/* This file is part of the Sub::Op Perl module.
 * See http://search.cpan.org/dist/Sub-Op/ */

#define PERL_NO_GET_CONTEXT
#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"

#define __PACKAGE__     "Sub::Op"
#define __PACKAGE_LEN__ (sizeof(__PACKAGE__)-1)

/* --- Compatibility wrappers ---------------------------------------------- */

#define SO_HAS_PERL(R, V, S) (PERL_REVISION > (R) || (PERL_REVISION == (R) && (PERL_VERSION > (V) || (PERL_VERSION == (V) && (PERL_SUBVERSION >= (S))))))

/* ... Thread safety and multiplicity ...................................... */

#ifndef SO_MULTIPLICITY
# if defined(MULTIPLICITY) || defined(PERL_IMPLICIT_CONTEXT)
#  define SO_MULTIPLICITY 1
# else
#  define SO_MULTIPLICITY 0
# endif
#endif
#if SO_MULTIPLICITY && !defined(tTHX)
# define tTHX PerlInterpreter*
#endif

#if SO_MULTIPLICITY && defined(USE_ITHREADS) && defined(dMY_CXT) && defined(MY_CXT) && defined(START_MY_CXT) && defined(MY_CXT_INIT) && (defined(MY_CXT_CLONE) || defined(dMY_CXT_SV))
# define SO_THREADSAFE 1
# ifndef MY_CXT_CLONE
#  define MY_CXT_CLONE \
    dMY_CXT_SV;                                                      \
    my_cxt_t *my_cxtp = (my_cxt_t*)SvPVX(newSV(sizeof(my_cxt_t)-1)); \
    Copy(INT2PTR(my_cxt_t*, SvUV(my_cxt_sv)), my_cxtp, 1, my_cxt_t); \
    sv_setuv(my_cxt_sv, PTR2UV(my_cxtp))
# endif
#else
# define SO_THREADSAFE 0
# undef  dMY_CXT
# define dMY_CXT      dNOOP
# undef  MY_CXT
# define MY_CXT       indirect_globaldata
# undef  START_MY_CXT
# define START_MY_CXT STATIC my_cxt_t MY_CXT;
# undef  MY_CXT_INIT
# define MY_CXT_INIT  NOOP
# undef  MY_CXT_CLONE
# define MY_CXT_CLONE NOOP
#endif

/* --- Global data --------------------------------------------------------- */

#define MY_CXT_KEY __PACKAGE__ "::_guts" XS_VERSION

typedef struct {
 HV  *map;
 AV  *next_pkg;
 AV  *next_name;
 CV  *placeholder;
#if SO_THREADSAFE
 tTHX owner;
#endif /* SO_THREADSAFE */
} my_cxt_t;

START_MY_CXT

#if SO_THREADSAFE

STATIC SV *so_clone(pTHX_ SV *sv, tTHX owner) {
#define so_clone(S, O) so_clone(aTHX_ (S), (O))
 CLONE_PARAMS  param;
 AV           *stashes = NULL;
 SV           *dupsv;

 if (SvTYPE(sv) == SVt_PVHV && HvNAME_get(sv))
  stashes = newAV();

 param.stashes    = stashes;
 param.flags      = 0;
 param.proto_perl = owner;

 dupsv = sv_dup(sv, &param);

 if (stashes) {
  av_undef(stashes);
  SvREFCNT_dec(stashes);
 }

 return SvREFCNT_inc(dupsv);
}

#endif /* SO_THREADSAFE */

/* --- Public API ---------------------------------------------------------- */

#include "sub_op.h"

void sub_op_register(pTHX_ const sub_op_keyword *k) {
 SV *key = newSViv(PTR2IV(k->pp));

 if (!PL_custom_op_names)
  PL_custom_op_names = newHV();
 (void) hv_store_ent(PL_custom_op_names, key, newSVpv(k->name, k->len), 0);

 if (!PL_custom_op_descs)
  PL_custom_op_descs = newHV();
 (void) hv_store_ent(PL_custom_op_descs, key, newSVpv(k->name, k->len), 0);

 if (k->check) {
  SV *check = newSViv(PTR2IV(k->check));
  sv_magicext(key, check, PERL_MAGIC_ext, NULL, k->ud, 0);
  SvREFCNT_dec(check);
 }

