# This Source Code Form is subject to the terms of the Mozilla Public License,
# v. 2.0. If a copy of the MPL was not distributed with this file, You can
# obtain one at https://mozilla.org/MPL/2.0/. -}
# frozen_string_literal: true

require 'uri'
require 'net/http'
require 'open3'

def gcc_verbose(gcc_binary)
  read, write = IO.pipe
  sh({'LANG' => 'C'}, gcc_binary, '--verbose', err: write)
  write.close
  output = read.read
  read.close
  output
end

def find_build_target(gcc_version)
  gcc_verbose('gcc')
    .lines
    .find { |line| line.start_with? 'Target: ' }
    .split(' ')
    .last
    .strip
end

def download_and_pipe(url, target, command)
  target.mkpath

  Net::HTTP.start(url.host, url.port, use_ssl: url.scheme == 'https') do |http|
    request = Net::HTTP::Get.new url.request_uri

    http.request request do |response|
      case response
      when Net::HTTPRedirection
        download_and_pipe URI.parse(response['location']), target, command
      when Net::HTTPSuccess
        Dir.chdir target.to_path do
          Open3.popen2(*command) do |stdin, stdout, wait_thread|
            Thread.new do
              stdout.each { |line| puts line }
            end

            response.read_body do |chunk|
              stdin.write chunk
            end
            stdin.close

            wait_thread.value
          end
        end
      else
        response.error!
      end
    end
  end
end

namespace :boot do
  # Dependencies.
  GCC_VERSION = "15.1.0"
  HOST_GCC = TMP + 'host/gcc'

  directory HOST_GCC
  directory(TMP + 'tools')

  desc 'Download and configure the bootstrap compiler'
  task configure: [TMP + 'tools', HOST_GCC, HOST_INSTALL] do
    url = URI.parse "https://gcc.gnu.org/pub/gcc/releases/gcc-#{GCC_VERSION}/gcc-#{GCC_VERSION}.tar.xz"
    build_target = find_build_target GCC_VERSION
    source_directory = TMP + "tools/gcc-#{GCC_VERSION}"
    frontend_link = source_directory + 'gcc'

    download_and_pipe url, source_directory.dirname, ['tar', '-Jxv']

    sh 'contrib/download_prerequisites', chdir: source_directory.to_path
    File.symlink Pathname.new('.').relative_path_from(frontend_link), (frontend_link + 'elna')

    configure_options = [
      "--prefix=#{HOST_INSTALL.realpath}",
      '--with-sysroot=/',
      '--enable-languages=c,c++,m2,elna',
      '--disable-bootstrap',
      '--disable-multilib',
      "--target=#{build_target}",
      "--build=#{build_target}",
      "--host=#{build_target}"
    ]
    flags = '-O0 -g -fPIC'
    env = {
      'CFLAGS' => flags,
      'CXXFLAGS' => flags,
    }
    configure = source_directory.relative_path_from(HOST_GCC) + 'configure'
    sh env, configure.to_path, *configure_options, chdir: HOST_GCC
  end

  desc 'Make and install the bootstrap compiler'
  task :make do
    sh 'make', '-j', Etc.nprocessors.to_s, chdir: HOST_GCC
    sh 'make', 'install', chdir: HOST_GCC
  end
end

desc 'Build the bootstrap compiler'
task boot: %w[boot:configure boot:make]