#include "typetiny.h"
#include "xs_version.h"

#define MY_CXT_KEY "Type::Tiny::XS::Util::_guts" XS_VERSION
typedef struct {
    HV* metas;
} my_cxt_t;
START_MY_CXT

#define ISA_CACHE "::LINEALIZED_ISA_CACHE::"

#ifdef no_mro_get_linear_isa
AV*
typetiny_mro_get_linear_isa(pTHX_ HV* const stash){
    GV* const cachegv = *(GV**)hv_fetchs(stash, ISA_CACHE, TRUE);
    AV* isa;
    SV* gen;
    CV* get_linear_isa;

    if(!isGV(cachegv))
        gv_init(cachegv, stash, ISA_CACHE, sizeof(ISA_CACHE)-1, TRUE);

    isa = GvAVn(cachegv);
    gen = GvSVn(cachegv);


    if(SvIOK(gen) && SvIVX(gen) == (IV)mro_get_pkg_gen(stash)){
        return isa; /* returns the cache if available */
    }
    else{
        SvREFCNT_dec(isa);
        GvAV(cachegv) = isa = newAV();
    }

    get_linear_isa = get_cv("Type::Tiny::XS::Util::get_linear_isa", TRUE);

    {
        SV* avref;
        dSP;

        ENTER;
        SAVETMPS;

        PUSHMARK(SP);
        mXPUSHp(HvNAME_get(stash), HvNAMELEN_get(stash));
        PUTBACK;

        call_sv((SV*)get_linear_isa, G_SCALAR);

        SPAGAIN;
        avref = POPs;
        PUTBACK;

        if(IsArrayRef(avref)){
            AV* const av  = (AV*)SvRV(avref);
            I32 const len = AvFILLp(av) + 1;
            I32 i;

            for(i = 0; i < len; i++){
                HV* const stash = gv_stashsv(AvARRAY(av)[i], FALSE);
                if(stash)
                    av_push(isa, newSVpv(HvNAME(stash), 0));
            }
            SvREADONLY_on(isa);
        }
        else{
            Perl_croak(aTHX_ "Type::Tiny::XS::Util::get_linear_isa() didn't return an ARRAY reference");
        }

        FREETMPS;
        LEAVE;
    }

    sv_setiv(gen, (IV)mro_get_pkg_gen(stash));
    return isa;
}
#endif /* !no_mor_get_linear_isa */

#ifdef DEBUGGING
SV*
typetiny_av_at_safe(pTHX_ AV* const av, I32 const ix){
    assert(av);
    assert(SvTYPE(av) == SVt_PVAV);
    assert(AvMAX(av) >= ix);
    return AvARRAY(av)[ix] ? AvARRAY(av)[ix] : &PL_sv_undef;
}
#endif

void
typetiny_throw_error(SV* const metaobject, SV* const data /* not used */, const char* const fmt, ...){
    dTHX;
    va_list args;
    SV* message;

    assert(metaobject);
    assert(fmt);

    va_start(args, fmt);
    message = vnewSVpvf(fmt, &args);
    va_end(args);

    {
        dSP;
        PUSHMARK(SP);
        EXTEND(SP, 6);

        PUSHs(metaobject);
        mPUSHs(message);

        if(data){ /* extra arg, might be useful for debugging */
            mPUSHs(newSVpvs("data"));
            PUSHs(data);
            mPUSHs(newSVpvs("depth"));
            mPUSHi(-1);
        }
        PUTBACK;
        if(SvOK(metaobject)) {
            call_method("throw_error", G_VOID);
        }
        else {
            call_pv("Type::Tiny::XS::Util::throw_error", G_VOID);
        }
        croak("throw_error() did not throw the error (%"SVf")", message);
    }
}

#if (PERL_BCDVERSION < 0x5014000)
/* workaround Perl-RT #69939 */
I32
typetiny_call_sv_safe(pTHX_ SV* const sv, I32 const flags) {
    I32 count;
    ENTER;
    /* Don't do SAVETMPS */

    SAVEGENERICSV(ERRSV); /* local $@ */
    ERRSV = newSV(0);

    count = Perl_call_sv(aTHX_ sv, flags | G_EVAL);

    if(sv_true(ERRSV)){
        SV* const err = sv_mortalcopy(ERRSV);
        LEAVE;
        sv_setsv(ERRSV, err);
        croak(NULL); /* rethrow */
    }

    LEAVE;

    return count;
}
#endif

void
typetiny_must_defined(pTHX_ SV* const value, const char* const name) {
    assert(value);
    assert(name);

    SvGETMAGIC(value);
    if(!SvOK(value)){
        croak("You must define %s", name);
    }
}

void
typetiny_must_ref(pTHX_ SV* const value, const char* const name, svtype const t) {
    assert(value);
    assert(name);

