// Compiler for JVM

import $file.lexer

import lexer._

import $file.parser

import parser._

val beginning = """

.class public XXX.XXX

.super java/lang/Object

.method public static write(I)V 

    .limit locals 1 

    .limit stack 2 

    getstatic java/lang/System/out Ljava/io/PrintStream; 

    iload 0

    invokevirtual java/io/PrintStream/print(I)V 

    return 

.end method

.method public static writes(Ljava/lang/String;)V

    .limit stack 2

    .limit locals 1

    getstatic java/lang/System/out Ljava/io/PrintStream;

    aload 0

    invokevirtual java/io/PrintStream/print(Ljava/lang/String;)V

    return

.end method

.method public static read()I 

    .limit locals 10 

    .limit stack 10

    ldc 0 

    istore 1  ; this will hold our final integer 

Label1: 

    getstatic java/lang/System/in Ljava/io/InputStream; 

    invokevirtual java/io/InputStream/read()I 

    istore 2 

    iload 2 

    ldc 10   ; the newline delimiter 

    isub 

    ifeq Label2 

    iload 2 

    ldc 32   ; the space delimiter 

    isub 

    ifeq Label2

    iload 2 

    ldc 48   ; we have our digit in ASCII, have to subtract it from 48 

    isub 

    ldc 10 

    iload 1 

    imul 

    iadd 

    istore 1 

    goto Label1 

Label2: 

    ;when we come here we have our integer computed in local variable 1 

    iload 1 

    ireturn 

.end method

.method public static main([Ljava/lang/String;)V

   .limit locals 200

   .limit stack 200

; COMPILED CODE STARTS

"""

val ending = """

; COMPILED CODE ENDS

   return

.end method

"""

// Compiler

var counter = -1

def Fresh(x: String) = {

  counter += 1

  x ++ "_" ++ counter.toString()

}

implicit def string_interpolations(sc: StringContext) = new {

    def i(args: Any*): String = "   " ++ sc.s(args:_*) ++ "\n"

    def l(args: Any*): String = sc.s(args:_*) ++ ":\n"

}

type Env = Map[String, Int]

def compile_op(op: String) = op match {

  case "+" => i"iadd"

  case "-" => i"isub"

  case "*" => i"imul"

  case "/" => i"idiv"

  case "%" => i"irem"

}

def compile_aexp(a: AExp, env : Env) : String = a match {

  case Num(i) => i"ldc $i"

  case Var(s) => i"iload ${env(s)} \t\t; $s"

  case Aop(op, a1, a2) => 

    compile_aexp(a1, env) ++ compile_aexp(a2, env) ++ compile_op(op)

}

def compile_bexp(b: BExp, env : Env, jmp: String) : String = b match {

  case True => ""

  case False => i"goto $jmp"

  case And(b1, b2) => compile_bexp(b1, env, jmp) ++ compile_bexp(b2, env, jmp)

  case Or(b1, b2) => {

    val b1_false = Fresh("Or_second");

    val or_end = Fresh("Or_end");

    compile_bexp(b1, env, b1_false) ++

    i"goto $or_end" ++

    l"$b1_false" ++

    compile_bexp(b2, env, jmp) ++

    l"$or_end"

  }

  case Bop("==", a1, a2) => 

    compile_aexp(a1, env) ++ compile_aexp(a2, env) ++ i"if_icmpne $jmp"

  case Bop("!=", a1, a2) => 

    compile_aexp(a1, env) ++ compile_aexp(a2, env) ++ i"if_icmpeq $jmp"

  case Bop("<", a1, a2) => 

    compile_aexp(a1, env) ++ compile_aexp(a2, env) ++ i"if_icmpge $jmp"

  case Bop(">", a1, a2) => 

    compile_aexp(a1, env) ++ compile_aexp(a2, env) ++ i"if_icmple $jmp"

}

def compile_stmt(s: Stmt, env: Env) : (String, Env) = s match {

  case Skip => ("", env)

  case Assign(x, a) => {

    val index = env.getOrElse(x, env.keys.size)

    (compile_aexp(a, env) ++ i"istore $index \t\t; $x", env + (x -> index))

