require 'compiler'
require 'stringio'

X86_exit = [0x89, 0xc3,         # mov ebx, eax (exit code)
            0xb8, 1, 0, 0, 0,   # mov eax, 1
            0xcd, 0x80          # int 0x80
           ].pack('c*')

def error(msg) STDERR.puts(msg) end

def parse(input)
  compiler = Compiler.new(input)
  compiler.parse                # tuple of [data, bss, code, binary]

rescue ParseError => e
  error("[error] #{e.message}")
  error("[context] #{e.context}")
  # error("Aborting!")
  error(e.caller)
  exit(1)
end

def interpolate(template, data)
  data.inject(template) do |template, mapping|
    token, replacement = *mapping
    template.sub("{#{token}}", replacement)
  end
end

def main(arg)
  input = if File.readable?(arg)
            File.open(arg)
          else
            # StringIO.new("5*(3-5)*2+2-9/3-8/2-4*(5+5+5)\n")
            StringIO.new("abc=999\nabc-888\n")
          end
  data, bss, code, binary = *parse(input)
  template = File.read("template.asm")
  asm = interpolate(template, :data => data, :bss => bss, :code => code)
  File.open("test.asm", "w") { |f| f.puts(asm) }
  File.open("test.bin", "wb") { |f|
    f.write(binary)
    f.write(X86_exit)
  }
end

main(ARGV[0].to_s)