			if (newValue != nil) {
				self.values[key] = newValue
			} else {
				self.values[key] = nil
				self.keys.remove(at: index)
			}
		}
	}
	
	subscript(key: Tk) -> Tv? {
		get {
			return self.values[key]
		}
		set(newValue) {
			if newValue == nil {
				self.values[key] = nil
				self.keys = self.keys.filter {$0 != key}
			} else {
				let oldValue = self.values.updateValue(newValue!, forKey: key)
				if oldValue == nil {
					self.keys.append(key)
				}
			}
		}
	}
	
	var description: String {
		var result = "{\n"
		for i in 0..<self.count {
			result += "[\(i)]: \(self.keys[i]) => \(String(describing: self[i]))\n"
		}
		result += "}"
		return result
	}
}