# frozen_string_literal: true
# Copyright © 2018 Martin J. Dürst (duerst@it.aoyama.ac.jp)

require "test/unit"

class BreakTest
  attr_reader :clusters, :string, :comment, :line_number

  def initialize (line_number, data, comment)
    @line_number = line_number
    @comment = comment
    @clusters = data.sub(/\A\s*÷\s*/, '')
                    .sub(/\s*÷\s*\z/, '')
                    .split(/\s*÷\s*/)
                    .map do |cl|
                      cl.split(/\s*×\s*/)
                        .map do |ch|
                          c = ch.to_i(16)
                           # eliminate cases with surrogates
                          raise ArgumentError if 0xD800 <= c and c <= 0xDFFF
                          c.chr('UTF-8')
                        end.join
                    end
    @string = @clusters.join
  end
end

class TestGraphemeBreaksFromFile < Test::Unit::TestCase
  UNICODE_VERSION = RbConfig::CONFIG['UNICODE_VERSION']
  path = File.expand_path("../../../enc/unicode/data/#{UNICODE_VERSION}", __dir__)
  UNICODE_DATA_PATH = File.directory?("#{path}/ucd/auxiliary") ? "#{path}/ucd/auxiliary" : path
  GRAPHEME_BREAK_TEST_FILE = File.expand_path("#{UNICODE_DATA_PATH}/GraphemeBreakTest.txt", __dir__)

  def self.file_available?
    File.exist? GRAPHEME_BREAK_TEST_FILE
  end

  def test_data_files_available
    unless TestGraphemeBreaksFromFile.file_available?
      skip "Unicode data file GraphemeBreakTest not available in #{UNICODE_DATA_PATH}."
    end
  end
end

TestGraphemeBreaksFromFile.file_available? and  class TestGraphemeBreaksFromFile
  def read_data
    tests = []
    IO.foreach(GRAPHEME_BREAK_TEST_FILE, encoding: Encoding::UTF_8) do |line|
      if $. == 1 and not line.start_with?("# GraphemeBreakTest-#{UNICODE_VERSION}.txt")
        raise "File Version Mismatch"
      end
      next if /\A#/.match? line
      tests << BreakTest.new($., *line.chomp.split('#')) rescue 'whatever'
    end
    tests
  end

  def all_tests
    @@tests ||= read_data
  rescue Errno::ENOENT
    @@tests ||= []
  end

  def test_each_grapheme_cluster
    all_tests.each do |test|
      expected = test.clusters
      actual = test.string.each_grapheme_cluster.to_a
      assert_equal expected, actual,
        "line #{test.line_number}, expected '#{expected}', " +
        "but got '#{actual}', comment: #{test.comment}"
    end
  end

  def test_backslash_X
    all_tests.each do |test|
      clusters = test.clusters.dup
      string = test.string.dup
      removals = 0
      while string.sub!(/\A\X/, '')
        removals += 1
        clusters.shift
        expected = clusters.join
        assert_equal expected, string,
          "line #{test.line_number}, removals: #{removals}, expected '#{expected}', " +
          "but got '#{string}', comment: #{test.comment}"
      end
      assert_equal expected, string,
        "line #{test.line_number}, after last removal, expected '#{expected}', " +
        "but got '#{string}', comment: #{test.comment}"
    end
  end
end