tattr.nim

import std/os, cligen/humanUt, cligen
when not declared(stdout): import std/syncio

proc tattr(attrs: seq[string]) =
  ## Emit to stdout an escape string activating text colors/styles, honoring
  ## $NO_COLOR & also reading ~/.config/cligen for $LC_THEME-based aliases.
  ##
  ## Non-color styles (prefix with '-' to turn off):
  ##   bold, faint, italic, inverse, struck, blink (slow), BLINK (fast),
  ##   under{line double dot dash curl}.
  ##
  ## Regular color keywords are in lower case; Bright bank in UPPER CASE:
  ##   black, red, green, yellow, blue, purple, cyan, white
  ##   BLACK, RED, GREEN, YELLOW, BLUE, PURPLE, CYAN, WHITE
  ## Colors are foreground by default.  Pre-pend "on_" for Background.
  ##
  ## 256-color or true color terminals like xterm|st|kitty also support:
  ##   {fbu}[0..23] for F)ORE/B)ACKgrnd U)NDER grey scale
  ##   {fbu}RGB where R, G, B are in 0..5
  ##   {fbu}RRGGBB with RR, GG, BB are in hexadecimal (true color)
  ##
  ## An element of color scale NAME {viridis hue wLen gray pm3d} can be chosen
  ## via:
  ##   {fbu}sNAME<0.-1>[,..]
  ## where only `hue` and `wLen` take [,sat,val] optionally.
  ## "wLen" is for "waveLength" - (yes, I know RGB light is a mixture; terms are
  ## just to contrast with "frequency order" or hot..cold / cold..hot).
  if attrs.len == 0:
    raise newException(ValueError, "\n  Need >= 1 attrs.  See tattr --help")
  stdout.write textAttrOn(attrs, plain=existsEnv("NO_COLOR"))

dispatch(tattr)