 {
  dMY_CXT;
  (void) hv_store(MY_CXT.map, k->name, k->len, key, 0);
 }
}

/* --- Private helpers ----------------------------------------------------- */

#define SO_LINKLIST(O) ((O)->op_next ? (O)->op_next : sub_op_linklist(O))

STATIC OP *sub_op_linklist(pTHX_ OP *o) {
#define sub_op_linklist(O) sub_op_linklist(aTHX_ (O))
    OP *first;

    if (o->op_next)
        return o->op_next;

    /* establish postfix order */
    first = cUNOPo->op_first;
    if (first) {
        register OP *kid;
        o->op_next = SO_LINKLIST(first);
        kid = first;
        for (;;) {
            if (kid->op_sibling) {
                kid->op_next = SO_LINKLIST(kid->op_sibling);
                kid = kid->op_sibling;
            } else {
                kid->op_next = o;
                break;
            }
        }
    }
    else
        o->op_next = o;

    return o->op_next;
}

STATIC IV sub_op_hint(pTHX) {
#define sub_op_hint() sub_op_hint(aTHX)
 SV *hint;

#if SO_HAS_PERL(5, 9, 5)
 hint = Perl_refcounted_he_fetch(aTHX_ PL_curcop->cop_hints_hash,
                                       NULL,
                                       __PACKAGE__, __PACKAGE_LEN__,
                                       0,
                                       0);
#else
 {
  SV **val = hv_fetch(GvHV(PL_hintgv), __PACKAGE__, __PACKAGE_LEN__, 0);
  if (!val)
   return 0;
  hint = *val;
 }
#endif

 return (SvOK(hint) && SvIOK(hint)) ? SvIVX(hint) : 0;
}

STATIC OP *(*sub_op_old_ck_entersub)(pTHX_ OP *) = 0;

STATIC OP *sub_op_ck_entersub(pTHX_ OP *o) {
 dMY_CXT;

 o = CALL_FPTR(sub_op_old_ck_entersub)(aTHX_ o);

 if (sub_op_hint()) {
  dMY_CXT;
  U32 hash = 0;
  SV *pkg, *name, *pp_sv;

  pkg  = av_pop(MY_CXT.next_pkg);
  if (!SvOK(pkg))
   return o;

  name = av_pop(MY_CXT.next_name);
  if (!SvOK(name)) {
   SvREFCNT_dec(pkg);
   return o;
  }

  {
   HV *stash = gv_stashsv(pkg, 0);

   if (stash) {
    HE *he = hv_fetch_ent(stash, name, 0, 0);

    if (he) {
     CV *cv;
     SV *gv = HeVAL(he);
     hash   = HeHASH(he);

     if (gv && SvTYPE(gv) >= SVt_PVGV && (cv = GvCV(gv)) == MY_CXT.placeholder){
      SvREFCNT_dec(cv);
      GvCV(gv) = NULL;
      if (!GvSV(gv) && !GvAV(gv) && !GvHV(gv) && !GvIO(gv) && !GvFORM(gv))
       (void) hv_delete_ent(stash, name, G_DISCARD, hash);
     }
    }
   }
  }

  {
   HE *he = hv_fetch_ent(MY_CXT.map, name, 0, hash);
   if (!he)
    goto skip;

   pp_sv = HeVAL(he);
   if (!SvOK(pp_sv))
    goto skip;
  }

  if (o->op_type != OP_ENTERSUB)
   goto skip;
  if (o->op_private & OPpENTERSUB_AMPER) /* hopefully \&foo */
   goto skip;

  {
   OP *ex_list  = cUNOPo->op_first;
   OP *rv2cv, *gvop;
   OP *last_arg = NULL;

   /* pushmark when a method call */
   if (!ex_list || ex_list->op_type != OP_NULL)
    goto skip;

   rv2cv = cUNOPx(ex_list)->op_first;
   if (!rv2cv)
    goto skip;

   while (1) {
    OP *next = rv2cv->op_sibling;
    if (!next)
     break;
    last_arg = rv2cv;
    rv2cv    = next;
   }

   if (!(rv2cv->op_flags & OPf_KIDS))
    goto skip;

   gvop = cUNOPx(rv2cv)->op_first;
   if (!gvop || gvop->op_type != OP_GV)
    goto skip;

