mcolor

#!/usr/bin/awk -f
# mcolor - colorize rendered mail

function co(n, c) { e = ENVIRON["MCOLOR_" n]; return e ? e : c }
function fg(c, s) { return sprintf("\033[38;5;%03dm%s\033[0m", c, s) }
function so(s) { return sprintf("\033[1m%s\033[0m", s) }
BEGIN { hdr = 1; if ("NO_COLOR" in ENVIRON || match(ENVIRON["TERM"], "^(dumb|network|9term)")) no_color = 1 }
no_color { print; next }
/\r$/ { sub(/\r$/, "") }
/^\014$/ { nextmail = 1; print(fg(co("FF",232), $0)); next }
/^$/ { hdr = 0; diff = 0 }
/^-- $/ { ftr = 1 }
/^diff -/ { diff = 1 }
/^--- .* ---/ { print fg(co("SEP",242), $0); ftr = 0; sig = 0; next }
/^-----BEGIN .* SIGNATURE-----/ { sig = 1 }
nextmail && /^From:/ { hdr = 1 }
hdr && /^From:/ { print so(fg(co("FROM",119), $0)); next }
hdr { print fg(co("HEADER",120), $0); next }
ftr { print fg(co("FOOTER",244), $0); next }
diff && /^-/ { print fg(co("DIFF_D",160), $0); next }
diff && /^\+/ { print fg(co("DIFF_I",40), $0); next }
diff && /^@/ { print fg(co("DIFF_R",226), $0); next }
/^-----BEGIN .* MESSAGE-----/ ||
/^-----END .* SIGNATURE-----/ { print fg(co("SIG",244), $0); sig = 0; next }
sig { print fg(co("SIG",244), $0); next }
/^> *> *>/ { print fg(co("QQQUOTE",152), $0); next }
/^> *>/ { print fg(co("QQUOTE",149), $0); next }
/^>/ { print fg(co("QUOTE",151), $0); next }
{ nextmail = 0; print }