DEV: Check English locale for errors in CI

Moves the most important checks into a linter. It gets executed by Lefthook as well as the docker rake task and Github actions. Doing those checks in rspec takes too long and it produces errors when the discourse:test Docker image contains old, invalid locale files.

script/i18n_lint.rb

@@ -0,0 +1,129 @@
+# frozen_string_literal: true
+
+require 'colored2'
+require 'psych'
+
+class I18nLinter
+  def initialize(filenames_or_patterns)
+    @filenames = filenames_or_patterns.map { |fp| Dir[fp] }.flatten
+    @errors = {}
+  end
+
+  def run
+    has_errors = false
+
+    @filenames.each do |filename|
+      validator = LocaleFileValidator.new(filename)
+
+      if validator.has_errors?
+        validator.print_errors
+        has_errors = true
+      end
+    end
+
+    exit 1 if has_errors
+  end
+end
+
+class LocaleFileValidator
+  ERROR_MESSAGES = {
+    invalid_relative_links: "The following keys have relative links, but do not start with %{base_url} or %{base_path}:",
+    invalid_relative_image_sources: "The following keys have relative image sources, but do not start with %{base_url} or %{base_path}:",
+    invalid_interpolation_key_format: "The following keys use {{key}} instead of %{key} for interpolation keys:",
+    wrong_pluralization_keys: "Pluralized strings must have only the sub-keys 'one' and 'other'.\nThe following keys have missing or additional keys:",
+    invald_one_keys: "The following keys contain the number 1 instead of the interpolation key %{count}:"
+  }
+
+  PLURALIZATION_KEYS = ['zero', 'one', 'two', 'few', 'many', 'other']
+  ENGLISH_KEYS = ['one', 'other']
+
+  def initialize(filename)
+    @filename = filename
+    @errors = {}
+  end
+
+  def has_errors?
+    yaml = Psych.safe_load(File.read(@filename), aliases: true)
+    yaml = yaml[yaml.keys.first]
+
+    validate_pluralizations(yaml)
+    validate_content(yaml)
+
+    @errors.any? { |_, value| value.any? }
+  end
+
+  def print_errors
+    puts "", "Errors in #{@filename}".red
+
+    @errors.each do |type, keys|
+      next if keys.empty?
+
+      ERROR_MESSAGES[type].split("\n").each { |msg| puts "  #{msg}" }
+      keys.each { |key| puts "    * #{key}" }
+    end
+  end
+
+  private
+
+  def each_translation(hash, parent_key = '', &block)
+    hash.each do |key, value|
+      current_key = parent_key.empty? ? key : "#{parent_key}.#{key}"
+
+      if Hash === value
+        each_translation(value, current_key, &block)
+      else
+        yield(current_key, value.to_s)
+      end
+    end
+  end
+
+  def validate_content(yaml)
+    @errors[:invalid_relative_links] = []
+    @errors[:invalid_relative_image_sources] = []
+    @errors[:invalid_interpolation_key_format] = []
+
+    each_translation(yaml) do |key, value|
+      if value.match?(/href\s*=\s*["']\/[^\/]|\]\(\/[^\/]/i)
+        @errors[:invalid_relative_links] << key
+      end
+
+      if value.match?(/src\s*=\s*["']\/[^\/]/i)
+        @errors[:invalid_relative_image_sources] << key
+      end
+
+      if value.match?(/{{.+?}}/) && !key.end_with?("_MF")
+        @errors[:invalid_interpolation_key_format] << key
+      end
+    end
+  end
+
+  def each_pluralization(hash, parent_key = '', &block)
+    hash.each do |key, value|
+      if Hash === value
+        current_key = parent_key.empty? ? key : "#{parent_key}.#{key}"
+        each_pluralization(value, current_key, &block)
+      elsif PLURALIZATION_KEYS.include? key
+        yield(parent_key, hash)
+      end
+    end
+  end
+
+  def validate_pluralizations(yaml)
+    @errors[:wrong_pluralization_keys] = []
+    @errors[:invald_one_keys] = []
+
+    each_pluralization(yaml) do |key, hash|
+      # ignore errors from some ActiveRecord messages
+      next if key.include?("messages.restrict_dependent_destroy")
+
+      @errors[:wrong_pluralization_keys] << key if hash.keys.sort != ENGLISH_KEYS
+
+      one_value = hash['one']
+      if one_value && one_value.include?('1') && !one_value.match?(/%{count}|{{count}}/)
+        @errors[:invald_one_keys] << key
+      end
+    end
+  end
+end
+
+I18nLinter.new(ARGV).run