   {
    GV         *gv   = cGVOPx_gv(gvop);
    STRLEN      len;
    const char *s    = SvPV_const(name, len);

    if (GvNAMELEN(gv) == len && strnEQ(GvNAME(gv), s, len)) {
     o->op_type   = OP_CUSTOM;
     o->op_ppaddr = INT2PTR(Perl_ppaddr_t, SvIVX(pp_sv));

     if (last_arg)
      last_arg->op_sibling = NULL;
     op_free(rv2cv);

     {
      MAGIC *mg = mg_find(pp_sv, PERL_MAGIC_ext);
      if (mg) {
       sub_op_check_t check = INT2PTR(sub_op_check_t, SvIVX(mg->mg_obj));
       o = CALL_FPTR(check)(aTHX_ o, mg->mg_ptr);
      }
     }

     sub_op_linklist(o);
    }
   }
  }

skip:
  SvREFCNT_dec(pkg);
  SvREFCNT_dec(name);
 }

 return o;
}

/* --- XS ------------------------------------------------------------------ */

MODULE = Sub::Op      PACKAGE = Sub::Op

PROTOTYPES: ENABLE

BOOT:
{
 MY_CXT_INIT;
 MY_CXT.map         = newHV();
 MY_CXT.next_pkg    = newAV();
 MY_CXT.next_name   = newAV();
 MY_CXT.placeholder = NULL;
#if SO_THREADSAFE
 MY_CXT.owner       = aTHX;
#endif /* SO_THREADSAFE */

 sub_op_old_ck_entersub = PL_check[OP_ENTERSUB];
 PL_check[OP_ENTERSUB]  = sub_op_ck_entersub;
}

#if SO_THREADSAFE

void
CLONE(...)
PROTOTYPE: DISABLE
PREINIT:
 HV  *map;
 CV  *placeholder;
 tTHX owner;
CODE:
 {
  dMY_CXT;
  owner       = MY_CXT.owner;
  map         = (HV *) so_clone((SV *) MY_CXT.map,         owner);
  placeholder = (CV *) so_clone((SV *) MY_CXT.placeholder, owner);
 }
 {
  MY_CXT_CLONE;
  MY_CXT.map         = map;
  MY_CXT.next_pkg    = newAV();
  MY_CXT.next_name   = newAV();
  MY_CXT.placeholder = placeholder;
  MY_CXT.owner = aTHX;
 }

#endif /* SO_THREADSAFE */

void
_placeholder(SV *sv)
PROTOTYPE: $
PPCODE:
 if (SvROK(sv)) {
  sv = SvRV(sv);
  if (SvTYPE(sv) >= SVt_PVCV) {
   dMY_CXT;
   SvREFCNT_dec(MY_CXT.placeholder);
   MY_CXT.placeholder = (CV *) SvREFCNT_inc(sv);
  }
 }
 XSRETURN(0);

void
_incoming(SV *name, SV *pkg)
PROTOTYPE: $$
PPCODE:
 dMY_CXT;
 av_push(MY_CXT.next_pkg,  SvREFCNT_inc(pkg));
 av_push(MY_CXT.next_name, SvREFCNT_inc(name));
 XSRETURN(0);

void
_custom_name(SV *op)
PROTOTYPE: $
PREINIT:
 OP *o;
 SV *key;
 HE *he;
PPCODE:
 if (!SvROK(op))
  XSRETURN_UNDEF;
 o = INT2PTR(OP *, SvIV(SvRV(op)));
 if (!o || o->op_type != OP_CUSTOM)
  XSRETURN_UNDEF;
 key = newSViv(PTR2IV(o->op_ppaddr));
 he  = hv_fetch_ent(PL_custom_op_names, key, 0, 0);
 SvREFCNT_dec(key);
 if (!he)
  XSRETURN_UNDEF;
 ST(0) = sv_mortalcopy(HeVAL(he));
 XSRETURN(1);