Map.swift

//
//  Map.swift
//  ObjectMapper
//
//  Created by Tristan Himmelman on 2015-10-09.
//
//  The MIT License (MIT)
//
//  Copyright (c) 2014-2015 Hearst
//
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the Software is
//  furnished to do so, subject to the following conditions:
//
//  The above copyright notice and this permission notice shall be included in
//  all copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
//  THE SOFTWARE.


import Foundation

/// A class used for holding mapping data
public final class Map {
	public let mappingType: MappingType
	
	public internal(set) var JSONDictionary: [String : AnyObject] = [:]
	public var currentValue: AnyObject?
	var currentKey: String?
	var keyIsNested = false

	let toObject: Bool // indicates whether the mapping is being applied to an existing object
	
	/// Counter for failing cases of deserializing values to `let` properties.
	private var failedCount: Int = 0
	
	public init(mappingType: MappingType, JSONDictionary: [String : AnyObject], toObject: Bool = false) {
		self.mappingType = mappingType
		self.JSONDictionary = JSONDictionary
		self.toObject = toObject
	}
	
	/// Sets the current mapper value and key.
	/// The Key paramater can be a period separated string (ex. "distance.value") to access sub objects.
	public subscript(key: String) -> Map {
		// save key and value associated to it
		return self[key, nested: true]
	}
	
	public subscript(key: String, nested nested: Bool) -> Map {
		// save key and value associated to it
		currentKey = key
		keyIsNested = nested
		
		// check if a value exists for the current key
		if nested == false {
			currentValue = JSONDictionary[key]
		} else {
			// break down the components of the key that are separated by .
			currentValue = valueFor(ArraySlice(key.componentsSeparatedByString(".")), dictionary: JSONDictionary)
		}
		
		return self
	}
	
	// MARK: Immutable Mapping
	
	public func value<T>() -> T? {
		return currentValue as? T
	}
	
	public func valueOr<T>(@autoclosure defaultValue: () -> T) -> T {
		return value() ?? defaultValue()
	}
	
	/// Returns current JSON value of type `T` if it is existing, or returns a
	/// unusable proxy value for `T` and collects failed count.
	public func valueOrFail<T>() -> T {
		if let value: T = value() {
			return value
		} else {
			// Collects failed count
			failedCount++
			
			// Returns dummy memory as a proxy for type `T`
			let pointer = UnsafeMutablePointer<T>.alloc(0)
			pointer.dealloc(0)
			return pointer.memory
		}
	}
	
	/// Returns whether the receiver is success or failure.
	public var isValid: Bool {
		return failedCount == 0
	}
}

/// Fetch value from JSON dictionary, loop through keyPathComponents until we reach the desired object
private func valueFor(keyPathComponents: ArraySlice<String>, dictionary: [String: AnyObject]) -> AnyObject? {
	// Implement it as a tail recursive function.
	if keyPathComponents.isEmpty {
		return nil
	}
	
	if let keyPath = keyPathComponents.first {
		let object = dictionary[keyPath]
		if object is NSNull {
			return nil
		} else if let dict = object as? [String : AnyObject] where keyPathComponents.count > 1 {
			let tail = keyPathComponents.dropFirst()
			return valueFor(tail, dictionary: dict)
		} else if let array = object as? [AnyObject] where keyPathComponents.count > 1 {
			let tail = keyPathComponents.dropFirst()
			return valueFor(tail, dictionary: array)
		} else {
			return object
		}
	}
	
	return nil
}

/// Fetch value from JSON Array, loop through keyPathComponents them until we reach the desired object
private func valueFor(keyPathComponents: ArraySlice<String>, dictionary: [AnyObject]) -> AnyObject? {
	// Implement it as a tail recursive function.
	
	if keyPathComponents.isEmpty {
		return nil
	}
	
	//Try to convert keypath to Int as index
	if let keyPath = keyPathComponents.first,
		let index = Int(keyPath) where index >= 0 && index < dictionary.count {

		let object = dictionary[index]
		
		if object is NSNull {
			return nil
		} else if let array = object as? [AnyObject] where keyPathComponents.count > 1 {
			let tail = keyPathComponents.dropFirst()
			return valueFor(tail, dictionary: array)
		} else if let dict = object as? [String : AnyObject] where keyPathComponents.count > 1 {
			let tail = keyPathComponents.dropFirst()
			return valueFor(tail, dictionary: dict)
		} else {
			return object
		}
	}
	
	return nil
}