# frozen_string_literal: true

# rubocop:disable Style/GlobalVars

ENV["RC_ARCHS"] = "" if RUBY_PLATFORM.include?("darwin")

require "mkmf"
require "rbconfig"
require "fileutils"
require "shellwords"
require "pathname"

# helpful constants
PACKAGE_ROOT_DIR = File.expand_path(File.join(File.dirname(__FILE__), "..", ".."))
REQUIRED_LIBXML_VERSION = "2.6.21"
RECOMMENDED_LIBXML_VERSION = "2.9.3"

REQUIRED_MINI_PORTILE_VERSION = "~> 2.8.2" # keep this version in sync with the one in the gemspec
REQUIRED_PKG_CONFIG_VERSION = "~> 1.1"

# Keep track of what versions of what libraries we build against
OTHER_LIBRARY_VERSIONS = {}

NOKOGIRI_HELP_MESSAGE = <<~HELP
  USAGE: ruby #{$PROGRAM_NAME} [options]

    Flags that are always valid:

      --use-system-libraries
      --enable-system-libraries
          Use system libraries instead of building and using the packaged libraries.

      --disable-system-libraries
          Use the packaged libraries, and ignore the system libraries. This is the default on most
          platforms, and overrides `--use-system-libraries` and the environment variable
          `NOKOGIRI_USE_SYSTEM_LIBRARIES`.

      --disable-clean
          Do not clean out intermediate files after successful build.

      --prevent-strip
          Take steps to prevent stripping the symbol table and debugging info from the shared
          library, potentially overriding RbConfig's CFLAGS/LDFLAGS/DLDFLAGS.


    Flags only used when using system libraries:

      General:

        --with-opt-dir=DIRECTORY
            Look for headers and libraries in DIRECTORY.

        --with-opt-lib=DIRECTORY
            Look for libraries in DIRECTORY.

        --with-opt-include=DIRECTORY
            Look for headers in DIRECTORY.


      Related to zlib:

        --with-zlib-dir=DIRECTORY
            Look for zlib headers and library in DIRECTORY.

        --with-zlib-lib=DIRECTORY
            Look for zlib library in DIRECTORY.

        --with-zlib-include=DIRECTORY
            Look for zlib headers in DIRECTORY.


      Related to iconv:

        --with-iconv-dir=DIRECTORY
            Look for iconv headers and library in DIRECTORY.

        --with-iconv-lib=DIRECTORY
            Look for iconv library in DIRECTORY.

        --with-iconv-include=DIRECTORY
            Look for iconv headers in DIRECTORY.


      Related to libxml2:

        --with-xml2-dir=DIRECTORY
            Look for xml2 headers and library in DIRECTORY.

        --with-xml2-lib=DIRECTORY
            Look for xml2 library in DIRECTORY.

        --with-xml2-include=DIRECTORY
            Look for xml2 headers in DIRECTORY.

        --with-xml2-source-dir=DIRECTORY
            (dev only) Build libxml2 from the source code in DIRECTORY


      Related to libxslt:

        --with-xslt-dir=DIRECTORY
            Look for xslt headers and library in DIRECTORY.

        --with-xslt-lib=DIRECTORY
            Look for xslt library in DIRECTORY.

        --with-xslt-include=DIRECTORY
            Look for xslt headers in DIRECTORY.

        --with-xslt-source-dir=DIRECTORY
            (dev only) Build libxslt from the source code in DIRECTORY


      Related to libexslt:

        --with-exslt-dir=DIRECTORY
            Look for exslt headers and library in DIRECTORY.

        --with-exslt-lib=DIRECTORY
            Look for exslt library in DIRECTORY.

        --with-exslt-include=DIRECTORY
            Look for exslt headers in DIRECTORY.


    Flags only used when building and using the packaged libraries:

      --disable-static
          Do not statically link packaged libraries, instead use shared libraries.

      --enable-cross-build
          Enable cross-build mode. (You probably do not want to set this manually.)


    Environment variables used:

      NOKOGIRI_USE_SYSTEM_LIBRARIES
          Equivalent to `--enable-system-libraries` when set, even if nil or blank.

      CC
          Use this path to invoke the compiler instead of `RbConfig::CONFIG['CC']`

      CPPFLAGS
          If this string is accepted by the C preprocessor, add it to the flags passed to the C preprocessor

      CFLAGS
          If this string is accepted by the compiler, add it to the flags passed to the compiler

      LDFLAGS
          If this string is accepted by the linker, add it to the flags passed to the linker

