(*  Title:      HOL/Tools/Transfer/transfer_bnf.ML

    Author:     Ondrej Kuncar, TU Muenchen

Setup for Lifting for types that are BNF.

*)

signature LIFTING_BNF =

sig

end

structure Lifting_BNF : LIFTING_BNF =

struct

open BNF_Util

open BNF_Def

open Transfer_BNF

(* Quotient map theorem *)

fun Quotient_tac bnf ctxt i =

  let

    val rel_Grp = rel_Grp_of_bnf bnf

    fun get_lhs thm = thm |> concl_of |> HOLogic.dest_Trueprop |> HOLogic.dest_eq |> fst

    val vars = get_lhs rel_Grp |> strip_comb |> snd |> map_filter (try (strip_comb #> snd #> hd))

    val UNIVs = map (fn var => HOLogic.mk_UNIV (var |> dest_Var |> snd |> dest_Type |> snd |> hd)) vars

    val inst = map2 (curry(pairself (certify ctxt))) vars UNIVs

    val rel_Grp_UNIV_sym = rel_Grp |> Drule.instantiate_normalize ([], inst) 

      |> Local_Defs.unfold ctxt @{thms subset_UNIV[THEN eqTrueI] UNIV_def[symmetric] simp_thms(21)}

      |> (fn thm => thm RS sym)

    val rel_mono = rel_mono_of_bnf bnf

    val rel_conversep_sym = rel_conversep_of_bnf bnf RS sym

  in

    EVERY' [SELECT_GOAL (Local_Defs.unfold_tac ctxt [@{thm Quotient_alt_def5}]), 

      REPEAT_DETERM o (etac conjE), rtac conjI, SELECT_GOAL (Local_Defs.unfold_tac ctxt [rel_Grp_UNIV_sym]),

      rtac rel_mono THEN_ALL_NEW atac, rtac conjI, SELECT_GOAL (Local_Defs.unfold_tac ctxt

        [rel_conversep_sym, rel_Grp_UNIV_sym]), rtac rel_mono THEN_ALL_NEW atac,

      SELECT_GOAL (Local_Defs.unfold_tac ctxt [rel_conversep_sym, rel_OO_of_bnf bnf RS sym]),

      hyp_subst_tac ctxt, rtac refl] i

  end

fun mk_Quotient args =

  let

    val argTs = map fastype_of args

  in

    list_comb (Const (@{const_name Quotient}, argTs ---> HOLogic.boolT), args)

  end

fun prove_Quotient_map bnf ctxt =

  let

    val live = live_of_bnf bnf

    val old_ctxt = ctxt

    val (((As, Bs), Ds), ctxt) = ctxt

      |> mk_TFrees live

      ||>> mk_TFrees live

      ||>> mk_TFrees (dead_of_bnf bnf)

    val argTss = map2 (fn a => fn b => [mk_pred2T a a, a --> b, b --> a,mk_pred2T a b]) As Bs

    val ((argss, argss'), ctxt) = fold_map2 mk_Frees ["R", "Abs", "Rep", "T"] (transpose argTss) ctxt

      |>> `transpose

    val assms = map (mk_Quotient #> HOLogic.mk_Trueprop) argss

    val R_rel = list_comb (mk_rel_of_bnf Ds As As bnf, nth argss' 0)

    val Abs_map = list_comb (mk_map_of_bnf Ds As Bs bnf, nth argss' 1)

    val Rep_map = list_comb (mk_map_of_bnf Ds Bs As bnf, nth argss' 2)

    val T_rel = list_comb (mk_rel_of_bnf Ds As Bs bnf, nth argss' 3)

    val concl = mk_Quotient [R_rel, Abs_map, Rep_map, T_rel] |> HOLogic.mk_Trueprop

    val goal = Logic.list_implies (assms, concl)

    val thm = Goal.prove ctxt [] [] goal 

      (fn {context = ctxt, prems = _} => Quotient_tac bnf ctxt 1)

  in

    Drule.zero_var_indexes (singleton (Variable.export ctxt old_ctxt) thm)

  end

fun Quotient_map bnf ctxt =

  let

    val Quotient = prove_Quotient_map bnf ctxt

    fun qualify defname suffix = Binding.qualified true suffix defname

    val Quotient_thm_name = qualify (base_name_of_bnf bnf) "Quotient"

    val notes = [((Quotient_thm_name, []), [([Quotient], @{attributes [quot_map]})])]

  in

    notes

  end

(* relator_eq_onp  *)

fun relator_eq_onp bnf ctxt =

  let

    val pred_data = lookup_defined_pred_data ctxt (type_name_of_bnf bnf)

  in

    [((Binding.empty, []), [([Transfer.rel_eq_onp pred_data], @{attributes [relator_eq_onp]})])]    

  end

(* relator_mono  *)

fun relator_mono bnf =

  [((Binding.empty, []), [([rel_mono_of_bnf bnf], @{attributes [relator_mono]})])]    

(* relator_distr  *)

fun relator_distr bnf =

  [((Binding.empty, []), [([rel_OO_of_bnf bnf RS sym], @{attributes [relator_distr]})])]

(* interpretation *)

fun lifting_bnf_interpretation bnf lthy =

  if dead_of_bnf bnf > 0 then lthy

  else

    let

      val notes = relator_eq_onp bnf lthy @ Quotient_map bnf lthy @ relator_mono bnf

        @ relator_distr bnf

    in

      snd (Local_Theory.notes notes lthy)

    end

val _ = Context.>> (Context.map_theory (bnf_interpretation

  (bnf_only_type_ctr (fn bnf => map_local_theory (lifting_bnf_interpretation bnf)))))

end