  } 

  case If(b, bl1, bl2) => {

    val if_else = Fresh("If_else")

    val if_end = Fresh("If_end")

    val (instrs1, env1) = compile_block(bl1, env)

    val (instrs2, env2) = compile_block(bl2, env1)

    (compile_bexp(b, env, if_else) ++

     instrs1 ++

     i"goto $if_end" ++

     l"$if_else" ++

     instrs2 ++

     l"$if_end", env2)

  }

  case While(b, bl) => {

    val loop_begin = Fresh("Loop_begin")

    val loop_end = Fresh("Loop_end")

    val (instrs1, env1) = compile_block(bl, env)

    (l"$loop_begin" ++

     compile_bexp(b, env, loop_end) ++

     instrs1 ++

     i"goto $loop_begin" ++

     l"$loop_end", env1)

  }

  case For(id, lower, upper, code) => {

      val (assignment_code, env1) = compile_stmt(Assign(id, lower), env)  // id := lower;

      val while_equivalent = While(

          Or(Bop("<", Var(id), upper), Bop("==", Var(id), upper)),    // while id <= upper do {

          code ++                                                     //    code  

          List(

            Assign(id, Aop("+", Var(id), Num(1)))                     //    id := id + 1

          ))                                                          // };

      val (while_code, env2) = compile_stmt(while_equivalent, env1)

      (assignment_code ++ while_code, env2)

  }

  case WriteId(x) => (i"iload ${env(x)} \t\t; $x" ++ 

     i"invokestatic XXX/XXX/write(I)V", env)

  case WriteString(x) => (s"   ldc ${x}\n" ++

     i"invokestatic XXX/XXX/writes(Ljava/lang/String;)V", env)

  case Read(x) => {

    val index = env.getOrElse(x, env.keys.size) 

    (i"invokestatic XXX/XXX/read()I" ++ 

     i"istore $index \t\t; $x", env + (x -> index))

  }

}

def compile_block(bl: Block, env: Env) : (String, Env) = bl match {

  case Nil => ("", env)

  case s::bl => {

    val (instrs1, env1) = compile_stmt(s, env)

    val (instrs2, env2) = compile_block(bl, env1)

    (instrs1 ++ instrs2, env2)

  }

}

def compile(bl: Block, class_name: String) : String = {

  val instructions = compile_block(bl, Map.empty)._1

  (beginning ++ instructions ++ ending).replaceAllLiterally("XXX", class_name)

}

// Compiling and running

import scala.util._

import scala.sys.process._

import scala.io

def compile_tofile(bl: Block, class_name: String) = {

  val output = compile(bl, class_name)

  val fw = new java.io.FileWriter(class_name + ".j") 

  fw.write(output) 

  fw.close()

}

def compile_all(bl: Block, class_name: String) : Unit = {

  compile_tofile(bl, class_name)

  println("compiled ")

  val test = ("java -jar jasmin.jar " + class_name + ".j").!!

  println("assembled ")

}

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

  val start = System.nanoTime()

  for (j <- 1 to i) code

  val end = System.nanoTime()

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

}

def compile_run(bl: Block, class_name: String) : Unit = {

  println("Start compilation")

  compile_all(bl, class_name)

  println("running")

  println("Time: " + time_needed(1, ("java " + class_name + "/" + class_name).!))

}

// ---- Q1

// Fibonacci

val fibonacciProgram = """write "Fib";

read n;

minus1 := 0;

minus2 := 1;

while n > 0 do {

  temp := minus2;

  minus2 := minus1 + minus2;

  minus1 := temp;

  n := n - 1

};

write "Result";

write minus2"""

//compile_all(Stmts.parse_all(tokenise(fibonacciProgram)).head, "fib")

val factorialProgram = """write "Factorial";

read n;

fact := 1;

while n > 0 do {

  fact := n * fact;

  n := n - 1

};

write "Result";

write fact

"""

compile_all(Stmts.parse_all(tokenise(factorialProgram)).head, "factorial")

// ---- Q3

/* compile_run(Stmts.parse_all(tokenise("""for i := 1 upto 10 do {

  for i := 1 upto 10 do {

    write i

  }

}""")).head, "nestedloop") */

compile_run(Stmts.parse_all(tokenise(os.read(os.pwd / "collatz2.while"))).head, "collatz2")