      LIBS
          Add this string to the flags passed to the linker
HELP

#
#  utility functions
#
def config_clean?
  enable_config("clean", true)
end

def config_static?
  default_static = !truffle?
  enable_config("static", default_static)
end

def config_cross_build?
  enable_config("cross-build")
end

def config_system_libraries?
  enable_config("system-libraries", ENV.key?("NOKOGIRI_USE_SYSTEM_LIBRARIES")) do |_, default|
    arg_config("--use-system-libraries", default)
  end
end

def windows?
  RbConfig::CONFIG["target_os"].match?(/mingw|mswin/)
end

def solaris?
  RbConfig::CONFIG["target_os"].include?("solaris")
end

def darwin?
  RbConfig::CONFIG["target_os"].include?("darwin")
end

def openbsd?
  RbConfig::CONFIG["target_os"].include?("openbsd")
end

def aix?
  RbConfig::CONFIG["target_os"].include?("aix")
end

def nix?
  !(windows? || solaris? || darwin?)
end

def truffle?
  RUBY_ENGINE == "truffleruby"
end

def concat_flags(*args)
  args.compact.join(" ")
end

def local_have_library(lib, func = nil, headers = nil)
  have_library(lib, func, headers) || have_library("lib#{lib}", func, headers)
end

def zlib_source(version_string)
  # As of 2022-12, I'm starting to see failed downloads often enough from zlib.net that I want to
  # change the default to github.
  if ENV["NOKOGIRI_USE_CANONICAL_ZLIB_SOURCE"]
    "https://zlib.net/fossils/zlib-#{version_string}.tar.gz"
  else
    "https://github.com/madler/zlib/releases/download/v#{version_string}/zlib-#{version_string}.tar.gz"
  end
end

def gnome_source
  # As of 2022-02-20, some mirrors have expired SSL certificates. I'm able to retrieve from my home,
  # but whatever host is resolved on the github actions workers see an expired cert.
  #
  # See https://github.com/sparklemotion/nokogiri/runs/5266206403?check_suite_focus=true
  if ENV["NOKOGIRI_USE_CANONICAL_GNOME_SOURCE"]
    "https://download.gnome.org"
  else
    "https://muug.ca/mirror/gnome" # old reliable
  end
end

LOCAL_PACKAGE_RESPONSE = Object.new
def LOCAL_PACKAGE_RESPONSE.%(package)
  package ? "yes: #{package}" : "no"
end

# wrapper around MakeMakefil#pkg_config and the PKGConfig gem
def try_package_configuration(pc)
  unless ENV.key?("NOKOGIRI_TEST_PKG_CONFIG_GEM")
    # try MakeMakefile#pkg_config, which uses the system utility `pkg-config`.
    return if checking_for("#{pc} using `pkg_config`", LOCAL_PACKAGE_RESPONSE) do
      pkg_config(pc)
    end
  end

  # `pkg-config` probably isn't installed, which appears to be the case for lots of freebsd systems.
  # let's fall back to the pkg-config gem, which knows how to parse .pc files, and wrap it with the
  # same logic as MakeMakefile#pkg_config
  begin
    require "rubygems"
    gem("pkg-config", REQUIRED_PKG_CONFIG_VERSION)
    require "pkg-config"

    checking_for("#{pc} using pkg-config gem version #{PKGConfig::VERSION}", LOCAL_PACKAGE_RESPONSE) do
      if PKGConfig.have_package(pc)
        cflags  = PKGConfig.cflags(pc)
        ldflags = PKGConfig.libs_only_L(pc)
        libs    = PKGConfig.libs_only_l(pc)

        Logging.message("pkg-config gem found package configuration for %s\n", pc)
        Logging.message("cflags: %s\nldflags: %s\nlibs: %s\n\n", cflags, ldflags, libs)

        [cflags, ldflags, libs]
      end
    end
  rescue LoadError
    message("Please install either the `pkg-config` utility or the `pkg-config` rubygem.\n")
  end
end

# set up mkmf to link against the library if we can find it
def have_package_configuration(opt: nil, pc: nil, lib:, func:, headers:)
  if opt
    dir_config(opt)
    dir_config("opt")
  end

  # see if we have enough path info to do this without trying any harder
  unless ENV.key?("NOKOGIRI_TEST_PKG_CONFIG")
    return true if local_have_library(lib, func, headers)
  end

  try_package_configuration(pc) if pc

  # verify that we can compile and link against the library
  local_have_library(lib, func, headers)
end

def ensure_package_configuration(opt: nil, pc: nil, lib:, func:, headers:)
  have_package_configuration(opt: opt, pc: pc, lib: lib, func: func, headers: headers) ||
    abort_could_not_find_library(lib)
end

def ensure_func(func, headers = nil)
  have_func(func, headers) || abort_could_not_find_library(func)
end

def preserving_globals
  values = [$arg_config, $INCFLAGS, $CFLAGS, $CPPFLAGS, $LDFLAGS, $DLDFLAGS, $LIBPATH, $libs].map(&:dup)
  yield
ensure
  $arg_config, $INCFLAGS, $CFLAGS, $CPPFLAGS, $LDFLAGS, $DLDFLAGS, $LIBPATH, $libs = values
end

def abort_could_not_find_library(lib)
  callers = caller(1..2).join("\n")
  abort("-----\n#{callers}\n#{lib} is missing. Please locate mkmf.log to investigate how it is failing.\n-----")
end

