(*  Title:      HOL/Tools/Lifting/lifting_setup.ML

    Author:     Ondrej Kuncar

Setting up the lifting infrastructure.

*)

signature LIFTING_SETUP =

sig

  exception SETUP_LIFTING_INFR of string

  val setup_lifting_infr: thm -> local_theory -> local_theory

  val setup_by_quotient: thm -> thm option -> local_theory -> local_theory

  val setup_by_typedef_thm: thm -> local_theory -> local_theory

end;

structure Lifting_Setup: LIFTING_SETUP =

struct

infix 0 MRSL

fun ants MRSL thm = fold (fn rl => fn thm => rl RS thm) ants thm

exception SETUP_LIFTING_INFR of string

fun define_cr_rel rep_fun lthy =

  let

    val (qty, rty) = (dest_funT o fastype_of) rep_fun

    val rep_fun_graph = (HOLogic.eq_const rty) $ Bound 1 $ (rep_fun $ Bound 0)

    val def_term = Abs ("x", rty, Abs ("y", qty, rep_fun_graph));

    val qty_name = (fst o dest_Type) qty

    val cr_rel_name = Binding.prefix_name "cr_" (Binding.qualified_name qty_name)  

    val (fixed_def_term, lthy') = yield_singleton (Variable.importT_terms) def_term lthy

    val ((_, (_ , def_thm)), lthy'') =

      Local_Theory.define ((cr_rel_name, NoSyn), ((Thm.def_binding cr_rel_name, []), fixed_def_term)) lthy'

  in

    (def_thm, lthy'')

  end

fun define_abs_type quot_thm lthy =

  if Lifting_Def.can_generate_code_cert quot_thm then

    let

      val abs_type_thm = quot_thm RS @{thm Quotient_abs_rep}

      val add_abstype_attribute = 

          Thm.declaration_attribute (fn thm => Context.mapping (Code.add_abstype thm) I)

        val add_abstype_attrib = Attrib.internal (K add_abstype_attribute);

    in

      lthy

        |> (snd oo Local_Theory.note) ((Binding.empty, [add_abstype_attrib]), [abs_type_thm])

    end

  else

    lthy

fun quot_thm_sanity_check ctxt quot_thm =

  let

    val ((_, [quot_thm_fixed]), ctxt') = Variable.importT [quot_thm] ctxt 

    val (rty, qty) = Lifting_Term.quot_thm_rty_qty quot_thm_fixed

    val rty_tfreesT = Term.add_tfree_namesT rty []

    val qty_tfreesT = Term.add_tfree_namesT qty []

    val extra_rty_tfrees =

      (case subtract (op =) qty_tfreesT rty_tfreesT of

        [] => []

      | extras => [Pretty.block ([Pretty.str "Extra variables in the raw type:",

                                 Pretty.brk 1] @ 

                                 ((Pretty.commas o map (Pretty.str o quote)) extras) @

                                 [Pretty.str "."])])

    val not_type_constr = 

      (case qty of

         Type _ => []

         | _ => [Pretty.block [Pretty.str "The quotient type ",

                                Pretty.quote (Syntax.pretty_typ ctxt' qty),

                                Pretty.brk 1,

                                Pretty.str "is not a type constructor."]])

    val errs = extra_rty_tfrees @ not_type_constr

  in

    if null errs then () else error (cat_lines (["Sanity check of the quotient theorem failed:",""] 

                                                @ (map Pretty.string_of errs)))

  end

fun setup_lifting_infr quot_thm lthy =

  let

    val _ = quot_thm_sanity_check lthy quot_thm

    val (_, qtyp) = Lifting_Term.quot_thm_rty_qty quot_thm

    val qty_full_name = (fst o dest_Type) qtyp

    val quotients = { quot_thm = quot_thm }

    fun quot_info phi = Lifting_Info.transform_quotients phi quotients

  in

    lthy

      |> Local_Theory.declaration {syntax = false, pervasive = true}

        (fn phi => Lifting_Info.update_quotients qty_full_name (quot_info phi))

      |> define_abs_type quot_thm

  end

fun setup_by_quotient quot_thm maybe_reflp_thm lthy =

  let

    val transfer_attr = Attrib.internal (K Transfer.transfer_add)

