fhiR: Handling HL7 FHIR® Resources in R

#' A S4 class containing a design for [fhir_crack()]
#'
#' A fhir_design is a named list of [fhir_table_description-class] objects. Each table_description
#' contains information on how to flatten one resource type which will result in one
#' data.frame. The fhir_design is passed to the function [fhir_crack()] along with a
#' list of bundles containing FHIR resources.
#'
#' @slot .Data The list of `fhir_table_description` objects.
#' @slot names The names of the table_descriptions. Those will also be the names of the
#' resulting data.frames.
#' @include fhir_table_description.R
#' @seealso [fhir_table_description()], [fhir_crack()]
#' @export
#'
setClass(
	Class    = "fhir_design",
	contains = "list",
	slots    = c(names = "character")
)

setValidity(
	Class = "fhir_design",
	method = function(object) {

		messages <- c()

		if(length(object) != length(object@names)) {
			messages <- c(messages, "You need exactly one name for every table_description in a design.")
		}

		if(any(duplicated(object@names))){
			messages <- c(messages, "Each fhir_table_description in the design must have a unique name.")
		}

		if(any(sapply(object, function(x) {class(x) != "fhir_table_description"}))) {
			messages <- c(messages, "A fhir_design musst contain only fhir_table_descriptions.")
		}

		#check table descriptions
	 	messages <- c(
	 		messages,
	 		unlist(
	 			sapply(
	 				object,
	 				function(o) {
	 					v <- validObject(o, complete = TRUE, test = TRUE)
	 					if(is.character(v)) {v}
	 				}
	 			)
	 		)
	 	)

		if(0 < length(messages)) {messages} else {TRUE}
	}
)

#' Create a [fhir_design-class] object
#'
#' A `fhir_design` is a named list of `fhir_table_description` objects (See [fhir_table_description()])
#' and should be created using the function described here. The design is used in [fhir_crack()] to tell
#' the function how to flatten each resource type.
#'
#'
#' @details
#'
#' A `fhir_design` looks for example like this:
#'
#' ```
#' A fhir_design with 2 table_descriptions:
#'	A fhir_table_description with the following elements:
#'
#' 	fhir_resource_type: Patient
#'
#' fhir_columns:
#' 	------------ -----------------
#' 	column name | xpath expression
#' ------------ -----------------
#' 	id          | id
#' name        | name/family
#' gender      | gender
#' ------------ -----------------
#'
#' 	sep:           '||'
#' brackets:      '[', ']'
#' rm_empty_cols: FALSE
#' format:        'compact'
#' keep_attr:     TRUE
#'
#' A fhir_table_description with the following elements:
#'
#' 	fhir_resource_type: MedicationAdministration
#'
#' fhir_columns:
#' 	An empty fhir_columns object
#'
#' sep:           ':::'
#' brackets:      no brackets
#' rm_empty_cols: FALSE
#' format:        'wide'
#' keep_attr:     TRUE
#' ```
#' The names of the table_descriptions are taken from the names of the arguments. If the table_descriptions are
#' created within the call to `fhir_design` and therefore have no names, the names will be created from the respective
#' resource type. See examples.
#'
#' For backwards compatibility it is for the moment also possible to build it from an
#' old-style design as used in `fhircrackr (< 1.0.0)`. See examples.
#'
#' If this function is given an object of class [fhir_df_list-class] or [fhir_dt_list-class], it will
#' extract the design that was used to create the respective list.
#'
#' @param ... One or more `fhir_table_description` objects or a named list containing
#' `fhir_table_description` objects, or an object of class [fhir_df_list-class]/[fhir_dt_list-class].
#' See [fhir_table_description()].
#' @docType methods
#' @seealso [fhir_table_description()], [fhir_crack()]
#' @rdname fhir_design-methods
#' @examples
#'
#' ####Example 1####
#'
#' ###create fhir_table_descriptions first
#' #see ?fhir_table_description for explanation
#'
#' pat <- fhir_table_description(
#'     resource      = "Patient",
#'     cols          = c(
#'         id            = "id",
#'         name          = "name/family",
#'         gender        = "gender"
#'     ),
#'     sep           = "||",
#'     brackets      = c("[", "]"),
#'     rm_empty_cols = FALSE
#'
#' )
#'
#' meds <- fhir_table_description(resource = "MedicationAdministration")
#'
#' ###create design
#' #First option: Explicitly define names
#'
#' design1 <- fhir_design(Pats = pat, Medics = meds)
#' print(design1)
#'
#'
#' #Second option: Names are taken from the object names
#'
#' design2 <- fhir_design(pat, meds)
#' print(design2)
#'
#'
#' #Third option: Create table_description within fhir_design
#'
#' design3 <- fhir_design(fhir_table_description(resource = "MedicationAdministration"))
#' print(design3)
#'
#'
#' #Fourth option: Names are taken from named list
#'
#' design3 <- fhir_design(list(Patients = pat, Medications = meds))
#' print(design3)
#'
#'
#' ###Example 2###
#' ###Extract design from fhir_df_list/fhir_dt_list
#'
#' #unserialize and crack example bundles
#' med_bundles <- fhir_unserialize(bundles = medication_bundles)
#' dfs <- fhir_crack(bundles = med_bundles, design = design1)
#'
#' #extract design
#'
#' fhir_design(dfs)
#'
#' @export
#'
setGeneric(
	name = "fhir_design",
	def = function(...) {
		standardGeneric("fhir_design")
	},
	signature = "..."
)