def chdir_for_build(&block)
  # When using rake-compiler-dock on Windows, the underlying Virtualbox shared
  # folders don't support symlinks, but libiconv expects it for a build on
  # Linux. We work around this limitation by using the temp dir for cooking.
  build_dir = /mingw|mswin|cygwin/.match?(ENV["RCD_HOST_RUBY_PLATFORM"].to_s) ? "/tmp" : "."
  Dir.chdir(build_dir, &block)
end

def sh_export_path(path)
  # because libxslt 1.1.29 configure.in uses AC_PATH_TOOL which treats ":"
  # as a $PATH separator, we need to convert windows paths from
  #
  #   C:/path/to/foo
  #
  # to
  #
  #   /C/path/to/foo
  #
  # which is sh-compatible, in order to find things properly during
  # configuration
  return path unless windows?

  match = Regexp.new("^([A-Z]):(/.*)").match(path)
  if match && match.length == 3
    return File.join("/", match[1], match[2])
  end

  path
end

def libflag_to_filename(ldflag)
  case ldflag
  when /\A-l(.+)/
    "lib#{Regexp.last_match(1)}.#{$LIBEXT}"
  end
end

def have_libxml_headers?(version = nil)
  source = if version.nil?
    <<~SRC
      #include <libxml/xmlversion.h>
    SRC
  else
    version_int = format("%d%2.2d%2.2d", *version.split("."))
    <<~SRC
      #include <libxml/xmlversion.h>
      #if LIBXML_VERSION < #{version_int}
      #  error libxml2 is older than #{version}
      #endif
    SRC
  end

  try_cpp(source)
end

def try_link_iconv(using = nil)
  checking_for(using ? "iconv using #{using}" : "iconv") do
    ["", "-liconv"].any? do |opt|
      preserving_globals do
        yield if block_given?

        try_link(<<~SRC, opt)
          #include <stdlib.h>
          #include <iconv.h>
          int main(void)
          {
              iconv_t cd = iconv_open("", "");
              iconv(cd, NULL, NULL, NULL, NULL);
              return EXIT_SUCCESS;
          }
        SRC
      end
    end
  end
end

def iconv_configure_flags
  # give --with-iconv-dir and --with-opt-dir first priority
  ["iconv", "opt"].each do |target|
    config = preserving_globals { dir_config(target) }
    next unless config.any? && try_link_iconv("--with-#{target}-* flags") { dir_config(target) }

    idirs, ldirs = config.map do |dirs|
      Array(dirs).flat_map do |dir|
        dir.split(File::PATH_SEPARATOR)
      end if dirs
    end

    return [
      "--with-iconv=yes",
      *("CPPFLAGS=#{idirs.map { |dir| "-I" + dir }.join(" ")}" if idirs),
      *("LDFLAGS=#{ldirs.map { |dir| "-L" + dir }.join(" ")}" if ldirs),
    ]
  end

  if try_link_iconv
    return ["--with-iconv=yes"]
  end

  config = preserving_globals { pkg_config("libiconv") }
  if config && try_link_iconv("pkg-config libiconv") { pkg_config("libiconv") }
    cflags, ldflags, libs = config

    return [
      "--with-iconv=yes",
      "CPPFLAGS=#{cflags}",
      "LDFLAGS=#{ldflags}",
      "LIBS=#{libs}",
    ]
  end

  abort_could_not_find_library("libiconv")
end

def process_recipe(name, version, static_p, cross_p, cacheable_p = true)
  require "rubygems"
  gem("mini_portile2", REQUIRED_MINI_PORTILE_VERSION) # gemspec is not respected at install time
  require "mini_portile2"
  message("Using mini_portile version #{MiniPortile::VERSION}\n")

  unless ["libxml2", "libxslt"].include?(name)
    OTHER_LIBRARY_VERSIONS[name] = version
  end

  MiniPortile.new(name, version).tap do |recipe|
    def recipe.port_path
      "#{@target}/#{RUBY_PLATFORM}/#{@name}/#{@version}"
    end

    # We use 'host' to set compiler prefix for cross-compiling. Prefer host_alias over host. And
    # prefer i686 (what external dev tools use) to i386 (what ruby's configure.ac emits).
    recipe.host = RbConfig::CONFIG["host_alias"].empty? ? RbConfig::CONFIG["host"] : RbConfig::CONFIG["host_alias"]
    recipe.host = recipe.host.gsub(/i386/, "i686")

    recipe.target = File.join(PACKAGE_ROOT_DIR, "ports") if cacheable_p
    recipe.configure_options << "--libdir=#{File.join(recipe.path, "lib")}"

    yield recipe

    env = Hash.new do |hash, key|
      hash[key] = (ENV[key]).to_s
    end

    recipe.configure_options.flatten!

