(* 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 Corify :> CORIFY = struct

structure EM = ErrorMsg
structure L = Expl
structure L' = Core

structure IM = IntBinaryMap
structure SM = BinaryMapFn(struct
                           type ord_key = string
                           val compare = String.compare
                           end)

local
    val count = ref 0
in

fun reset v = count := v

fun alloc () =
    let
        val r = !count
    in
        count := r + 1;
        r
end

end

structure St : sig
    type t

    val empty : t

    val enter : t -> t
    val leave : t -> {outer : t, inner : t}
    val ffi : string -> L'.con SM.map -> t

    val bindCore : t -> string -> int -> t * int
    val lookupCoreById : t -> int -> int option

    datatype core =
             Normal of int
           | Ffi of string * L'.con option
    val lookupCoreByName : t -> string -> core

    val bindStr : t -> string -> int -> t -> t
    val lookupStrById : t -> int -> t
    val lookupStrByName : string * t -> t

    val bindFunctor : t -> string -> int -> int -> L.str -> t
    val lookupFunctorById : t -> int -> int * L.str
    val lookupFunctorByName : string * t -> int * L.str
end = struct

datatype flattening =
         FNormal of {core : int SM.map,
                     strs : flattening SM.map,
                     funs : (int * L.str) SM.map}
       | FFfi of string * L'.con SM.map
                           
type t = {
     core : int IM.map,
     strs : flattening IM.map,
     funs : (int * L.str) IM.map,
     current : flattening,
     nested : flattening list
}

val empty = {
    core = IM.empty,
    strs = IM.empty,
    funs = IM.empty,
    current = FNormal { core = SM.empty, strs = SM.empty, funs = SM.empty },
    nested = []
}

datatype core =
         Normal of int
       | Ffi of string * L'.con option

fun bindCore {core, strs, funs, current, nested} s n =
    let
        val n' = alloc ()

        val current =
            case current of
                FFfi _ => raise Fail "Binding inside FFfi"
              | FNormal {core, strs, funs} =>
                FNormal {core = SM.insert (core, s, n'),
                         strs = strs,
                         funs = funs}
    in
        ({core = IM.insert (core, n, n'),
          strs = strs,
          funs = funs,
          current = current,
          nested = nested},
         n')
    end

fun lookupCoreById ({core, ...} : t) n = IM.find (core, n)

fun lookupCoreByName ({current, ...} : t) x =
    case current of
        FFfi (m, cmap) => Ffi (m, SM.find (cmap, x))
      | FNormal {core, ...} =>
        case SM.find (core, x) of
            NONE => raise Fail "Corify.St.lookupCoreByName"
          | SOME n => Normal n

fun enter {core, strs, funs, current, nested} =
    {core = core,
     strs = strs,
     funs = funs,
     current = FNormal {core = SM.empty,
                        strs = SM.empty,
                        funs = SM.empty},
     nested = current :: nested}

fun dummy f = {core = IM.empty,
               strs = IM.empty,
               funs = IM.empty,
               current = f,
               nested = []}

fun leave {core, strs, funs, current, nested = m1 :: rest} =
        {outer = {core = core,
                  strs = strs,
                  funs = funs,
                  current = m1,
                  nested = rest},
         inner = dummy current}
  | leave _ = raise Fail "Corify.St.leave"

fun ffi m cmap = dummy (FFfi (m, cmap))

fun bindStr ({core, strs, funs, current = FNormal {core = mcore, strs = mstrs, funs = mfuns}, nested} : t)
            x n ({current = f, ...} : t) =
    {core = core,
     strs = IM.insert (strs, n, f),
     funs = funs,
     current = FNormal {core = mcore,
                  strs = SM.insert (mstrs, x, f),
                  funs = mfuns},
     nested = nested}
  | bindStr _ _ _ _ = raise Fail "Corify.St.bindStr"

fun lookupStrById ({strs, ...} : t) n =
    case IM.find (strs, n) of
        NONE => raise Fail "Corify.St.lookupStrById"
      | SOME f => dummy f

fun lookupStrByName (m, {current = FNormal {strs, ...}, ...} : t) =
    (case SM.find (strs, m) of
         NONE => raise Fail "Corify.St.lookupStrByName"
       | SOME f => dummy f)
  | lookupStrByName _ = raise Fail "Corify.St.lookupStrByName"

fun bindFunctor ({core, strs, funs, current = FNormal {core = mcore, strs = mstrs, funs = mfuns}, nested} : t)
                x n na str =
    {core = core,
     strs = strs,
     funs = IM.insert (funs, n, (na, str)),
     current = FNormal {core = mcore,
                        strs = mstrs,
                        funs = SM.insert (mfuns, x, (na, str))},
     nested = nested}
  | bindFunctor _ _ _ _ _ = raise Fail "Corify.St.bindFunctor"

