/* 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))))))

#ifndef GvCV_set
# define GvCV_set(G, C) (GvCV(G) = (C))
#endif

/* ... 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

#if defined(OP_CHECK_MUTEX_LOCK) && defined(OP_CHECK_MUTEX_UNLOCK)
# define SO_CHECK_MUTEX_LOCK   OP_CHECK_MUTEX_LOCK
# define SO_CHECK_MUTEX_UNLOCK OP_CHECK_MUTEX_UNLOCK
#else
# define SO_CHECK_MUTEX_LOCK   OP_REFCNT_LOCK
# define SO_CHECK_MUTEX_UNLOCK OP_REFCNT_UNLOCK
#endif

typedef OP *(*so_ck_t)(pTHX_ OP *);

#ifdef wrap_op_checker

# define so_ck_replace(T, NC, OCP) wrap_op_checker((T), (NC), (OCP))

#else

STATIC void so_ck_replace(pTHX_ OPCODE type, so_ck_t new_ck, so_ck_t *old_ck_p){
#define so_ck_replace(T, NC, OCP) so_ck_replace(aTHX_ (T), (NC), (OCP))
 SO_CHECK_MUTEX_LOCK;
 if (!*old_ck_p) {
  *old_ck_p      = PL_check[type];
  PL_check[type] = new_ck;
 }
 SO_CHECK_MUTEX_UNLOCK;
}

#endif

STATIC void so_ck_restore(pTHX_ OPCODE type, so_ck_t *old_ck_p) {
#define so_ck_restore(T, OCP) so_ck_restore(aTHX_ (T), (OCP))
 SO_CHECK_MUTEX_LOCK;
 if (*old_ck_p) {
  PL_check[type] = *old_ck_p;
  *old_ck_p      = 0;
 }
 SO_CHECK_MUTEX_UNLOCK;
}

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

#define MY_CXT_KEY __PACKAGE__ "::_guts" XS_VERSION

typedef struct {
 HV  *map;
 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_init(sub_op_config_t *c) {
 c->name     = NULL;
 c->namelen  = 0;
 c->proto    = NULL;
 c->protolen = 0;
 c->call     = 0;
 c->ref      = 0;
 c->ud       = NULL;

 return;
}

void sub_op_register(pTHX_ const sub_op_config_t *c, U32 flags) {
 dMY_CXT;

 if (!(flags & SUB_OP_REGISTER_STEAL))
  c = sub_op_dup(aTHX_ c);

 (void) hv_store(MY_CXT.map, c->name, c->namelen, newSViv(PTR2IV(c)), 0);
}

STATIC const char *so_strndup(pTHX_ const char *s, STRLEN len) {
#define so_strndup(S, L) so_strndup(aTHX_ (S), (L))
 const char *d;

 if (!s)
  return NULL;

 d = PerlMemShared_malloc(len + 1);
 Copy(s, d, len, char);
 ((char *) d)[len] = '\0';

 return d;
}

sub_op_config_t *sub_op_dup(pTHX_ const sub_op_config_t *orig) {
 sub_op_config_t *dupe = PerlMemShared_malloc(sizeof *dupe);

 dupe->name    = so_strndup(orig->name, orig->namelen);
 dupe->namelen = orig->namelen;

 dupe->proto    = so_strndup(orig->proto, orig->protolen);
 dupe->protolen = orig->protolen;

 dupe->call = orig->call;
 dupe->ref  = orig->ref;
 dupe->ud   = orig->ud;

 return dupe;
}

void sub_op_free(pTHX_ sub_op_config_t *c) {
 PerlMemShared_free((char *) c->name);
 PerlMemShared_free(c);

 return;
}

OP *sub_op_study(const OP *o, OP **last_arg_p, OP **rv2cv_p) {
 OP *ex_list, *last_arg, *rv2cv, *gvop;

 ex_list = cUNOPo->op_first;
 /* 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 done;

skip:
 last_arg = NULL;
 rv2cv    = NULL;
 gvop     = NULL;

done:
 if (last_arg_p)
  *last_arg_p = last_arg;
 if (rv2cv_p)
  *rv2cv_p    = rv2cv;

 return gvop;
}

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

STATIC IV so_hint(pTHX) {
#define so_hint() so_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 *so_find_gvop(const OP *o) {
 OP *ex_list, *last_arg, *rv2cv, *gvop;

 ex_list = cUNOPo->op_first;
 /* 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;
  rv2cv = next;
 }

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

 gvop = cUNOPx(rv2cv)->op_first;
 if (gvop && gvop->op_type == OP_GV)
  return gvop;

skip:
 return NULL;
}

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

STATIC OP *so_ck_entersub(pTHX_ OP *o) {
 o = CALL_FPTR(so_old_ck_entersub)(aTHX_ o);

 if (so_hint()) {
  OP *gvop;
  GV *gv;

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

  gvop = so_find_gvop(o);
  if (!gvop)
   goto skip;

  gv = cGVOPx_gv(gvop);

