library("colorspace")
library("jsonlite")
library("purrr")

# usage: writeLines(cvd_json(), filename)

# references:
#  - colorspace package: <https://hclwizard.org/r-colorspace/>
#  - Machado et al.: <https://www.inf.ufrgs.br/~oliveira/pubs_files/CVD_Simulation/CVD_Simulation.html>

# given a colorspace matrix-list, return array (of matrices)
cvd_array <- function(cvd_list) {

  # we need to transpose because R is column-based,
  # we will serialize as rowbased
  result <- purrr::reduce(cvd_list, ~c(.x, t(.y)))
  result <- array(result, c(3, 3, length(cvd_list)))

  result
}

# return a list of arrays (of matrices)
cvd_object <- function() {
  obj <- list(
    protan = colorspace::protanomaly_cvd,
    deuteran = colorspace::deutanomaly_cvd,
    tritan = colorspace::tritanomaly_cvd
  )

  purrr::map(obj, cvd_array)
}

# return a JSON-serialized object
cvd_json <- function(...) {
  jsonlite::toJSON(
    cvd_object(),
    matrix = "columnmajor",
    pretty = TRUE,
    digits = 6,
    ...
  )
}