(* Copyright (c) 2008, Adam Chlipala
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * - The names of contributors may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *)

structure Cjrize :> CJRIZE = struct

structure L = Mono
structure L' = Cjr

structure Sm :> sig
    type t

    val empty : t
    val find : t * (string * L.typ) list * (string * L'.typ) list -> t * int

    val declares : t -> (int * (string * L'.typ) list) list
end = struct

structure FM = BinaryMapFn(struct
                           type ord_key = L.typ
                           val compare = MonoUtil.Typ.compare
                           end)

type t = int * int FM.map * (int * (string * L'.typ) list) list

val empty : t = (1, FM.insert (FM.empty, (L.TRecord [], ErrorMsg.dummySpan), 0), [])

fun find ((n, m, ds), xts, xts') =
    let
        val t = (L.TRecord xts, ErrorMsg.dummySpan)
    in
        case FM.find (m, t) of
            NONE => ((n+1, FM.insert (m, t, n), (n, xts') :: ds), n)
          | SOME i => ((n, m, ds), i)
    end

fun declares (_, _, ds) = ds

end

fun cifyTyp ((t, loc), sm) =
    case t of
        L.TFun (t1, t2) =>
        let
            val (t1, sm) = cifyTyp (t1, sm)
            val (t2, sm) = cifyTyp (t2, sm)
        in
            ((L'.TFun (t1, t2), loc), sm)
        end
      | L.TRecord xts =>
        let
            val old_xts = xts
            val (xts, sm) = ListUtil.foldlMap (fn ((x, t), sm) =>
                                                  let
                                                      val (t, sm) = cifyTyp (t, sm)
                                                  in
                                                      ((x, t), sm)
                                                  end)
                                              sm xts
            val (sm, si) = Sm.find (sm, old_xts, xts)
        in
            ((L'.TRecord si, loc), sm)
        end
      | L.TDatatype (n, xncs) =>
        let
            val (xncs, sm) = ListUtil.foldlMap (fn ((x, n, to), sm) =>
                                                   case to of
                                                       NONE => ((x, n, NONE), sm)
                                                     | SOME t =>
                                                       let
                                                           val (t, sm) = cifyTyp (t, sm)
                                                       in
                                                           ((x, n, SOME t), sm)
                                                       end)
                             sm xncs
        in
            ((L'.TDatatype (n, xncs), loc), sm)
        end
      | L.TFfi mx => ((L'.TFfi mx, loc), sm)

val dummye = (L'.EPrim (Prim.Int 0), ErrorMsg.dummySpan)

fun cifyPatCon pc =
    case pc of
        L.PConVar n => L'.PConVar n
      | L.PConFfi mx => L'.PConFfi mx

fun cifyPat ((p, loc), sm) =
    case p of
        L.PWild => ((L'.PWild, loc), sm)
      | L.PVar (x, t) =>
        let
            val (t, sm) = cifyTyp (t, sm)
        in
            ((L'.PVar (x, t), loc), sm)
        end
      | L.PPrim p => ((L'.PPrim p, loc), sm)
      | L.PCon (pc, NONE) => ((L'.PCon (cifyPatCon pc, NONE), loc), sm)
      | L.PCon (pc, SOME p) =>
        let
            val (p, sm) = cifyPat (p, sm)
        in
            ((L'.PCon (cifyPatCon pc, SOME p), loc), sm)
        end
      | L.PRecord xps =>
        let
            val (xps, sm) = ListUtil.foldlMap (fn ((x, p, t), sm) =>
                                                  let
                                                      val (p, sm) = cifyPat (p, sm)
                                                      val (t, sm) = cifyTyp (t, sm)
                                                  in
                                                      ((x, p, t), sm)
                                                  end) sm xps
        in
            ((L'.PRecord xps, loc), sm)
        end

fun cifyExp ((e, loc), sm) =
    case e of
        L.EPrim p => ((L'.EPrim p, loc), sm)
      | L.ERel n => ((L'.ERel n, loc), sm)
      | L.ENamed n => ((L'.ENamed n, loc), sm)
      | L.ECon (n, eo) =>
        let
            val (eo, sm) =
                case eo of
                    NONE => (NONE, sm)
                  | SOME e =>
                    let
                        val (e, sm) = cifyExp (e, sm)
                    in
                        (SOME e, sm)
                    end
        in
            ((L'.ECon (n, eo), loc), sm)
        end
      | L.EFfi mx => ((L'.EFfi mx, loc), sm)
      | L.EFfiApp (m, x, es) =>
        let
            val (es, sm) = ListUtil.foldlMap cifyExp sm es
        in
            ((L'.EFfiApp (m, x, es), loc), sm)
        end
      | L.EApp (e1, e2) =>
        let
            val (e1, sm) = cifyExp (e1, sm)
            val (e2, sm) = cifyExp (e2, sm)
        in
            ((L'.EApp (e1, e2), loc), sm)
        end
      | L.EAbs _ => (ErrorMsg.errorAt loc "Anonymous function remains at code generation";
                     (dummye, sm))

      | L.ERecord xes =>
        let
            val old_xts = map (fn (x, _, t) => (x, t)) xes

            val (xets, sm) = ListUtil.foldlMap (fn ((x, e, t), sm) =>
                                                  let
                                                      val (e, sm) = cifyExp (e, sm)
                                                      val (t, sm) = cifyTyp (t, sm)
                                                  in
                                                      ((x, e, t), sm)
                                                  end)
                            sm xes

            val (sm, si) = Sm.find (sm, old_xts, map (fn (x, _, t) => (x, t)) xets)

