(*  Title:      HOL/Codatatype/Tools/bnf_fp_sugar_tactics.ML

     Author:     Jasmin Blanchette, TU Muenchen

     Copyright   2012

 Tactics for the LFP/GFP sugar.

 *)

 signature BNF_FP_SUGAR_TACTICS =

 sig

   val mk_case_tac: Proof.context -> int -> int -> int -> thm -> thm -> thm -> tactic

   val mk_coiter_like_tac: thm list -> thm list -> thm -> thm -> thm -> Proof.context -> tactic

   val mk_exhaust_tac: Proof.context -> int -> thm list -> thm -> thm -> tactic

   val mk_fld_iff_unf_tac: Proof.context -> ctyp option list -> cterm -> cterm -> thm -> thm ->

     tactic

   val mk_half_distinct_tac: Proof.context -> thm -> thm list -> tactic

   val mk_induct_tac: Proof.context -> int list -> int list list ->

     ((int * int) * (int * int)) list list list -> thm list -> thm -> thm list -> thm list list ->

     tactic

   val mk_inject_tac: Proof.context -> thm -> thm -> tactic

   val mk_iter_like_tac: thm list -> thm list -> thm list -> thm -> thm -> Proof.context -> tactic

 end;

 structure BNF_FP_Sugar_Tactics : BNF_FP_SUGAR_TACTICS =

 struct

 open BNF_Tactics

 open BNF_Util

 open BNF_FP_Util

 val meta_mp = @{thm meta_mp};

 val meta_spec = @{thm meta_spec};

 fun smash_spurious_fs lthy thm =

   let

     val spurious_fs =

       Term.add_vars (prop_of thm) []

       |> filter (fn (_, Type (@{type_name fun}, [_, T'])) => T' <> HOLogic.boolT | _ => false);

     val cxs =

       map (fn s as (_, T) =>

         (certify lthy (Var s), certify lthy (id_abs (domain_type T)))) spurious_fs;

   in

     Drule.cterm_instantiate cxs thm

   end;

 val smash_spurious_fs_tac = PRIMITIVE o smash_spurious_fs;

 fun mk_case_tac ctxt n k m case_def ctr_def unf_fld =

   Local_Defs.unfold_tac ctxt [case_def, ctr_def, unf_fld] THEN

   (rtac (mk_sum_casesN_balanced n k RS ssubst) THEN'

    REPEAT_DETERM_N (Int.max (0, m - 1)) o rtac (@{thm split} RS ssubst) THEN'

    rtac refl) 1;

 fun mk_exhaust_tac ctxt n ctr_defs fld_iff_unf sumEN' =

   Local_Defs.unfold_tac ctxt (fld_iff_unf :: ctr_defs) THEN rtac sumEN' 1 THEN

   Local_Defs.unfold_tac ctxt @{thms all_prod_eq} THEN

   EVERY' (maps (fn k => [select_prem_tac n (rotate_tac 1) k, REPEAT_DETERM o dtac meta_spec,

     etac meta_mp, atac]) (1 upto n)) 1;

 fun mk_fld_iff_unf_tac ctxt cTs cfld cunf fld_unf unf_fld =

   (rtac iffI THEN'

    EVERY' (map3 (fn cTs => fn cx => fn th =>

      dtac (Drule.instantiate' cTs [NONE, NONE, SOME cx] arg_cong) THEN'

      SELECT_GOAL (Local_Defs.unfold_tac ctxt [th]) THEN'

      atac) [rev cTs, cTs] [cunf, cfld] [unf_fld, fld_unf])) 1;

 fun mk_half_distinct_tac ctxt fld_inject ctr_defs =

   Local_Defs.unfold_tac ctxt (fld_inject :: @{thms sum.inject} @ ctr_defs) THEN

   rtac @{thm sum.distinct(1)} 1;

 fun mk_inject_tac ctxt ctr_def fld_inject =

   Local_Defs.unfold_tac ctxt [ctr_def] THEN rtac (fld_inject RS ssubst) 1 THEN

   Local_Defs.unfold_tac ctxt @{thms sum.inject Pair_eq conj_assoc} THEN rtac refl 1;

 val iter_like_thms =

   @{thms case_unit comp_def convol_def id_apply map_pair_def sum.simps(5,6) sum_map.simps

       split_conv};

 fun mk_iter_like_tac pre_map_defs map_ids iter_like_defs fld_iter_like ctr_def ctxt =

   Local_Defs.unfold_tac ctxt (ctr_def :: fld_iter_like :: iter_like_defs @ pre_map_defs @ map_ids @

     iter_like_thms) THEN Local_Defs.unfold_tac ctxt @{thms id_def} THEN rtac refl 1;

 val coiter_like_ss = ss_only @{thms if_True if_False};

 val coiter_like_thms = @{thms id_apply map_pair_def sum_map.simps prod.cases};

 fun mk_coiter_like_tac coiter_like_defs map_ids fld_unf_coiter_like pre_map_def ctr_def ctxt =