    recipe.configure_options.delete_if do |option|
      case option
      when /\A(\w+)=(.*)\z/
        env[Regexp.last_match(1)] = if env.key?(Regexp.last_match(1))
          concat_flags(env[Regexp.last_match(1)], Regexp.last_match(2))
        else
          Regexp.last_match(2)
        end
        true
      else
        false
      end
    end

    if static_p
      recipe.configure_options += [
        "--disable-shared",
        "--enable-static",
      ]
      env["CFLAGS"] = concat_flags(env["CFLAGS"], "-fPIC")
    else
      recipe.configure_options += [
        "--enable-shared",
        "--disable-static",
      ]
    end

    if cross_p
      recipe.configure_options += [
        "--target=#{recipe.host}",
        "--host=#{recipe.host}",
      ]
    end

    if RbConfig::CONFIG["target_cpu"] == "universal"
      ["CFLAGS", "LDFLAGS"].each do |key|
        unless env[key].include?("-arch")
          env[key] = concat_flags(env[key], RbConfig::CONFIG["ARCH_FLAG"])
        end
      end
    end

    recipe.configure_options += env.map do |key, value|
      "#{key}=#{value.strip}"
    end

    checkpoint = "#{recipe.target}/#{recipe.name}-#{recipe.version}-#{RUBY_PLATFORM}.installed"
    if File.exist?(checkpoint) && !recipe.source_directory
      message("Building Nokogiri with a packaged version of #{name}-#{version}.\n")
    else
      message(<<~EOM)
        ---------- IMPORTANT NOTICE ----------
        Building Nokogiri with a packaged version of #{name}-#{version}.
        Configuration options: #{recipe.configure_options.shelljoin}
      EOM

      unless recipe.patch_files.empty?
        message("The following patches are being applied:\n")

        recipe.patch_files.each do |patch|
          message(format("  - %s\n", File.basename(patch)))
        end
      end

      message(<<~EOM) if name != "libgumbo"

        The Nokogiri maintainers intend to provide timely security updates, but if
        this is a concern for you and want to use your OS/distro system library
        instead, then abort this installation process and install nokogiri as
        instructed at:

          https://nokogiri.org/tutorials/installing_nokogiri.html#installing-using-standard-system-libraries

      EOM

      message(<<~EOM) if name == "libxml2"
        Note, however, that nokogiri cannot guarantee compatibility with every
        version of libxml2 that may be provided by OS/package vendors.

      EOM

      chdir_for_build { recipe.cook }
      FileUtils.touch(checkpoint)
    end
    recipe.activate
  end
end

def copy_packaged_libraries_headers(to_path:, from_recipes:)
  FileUtils.rm_rf(to_path, secure: true)
  FileUtils.mkdir(to_path)
  from_recipes.each do |recipe|
    FileUtils.cp_r(Dir[File.join(recipe.path, "include/*")], to_path)
  end
end

def do_help
  print(NOKOGIRI_HELP_MESSAGE)
  exit!(0)
end

def do_clean
  root = Pathname(PACKAGE_ROOT_DIR)
  pwd  = Pathname(Dir.pwd)

  # Skip if this is a development work tree
  unless (root + ".git").exist?
    message("Cleaning files only used during build.\n")

    # (root + 'tmp') cannot be removed at this stage because
    # nokogiri.so is yet to be copied to lib.

    # clean the ports build directory
    Pathname.glob(pwd.join("tmp", "*", "ports")) do |dir|
      FileUtils.rm_rf(dir, verbose: true)
    end

    if config_static?
      # ports installation can be safely removed if statically linked.
      FileUtils.rm_rf(root + "ports", verbose: true)
    else
      FileUtils.rm_rf(root + "ports" + "archives", verbose: true)
    end
  end

  exit!(0)
end

# In ruby 3.2, symbol resolution changed on Darwin, to introduce the `-bundle_loader` flag to
# resolve symbols against the ruby binary.
#
# This makes it challenging to build a single extension that works with both a ruby with
# `--enable-shared` and one with `--disable-shared. To work around that, we choose to add
# `-flat_namespace` to the link line (later in this file).
#
# The `-flat_namespace` line introduces its own behavior change, which is that (similar to on
# Linux), any symbols in the extension that are exported may now be resolved by shared libraries
# loaded by the Ruby process. Specifically, that means that libxml2 and libxslt, which are
# statically linked into the nokogiri bundle, will resolve (at runtime) to a system libxml2 loaded
# by Ruby on Darwin. And it appears that often Ruby on Darwin does indeed load the system libxml2,
# and that messes with our assumptions about whether we're running with a patched libxml2 or a
# vanilla libxml2.
#
# We choose to use `-load_hidden` in this case to prevent exporting those symbols from libxml2 and
# libxslt, which ensures that they will be resolved to the static libraries in the bundle. In other
# words, when we use `load_hidden`, what happens in the extension stays in the extension.
#
# See https://github.com/rake-compiler/rake-compiler-dock/issues/87 for more info.
#
# Anyway, this method is the logical bit to tell us when to turn on these workarounds.
def needs_darwin_linker_hack
  config_cross_build? &&
    darwin? &&
    Gem::Requirement.new("~> 3.2").satisfied_by?(Gem::Version.new(RbConfig::CONFIG["ruby_version"].split("+").first))
end