    SvGETMAGIC(value);
    if(!(SvROK(value) && (t == SVt_NULL || SvTYPE(SvRV(value)) == t))) {
        croak("You must pass %s, not %s",
            name, SvOK(value) ? SvPV_nolen(value) : "undef");
    }
}


bool
typetiny_is_class_loaded(pTHX_ SV * const klass){
    HV *stash;
    GV** gvp;
    HE* he;

    if (!(SvPOKp(klass) && SvCUR(klass))) { /* XXX: SvPOK does not work with magical scalars */
        return FALSE;
    }

    stash = gv_stashsv(klass, FALSE);
    if (!stash) {
        return FALSE;
    }

    if (( gvp = (GV**)hv_fetchs(stash, "VERSION", FALSE) )) {
        if(isGV(*gvp) && GvSV(*gvp) && SvOK(GvSV(*gvp))){
            return TRUE;
        }
    }

    if (( gvp = (GV**)hv_fetchs(stash, "ISA", FALSE) )) {
        if(isGV(*gvp) && GvAV(*gvp) && av_len(GvAV(*gvp)) != -1){
            return TRUE;
        }
    }

    hv_iterinit(stash);
    while(( he = hv_iternext(stash) )){
        GV* const gv = (GV*)HeVAL(he);

        if(isGV(gv)){
            if(GvCVu(gv)){ /* is GV and has CV */
                hv_iterinit(stash); /* reset */
                return TRUE;
            }
        }
        else if(SvOK(gv)){ /* is a stub or constant */
            hv_iterinit(stash); /* reset */
            return TRUE;
        }
    }
    return FALSE;
}


SV*
typetiny_call0 (pTHX_ SV* const self, SV* const method) {
    dSP;
    SV *ret;

    PUSHMARK(SP);
    XPUSHs(self);
    PUTBACK;

    call_sv_safe(method, G_SCALAR | G_METHOD);

    SPAGAIN;
    ret = POPs;
    PUTBACK;

    return ret;
}

SV*
typetiny_call1 (pTHX_ SV* const self, SV* const method, SV* const arg1) {
    dSP;
    SV *ret;

    PUSHMARK(SP);
    EXTEND(SP, 2);
    PUSHs(self);
    PUSHs(arg1);
    PUTBACK;

    call_sv_safe(method, G_SCALAR | G_METHOD);

    SPAGAIN;
    ret = POPs;
    PUTBACK;

    return ret;
}

int
typetiny_predicate_call(pTHX_ SV* const self, SV* const method) {
    return sv_true( mcall0(self, method) );
}

SV*
typetiny_get_metaclass(pTHX_ SV* metaclass_name){
    dMY_CXT;
    HE* he;

    assert(metaclass_name);
    assert(MY_CXT.metas);

    if(IsObject(metaclass_name)){
        HV* const stash = SvSTASH(SvRV(metaclass_name));

        metaclass_name = newSVpvn_share(HvNAME_get(stash), HvNAMELEN_get(stash), 0U);
        sv_2mortal(metaclass_name);
    }

    he = hv_fetch_ent(MY_CXT.metas, metaclass_name, FALSE, 0U);

    return he ? HeVAL(he) : &PL_sv_undef;
}

MAGIC*
typetiny_mg_find(pTHX_ SV* const sv, const MGVTBL* const vtbl, I32 const flags){
    MAGIC* mg;

    assert(sv != NULL);
    for(mg = SvMAGIC(sv); mg; mg = mg->mg_moremagic){
        if(mg->mg_virtual == vtbl){
            return mg;
        }
    }

    if(flags & TYPETINYf_DIE_ON_FAIL){
        croak("typetiny_mg_find: no MAGIC found for %"SVf, sv_2mortal(newRV_inc(sv)));
    }
    return NULL;
}

GV*
typetiny_stash_fetch(pTHX_ HV* const stash, const char* const name, I32 const namelen, I32 const create) {
    GV** const gvp = (GV**)hv_fetch(stash, name, namelen, create);

    if(gvp){
        if(!isGV(*gvp)){
            gv_init(*gvp, stash, name, namelen, GV_ADDMULTI);
        }
        return *gvp;
    }
    else{
        return NULL;
    }
}

void
typetiny_install_sub(pTHX_ GV* const gv, SV* const code_ref) {
    CV* cv;

    assert(gv != NULL);
    assert(code_ref != NULL);
    assert(isGV(gv));
    assert(IsCodeRef(code_ref));

    if(GvCVu(gv)){ /* delete *slot{gv} to work around "redefine" warning */
        SvREFCNT_dec(GvCV(gv));
        GvCV_set(gv, NULL);
    }

    sv_setsv_mg((SV*)gv, code_ref); /* *gv = $code_ref */

    /* name the CODE ref if it's anonymous */
    cv = (CV*)SvRV(code_ref);
    if(CvANON(cv)
        && CvGV(cv) /* a cv under construction has no gv */ ){
        HV* dbsub;

        /* update %DB::sub to make NYTProf happy */
        if((PL_perldb & (PERLDBf_SUBLINE|PERLDB_NAMEANON))
            && PL_DBsub && (dbsub = GvHV(PL_DBsub))
        ){
            /* see Perl_newATTRSUB() in op.c */
            SV* const subname = sv_newmortal();
            HE* orig;

            gv_efullname3(subname, CvGV(cv), NULL);
            orig = hv_fetch_ent(dbsub, subname, FALSE, 0U);
            if(orig){
                gv_efullname3(subname, gv, NULL);
                (void)hv_store_ent(dbsub, subname, HeVAL(orig), 0U);
                SvREFCNT_inc_simple_void_NN(HeVAL(orig));
            }
        }