   Local_Defs.unfold_tac ctxt (ctr_def :: coiter_like_defs) THEN

   subst_tac ctxt [fld_unf_coiter_like] 1 THEN asm_simp_tac coiter_like_ss 1 THEN

   Local_Defs.unfold_tac ctxt (pre_map_def :: coiter_like_thms @ map_ids) THEN

   Local_Defs.unfold_tac ctxt @{thms id_def} THEN

   TRY ((rtac refl ORELSE' subst_tac ctxt @{thms unit_eq} THEN' rtac refl) 1);

 fun mk_induct_prelude_tac ctxt ctr_defs fld_induct' =

   Local_Defs.unfold_tac ctxt ctr_defs THEN rtac fld_induct' 1 THEN smash_spurious_fs_tac ctxt;

 fun mk_induct_prepare_prem_tac n m k =

   EVERY' [select_prem_tac n (rotate_tac 1) k, rotate_tac ~1, hyp_subst_tac,

     REPEAT_DETERM_N m o (dtac meta_spec THEN' rotate_tac ~1)] 1;

 (* FIXME: why not in "Pure"? *)

 fun prefer_tac i = defer_tac i THEN PRIMITIVE (Thm.permute_prems 0 ~1);

 fun mk_induct_prepare_prem_prems_tac r =

   REPEAT_DETERM_N r (rotate_tac ~1 1 THEN dtac meta_mp 1 THEN rotate_tac 1 1 THEN prefer_tac 2) THEN

   PRIMITIVE Raw_Simplifier.norm_hhf;

 val induct_prem_prem_thms =

   @{thms SUP_empty Sup_empty Sup_insert UN_compreh_bex UN_insert Un_assoc[symmetric] Un_empty_left

       Un_empty_right Union_Un_distrib collect_def[abs_def] fst_conv image_def o_apply snd_conv

       snd_prod_fun sum.cases sup_bot_right fst_map_pair map_pair_simp sum_map.simps};

 (* These rules interfere with the "set_natural'" properties of "sum" and "prod", so we explicitly

    delay them. *)

 val induct_prem_prem_thms_delayed =

   @{thms fsts_def[abs_def] snds_def[abs_def] sum_setl_def[abs_def] sum_setr_def[abs_def]};

 (* TODO: Get rid of the "auto_tac" (or at least use a naked context) *)

 fun mk_induct_prem_prem_endgame_tac _ 0 = atac ORELSE' rtac @{thm singletonI}

   | mk_induct_prem_prem_endgame_tac ctxt qq =

     REPEAT_DETERM_N qq o

       (SELECT_GOAL (Local_Defs.unfold_tac ctxt @{thms Union_iff bex_simps(6)}) THEN'

        etac @{thm induct_set_step}) THEN'

     atac ORELSE' SELECT_GOAL (auto_tac ctxt);

 fun mk_induct_discharge_prem_prems_tac ctxt nn ixs set_natural's pre_set_defs =

   EVERY' (maps (fn ((pp, jj), (qq, kk)) =>

       [select_prem_tac nn (dtac meta_spec) kk, rotate_tac ~1 (*FIXME: needed?*), etac meta_mp,

        SELECT_GOAL (Local_Defs.unfold_tac ctxt pre_set_defs), (* FIXME: ### why on a line of its own? *)

        SELECT_GOAL (Local_Defs.unfold_tac ctxt (set_natural's @ induct_prem_prem_thms)),

        SELECT_GOAL (Local_Defs.unfold_tac ctxt

          (induct_prem_prem_thms_delayed @ induct_prem_prem_thms)),

        rtac (mk_UnIN pp jj) THEN' mk_induct_prem_prem_endgame_tac ctxt qq ORELSE'

          SELECT_GOAL (auto_tac ctxt)])

     (rev ixs)) 1;

 fun mk_induct_discharge_prem_tac ctxt nn n set_natural's pre_set_defs m k ixs =

   EVERY [mk_induct_prepare_prem_tac n m k,

     mk_induct_prepare_prem_prems_tac (length ixs), atac 1,

     mk_induct_discharge_prem_prems_tac ctxt nn ixs set_natural's pre_set_defs];

 fun mk_induct_tac ctxt ns mss ixsss ctr_defs fld_induct' set_natural's pre_set_defss =

   let

     val nn = length ns;

     val n = Integer.sum ns;

   in

     mk_induct_prelude_tac ctxt ctr_defs fld_induct' THEN

     EVERY (map4 (EVERY oooo map3 o mk_induct_discharge_prem_tac ctxt nn n set_natural's)

       pre_set_defss mss (unflat mss (1 upto n)) ixsss)

   end;

 end;