// A Transpiler for the Brainf*** language

//=========================================

import io.Source

import scala.util._

// loding a bf-file 

def load_bff(name: String) : String = 

  Try(Source.fromFile(name)("ISO-8859-1").mkString).getOrElse("")

// simple instructions

def instr(c: Char) : String = c match {

  case '>' => "ptr++;"

  case '<' => "ptr--;"

  case '+' => "(*ptr)++;"

  case '-' => "(*ptr)--;"

  case '.' => "putchar(*ptr);"

  case ',' => "*ptr = getchar();\n"

  case '['  => "while(*ptr){"

  case ']'  => "}"

  case _ => ""

}

def instrs(prog: String) : String =

  prog.toList.map(instr(_)).mkString

def compile_str(prog: String) : String = {

  "#include <string.h>\n" ++

  "#include <stdio.h>\n" ++

  "char field[30000];\n" ++

  "char *ptr = &field[15000];" ++

  "int main()\n{\n" ++

  "memset(field, '\\0', 30000);\n" ++

  instrs(prog) ++

  "\n return 0;\n}"

}

def compile(name: String, prog: String) = {

  val fw = new java.io.FileWriter(name + ".c") 

  val is = compile_str(prog)

  //println(is)

  fw.write(is) 

  fw.close()

}

// running the c-compiler over the transpiled

// BF program and running the result

import sys.process._

def compile_run(prog: String) = {

  compile("tmp", prog)

  "gcc -O0 -o tmp tmp.c".!

  "./tmp".!

  ()

}

def time_needed[T](n: Int, code: => T) = {

  val start = System.nanoTime()

  for (i <- 0 until n) code

  val end = System.nanoTime()

  (end - start)/(n * 1.0e9)

}

val b0 = load_bff("mandelbrot.bf")

println(s"${time_needed(1, compile_run(b0))} secs")

// a benchmark program (counts down from 'Z' to 'A')

val b1 = """>++[<+++++++++++++>-]<[[>+>+<<-]>[<+>-]++++++++

            [>++++++++<-]>.[-]<<>++++++++++[>++++++++++[>++

            ++++++++[>++++++++++[>++++++++++[>++++++++++[>+

            +++++++++[-]<-]<-]<-]<-]<-]<-]<-]++++++++++."""

println(s"${time_needed(1, compile_run(b1))} secs")