  {
   SV **svp;
   CV  *cv = NULL;
   const char *name = GvNAME(gv);
   I32         len  = GvNAMELEN(gv);
   const sub_op_config_t *c;
   dMY_CXT;

   svp = hv_fetch(MY_CXT.map, name, len, 0);
   if (!svp)
    goto skip;

   c = INT2PTR(const sub_op_config_t *, SvIVX(*svp));

   if (gv && SvTYPE(gv) >= SVt_PVGV && (cv = GvCV(gv)) == MY_CXT.placeholder) {
    SvREFCNT_dec(cv);
    GvCV_set(gv, NULL);
   }

   if (c->call)
    o = CALL_FPTR(c->call)(aTHX_ o, c->ud);
  }
 }

skip:
 return o;
}

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

STATIC OP *so_ck_refgen(pTHX_ OP *o) {
 o = CALL_FPTR(so_old_ck_refgen)(aTHX_ o);

 if (so_hint()) {
  OP *kid    = o;
  OP *prev   = NULL;
  OP *parent = NULL;

  while (kid->op_flags & OPf_KIDS) {
   parent = kid;
   kid    = cUNOPx(kid)->op_first;
  }

  if (!parent)
   goto skip;

  for (kid; kid; prev = kid, kid = kid->op_sibling) {
   OP *gvop;
   GV *gv;
   const sub_op_config_t *c;

   if (kid->op_type != OP_RV2CV)
    continue;

   gvop = so_find_gvop(kid);
   if (!gvop)
    continue;

   gv = cGVOPx_gv(gvop);

   {
    SV **svp;
    const char *name = GvNAME(gv);
    I32         len  = GvNAMELEN(gv);
    dMY_CXT;

    svp = hv_fetch(MY_CXT.map, name, len, 0);
    if (!svp)
     continue;

    c = INT2PTR(const sub_op_config_t *, SvIVX(*svp));
   }

   if (c->ref) {
    OP *new_kid = CALL_FPTR(c->ref)(aTHX_ kid, c->ud);

    if (new_kid != kid) {
     new_kid->op_sibling = kid->op_sibling;
     new_kid->op_next = new_kid;
     if (prev)
      prev->op_sibling = new_kid;
     else
      cUNOPx(parent)->op_first = new_kid;
     op_null(kid);
     kid = new_kid;
    }
   }
  }
 }

skip:
 return o;
}

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

STATIC OP *so_ck_gelem(pTHX_ OP *o) {
 o = CALL_FPTR(so_old_ck_entersub)(aTHX_ o);

 if (so_hint()) {
  OP *rv2gv, *gvop;
  GV *gv;

  rv2gv = cUNOPo->op_first;
  if (!rv2gv)
   goto skip;

  gvop = cUNOPx(rv2gv)->op_first;
  if (!gvop || gvop->op_type != OP_GV)
   goto skip;

  gv = cGVOPx_gv(gvop);
  if (!gv)
   goto skip;

  {
   CV *cv;
   dMY_CXT;

   if (gv && SvTYPE(gv) >= SVt_PVGV && (cv = GvCV(gv)) == MY_CXT.placeholder) {
    SvREFCNT_dec(cv);
    GvCV_set(gv, NULL);
   }
  }
 }

skip:
 return o;
}

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

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

PROTOTYPES: ENABLE

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

 so_ck_replace(OP_ENTERSUB, so_ck_entersub, &so_old_ck_entersub);
 so_ck_replace(OP_REFGEN,   so_ck_refgen,   &so_old_ck_refgen);
 so_ck_replace(OP_GELEM,    so_ck_gelem,    &so_old_ck_gelem);
}

#if SO_THREADSAFE

void
CLONE(...)
PROTOTYPE: DISABLE
PREINIT:
 HV  *map;
 CV  *placeholder;
 tTHX owner;
PPCODE:
 {
  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.placeholder = placeholder;
  MY_CXT.owner       = aTHX;
 }
 XSRETURN(0);

#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
_constant_sub(SV *sv)
PROTOTYPE: $
PPCODE:
 if (!SvROK(sv))
  XSRETURN_UNDEF;
 sv = SvRV(sv);
 if (SvTYPE(sv) < SVt_PVCV)
  XSRETURN_UNDEF;
 ST(0) = sv_2mortal(newSVuv(CvCONST(sv)));
 XSRETURN(1);

SV *
_get_prototype(SV *name)
PROTOTYPE: $
PREINIT:
 HE *he;
 const sub_op_config_t *c;
PPCODE:
 dMY_CXT;
 he = hv_fetch_ent(MY_CXT.map, name, 0, 0);
 if (!he)
  XSRETURN_UNDEF;
 c = INT2PTR(const sub_op_config_t *, SvIVX(HeVAL(he)));
 if (!c->proto)
  XSRETURN_UNDEF;
 ST(0) = sv_2mortal(newSVpvn(c->proto, c->protolen));
 XSRETURN(1);