#method for fhir_table_list in fhir_table_list.R
#' @rdname fhir_design-methods
#' @aliases fhir_design,fhir_table_description-method
setMethod(
	f = "fhir_design",
	signature = c(... = "fhir_table_description"),
	definition = function(...) {

		args <- list(...)
		names <- paste0(sapply(args, function(x) {x@resource}), "s")
		name_index <- sapply(substitute(list(...))[-1], function(x) {class(x) == "name"})
		names[name_index] <- as.character(sapply(substitute(list(...))[-1], deparse))[name_index]
		names[names(args) != ""] <- names(args)[names(args) != ""]
		new(Class = "fhir_design", args, names = names)
	}
)
#' @rdname fhir_design-methods
#' @aliases fhir_design,list-method
setMethod(
	f = "fhir_design",
	signature = c(... = "list"),
	definition = function(...) {

		args <- list(...)

		if(length(args) == 1) {
			args <- unlist(args, recursive = FALSE)

			if(all(sapply(args, is, "fhir_table_description"))) {
				new(Class = "fhir_design", args, names  = attr(args, "names"))
			} else {

				stop("It looks like you are trying to use an old design from fhircrackr < 1.0.0, which is now deprecated.\n",
					 "Please create a design from fhir_table_descriptions (see ?fhir_table_description).")

			}
		} else {
			stop("You can only provide one list to fhir_design()")
		}
	}
)


setMethod(
	f = "show",
	signature = "fhir_design",
	definition = function(object) {

		if(length(object) == 0) {
			cat("An empty fhir_design_object")
		} else {
			cat(paste0("A fhir_design with ", length(object), " table descriptions:\n"))
			lapply(
				seq_len(length(object)),
				function(i) {
					show(object[[i]])
					# cat("=====================================================\n")
					# cat(paste0("Name: ", names(object)[i]))
					# cat("\n\n")
					# cat(paste0("Resource type: ", as.character(df_desc@resource), "\n\n"))
					# cat("Columns: \n")
					# show(df_desc@cols)
					# cat("Sep: ")
					# show(df_desc@sep)
					# cat("Brackets: \n")
					# cat("  Open: \n")
					# show(df_desc@brackets[1])
					# cat("  Close: \n")
					# show(df_desc@brackets[2])
					# cat("rm_empty_cols: \n")
					# show(df_desc@rm_empty_cols)
					# cat("format: \n")
					# show(df_desc$format)
					# cat("keep_attr: \n")
					# show(df_desc$keep_attr)
					# cat("\n")
				}
			)
		}
	}
)