Resource.swift

//
//  Resource.swift
//  Pods
//
//  Created by Mauro Bender on 13/8/16.
//
//

import Alamofire

public protocol JSONSerializable {
	init( fromJSON json: [ String: AnyObject ] )
	func toJSON() -> [ String: AnyObject ]
}

open class Resource {
	open let api: Api
	open let path: String
	open var responseKeyPath: String?   = "response"
	open var paginationKeyPath: String? = "pagination"
	
	init( api: Api, path: String ) {
		self.api  = api
		self.path = path
	}
}

// MARK: REQUESTS
extension Resource {
	public func request( _ method: ApiMethod, path: String? = nil,
	                     parameters: [String: AnyObject]? = nil, encoding: ParameterEncoding = URLEncoding.default,
	                     headers: [String: String]? = nil, completion: @escaping (DataResponse<Any>) -> Void )
	{
		let requestPath = path != nil ? "\(self.path)/\(path!)" : self.path
		api.request( method, path: requestPath, parameters: parameters, encoding: encoding,
		             headers: headers, completion: completion )
	}
	
	public func get( _ path: String? = nil, parameters: [String: AnyObject]? = nil, encoding: ParameterEncoding = URLEncoding.default,
	                 headers: [String: String]? = nil, completion: @escaping (DataResponse<Any>) -> Void )
	{
		return request( .get, path: path, parameters: parameters, encoding: encoding,
		                headers: headers, completion: completion)
	}
	
	public func post( _ path: String? = nil, parameters: [String: AnyObject]? = nil, encoding: ParameterEncoding = URLEncoding.default,
	                  headers: [String: String]? = nil, completion: @escaping (DataResponse<Any>) -> Void )
	{
		return request( .post, path: path, parameters: parameters, encoding: encoding,
		                headers: headers, completion: completion)
	}
	
	public func put( _ path: String? = nil, parameters: [String: AnyObject]? = nil, encoding: ParameterEncoding = URLEncoding.default,
	                 headers: [String: String]? = nil, completion: @escaping (DataResponse<Any>) -> Void )
	{
		return request( .put, path: path, parameters: parameters, encoding: encoding,
		                headers: headers, completion: completion)
	}
	
	public func patch( _ path: String? = nil, parameters: [String: AnyObject]? = nil, encoding: ParameterEncoding = URLEncoding.default,
	                 headers: [String: String]? = nil, completion: @escaping (DataResponse<Any>) -> Void )
	{
		return request( .patch, path: path, parameters: parameters, encoding: encoding,
		                headers: headers, completion: completion)
	}
	
	public func delete( _ path: String? = nil, parameters: [String: AnyObject]? = nil, encoding: ParameterEncoding = URLEncoding.default,
	                    headers: [String: String]? = nil, completion: @escaping (DataResponse<Any>) -> Void )
	{
		return request( .delete, path: path, parameters: parameters, encoding: encoding,
		                headers: headers, completion: completion)
	}
}

// MARK: CRUD
extension Resource {
	public func item<T: JSONSerializable>( _ id: Any, parameters: [ String: AnyObject ]? = nil,
	                 headers: [ String: String]? = nil, completion: @escaping ( ( ApiResult< T? > ) -> Void ) )
	{
		get( "\(id)", parameters: parameters, headers: headers ) { response in
			completion( itemResult( response, keyPath: self.responseKeyPath ) )
		}
	}
	
	public func list<T: JSONSerializable>( _ parameters: [ String: AnyObject ]? = nil,
	                 headers: [ String: String]? = nil, completion: @escaping ( (  ApiResult< [T]? > ) -> Void ) )
	{
		get( parameters: parameters, headers: headers ) { response in
			completion( listResult( response, keyPath: self.responseKeyPath ) )
		}
	}
	
	public func paginate<T: JSONSerializable>( _ parameters: [ String: AnyObject ]? = nil, headers: [ String: String]? = nil,
	                 completion: @escaping ( ( ApiResult< ([T], Pagination)? > ) -> Void ) )
	{
		get( parameters: parameters, headers: headers ) { response in
			completion( paginatedListResult( response,
				keyPath: self.responseKeyPath, paginationKeyPath: self.paginationKeyPath ) )
		}
	}
	
	public func create<T: JSONSerializable>( _ item: T, parameters: [ String: AnyObject ]? = nil,
	                   headers: [ String: String]? = nil, encoding: ParameterEncoding = JSONEncoding.default,
	                   completion: @escaping ( ( ApiResult< T? > ) -> Void ) )
	{
		var requestParameters = item.toJSON()
		if parameters != nil { requestParameters += parameters! }
		
		post( parameters: requestParameters, encoding: encoding, headers: headers ) { response in
			completion( itemResult( response, keyPath: self.responseKeyPath ) )
		}
	}
	
	public func edit<T: JSONSerializable>( _ id: Any, item: T, parameters: [ String: AnyObject ]? = nil,
	                   headers: [ String: String]? = nil, encoding: ParameterEncoding = JSONEncoding.default,
	                   completion: @escaping ( ( ApiResult< T? > ) -> Void ) )
	{
		var requestParameters = item.toJSON()
		if parameters != nil { requestParameters += parameters! }
		
		patch( "\(id)", parameters: requestParameters, encoding: encoding, headers: headers ) { response in
			completion( itemResult( response, keyPath: self.responseKeyPath ) )
		}
	}
	
	public func destroy( _ id: Any, parameters: [ String: AnyObject ]? = nil,
	                     headers: [ String: String]? = nil, completion: @escaping ( ( EmptyResult ) -> Void ) )
	{
		delete( "\(id)", parameters: parameters, headers: headers ) { response in
			completion( emptyResult( response ) )
		}
	}
}

// MARK: NESTED RESOURCES
extension Resource {
	public func member( _ memberID: Any ) -> Resource {
		let memberPath = resourceMemberPath( memberID )
		return Resource( api: api, path: memberPath )
	}
	
	public func resource( _ resourcePath: String ) -> Resource {
		let nestedPath = nestedResourcePath( resourcePath )
		return Resource( api: api, path: nestedPath )
	}
	
	func resourceMemberPath( _ memberId: Any ) -> String {
		return "\(path)/\(memberId)"
	}
	
	func nestedResourcePath( _ nestedResourcePath: String ) -> String {
		return "\(path)/\(nestedResourcePath)"
	}
}