fun lookupFunctorById ({funs, ...} : t) n =
    case IM.find (funs, n) of
        NONE => raise Fail "Corify.St.lookupFunctorById"
      | SOME v => v

fun lookupFunctorByName (m, {current = FNormal {funs, ...}, ...} : t) =
    (case SM.find (funs, m) of
         NONE => raise Fail "Corify.St.lookupFunctorByName"
       | SOME v => v)
  | lookupFunctorByName _ = raise Fail "Corify.St.lookupFunctorByName"

end


fun corifyKind (k, loc) =
    case k of
        L.KType => (L'.KType, loc)
      | L.KArrow (k1, k2) => (L'.KArrow (corifyKind k1, corifyKind k2), loc)
      | L.KName => (L'.KName, loc)
      | L.KRecord k => (L'.KRecord (corifyKind k), loc)

fun corifyCon st (c, loc) =
    case c of
        L.TFun (t1, t2) => (L'.TFun (corifyCon st t1, corifyCon st t2), loc)
      | L.TCFun (x, k, t) => (L'.TCFun (x, corifyKind k, corifyCon st t), loc)
      | L.TRecord c => (L'.TRecord (corifyCon st c), loc)

      | L.CRel n => (L'.CRel n, loc)
      | L.CNamed n =>
        (case St.lookupCoreById st n of
             NONE => (L'.CNamed n, loc)
           | SOME n => (L'.CNamed n, loc))
      | L.CModProj (m, ms, x) =>
        let
            val st = St.lookupStrById st m
            val st = foldl St.lookupStrByName st ms
        in
            case St.lookupCoreByName st x of
                St.Normal n => (L'.CNamed n, loc)
              | St.Ffi (m, _) => (L'.CFfi (m, x), loc)
        end

      | L.CApp (c1, c2) => (L'.CApp (corifyCon st c1, corifyCon st c2), loc)
      | L.CAbs (x, k, c) => (L'.CAbs (x, corifyKind k, corifyCon st c), loc)

      | L.CName s => (L'.CName s, loc)

      | L.CRecord (k, xcs) =>
        (L'.CRecord (corifyKind k, map (fn (c1, c2) => (corifyCon st c1, corifyCon st c2)) xcs), loc)
      | L.CConcat (c1, c2) => (L'.CConcat (corifyCon st c1, corifyCon st c2), loc)

fun corifyExp st (e, loc) =
    case e of
        L.EPrim p => (L'.EPrim p, loc)
      | L.ERel n => (L'.ERel n, loc)
      | L.ENamed n =>
        (case St.lookupCoreById st n of
             NONE => (L'.ENamed n, loc)
           | SOME n => (L'.ENamed n, loc))
      | L.EModProj (m, ms, x) =>
        let
            val st = St.lookupStrById st m
            val st = foldl St.lookupStrByName st ms
        in
            case St.lookupCoreByName st x of
                St.Normal n => (L'.ENamed n, loc)
              | St.Ffi (_, NONE) => raise Fail "corifyExp: Unknown type for FFI expression variable"
              | St.Ffi (m, SOME t) =>
                case t of
                    (L'.TFun (dom as (L'.TRecord (L'.CRecord (_, []), _), _), ran), _) =>
                    (L'.EAbs ("arg", dom, ran, (L'.EFfiApp (m, x, []), loc)), loc)
                  | t as (L'.TFun _, _) =>
                    let
                        fun getArgs (all as (t, _), args) =
                            case t of
                                L'.TFun (dom, ran) => getArgs (ran, dom :: args)
                              | _ => (all, rev args)
                                     
                        val (result, args) = getArgs (t, [])

                        val (actuals, _) = foldr (fn (_, (actuals, n)) =>
                                                     ((L'.ERel n, loc) :: actuals,
                                                      n + 1)) ([], 0) args
                        val app = (L'.EFfiApp (m, x, actuals), loc)
                        val (abs, _, _) = foldr (fn (t, (abs, ran, n)) =>
                                                    ((L'.EAbs ("arg" ^ Int.toString n,
                                                               t,
                                                               ran,
                                                               abs), loc),
                                                     (L'.TFun (t, ran), loc),
                                                     n - 1)) (app, result, length args - 1) args
                    in
                        abs
                    end
                  | _ => (L'.EFfi (m, x), loc)
        end
      | L.EApp (e1, e2) => (L'.EApp (corifyExp st e1, corifyExp st e2), loc)
      | L.EAbs (x, dom, ran, e1) => (L'.EAbs (x, corifyCon st dom, corifyCon st ran, corifyExp st e1), loc)
      | L.ECApp (e1, c) => (L'.ECApp (corifyExp st e1, corifyCon st c), loc)
      | L.ECAbs (x, k, e1) => (L'.ECAbs (x, corifyKind k, corifyExp st e1), loc)

