# frozen_string_literal: true

require 'minitest/autorun'
require 'open3'
require 'tmpdir'
require 'fileutils'

# Runs the examples from the printed handbook (demo/handbuch/beispiele.txt) and
# compares each output with the one printed in the book. Whitespace does not
# count: the book aligns columns with spaces, we write tabs.
class HandbuchTest < Minitest::Test
  ROOT = File.expand_path('..', __dir__)
  DIR = File.join(ROOT, 'demo', 'handbuch')

  Example = Struct.new(:dir, :title, :cmd, :expected, :deviation)

  def self.examples
    list = []
    dir = '.'
    title = nil
    deviation = nil
    cur = nil
    lines = File.readlines(File.join(DIR, 'beispiele.txt'), chomp: true)
    until lines.empty?
      line = lines.shift
      if line.start_with?('$ ')
        cmd = line[2..]
        cmd += "\n" + lines.shift while cmd.match?(/[|\\]\s*\z/) && lines.any?
        cur = Example.new(dir, title, cmd, [], deviation)
        list << cur
      elsif line.start_with?('@ ')
        dir = line[2..].strip
        cur = nil
      elsif line.start_with?('## ')
        title = line[3..]
        deviation = nil
        cur = nil
      elsif line.start_with?('! ')
        deviation = line[2..]
      elsif line.start_with?('#')
        next
      elsif cur
        cur.expected << line
      end
    end
    list
  end

  # Cells without whitespace; dash runs count as one dash; blank lines drop out.
  def self.normalize(lines)
    lines.map { |l| l.split.map { |w| w.match?(/\A-+\z/) ? '-' : w }.join(' ') }.reject(&:empty?)
  end

  def run_example(ex, scratch)
    env = { 'PATH' => "#{File.join(ROOT, 'bin')}:#{ENV['PATH']}" }
    out, _st = Open3.capture2e(env, 'sh', '-c', ex.cmd, chdir: File.join(scratch, ex.dir), stdin_data: '')
    out.lines(chomp: true)
  end

  def test_examples_from_the_book
    failures = []
    fixed = []
    Dir.mktmpdir('rdb-handbuch') do |scratch|
      FileUtils.cp_r(Dir[File.join(DIR, '*')], scratch)
      self.class.examples.each do |ex|
        got = self.class.normalize(run_example(ex, scratch))
        next if ex.expected.empty?

        want = self.class.normalize(ex.expected)
        if ex.deviation
          fixed << "#{ex.title}: stimmt jetzt mit dem Buch überein, '!' entfernen" if got == want
        elsif got != want
          failures << "#{ex.title}\n  $ #{ex.cmd}\n  Buch:     #{want.inspect}\n  erhalten: #{got.inspect}"
        end
      end
    end
    assert_empty failures + fixed, (failures + fixed).join("\n\n")
  end
end