#
#  main
#
do_help if arg_config("--help")
do_clean if arg_config("--clean")

if openbsd? && !config_system_libraries?
  unless %x(#{ENV["CC"] || "/usr/bin/cc"} -v 2>&1).include?("clang")
    (ENV["CC"] ||= find_executable("egcc")) ||
      abort("Please install gcc 4.9+ from ports using `pkg_add -v gcc`")
  end
  append_cppflags "-I/usr/local/include"
end

if ENV["CC"]
  RbConfig::CONFIG["CC"] = RbConfig::MAKEFILE_CONFIG["CC"] = ENV["CC"]
end

# use same c compiler for libxml and libxslt
ENV["CC"] = RbConfig::CONFIG["CC"]

if arg_config("--prevent-strip")
  old_cflags = $CFLAGS.split.join(" ")
  old_ldflags = $LDFLAGS.split.join(" ")
  old_dldflags = $DLDFLAGS.split.join(" ")
  $CFLAGS = $CFLAGS.split.reject { |flag| flag == "-s" }.join(" ")
  $LDFLAGS = $LDFLAGS.split.reject { |flag| flag == "-s" }.join(" ")
  $DLDFLAGS = $DLDFLAGS.split.reject { |flag| flag == "-s" }.join(" ")
  puts "Prevent stripping by removing '-s' from $CFLAGS" if old_cflags != $CFLAGS
  puts "Prevent stripping by removing '-s' from $LDFLAGS" if old_ldflags != $LDFLAGS
  puts "Prevent stripping by removing '-s' from $DLDFLAGS" if old_dldflags != $DLDFLAGS
end

# adopt environment config
append_cflags(ENV["CFLAGS"].split) unless ENV["CFLAGS"].nil?
append_cppflags(ENV["CPPFLAGS"].split) unless ENV["CPPFLAGS"].nil?
append_ldflags(ENV["LDFLAGS"].split) unless ENV["LDFLAGS"].nil?
$LIBS = concat_flags($LIBS, ENV["LIBS"])

# nokogumbo code uses C90/C99 features, let's make sure older compilers won't give
# errors/warnings. see #2302
append_cflags(["-std=c99", "-Wno-declaration-after-statement"])

# gumbo html5 serialization is slower with O3, let's make sure we use O2
append_cflags("-O2")

# always include debugging information
append_cflags("-g")

# we use at least one inline function in the C extension
append_cflags("-Winline")

# good to have no matter what Ruby was compiled with
append_cflags("-Wmissing-noreturn")

# check integer loss of precision
if darwin?
  append_cflags("-Wshorten-64-to-32")
else
  append_cflags("-Wconversion -Wno-sign-conversion")
end

# handle clang variations, see #1101
if darwin?
  append_cflags("-Wno-error=unused-command-line-argument-hard-error-in-future")
  append_cflags("-Wno-unknown-warning-option")
end

# these tend to be noisy, but on occasion useful during development
# append_cflags(["-Wcast-qual", "-Wwrite-strings"])

# Add SDK-specific include path for macOS and brew versions before v2.2.12 (2020-04-08) [#1851, #1801]
macos_mojave_sdk_include_path = "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/libxml2"
if config_system_libraries? && darwin? && Dir.exist?(macos_mojave_sdk_include_path)
  append_cppflags("-I#{macos_mojave_sdk_include_path}")
end

# Work around a character escaping bug in MSYS by passing an arbitrary double-quoted parameter to gcc.
# See https://sourceforge.net/p/mingw/bugs/2142
append_cppflags(' "-Idummypath"') if windows?

if config_system_libraries?
  message "Building nokogiri using system libraries.\n"
  ensure_package_configuration(
    opt: "zlib",
    pc: "zlib",
    lib: "z",
    headers: "zlib.h",
    func: "gzdopen",
  )
  ensure_package_configuration(
    opt: "xml2",
    pc: "libxml-2.0",
    lib: "xml2",
    headers: "libxml/parser.h",
    func: "xmlParseDoc",
  )
  ensure_package_configuration(
    opt: "xslt",
    pc: "libxslt",
    lib: "xslt",
    headers: "libxslt/xslt.h",
    func: "xsltParseStylesheetDoc",
  )
  ensure_package_configuration(
    opt: "exslt",
    pc: "libexslt",
    lib: "exslt",
    headers: "libexslt/exslt.h",
    func: "exsltFuncRegister",
  )

  have_libxml_headers?(REQUIRED_LIBXML_VERSION) ||
    abort("ERROR: libxml2 version #{REQUIRED_LIBXML_VERSION} or later is required!")
  have_libxml_headers?(RECOMMENDED_LIBXML_VERSION) ||
    warn("WARNING: libxml2 version #{RECOMMENDED_LIBXML_VERSION} or later is highly recommended, but proceeding anyway.")

