#' Apply the Civilytics brand styling to a flextable
#'
#' Applies *only* the visual Civilytics brand to an already-structured
#' [flextable::flextable()] — header fill and color, body font and size,
#' zebra striping, borders, footer styling, and a fixed table layout. The
#' caller remains responsible for table *structure*: labels
#' ([flextable::set_header_labels()]), header/title lines
#' ([flextable::add_header_lines()]), column widths ([flextable::width()]),
#' alignment ([flextable::align()]), and footer text
#' ([flextable::add_footer_lines()]). This separation keeps styling reusable
#' across projects while leaving content decisions where they belong.
#'
#' `flextable`, `officer`, and `ragg` are Suggested (not Imported) to keep the
#' base install light, so this function errors with an install hint if
#' `flextable` is unavailable.
#'
#' @param ft A [flextable::flextable()] object.
#' @param header_bg Character. Header background fill. Default `"#2c3e50"`.
#' @param header_color Character. Header text color. Default `"white"`.
#' @param title_fontsize Numeric. Font size for the first header line (the
#'   title row, `i = 1`). Default `14`.
#' @param body_fontsize Numeric. Body font size. Default `11`.
#' @param font_name Character. Font family applied to all parts. Default
#'   `"Arial"`.
#' @param zebra Logical. Apply alternating-row striping to even body rows.
#'   Default `TRUE`. Safely skipped for tables with fewer than two body rows.
#' @param zebra_bg Character. Fill color for striped (even) body rows.
#'   Default `"#f0f0eb"`.
#' @param outer_border_color Character. Outer border color. Default
#'   `"#888888"`.
#' @param outer_border_width Numeric. Outer border width. Default `1`.
#' @param inner_border_color Character. Inner horizontal border color (body).
#'   Default `"#cccccc"`.
#' @param inner_border_width Numeric. Inner horizontal border width. Default
#'   `0.5`.
#' @param footer_fontsize Numeric. Footer font size (applied only if a footer
#'   part exists). Default `9`.
#' @param footer_color Character. Footer text color. Default `"#555555"`.
#'
#' @return The styled [flextable::flextable()] object.
#' @export
#' @seealso [save_branded_flextable_png()] to export the styled table to a
#'   logo-stamped PNG.
#' @examples
#' \dontrun{
#' library(flextable)
#' ft <- flextable(head(mtcars)) |>
#'   add_header_lines("Motor Trend Cars") |>
#'   add_footer_lines("Source: mtcars") |>
#'   style_flextable_civilytics()
#' }
style_flextable_civilytics <- function(ft,
                                       header_bg = "#2c3e50",
                                       header_color = "white",
                                       title_fontsize = 14,
                                       body_fontsize = 11,
                                       font_name = "Arial",
                                       zebra = TRUE,
                                       zebra_bg = "#f0f0eb",
                                       outer_border_color = "#888888",
                                       outer_border_width = 1,
                                       inner_border_color = "#cccccc",
                                       inner_border_width = 0.5,
                                       footer_fontsize = 9,
                                       footer_color = "#555555") {
  if (!requireNamespace("flextable", quietly = TRUE)) {
    stop("Install 'flextable' to use this function.", call. = FALSE)
  }
  if (!requireNamespace("officer", quietly = TRUE)) {
    stop("Install 'officer' to use this function.", call. = FALSE)
  }

  # Header: navy fill, white bold text, larger title line.
  ft <- flextable::bg(ft, bg = header_bg, part = "header")
  ft <- flextable::color(ft, color = header_color, part = "header")
  ft <- flextable::bold(ft, part = "header")
  ft <- flextable::fontsize(ft, i = 1, size = title_fontsize, part = "header")

  # Body: readable size, brand font across all parts.
  ft <- flextable::fontsize(ft, size = body_fontsize, part = "body")
  ft <- flextable::font(ft, fontname = font_name, part = "all")

  # Zebra striping on even body rows, guarded for tables with < 2 rows.
  nrow_body <- flextable::nrow_part(ft, part = "body")
  if (zebra && nrow_body >= 2) {
    ft <- flextable::bg(ft, i = seq(2, nrow_body, 2), bg = zebra_bg,
                        part = "body")
  }

  # Borders: outer frame on all parts, light horizontal rules in the body.
  ft <- flextable::border_outer(
    ft,
    border = officer::fp_border(color = outer_border_color,
                                width = outer_border_width),
    part = "all"
  )
  ft <- flextable::border_inner_h(
    ft,
    border = officer::fp_border(color = inner_border_color,
                                width = inner_border_width),
    part = "body"
  )

  # Footer styling — only if the table actually has a footer part.
  if (flextable::nrow_part(ft, part = "footer") > 0) {
    ft <- flextable::fontsize(ft, size = footer_fontsize, part = "footer")
    ft <- flextable::color(ft, color = footer_color, part = "footer")
  }

  flextable::set_table_properties(ft, layout = "fixed")
}


#' Save a branded flextable to a logo-stamped PNG
#'
#' Exports a styled [flextable::flextable()] to a PNG via
#' [ragg::agg_png()] (sized to the table's own dimensions plus a little
#' headroom for the logo), then optionally stamps the Civilytics logo onto the
#' file with [stamp_logo_png()] so file-based tables stay visually consistent
#' with [civilytics_logo()]-branded plots.
#'
#' `ragg` and `flextable` are Suggested (not Imported); this function errors
#' with an install hint if either is unavailable.
#'
#' @param ft A [flextable::flextable()] object, typically already styled with
#'   [style_flextable_civilytics()].
#' @param path Character. Output PNG path. Returned invisibly.
#' @param logo Logical. Stamp the Civilytics logo onto the saved PNG via
#'   [stamp_logo_png()]. Default `TRUE`.
#' @param res Numeric. Output resolution in PPI passed to [ragg::agg_png()].
#'   Default `300`.
#' @param extra_height Numeric. Additional height in inches added to the
#'   table's natural height to leave room for the stamped logo. Default `0.4`.
#' @param ... Additional arguments forwarded to [stamp_logo_png()] (e.g.
#'   `type`, `variant`, `position`, `width_frac`, `margin_frac`).
#'
#' @return `path`, invisibly.
#' @export
#' @seealso [style_flextable_civilytics()] to apply the brand styling, and
#'   [stamp_logo_png()] for the underlying logo compositing.
#' @examples
#' \dontrun{
#' library(flextable)
#' ft <- flextable(head(mtcars)) |>
#'   add_footer_lines("Source: mtcars") |>
#'   style_flextable_civilytics()
#' save_branded_flextable_png(ft, "table.png")
#' save_branded_flextable_png(ft, "table.png", position = "bottom-left")
#' knitr::include_graphics("table.png")
#' }
save_branded_flextable_png <- function(ft, path, logo = TRUE, res = 300,
                                       extra_height = 0.4, ...) {
  if (!requireNamespace("flextable", quietly = TRUE)) {
    stop("Install 'flextable' to use this function.", call. = FALSE)
  }
  if (!requireNamespace("ragg", quietly = TRUE)) {
    stop("Install 'ragg' to use this function.", call. = FALSE)
  }

  d <- flextable::flextable_dim(ft)
  ragg::agg_png(path, width = d$width, height = d$height + extra_height,
                units = "in", res = res)
  on.exit(grDevices::dev.off(), add = TRUE)
  plot(ft)

  if (logo) {
    # dev.off() must run before stamp_logo_png() re-reads the file. Flush the
    # device now and clear the on.exit handler so it does not fire twice.
    grDevices::dev.off()
    on.exit()
    stamp_logo_png(path, ...)
  }

  invisible(path)
}