# Font family name constants used as defaults in theme functions.
# These match the --cv-font-* CSS custom properties on www.civilytics.com.
CV_FONT_DISPLAY <- "Libre Franklin"  # headings / display text
CV_FONT_SANS    <- "Inter"           # axis text, legends, UI elements
CV_FONT_SERIF   <- "Source Serif 4"  # body prose (not used in default theme)

# Internal flag so civilytics_load_fonts() is idempotent within a session.
.cv_fonts_loaded <- FALSE

#' Load Civilytics brand fonts
#'
#' Downloads Inter and Libre Franklin from Google Fonts via
#' [sysfonts::font_add_google()], then calls [showtext::showtext_auto()] so
#' that all graphics devices render text with those fonts. This is called
#' automatically when the package loads; use this function to retry if the
#' initial load failed (e.g., the machine was offline at load time).
#'
#' @return Invisibly returns `NULL`.
#' @export
#'
#' @examples
#' \dontrun{
#' civilytics_load_fonts()
#' }
civilytics_load_fonts <- function() {
  sysfonts::font_add_google("Inter",          family = "Inter")
  sysfonts::font_add_google("Libre Franklin", family = "Libre Franklin")
  showtext::showtext_auto()
  .cv_fonts_loaded <<- TRUE
  invisible(NULL)
}

.onLoad <- function(libname, pkgname) {
  tryCatch(
    civilytics_load_fonts(),
    error = function(e) {
      # Store the failure so .onAttach can surface a message to the user.
      options(.civilytics_fonts_failed = TRUE)
    }
  )
}

.onAttach <- function(libname, pkgname) {
  if (isTRUE(getOption(".civilytics_fonts_failed"))) {
    packageStartupMessage(
      "[civilytics] Brand fonts (Inter, Libre Franklin) could not be loaded ",
      "from Google Fonts. Charts will fall back to system fonts. ",
      "Call civilytics_load_fonts() once you have an internet connection."
    )
  }
}