else
  message "Building nokogiri using packaged libraries.\n"

  static_p = config_static?
  message "Static linking is #{static_p ? "enabled" : "disabled"}.\n"

  cross_build_p = config_cross_build?
  message "Cross build is #{cross_build_p ? "enabled" : "disabled"}.\n"

  if needs_darwin_linker_hack
    append_ldflags("-Wl,-flat_namespace")
  end

  require "yaml"
  dependencies = YAML.load_file(File.join(PACKAGE_ROOT_DIR, "dependencies.yml"))

  dir_config("zlib")

  if cross_build_p || windows?
    zlib_recipe = process_recipe("zlib", dependencies["zlib"]["version"], static_p, cross_build_p) do |recipe|
      recipe.files = [{
        url: zlib_source(recipe.version),
        sha256: dependencies["zlib"]["sha256"],
      }]
      if windows?
        class << recipe
          attr_accessor :cross_build_p

          def configure
            Dir.chdir(work_path) do
              mk = File.read("win32/Makefile.gcc")
              File.open("win32/Makefile.gcc", "wb") do |f|
                f.puts "BINARY_PATH = #{path}/bin"
                f.puts "LIBRARY_PATH = #{path}/lib"
                f.puts "INCLUDE_PATH = #{path}/include"
                mk.sub!(/^PREFIX\s*=\s*$/, "PREFIX = #{host}-") if cross_build_p
                f.puts mk
              end
            end
          end

          def configured?
            Dir.chdir(work_path) do
              !!(File.read("win32/Makefile.gcc") =~ /^BINARY_PATH/)
            end
          end

          def compile
            execute("compile", "make -f win32/Makefile.gcc")
          end

          def install
            execute("install", "make -f win32/Makefile.gcc install")
          end
        end
        recipe.cross_build_p = cross_build_p
      else
        class << recipe
          def configure
            env = {}
            env["CFLAGS"] = concat_flags(ENV["CFLAGS"], "-fPIC", "-g")
            env["CHOST"] = host
            execute("configure", ["./configure", "--static", configure_prefix], { env: env })
            if darwin?
              # needed as of zlib 1.2.13
              Dir.chdir(work_path) do
                makefile = File.read("Makefile").gsub(/^AR=.*$/, "AR=#{host}-libtool")
                File.open("Makefile", "w") { |m| m.write(makefile) }
              end
            end
          end
        end
      end
    end

    unless nix?
      libiconv_recipe = process_recipe(
        "libiconv",
        dependencies["libiconv"]["version"],
        static_p,
        cross_build_p,
      ) do |recipe|
        recipe.files = [{
          url: "https://ftp.gnu.org/pub/gnu/libiconv/#{recipe.name}-#{recipe.version}.tar.gz",
          sha256: dependencies["libiconv"]["sha256"],
        }]

        # The libiconv configure script doesn't accept "arm64" host string but "aarch64"
        recipe.host = recipe.host.gsub("arm64-apple-darwin", "aarch64-apple-darwin")

        cflags = concat_flags(ENV["CFLAGS"], "-O2", "-U_FORTIFY_SOURCE", "-g")

        recipe.configure_options += [
          "--disable-dependency-tracking",
          "CPPFLAGS=-Wall",
          "CFLAGS=#{cflags}",
          "CXXFLAGS=#{cflags}",
          "LDFLAGS=",
        ]
      end
    end
  elsif darwin? && !have_header("iconv.h")
    abort(<<~EOM.chomp)
      -----
      The file "iconv.h" is missing in your build environment,
      which means you haven't installed Xcode Command Line Tools properly.

      To install Command Line Tools, try running `xcode-select --install` on
      terminal and follow the instructions.  If it fails, open Xcode.app,
      select from the menu "Xcode" - "Open Developer Tool" - "More Developer
      Tools" to open the developer site, download the installer for your OS
      version and run it.
      -----
    EOM
  end

  if zlib_recipe
    append_cppflags("-I#{zlib_recipe.path}/include")
    $LIBPATH = ["#{zlib_recipe.path}/lib"] | $LIBPATH
    ensure_package_configuration(
      opt: "zlib",
      pc: "zlib",
      lib: "z",
      headers: "zlib.h",
      func: "gzdopen",
    )
  end

  if libiconv_recipe
    append_cppflags("-I#{libiconv_recipe.path}/include")
    $LIBPATH = ["#{libiconv_recipe.path}/lib"] | $LIBPATH
    ensure_package_configuration(
      opt: "iconv",
      pc: "iconv",
      lib: "iconv",
      headers: "iconv.h",
      func: "iconv_open",
    )
  end

  libxml2_recipe = process_recipe("libxml2", dependencies["libxml2"]["version"], static_p, cross_build_p) do |recipe|
    source_dir = arg_config("--with-xml2-source-dir")
    if source_dir
      recipe.source_directory = source_dir
    else
      minor_version = Gem::Version.new(recipe.version).segments.take(2).join(".")
      recipe.files = [{
        url: "#{gnome_source}/sources/libxml2/#{minor_version}/#{recipe.name}-#{recipe.version}.tar.xz",
        sha256: dependencies["libxml2"]["sha256"],
      }]
      recipe.patch_files = Dir[File.join(PACKAGE_ROOT_DIR, "patches", "libxml2", "*.patch")].sort
    end

