Dir.chdir __dir__
version_re  = /\d+(\.\d+)*/
version     = `command grep 'VERSION =' lib/zscan.rb`[version_re]
gem_files   = Dir.glob('{rakefile,zscan.gemspec,readme.md,**/*.{rb,c}}')
gem_package = "zscan-#{version}.gem"

bspec_types = %w[INT8 INT16 INT32 INT64 UINT8 UINT16 UINT32 UINT64 SINGLE DOUBLE]
bspec_insns = bspec_types.flat_map{|ty|
  if ty =~ /INT8/
    ty
  else
    [ty, "#{ty}_SWAP"]
  end
}
def bspec_incr ins
  case ins
  when /INT(\d+)/; $1.to_i / 8
  when /SINGLE/; 4
  when /DOUBLE/; 8
  else; raise 'bad'
  end
end
def bspec_c_type ins
  case ins
  when /(U?INT\d+)/; "#{$1.downcase}_t"
  when /SINGLE/; 'float'
  when /DOUBLE/; 'double'
  else; raise 'bad'
  end
end
def bspec_extract ins
  type = bspec_c_type ins
  len = bspec_incr(ins) * 8
  r = "((uint#{len}_t*)s)[0]"
  if ins.end_with?('SWAP')
    r = "swap#{len}(#{r})"
  end
  "uint#{len}_t r = #{r}"
end
def bspec_convert ins
  case ins
  when /(U)?INT64|UINT32/
    if ins.start_with?('U')
      "UINT64toNUM(r)"
    else
      "INT64toNUM(CAST(r, int64_t))"
    end
  when /INT32/
    "INT2NUM(CAST(r, int32_t))"
  when /INT(16|8)/
    "INT2FIX(CAST(r, #{bspec_c_type ins}))"
  when /SINGLE/
    "DBL2NUM((double)CAST(r, float))"
  when /DOUBLE/
    "DBL2NUM(CAST(r, double))"
  else
    raise 'bad'
  end
end

desc "build and test"
task :default => [:test, gem_package]

desc "build and run test"
task :test do
  sh "make -C ext"
  sh "rspec"
end

desc "pack gem"
file gem_package => gem_files do
  sh "rm zscan-*.gem"

  new_version = false
  lines = File.readlines('zscan.gemspec')
  lines.each do |line|
    if line =~ /s\.version =/ and (line.sub! version_re, version)
      new_version = true
      break
    end
  end
  if new_version
    File.open('zscan.gemspec', 'w'){|f| f << lines.join }
  end
  sh "gem build zscan.gemspec"
end

desc "generate files"
task :gen => %w[ext/bspec_exec.inc ext/bspec_init.inc lib/zscan/instructions.rb]

file 'ext/bspec_exec.inc' => __FILE__ do
  puts "generating ext/bspec_exec.inc"
  opcode_list = bspec_insns.map do |ins|
    "&&BS_#{ins}"
  end.join ', '

  opcode_segs = bspec_insns.map do |ins|
%Q{BS_#{ins}:
  {
    #{bspec_extract ins};
    rb_ary_push(a, #{bspec_convert ins});
    s += #{bspec_incr ins};
    goto **(ip++);
  }
}
  end.join "\n"

  File.open 'ext/bspec_exec.inc', 'w' do |f|
    f.puts %Q|// GENERATED WITH: rake gen
#line 2 "ext/bspec_exec.inc"
__attribute__((__noinline__))
static VALUE bspec_exec(void** ip, char* s, VALUE a) {
  static void* opcodes[] = { &&BS_RET, #{opcode_list} };
  if (ip == NULL) {
    return (VALUE)opcodes;
  }
  goto **(ip++);
BS_RET:
  return a;
#{opcode_segs}
}|
  end
end

file 'ext/bspec_init.inc' => __FILE__ do
  puts 'generating ext/bspec_init.inc'
  opcode_incrs = bspec_insns.map{|ins| bspec_incr ins}.join ', '
  File.open 'ext/bspec_init.inc', 'w' do |f|
    f.puts "// GENERATED WITH: rake gen"
    f.puts %Q|static const long bspec_s_sizes[] = {0, #{opcode_incrs}};|
    f.puts %Q|static const long bspec_opcodes_size = #{bspec_insns.size + 1};|
  end
end

file 'lib/zscan/instructions.rb' => __FILE__ do
  puts 'generating lib/zscan/instructions.rb'
  File.open 'lib/zscan/instructions.rb', 'w' do |f|
    f.puts "# GENERATED WITH: rake gen"
    f.puts "class ZScan::BinarySpec"

    bspec_insns.each_with_index do |ins, i|
      f.puts <<-RUBY
  def #{ins.downcase} n=1
    raise ArgumentError, "repeat count should be >= 1, but got \#{n}" if n < 1
    n.times do
      append #{i + 1}
    end
  end
      RUBY
    end

    alias_ins = (bspec_types - ['INT8', 'UINT8']).map &:downcase
    f.puts "  if ZScan::BinarySpec.big_endian?"
    alias_ins.each do |ins|
    f.puts "    alias #{ins}_be #{ins}"
    f.puts "    alias #{ins}_le #{ins}_swap"
    end
    f.puts "  else"
    alias_ins.each do |ins|
    f.puts "    alias #{ins}_le #{ins}"
    f.puts "    alias #{ins}_be #{ins}_swap"
    end
    f.puts "  end"
    swap_ins = alias_ins.map{|ins| "#{ins}_swap"}
    f.puts "  undef #{swap_ins.join ', '}"
    f.puts "end"
  end
end