home-manager: add basic i18n support

The support for translated strings is, for now, limited to strings
generated in Bash code.

lib/bash/home-manager.sh

@@ -0,0 +1,85 @@
+#!/usr/bin/env bash
+
+#
+# This file contains a number of utilities for use by the home-manager tool and
+# the generated Home Manager activation scripts. No guarantee is made about
+# backwards or forward compatibility.
+#
+
+# Sets up colors suitable for the `errorEcho`, `warnEcho`, and `noteEcho`
+# functions.
+#
+# The check for terminal output and color support is heavily inspired by
+# https://unix.stackexchange.com/a/10065.
+#
+# The setup respects the `NO_COLOR` environment variable.
+function setupColors() {
+    normalColor=""
+    errorColor=""
+    warnColor=""
+    noteColor=""
+
+    # Enable colors for terminals, and allow opting out.
+    if [[ ! -v NO_COLOR && -t 1 ]]; then
+        # See if it supports colors.
+        local ncolors
+        ncolors=$(tput colors)
+
+        if [[ -n "$ncolors" && "$ncolors" -ge 8 ]]; then
+            normalColor="$(tput sgr0)"
+            errorColor="$(tput bold)$(tput setaf 1)"
+            warnColor="$(tput setaf 3)"
+            noteColor="$(tput bold)$(tput setaf 6)"
+        fi
+    fi
+}
+
+setupColors
+
+function errorEcho() {
+    echo "${errorColor}$*${normalColor}"
+}
+
+function warnEcho() {
+    echo "${warnColor}$*${normalColor}"
+}
+
+function noteEcho() {
+    echo "${noteColor}$*${normalColor}"
+}
+
+function _i() {
+    local msgid="$1"
+    shift
+
+    # shellcheck disable=2059
+    printf "$(gettext "$msgid")\n" "$@"
+}
+
+function _ip() {
+    local msgid="$1"
+    local msgidPlural="$2"
+    local count="$3"
+    shift 3
+
+    # shellcheck disable=2059
+    printf "$(ngettext "$msgid" "$msgidPlural" "$count")\n" "$@"
+}
+
+function _iError() {
+    echo -n "${errorColor}"
+    _i "$@"
+    echo -n "${normalColor}"
+}
+
+function _iWarn() {
+    echo -n "${warnColor}"
+    _i "$@"
+    echo -n "${normalColor}"
+}
+
+function _iNote() {
+    echo -n "${noteColor}"
+    _i "$@"
+    echo -n "${normalColor}"
+}