        CvGV_set(cv, gv);
        CvANON_off(cv);
    }
}

MODULE = Type::Tiny::XS::Util  PACKAGE = Type::Tiny::XS::Util

PROTOTYPES:   DISABLE
VERSIONCHECK: DISABLE

BOOT:
{
    MY_CXT_INIT;
    MY_CXT.metas = NULL;
}

void
__register_metaclass_storage(HV* metas, bool cloning)
CODE:
{
    if(cloning){
        MY_CXT_CLONE;
        MY_CXT.metas = NULL;
    }
    {
        dMY_CXT;
        if(MY_CXT.metas && ckWARN(WARN_REDEFINE)){
            Perl_warner(aTHX_ packWARN(WARN_REDEFINE), "Metaclass storage more than once");
        }
        MY_CXT.metas = metas;
        SvREFCNT_inc_simple_void_NN(metas);
    }
}

bool
is_valid_class_name(SV* sv)
CODE:
{
    SvGETMAGIC(sv);
    if(SvPOKp(sv) && SvCUR(sv) > 0){
        UV i;
        RETVAL = TRUE;
        for(i = 0; i < SvCUR(sv); i++){
            char const c = SvPVX(sv)[i];
            if(!(isALNUM(c) || c == ':')){
                RETVAL = FALSE;
                break;
            }
        }
    }
    else{
        RETVAL = SvNIOKp(sv) ? TRUE : FALSE;
    }
}
OUTPUT:
    RETVAL

bool
is_class_loaded(SV* sv)

void
get_code_info(CV* code)
PREINIT:
    GV* gv;
    HV* stash;
PPCODE:
    if((gv = CvGV(code)) && isGV(gv) && (stash = GvSTASH(gv))){
        EXTEND(SP, 2);
        mPUSHs(newSVpvn_share(HvNAME_get(stash), HvNAMELEN_get(stash), 0U));
        mPUSHs(newSVpvn_share(GvNAME_get(gv), GvNAMELEN_get(gv), 0U));
    }

SV*
get_code_package(CV* code)
PREINIT:
    HV* stash;
CODE:
    if(CvGV(code) && isGV(CvGV(code)) && (stash = GvSTASH(CvGV(code)))){
        RETVAL = newSVpvn_share(HvNAME_get(stash), HvNAMELEN_get(stash), 0U);
    }
    else{
        RETVAL = &PL_sv_no;
    }
OUTPUT:
    RETVAL

CV*
get_code_ref(SV* package, SV* name)
CODE:
{
    HV* stash;
    STRLEN name_len;
    const char* name_pv;
    GV* gv;

    must_defined(package, "a package name");
    must_defined(name,    "a subroutine name");

    stash = gv_stashsv(package, FALSE);
    if(!stash){
        XSRETURN_UNDEF;
    }

    name_pv = SvPV_const(name, name_len);
    gv = stash_fetch(stash, name_pv, name_len, FALSE);
    RETVAL = gv ? GvCVu(gv) : NULL;

    if(!RETVAL){
        XSRETURN_UNDEF;
    }
}
OUTPUT:
    RETVAL

void
generate_isa_predicate_for(SV* arg, SV* predicate_name = NULL)
ALIAS:
    generate_isa_predicate_for = 0
    generate_can_predicate_for = 1
PPCODE:
{
    const char* name_pv = NULL;
    CV* xsub;

    must_defined(arg, ix == 0 ? "a class_name" : "method names");

    if(predicate_name){
        must_defined(predicate_name, "a predicate name");
        name_pv = SvPV_nolen_const(predicate_name);
    }

    if(ix == 0){
        xsub = typetiny_generate_isa_predicate_for(aTHX_ arg, name_pv);
    }
    else{
        xsub = typetiny_generate_can_predicate_for(aTHX_ arg, name_pv);
    }

    if(predicate_name == NULL){ /* anonymous predicate */
        mXPUSHs( newRV_inc((SV*)xsub) );
    }
}

# This xsub will redefine &Type::Tiny::XS::Util::install_subroutines()
void
install_subroutines(SV* into, ...)
CODE:
{
    HV* stash;
    I32 i;

    must_defined(into, "a package name");
    stash = gv_stashsv(into, TRUE);

    if( ((items-1) % 2) != 0 ){
        croak_xs_usage(cv, "into, name => coderef [, other_name, other_coderef ...]");
    }

    for(i = 1; i < items; i += 2) {
        SV* const name = ST(i);
        SV* const code = ST(i+1);
        STRLEN len;
        const char* pv;
        GV* gv;

        must_defined(name, "a subroutine name");
        must_ref(code, "a CODE reference", SVt_PVCV);

        pv = SvPV_const(name, len);
        gv = stash_fetch(stash, pv, len, TRUE);

        typetiny_install_sub(aTHX_ gv, code);
    }
}