# frozen_string_literal: true

require "shellwords"

class ThreadIdRakeCargoHelper
  attr_reader :gemname

  def initialize(gemname=File.basename(__dir__))
    @gemname = gemname
  end

  def self.command?(name)
    exts = ENV["PATHEXT"] ? ENV["PATHEXT"].split(";") : [""]
    ENV["PATH"].split(File::PATH_SEPARATOR).any? do |path|
      exts.any? do |ext|
        exe = File.join(path, "#{name}#{ext}")
        File.executable?(exe) && !File.directory?(exe)
      end
    end
  end

  def self.rust_toolchain
    # return env variable if set
    target = ENV["RUST_TARGET"]
    return target if target

    str = `rustc --version --verbose`
    info = str.lines.map {|l| l.chomp.split(/:\s+/, 2)}.drop(1).to_h
    info["host"]
  end

  def self.cargo_target_dir
    return @cargo_target_dir if defined? @cargo_target_dir

    str = `cargo metadata --format-version 1 --offline --no-deps --quiet`
    begin
      require "json"
      dir = JSON.parse(str)["target_directory"]
    rescue LoadError # json is usually part of the stdlib, but just in case
      /"target_directory"\s*:\s*"(?<dir>[^"]*)"/ =~ str
    end
    @cargo_target_dir = dir || "target"
  end

  def self.flags
    cc_flags = Shellwords.split(RbConfig.expand(RbConfig::MAKEFILE_CONFIG["CC"].dup))

    ["-C", "linker=#{cc_flags.shift}",
      *cc_flags.flat_map {|a| ["-C", "link-arg=#{a}"] },
      "-L", "native=#{RbConfig::CONFIG["libdir"]}",
      *dld_flags,
      *platform_flags]
  end

  def self.dld_flags
    Shellwords.split(RbConfig::CONFIG["DLDFLAGS"]).flat_map do |arg|
      arg = arg.gsub(/\$\((\w+)\)/) do
        $1 == "DEFFILE" ? nil : RbConfig::CONFIG[name]
      end.strip
      next [] if arg.empty?

      transform_flag(arg)
    end
  end

  def self.platform_flags
    return unless RbConfig::CONFIG["target_os"] =~ /mingw/i

    [*Shellwords.split(RbConfig::CONFIG["LIBRUBYARG"]).flat_map {|arg| transform_flag(arg)},
      "-C", "link-arg=-Wl,--dynamicbase",
      "-C", "link-arg=-Wl,--disable-auto-image-base",
      "-C", "link-arg=-static-libgcc"]
  end

  def self.transform_flag(arg)
    k, v = arg.split(/(?<=..)/, 2)
    case k
    when "-L"
      [k, "native=#{v}"]
    when "-l"
      [k, v]
    when "-F"
      ["-l", "framework=#{v}"]
    else
      ["-C", "link_arg=#{k}#{v}"]
    end
  end

  def install_dir
    File.expand_path(File.join("..", "..", "lib", gemname), __dir__)
  end

  def rust_name
    prefix = "lib" unless Gem.win_platform?
    suffix = if RbConfig::CONFIG["target_os"] =~ /darwin/i
      ".dylib"
    elsif Gem.win_platform?
      ".dll"
    else
      ".so"
    end
    "#{prefix}#{gemname}#{suffix}"
  end

  def ruby_name
    "#{gemname}.#{RbConfig::CONFIG["DLEXT"]}"
  end

end

task default: [:thread_id_install, :thread_id_clean]
task thread_id: [:thread_id_install, :thread_id_clean]

desc "set dev mode for subsequent task, run like `rake dev install`"
task :thread_id_dev do
  @dev = true
end

desc "build gem native extension and copy to lib"
task thread_id_install: [:thread_id_cd, :thread_id_build] do
  helper = ThreadIdRakeCargoHelper.new
  profile_dir = @dev ? "debug" : "release"
  arch_dir = RbspyRakeCargoHelper.rust_toolchain
  source = File.join(ThreadIdRakeCargoHelper.cargo_target_dir, arch_dir, profile_dir, helper.rust_name)
  dest = File.join(helper.install_dir, helper.ruby_name)
  mkdir_p(helper.install_dir)
  rm(dest) if File.exist?(dest)
  cp(source, dest)
end

desc "build gem native extension"
task thread_id_build: [:thread_id_cargo, :thread_id_cd] do
  sh "cargo", "rustc", *(["--locked", "--release"] unless @dev), "--target=#{RbspyRakeCargoHelper.rust_toolchain}", "--", *RbspyRakeCargoHelper.flags
end

desc "clean up release build artifacts"
task thread_id_clean: [:thread_id_cargo, :thread_id_cd] do
  sh "cargo clean --release"
end

desc "clean up build artifacts"
task thread_id_clobber: [:thread_id_cargo, :thread_id_cd] do
  sh "cargo clean"
end

desc "check for cargo"
task :thread_id_cargo do
  raise <<-MSG unless ThreadIdRakeCargoHelper.command?("cargo")
    This gem requires a Rust compiler and the `cargo' build tool to build the
    gem's native extension. See https://www.rust-lang.org/tools/install for
    how to install Rust. `cargo' is usually part of the Rust installation.
  MSG

  raise <<-MSG if Gem.win_platform? && ThreadIdRakeCargoHelper.rust_toolchain !~ /gnu/
    Found Rust toolchain `#{ThreadIdRakeCargoHelper.rust_toolchain}' but the gem native
    extension requires the gnu toolchain on Windows.
  MSG
end

# ensure task is running in the right dir
task :thread_id_cd do
  cd(__dir__) unless __dir__ == pwd
end