      | L.ERecord xes => (L'.ERecord (map (fn (c, e, t) => (corifyCon st c, corifyExp st e, corifyCon st t)) xes), loc)
      | L.EField (e1, c, {field, rest}) => (L'.EField (corifyExp st e1, corifyCon st c,
                                                       {field = corifyCon st field, rest = corifyCon st rest}), loc)

fun corifyDecl ((d, loc : EM.span), st) =
    case d of
        L.DCon (x, n, k, c) =>
        let
            val (st, n) = St.bindCore st x n
        in
            ([(L'.DCon (x, n, corifyKind k, corifyCon st c), loc)], st)
        end
      | L.DVal (x, n, t, e) =>
        let
            val (st, n) = St.bindCore st x n
        in
            ([(L'.DVal (x, n, corifyCon st t, corifyExp st e), loc)], st)
        end
                                                                        
      | L.DSgn _ => ([], st)

      | L.DStr (x, n, _, (L.StrFun (_, na, _, _, str), _)) =>
        ([], St.bindFunctor st x n na str)

      | L.DStr (x, n, _, str) =>
        let
            val (ds, {inner, outer}) = corifyStr (str, st)
            val st = St.bindStr outer x n inner
        in
            (ds, st)
        end

      | L.DFfiStr (m, n, (sgn, _)) =>
        (case sgn of
             L.SgnConst sgis =>
             let
                 val (ds, cmap, st) =
                     foldl (fn ((sgi, _), (ds, cmap, st)) =>
                               case sgi of
                                   L.SgiConAbs (x, n, k) =>
                                   let
                                       val (st, n') = St.bindCore st x n
                                   in
                                       ((L'.DCon (x, n', corifyKind k, (L'.CFfi (m, x), loc)), loc) :: ds,
                                        cmap,
                                        st)
                                   end
                                 | L.SgiCon (x, n, k, _) =>
                                   let
                                       val (st, n') = St.bindCore st x n
                                   in
                                       ((L'.DCon (x, n', corifyKind k, (L'.CFfi (m, x), loc)), loc) :: ds,
                                        cmap,
                                        st)
                                   end

                                 | L.SgiVal (x, _, c) =>
                                   (ds,
                                    SM.insert (cmap, x, corifyCon st c),
                                    st)
                                 | _ => (ds, cmap, st)) ([], SM.empty, st) sgis

                 val st = St.bindStr st m n (St.ffi m cmap)
             in
                 (rev ds, st)
             end
           | _ => raise Fail "Non-const signature for FFI structure")


and corifyStr ((str, _), st) =
    case str of
        L.StrConst ds =>
        let
            val st = St.enter st
            val (ds, st) = ListUtil.foldlMapConcat corifyDecl st ds
        in
            (ds, St.leave st)
        end
      | L.StrVar n => ([], {inner = St.lookupStrById st n, outer = st})
      | L.StrProj (str, x) =>
        let
            val (ds, {inner, outer}) = corifyStr (str, st)
        in
            (ds, {inner = St.lookupStrByName (x, inner), outer = outer})
        end
      | L.StrFun _ => raise Fail "Corify of nested functor definition"
      | L.StrApp (str1, str2) =>
        let
            fun unwind' (str, _) =
                case str of
                    L.StrVar n => St.lookupStrById st n
                  | L.StrProj (str, x) => St.lookupStrByName (x, unwind' str)
                  | _ => raise Fail "Corify of fancy functor application [1]"

            fun unwind (str, _) =
                case str of
                    L.StrVar n => St.lookupFunctorById st n
                  | L.StrProj (str, x) => St.lookupFunctorByName (x, unwind' str)
                  | _ => raise Fail "Corify of fancy functor application [2]"

            val (na, body) = unwind str1

            val (ds1, {inner, outer}) = corifyStr (str2, st)
            val (ds2, sts) = corifyStr (body, St.bindStr outer "ARG" na inner)
        in
            (ds1 @ ds2, sts)
        end

fun maxName ds = foldl (fn ((d, _), n) =>
                           case d of
                               L.DCon (_, n', _, _) => Int.max (n, n')
                             | L.DVal (_, n', _ , _) => Int.max (n, n')
                             | L.DSgn (_, n', _) => Int.max (n, n')
                             | L.DStr (_, n', _, str) => Int.max (n, Int.max (n', maxNameStr str))
                             | L.DFfiStr (_, n', _) => Int.max (n, n'))
                 0 ds

and maxNameStr (str, _) =
    case str of
        L.StrConst ds => maxName ds
      | L.StrVar n => n
      | L.StrProj (str, _) => maxNameStr str
      | L.StrFun (_, _, _, _, str) => maxNameStr str
      | L.StrApp (str1, str2) => Int.max (maxNameStr str1, maxNameStr str2)

fun corify ds =
    let
        val () = reset (maxName ds + 1)
        val (ds, _) = ListUtil.foldlMapConcat corifyDecl St.empty ds
    in
        ds
    end

end