# 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 'open3'
require 'rake/clean'

CROSS_GCC = '../eugenios/build/rootfs/bin/riscv32-unknown-linux-gnu-gcc'
SYSROOT = '../eugenios/build/sysroot'
QEMU = 'qemu-riscv32'

CLEAN.include 'build/boot', 'build/valid'

directory 'build/boot'
directory 'build/valid'

desc 'Final stage'
task default: ['build/valid/stage3', 'build/valid/stage3.s', 'boot/stage3.elna'] do |t|
  exe, expected, source = t.prerequisites

  cat_arguments = ['cat', source]
  compiler_arguments = [QEMU, '-L', SYSROOT, exe]
  diff_arguments = ['diff', '-Nur', '--text', expected, '-']
  Open3.pipeline(cat_arguments, compiler_arguments, diff_arguments)
end

desc 'Convert stage2 language into the stage3 language'
task :convert do
  File.open('boot/stage3.elna', 'w') do |stage2|
    li_value = nil

    File.readlines('boot/stage2.elna').each do |line|
      if line.start_with?("\tj ")
        stage2 << "\tgoto " + line.chomp.delete_prefix("\tj ") + ";\n"
        li_value = nil
      elsif line.match?(/^\tli a0, [[:digit:]]/)
        li_value = line.delete_prefix("\tli a0, ").chomp
      elsif line == "\tli a0, '\\n'\n"
        li_value = "'\\n'"
      elsif !li_value.nil? && line.start_with?("\t_")
        stage2 << "\t" + line[1..-4] + li_value + ");\n"
        li_value = nil
      else
        stage2 << "\tli a0, #{li_value}\n" unless li_value.nil?
        stage2 << line
        li_value = nil
      end
    end
  end
end

#
# Stage 3.
#

file 'build/valid/stage3' => 'build/valid/stage3.s' do |t|
  sh CROSS_GCC, '-nostdlib', '-o', t.name, *t.prerequisites
end

file 'build/valid/stage3.s' => ['build/boot/stage3', 'boot/stage3.elna'] do |t|
  exe, source = t.prerequisites

  cat_arguments = ['cat', source]
  compiler_arguments = [QEMU, '-L', SYSROOT, exe]
  last_stdout, wait_threads = Open3.pipeline_r(cat_arguments, compiler_arguments)

  IO.copy_stream last_stdout, t.name
end

file 'build/boot/stage3' => 'build/boot/stage3.s' do |t|
  sh CROSS_GCC, '-nostdlib', '-o', t.name, *t.prerequisites
end

file 'build/boot/stage3.s' => ['build/valid/stage2', 'boot/stage3.elna'] do |t|
  exe, source = t.prerequisites

  cat_arguments = ['cat', source]
  compiler_arguments = [QEMU, '-L', SYSROOT, exe]
  last_stdout, wait_threads = Open3.pipeline_r(cat_arguments, compiler_arguments)

  IO.copy_stream last_stdout, t.name
end

#
# Stage 2.
#

file 'build/valid/stage2' => 'build/valid/stage2.s' do |t|
  sh CROSS_GCC, '-nostdlib', '-o', t.name, *t.prerequisites
end

file 'build/valid/stage2.s' => ['build/boot/stage2', 'boot/stage2.elna'] do |t|
  exe, source = t.prerequisites

  cat_arguments = ['cat', source]
  compiler_arguments = [QEMU, '-L', SYSROOT, exe]
  last_stdout, wait_threads = Open3.pipeline_r(cat_arguments, compiler_arguments)

  IO.copy_stream last_stdout, t.name
end

file 'build/boot/stage2' => 'build/boot/stage2.s' do |t|
  sh CROSS_GCC, '-nostdlib', '-o', t.name, *t.prerequisites
end

file 'build/boot/stage2.s' => ['build/valid/stage1', 'boot/stage2.elna'] do |t|
  exe, source = t.prerequisites

  cat_arguments = ['cat', source]
  compiler_arguments = [QEMU, '-L', SYSROOT, exe]
  last_stdout, wait_threads = Open3.pipeline_r(cat_arguments, compiler_arguments)

  IO.copy_stream last_stdout, t.name
end

#
# Stage 1.
#

file 'build/valid/stage1' => ['build/valid', 'build/valid/stage1.s'] do |t|
  source = t.prerequisites.select { |prerequisite| prerequisite.end_with? '.s' }

  sh CROSS_GCC, '-nostdlib', '-o', t.name, *source
end

file 'build/valid/stage1.s' => ['build/boot/stage1', 'boot/stage1.s', 'build/valid'] do |t|
  source, exe, = t.prerequisites.partition { |prerequisite| prerequisite.end_with? '.s' }

  cat_arguments = ['cat', *source]
  compiler_arguments = [QEMU, '-L', SYSROOT, *exe]
  last_stdout, wait_threads = Open3.pipeline_r(cat_arguments, compiler_arguments)

  IO.copy_stream last_stdout, t.name
end

file 'build/boot/stage1' => ['build/boot', 'boot/stage1.s'] do |t|
  source = t.prerequisites.select { |prerequisite| prerequisite.end_with? '.s' }

  sh CROSS_GCC, '-nostdlib', '-o', t.name, *source
end