#' Method to get convergence information
#'
#' @param object The object to investigate
#' @param x The object to be printed
#' @param \dots For potential future extensions
#' @return For [mkinfit] objects, a character vector containing
#' For [mmkin] objects, an object of class 'convergence.mmkin' with a
#' suitable printing method.
#' @export
convergence <- function(object, ...)
{
  UseMethod("convergence", object)
}

#' @rdname convergence
#' @export
#' @examples
#' \dontrun{
#' fits <- mmkin(
#'   c("SFO", "FOMC"),
#'   list("FOCUS A" = FOCUS_2006_A,
#'        "FOCUS B" = FOCUS_2006_C),
#'   quiet = TRUE)
#' convergence(fits)
#' }
convergence.mmkin <- function(object, ...) {
  all_summary_warnings <- character()
  sww <- 0 # Counter for Shapiro-Wilks warnings

  result <- lapply(object,
    function(fit) {
      if (inherits(fit, "try-error")) return("E")
      sw <- fit$summary_warnings
      swn <- names(sw)
      if (length(sw) > 0) {
        if (any(grepl("S", swn))) {
          sww <<- sww + 1
          swn <- gsub("S", paste0("S", sww), swn)
        }
        warnstring <- paste(swn, collapse = ", ")
        names(sw) <- swn
        all_summary_warnings <<- c(all_summary_warnings, sw)
        return(warnstring)
      } else {
        return("OK")
      }
    })
  result <- unlist(result)
  dim(result) <- dim(object)
  dimnames(result) <- dimnames(object)

  u_swn <- unique(names(all_summary_warnings))
  attr(result, "unique_warnings") <- all_summary_warnings[u_swn]
  class(result) <- "convergence.mmkin"
  return(result)
}

#' @rdname convergence
#' @export
print.convergence.mmkin <- function(x, ...) {
  u_w <- attr(x, "unique_warnings")
  attr(x, "unique_warnings") <- NULL
  class(x) <- NULL
  print(x, quote = FALSE)
  cat("\n")
  for (i in seq_along(u_w)) {
    cat(names(u_w)[i], ": ", u_w[i], "\n", sep = "")
  }
  if (any(x == "OK")) cat("OK: No warnings\n")
  if (any(x == "E")) cat("E: Error\n")
}