Add a locale-aware relative-time helper; drop stale locale overrides

Node.recently_changed and the new dashboard need "X ago" rendered
correctly in both locales. Rails' own distance_of_time_in_words/
time_ago_in_words can't do this on their own -- the scope option
changes which translation key is looked up, not the underlying
grammar, and German's "vor" requires dative case, which is a
different word form than the nominative plural Rails computes by
default. relative_time_phrase/relative_distance is a small, from-
scratch bucketing helper instead, with an explicit, hand-checked
translation table per unit per locale.

Also removes de.yml's datetime.distance_in_words and activerecord.
errors blocks. Both used the old {{count}}/{{model}} interpolation
syntax the current i18n gem no longer recognizes -- it silently
leaves the literal placeholder text in the rendered output rather
than erroring, which is why this went unnoticed until now. Both were
shadowing rails-i18n's own current, correct translations for exactly
these keys; deleting the local override lets the gem's version take
over instead of maintaining a second, broken copy.

1 files changed, 53 insertions, 0 deletions

diff --git a/app/helpers/datetime_helper.rb b/app/helpers/datetime_helper.rb
new file mode 100644
index 0000000..8497b1c
--- /dev/null
+++ b/app/helpers/datetime_helper.rb
@@ -0,0 +1,53 @@
+module DatetimeHelper
+
+  def relative_distance(time, now = Time.current)
+    seconds = (now - time).abs
+
+    case seconds
+    when 0...90
+      [1, :minute]
+    when 90...45.minutes
+      [(seconds / 60).round, :minute]
+    when 45.minutes...24.hours
+      [(seconds / 1.hour).round, :hour]
+    when 24.hours...30.days
+      [(seconds / 1.day).round, :day]
+    when 30.days...365.days
+      [(seconds / 30.days).round, :month]
+    else
+      [(seconds / 365.days).round, :year]
+    end
+  end
+
+  RELATIVE_TIME_UNIT_FORMS = {
+    en: {
+      minute: { one: "minute", other: "minutes" },
+      hour:   { one: "hour",   other: "hours" },
+      day:    { one: "day",    other: "days" },
+      month:  { one: "month",  other: "months" },
+      year:   { one: "year",   other: "years" },
+    },
+    de: {
+      # "other" here is the DATIVE plural needed after "vor" -- not the
+      # nominative plural you'd use standing alone ("3 Tage" vs "vor 3
+      # Tagen"). All five happen to be the nominative plural + "n", since
+      # none of them already end in -n or -s -- a property of these five
+      # specific words, not a rule to extend to new units without checking.
+      minute: { one: "Minute", other: "Minuten" },
+      hour:   { one: "Stunde", other: "Stunden" },
+      day:    { one: "Tag",    other: "Tagen" },
+      month:  { one: "Monat",  other: "Monaten" },
+      year:   { one: "Jahr",   other: "Jahren" },
+    },
+  }.freeze
+
+  def relative_time_phrase(time, now = Time.current)
+    count, unit = relative_distance(time, now)
+    locale = I18n.locale.to_sym
+    forms = RELATIVE_TIME_UNIT_FORMS.fetch(locale, RELATIVE_TIME_UNIT_FORMS[:en])
+    word = forms.fetch(unit).fetch(count == 1 ? :one : :other)
+
+    locale == :de ? "vor #{count} #{word}" : "#{count} #{word} ago"
+  end
+
+end