#' Forecast
#'
#' Forecast encapsulation
#'
#' @docType class
#' @importFrom R6 R6Class
#'
#' @field .pred List with \itemize{
#'   \item serie: forecasted serie
#'   \item params: corresponding list of parameters (weights, neighbors...)
#'   \item index_in_data: corresponding index in data object}
#' @field .dates vector of day indices where forcast occurs
#'
#' @section Methods:
#' \describe{
#' \item{\code{initialize(dates)}}{
#'   Initialize a Forecast object with a series of date indices.}
#' \item{\code{getSize()}}{
#'   Return number of individual forecasts.}
#' \item{\code{append(new_serie, new_params, new_index_in_data)}}{
#'   Acquire a new individual forecast, with its (optimized) parameters and the corresponding
#'   index in the dataset.}
#' \item{\code{getDates()}}{
#'   Get dates where forecast occurs.}
#' \item{\code{getSerie(index)}}{
#'   Get forecasted serie at specified index.}
#' \item{\code{getParams(index)}}{
#'   Get parameters at specified index (for 'Neighbors' method).}
#' \item{\code{getIndexInData(index)}}{
#'   Get index in data which corresponds to current forecast.}
#' }
Forecast = R6::R6Class("Forecast",
	private = list(
		.pred = list(),
		.dates = integer(0) #store dates as integers (from 1970-01-01)
	),
	public = list(
		initialize = function(dates)
		{
			private$.dates <- dates
			invisible(self)
		},
		getSize = function()
			length(private$.pred)
		,
		append = function(new_serie, new_params, new_index_in_data)
		{
			private$.pred[[length(private$.pred)+1]] <-
				list("serie"=new_serie, "params"=new_params, "index_in_data"=new_index_in_data)
		},
		getDates = function()
			as.Date( private$.dates, origin="1970-01-01" )
		,
		getSerie = function(index)
		{
			if (is(index,"Date"))
				index = match(index, private$.dates)
			private$.pred[[index]]$serie
		},
		getParams = function(index)
		{
			if (is(index,"Date"))
				index = match(index, private$.dates)
			private$.pred[[index]]$params
		},
		getIndexInData = function(index)
		{
			if (is(index,"Date"))
				index = match(index, private$.dates)
			private$.pred[[index]]$index_in_data
		}
	)
)