    val lthy' = case maybe_reflp_thm of

      SOME reflp_thm => lthy

        |> (snd oo Local_Theory.note) ((Binding.empty, [transfer_attr]), 

          [[quot_thm, reflp_thm] MRSL @{thm Quotient_bi_total}])

        |> (snd oo Local_Theory.note) ((Binding.empty, [transfer_attr]), 

          [[quot_thm, reflp_thm] MRSL @{thm Quotient_id_abs_transfer}])

      | NONE => lthy

  in

    lthy'

      |> (snd oo Local_Theory.note) ((Binding.empty, [transfer_attr]), 

        [quot_thm RS @{thm Quotient_right_unique}])

      |> (snd oo Local_Theory.note) ((Binding.empty, [transfer_attr]), 

        [quot_thm RS @{thm Quotient_right_total}])

      |> (snd oo Local_Theory.note) ((Binding.empty, [transfer_attr]), 

        [quot_thm RS @{thm Quotient_rel_eq_transfer}])

      |> setup_lifting_infr quot_thm

  end

fun setup_by_typedef_thm typedef_thm lthy =

  let

    val transfer_attr = Attrib.internal (K Transfer.transfer_add)

    val (_ $ rep_fun $ _ $ typedef_set) = (HOLogic.dest_Trueprop o prop_of) typedef_thm

    val (T_def, lthy') = define_cr_rel rep_fun lthy

    val quot_thm = (case typedef_set of

      Const ("Orderings.top_class.top", _) => 

        [typedef_thm, T_def] MRSL @{thm UNIV_typedef_to_Quotient}

      | Const (@{const_name "Collect"}, _) $ Abs (_, _, _) => 

        [typedef_thm, T_def] MRSL @{thm open_typedef_to_Quotient}

      | _ => 

        [typedef_thm, T_def] MRSL @{thm typedef_to_Quotient})

    val lthy'' = (case typedef_set of

      Const ("Orderings.top_class.top", _) => (snd oo Local_Theory.note) ((Binding.empty, [transfer_attr]), 

        [[typedef_thm,T_def] MRSL @{thm copy_type_bi_total}]) lthy'

      | _ => lthy')

  in

    lthy''

      |> (snd oo Local_Theory.note) ((Binding.empty, [transfer_attr]), 

        [[typedef_thm, T_def] MRSL @{thm typedef_bi_unique}])

      |> (snd oo Local_Theory.note) ((Binding.empty, [transfer_attr]), 

        [[typedef_thm, T_def] MRSL @{thm typedef_right_total}])

      |> (snd oo Local_Theory.note) ((Binding.empty, [transfer_attr]), 

        [[typedef_thm, T_def] MRSL @{thm typedef_rep_transfer}])

      |> (snd oo Local_Theory.note) ((Binding.empty, [transfer_attr]), 

        [[typedef_thm, T_def] MRSL @{thm typedef_transfer_All}])

      |> (snd oo Local_Theory.note) ((Binding.empty, [transfer_attr]), 

        [[typedef_thm, T_def] MRSL @{thm typedef_transfer_Ex}])

      |> (snd oo Local_Theory.note) ((Binding.empty, [transfer_attr]), 

        [[typedef_thm, T_def] MRSL @{thm typedef_transfer_bforall}])

      |> setup_lifting_infr quot_thm

  end

fun setup_lifting_cmd xthm lthy =

  let 

    val input_thm = singleton (Attrib.eval_thms lthy) xthm

    val input_term = (HOLogic.dest_Trueprop o prop_of) input_thm

  in

    case input_term of

      (Const (@{const_name Quotient}, _) $ _ $ _ $ _ $ _) => setup_lifting_infr input_thm lthy

      | (Const (@{const_name type_definition}, _) $ _ $ _ $ _) => setup_by_typedef_thm input_thm lthy

      | _ => error "Unsupported type of a theorem. Only Quotient or type_definition are supported."

  end

val _ = 

  Outer_Syntax.local_theory @{command_spec "setup_lifting"}

    "Setup lifting infrastructure" 

      (Parse_Spec.xthm >> (fn xthm => setup_lifting_cmd xthm))

end;