    cppflags = concat_flags(ENV["CPPFLAGS"])
    cflags = concat_flags(ENV["CFLAGS"], "-O2", "-U_FORTIFY_SOURCE", "-g")

    if cross_build_p
      cppflags = concat_flags(cppflags, "-DNOKOGIRI_PRECOMPILED_LIBRARIES")
    end

    if zlib_recipe
      recipe.configure_options << "--with-zlib=#{zlib_recipe.path}"
    end

    if libiconv_recipe
      recipe.configure_options << "--with-iconv=#{libiconv_recipe.path}"
    else
      recipe.configure_options += iconv_configure_flags
    end

    if darwin? && !cross_build_p
      recipe.configure_options += ["RANLIB=/usr/bin/ranlib", "AR=/usr/bin/ar"]
    end

    if windows?
      cflags = concat_flags(cflags, "-ULIBXML_STATIC", "-DIN_LIBXML")
    end

    recipe.configure_options << if source_dir
      "--config-cache"
    else
      "--disable-dependency-tracking"
    end

    recipe.configure_options += [
      "--without-python",
      "--without-readline",
      "--with-c14n",
      "--with-debug",
      "--with-threads",
      "CPPFLAGS=#{cppflags}",
      "CFLAGS=#{cflags}",
    ]
  end

  libxslt_recipe = process_recipe("libxslt", dependencies["libxslt"]["version"], static_p, cross_build_p) do |recipe|
    source_dir = arg_config("--with-xslt-source-dir")
    if source_dir
      recipe.source_directory = source_dir
    else
      minor_version = Gem::Version.new(recipe.version).segments.take(2).join(".")
      recipe.files = [{
        url: "#{gnome_source}/sources/libxslt/#{minor_version}/#{recipe.name}-#{recipe.version}.tar.xz",
        sha256: dependencies["libxslt"]["sha256"],
      }]
      recipe.patch_files = Dir[File.join(PACKAGE_ROOT_DIR, "patches", "libxslt", "*.patch")].sort
    end

    cflags = concat_flags(ENV["CFLAGS"], "-O2", "-U_FORTIFY_SOURCE", "-g")

    if darwin? && !cross_build_p
      recipe.configure_options += ["RANLIB=/usr/bin/ranlib", "AR=/usr/bin/ar"]
    end

    if windows?
      cflags = concat_flags(cflags, "-ULIBXSLT_STATIC", "-DIN_LIBXSLT")
      cflags = concat_flags(cflags, "-ULIBEXSLT_STATIC", "-DIN_LIBEXSLT")
    end

    recipe.configure_options << if source_dir
      "--config-cache"
    else
      "--disable-dependency-tracking"
    end

    recipe.configure_options += [
      "--without-python",
      "--without-crypto",
      "--with-debug",
      "--with-libxml-prefix=#{sh_export_path(libxml2_recipe.path)}",
      "CFLAGS=#{cflags}",
    ]
  end

  append_cppflags("-DNOKOGIRI_PACKAGED_LIBRARIES")
  append_cppflags("-DNOKOGIRI_PRECOMPILED_LIBRARIES") if cross_build_p

  $libs = $libs.shellsplit.tap do |libs|
    [libxml2_recipe, libxslt_recipe].each do |recipe|
      libname = recipe.name[/\Alib(.+)\z/, 1]
      config_basename = "#{libname}-config"
      File.join(recipe.path, "bin", config_basename).tap do |config|
        # call config scripts explicit with 'sh' for compat with Windows
        cflags = %x(sh #{config} --cflags).strip
        message("#{config_basename} cflags: #{cflags}\n")
        $CPPFLAGS = concat_flags(cflags, $CPPFLAGS) # prepend

        %x(sh #{config} --libs).strip.shellsplit.each do |arg|
          case arg
          when /\A-L(.+)\z/
            # Prioritize ports' directories
            $LIBPATH = if Regexp.last_match(1).start_with?(PACKAGE_ROOT_DIR + "/")
              [Regexp.last_match(1)] | $LIBPATH
            else
              $LIBPATH | [Regexp.last_match(1)]
            end
          when /\A-l./
            libs.unshift(arg)
          else
            $LDFLAGS << " " << arg.shellescape
          end
        end
      end

      patches_string = recipe.patch_files.map { |path| File.basename(path) }.join(" ")
      append_cppflags(%[-DNOKOGIRI_#{recipe.name.upcase}_PATCHES="\\"#{patches_string}\\""])

      case libname
      when "xml2"
        # xslt-config --libs or pkg-config libxslt --libs does not include
        # -llzma, so we need to add it manually when linking statically.
        if static_p && preserving_globals { local_have_library("lzma") }
          # Add it at the end; GH #988
          libs << "-llzma"
        end
      when "xslt"
        # xslt-config does not have a flag to emit options including
        # -lexslt, so add it manually.
        libs.unshift("-lexslt")
      end
    end
  end.shelljoin

