#!/usr/bin/env ruby
require 'fileutils'
require 'tmpdir'

HAML_REPO    = 'haml/haml'
HAML_VERSION = 'v5.2.0'

module GitHubFetcher
  def self.fetch(repo, tag:, path:)
    Dir.mktmpdir do |dir|
      Dir.chdir(dir) do
        url = "https://github.com/#{repo}/archive/#{tag}.tar.gz"
        system("curl -L --fail --retry 3 --retry-delay 1 #{url} -o - | tar zxf -")
        FileUtils.mv("#{File.basename(repo)}-#{tag.sub(/\Av/, '')}", path)
      end
    end
  end
end

class LicenseBuilder
  DELIMITER = "\n==="

  def initialize(haml_license:, hamlit_license:)
    @haml_license = haml_license
    @hamlit_license = hamlit_license
  end

  def build
    license = [
      File.read(@haml_license),
      File.read(@hamlit_license).split(DELIMITER, 2).last,
    ].join(DELIMITER)
    File.write(@hamlit_license, license)
  end
end

# Generate lib/hamlit/parser from haml
class HamlitParserBuilder
  TARGET_FILES = [
    'attribute_builder.rb',
    'buffer.rb',
    'error.rb',
    'helpers.rb',
    'options.rb',
    'temple_engine.rb',
    # TODO: make the upstream sharable first
    # 'parser.rb',
    'util.rb',
    'helpers/xss_mods.rb',
  ]

  # Classes which are just referenced by Options and not really used by the parser
  DUMMY_CLASSES = {
    'compiler.rb' => 'Compiler',
    'escapable.rb' => 'Escapable',
    'generator.rb' => 'Generator',
  }

  def initialize(haml:, hamlit_parser:)
    @haml = haml
    @hamlit_parser = hamlit_parser
  end

  def build
    TARGET_FILES.each do |file|
      src_path  = File.join(@haml, file)
      dest_path = File.join(@hamlit_parser, "haml_#{file}")

      FileUtils.mkdir_p(File.dirname(dest_path))
      FileUtils.cp(src_path, dest_path)

      src = File.read(dest_path)
      patch_source!(src, file: file)
      File.write(dest_path, src)
    end

    DUMMY_CLASSES.each do |file, klass|
      dest_path = File.join(@hamlit_parser, "haml_#{file}")
      src = "class Hamlit::Haml#{klass}; end"
      File.write(dest_path, src)
    end
  end

  private

  def patch_source!(src, file:)
    # Use Hamlit::HamlFoo instead of Haml::Foo
    src.gsub!(/^module Haml\n((?:  #[^\n]+\n)*)  (module|class) ([^ ]+)/, "module Hamlit\n\\1  \\2 Haml\\3")
    src.gsub!(/\bHaml::/, 'Hamlit::Haml')

    # Prefix Haml to references without Haml::
    src.gsub!(/\b(AttributeBuilder|Error|InvalidAttributeNameError|Options|Parser|SyntaxError)\./, 'Haml\0')
    src.gsub!(/\brescue SyntaxError /, 'rescue HamlSyntaxError ')

    # Hamlit should not rely on Haml
    src.gsub!(/^require 'haml\/([^']+)'/, "require 'hamlit/parser/haml_\\1'")

    case file
    when 'error.rb'
      src.gsub!(/^  class ([^ ]+) < ([^ ]+);/, '  class Haml\1 < Haml\2;')
    when 'helpers.rb'
      src.gsub!(/^  def is_haml\?\n    false\n  end/m) { |str| str.gsub(/^  /, '  # ') } # not needed for the parser
    when 'options.rb'
      src.gsub!(/\.is_a\?\(Options\)/, '.is_a?(HamlOptions)')
    when 'temple_engine.rb'
      src.gsub!(/\buse (Generator|Escapable)$/, 'use Haml\1')
    end
  end
end

FileUtils.rm_rf(haml = File.expand_path('../haml', __dir__))
GitHubFetcher.fetch(HAML_REPO, tag: HAML_VERSION, path: haml)

hamlit = File.expand_path('..', __dir__)
LicenseBuilder.new(
  haml_license: File.join(haml, 'MIT-LICENSE'),
  hamlit_license: File.join(hamlit, 'LICENSE.txt'),
).build

hamlit_parser = File.join(hamlit, 'lib/hamlit/parser')
# TODO: FileUtils.rm_rf(hamlit_parser = File.join(hamlit, 'lib/hamlit/parser'))
HamlitParserBuilder.new(
  haml: File.join(haml, 'lib/haml'),
  hamlit_parser: hamlit_parser,
).build