            val xes = map (fn (x, e, _) => (x, e)) xets
            val xes = ListMergeSort.sort (fn ((x1, _), (x2, _)) => String.compare (x1, x2) = GREATER) xes
        in
            ((L'.ERecord (si, xes), loc), sm)
        end
      | L.EField (e, x) =>
        let
            val (e, sm) = cifyExp (e, sm)
        in
            ((L'.EField (e, x), loc), sm)
        end

      | L.ECase (e, pes, {disc, result}) =>
        let
                val (e, sm) = cifyExp (e, sm)
                val (pes, sm) = ListUtil.foldlMap
                                    (fn ((p, e), sm) =>
                                        let
                                            val (e, sm) = cifyExp (e, sm)
                                            val (p, sm) = cifyPat (p, sm)
                                        in
                                            ((p, e), sm)
                                        end) sm pes
                val (disc, sm) = cifyTyp (disc, sm)
                val (result, sm) = cifyTyp (result, sm)
            in
                ((L'.ECase (e, pes, {disc = disc, result = result}), loc), sm)
            end

      | L.EStrcat (e1, e2) =>
        let
            val (e1, sm) = cifyExp (e1, sm)
            val (e2, sm) = cifyExp (e2, sm)
        in
            ((L'.EFfiApp ("Basis", "strcat", [e1, e2]), loc), sm)
        end

      | L.EWrite e =>
        let
            val (e, sm) = cifyExp (e, sm)
        in
            ((L'.EWrite e, loc), sm)
        end

      | L.ESeq (e1, e2) =>
        let
            val (e1, sm) = cifyExp (e1, sm)
            val (e2, sm) = cifyExp (e2, sm)
        in
            ((L'.ESeq (e1, e2), loc), sm)
        end

      | L.EClosure _ => (ErrorMsg.errorAt loc "Nested closure remains in code generation";
                         (dummye, sm))

fun cifyDecl ((d, loc), sm) =
    case d of
        L.DDatatype (x, n, xncs) =>
        let
            val (xncs, sm) = ListUtil.foldlMap (fn ((x, n, to), sm) =>
                                                   case to of
                                                       NONE => ((x, n, NONE), sm)
                                                     | SOME t =>
                                                       let
                                                           val (t, sm) = cifyTyp (t, sm)
                                                       in
                                                           ((x, n, SOME t), sm)
                                                       end) sm xncs
        in
            (SOME (L'.DDatatype (x, n, xncs), loc), NONE, sm)
        end

      | L.DVal (x, n, t, e, _) =>
        let
            val (t, sm) = cifyTyp (t, sm)

            val (d, sm) = case #1 t of
                              L'.TFun _ =>
                              let
                                  fun unravel (tAll as (t, _), eAll as (e, _)) =
                                      case (t, e) of
                                          (L'.TFun (dom, ran), L.EAbs (ax, _, _, e)) =>
                                          let
                                              val (args, t, e) = unravel (ran, e)
                                          in
                                              ((ax, dom) :: args, t, e)
                                          end
                                        | (L'.TFun _, _) =>
                                          (ErrorMsg.errorAt loc "Function isn't explicit at code generation";
                                           ([], tAll, eAll))
                                        | _ => ([], tAll, eAll)

                                  val (args, ran, e) = unravel (t, e)
                                  val (e, sm) = cifyExp (e, sm)
                              in
                                  (L'.DFun (x, n, args, ran, e), sm)
                              end

                            | _ =>
                              let
                                  val (e, sm) = cifyExp (e, sm)
                              in
                                  (L'.DVal (x, n, t, e), sm)
                              end
        in
            (SOME (d, loc), NONE, sm)
        end
      | L.DValRec vis =>
        let
            val (vis, sm) = ListUtil.foldlMap
                            (fn ((x, n, t, e, _), sm) =>
                                let                                    
                                    val (t, sm) = cifyTyp (t, sm)

                                    fun unravel (tAll as (t, _), eAll as (e, _)) =
                                        case (t, e) of
                                            (L'.TFun (dom, ran), L.EAbs (ax, _, _, e)) =>
                                            let
                                                val (args, t, e) = unravel (ran, e)
                                            in
                                                ((ax, dom) :: args, t, e)
                                            end
                                          | (L'.TFun _, _) =>
                                            (ErrorMsg.errorAt loc "Function isn't explicit at code generation";
                                             ([], tAll, eAll))
                                          | _ => ([], tAll, eAll)
                                                 
                                    val (args, ran, e) = unravel (t, e)
                                    val (e, sm) = cifyExp (e, sm)
                              in
                                  ((x, n, args, ran, e), sm)
                              end)
                            sm vis
        in
            (SOME (L'.DFunRec vis, loc), NONE, sm)
        end        

      | L.DExport (ek, s, n, ts) =>
        let
            val (ts, sm) = ListUtil.foldlMap cifyTyp sm ts
        in
            (NONE, SOME (ek, "/" ^ s, n, ts), sm)
        end

fun cjrize ds =
    let
        val (ds, ps, sm) = foldl (fn (d, (ds, ps, sm)) =>
                                     let
                                         val (dop, pop, sm) = cifyDecl (d, sm)
                                         val ds = case dop of
                                                      NONE => ds
                                                    | SOME d => d :: ds
                                         val ps = case pop of
                                                      NONE => ps
                                                    | SOME p => p :: ps 
                                     in
                                         (ds, ps, sm)
                                     end)
                           ([], [], Sm.empty) ds
    in
        (List.revAppend (map (fn v => (L'.DStruct v, ErrorMsg.dummySpan)) (Sm.declares sm),
                         rev ds),
         ps)
    end

end