  if static_p
    static_archive_ld_flag = needs_darwin_linker_hack ? ["-load_hidden"] : []
    $libs = $libs.shellsplit.map do |arg|
      case arg
      when "-lxml2"
        static_archive_ld_flag + [File.join(libxml2_recipe.path, "lib", libflag_to_filename(arg))]
      when "-lxslt", "-lexslt"
        static_archive_ld_flag + [File.join(libxslt_recipe.path, "lib", libflag_to_filename(arg))]
      else
        arg
      end
    end.flatten.shelljoin
  end

  ensure_func("xmlParseDoc", "libxml/parser.h")
  ensure_func("xsltParseStylesheetDoc", "libxslt/xslt.h")
  ensure_func("exsltFuncRegister", "libexslt/exslt.h")
end

libgumbo_recipe = process_recipe("libgumbo", "1.0.0-nokogiri", static_p, cross_build_p, false) do |recipe|
  recipe.configure_options = []

  class << recipe
    def downloaded?
      true
    end

    def extract
      target = File.join(tmp_path, "gumbo-parser")
      output("Copying gumbo-parser files into #{target}...")
      FileUtils.mkdir_p(target)
      FileUtils.cp(Dir.glob(File.join(PACKAGE_ROOT_DIR, "gumbo-parser/src/*")), target)
    end

    def configured?
      true
    end

    def install
      lib_dir = File.join(port_path, "lib")
      inc_dir = File.join(port_path, "include")
      FileUtils.mkdir_p([lib_dir, inc_dir])
      FileUtils.cp(File.join(work_path, "libgumbo.a"), lib_dir)
      FileUtils.cp(Dir.glob(File.join(work_path, "*.h")), inc_dir)
    end

    def compile
      cflags = concat_flags(ENV["CFLAGS"], "-fPIC", "-O2", "-g")

      env = { "CC" => gcc_cmd, "CFLAGS" => cflags }
      if config_cross_build?
        if host.include?("darwin")
          env["AR"] = "#{host}-libtool"
          env["ARFLAGS"] = "-o"
        else
          env["AR"] = "#{host}-ar"
        end
        env["RANLIB"] = "#{host}-ranlib"
      end

      execute("compile", make_cmd, { env: env })
    end
  end
end
append_cppflags("-I#{File.join(libgumbo_recipe.path, "include")}")
$libs = $libs + " " + File.join(libgumbo_recipe.path, "lib", "libgumbo.a")
$LIBPATH = $LIBPATH | [File.join(libgumbo_recipe.path, "lib")]
ensure_func("gumbo_parse_with_options", "nokogiri_gumbo.h")

have_func("xmlHasFeature") || abort("xmlHasFeature() is missing.") # introduced in libxml 2.6.21
have_func("xmlFirstElementChild") # introduced in libxml 2.7.3
have_func("xmlRelaxNGSetParserStructuredErrors") # introduced in libxml 2.6.24
have_func("xmlRelaxNGSetValidStructuredErrors") # introduced in libxml 2.6.21
have_func("xmlSchemaSetValidStructuredErrors") # introduced in libxml 2.6.23
have_func("xmlSchemaSetParserStructuredErrors") # introduced in libxml 2.6.23
have_func("rb_gc_location") # introduced in Ruby 2.7
have_func("rb_category_warning") # introduced in Ruby 3.0

other_library_versions_string = OTHER_LIBRARY_VERSIONS.map { |k, v| [k, v].join(":") }.join(",")
append_cppflags(%[-DNOKOGIRI_OTHER_LIBRARY_VERSIONS="\\"#{other_library_versions_string}\\""])

unless config_system_libraries?
  if cross_build_p
    # When precompiling native gems, copy packaged libraries' headers to ext/nokogiri/include
    # These are packaged up by the cross-compiling callback in the ExtensionTask
    copy_packaged_libraries_headers(
      to_path: File.join(PACKAGE_ROOT_DIR, "ext/nokogiri/include"),
      from_recipes: [libxml2_recipe, libxslt_recipe],
    )
  else
    # When compiling during installation, install packaged libraries' header files into ext/nokogiri/include
    copy_packaged_libraries_headers(
      to_path: "include",
      from_recipes: [libxml2_recipe, libxslt_recipe],
    )
    $INSTALLFILES << ["include/**/*.h", "$(rubylibdir)"]
  end
end

create_makefile("nokogiri/nokogiri")

if config_clean?
  # Do not clean if run in a development work tree.
  File.open("Makefile", "at") do |mk|
    mk.print(<<~EOF)

      all: clean-ports
      clean-ports: $(DLLIB)
      \t-$(Q)$(RUBY) $(srcdir)/extconf.rb --clean --#{static_p ? "enable" : "disable"}-static
    EOF
  end
end

# rubocop:enable Style/GlobalVars
