/*
  math.c
  Ruby/Numo::NArray - Numerical Array class for Ruby
    Copyright (C) 1999-2020 Masahiro TANAKA
*/
#include <ruby.h>
#include "numo/narray.h"

VALUE numo_mNMath;
extern VALUE numo_mDFloatMath, numo_mDComplexMath;
extern VALUE numo_mSFloatMath, numo_mSComplexMath;
static ID id_send;
static ID id_UPCAST;
static ID id_DISPATCH;
static ID id_extract;

static VALUE
nary_type_s_upcast(VALUE type1, VALUE type2)
{
    VALUE upcast_hash;
    VALUE result_type;

    if (type1==type2) return type1;
    upcast_hash = rb_const_get(type1, id_UPCAST);
    result_type = rb_hash_aref(upcast_hash, type2);
    if (NIL_P(result_type)) {
        if (TYPE(type2)==T_CLASS) {
            if ( RTEST(rb_class_inherited_p(type2,cNArray)) ) {
                upcast_hash = rb_const_get(type2, id_UPCAST);
                result_type = rb_hash_aref(upcast_hash, type1);
            }
        }
    }
    return result_type;
}


static VALUE nary_math_cast2(VALUE type1, VALUE type2)
{
    if ( RTEST(rb_class_inherited_p( type1, cNArray )) ){
	return nary_type_s_upcast( type1, type2 );
    }
    if ( RTEST(rb_class_inherited_p( type2, cNArray )) ){
	return nary_type_s_upcast( type2, type1 );
    }
    if ( RTEST(rb_class_inherited_p( type1, rb_cNumeric )) &&
	 RTEST(rb_class_inherited_p( type2, rb_cNumeric )) ){
	if ( RTEST(rb_class_inherited_p( type1, rb_cComplex)) ||
	     RTEST(rb_class_inherited_p( type2, rb_cComplex )) ){
	    return rb_cComplex;
	}
	return rb_cFloat;
    }
    return type2;
}


VALUE na_ary_composition_dtype(VALUE);

static VALUE nary_mathcast(int argc, VALUE *argv)
{
    VALUE type, type2;
    int i;

    type = na_ary_composition_dtype(argv[0]);
    for (i=1; i<argc; i++) {
        type2 = na_ary_composition_dtype(argv[i]);
        type = nary_math_cast2(type, type2);
        if (NIL_P(type)) {
            rb_raise(rb_eTypeError,"includes unknown DataType for upcast");
        }
    }
    return type;
}


/*
  Dispatches method to Math module of upcasted type,
  eg, Numo::DFloat::Math.
  @overload method_missing(name,x,...)
  @param [Symbol] name  method name.
  @param [NArray,Numeric] x  input array.
  @return [NArray] result.
*/
static VALUE nary_math_method_missing(int argc, VALUE *argv, VALUE mod)
{
    VALUE type, ans, typemod, hash;
    if (argc>1) {
	type = nary_mathcast(argc-1,argv+1);

	hash = rb_const_get(mod, id_DISPATCH);
	typemod = rb_hash_aref( hash, type );
	if (NIL_P(typemod)) {
	    rb_raise(rb_eTypeError,"%s is unknown for Numo::NMath",
		     rb_class2name(type));
	}

	ans = rb_funcall2(typemod,id_send,argc,argv);

	if (!RTEST(rb_class_inherited_p(type,cNArray)) &&
	    IsNArray(ans) ) {
	    ans = rb_funcall(ans,id_extract,0);
	}
	return ans;
    }
    rb_raise(rb_eArgError,"argument or method missing");
    return Qnil;
}


void
Init_nary_math()
{
    VALUE hCast;

    numo_mNMath = rb_define_module_under(mNumo, "NMath");
    rb_define_singleton_method(numo_mNMath, "method_missing", nary_math_method_missing, -1);

    hCast = rb_hash_new();
    rb_define_const(numo_mNMath, "DISPATCH", hCast);
    rb_hash_aset(hCast, numo_cInt64,    numo_mDFloatMath);
    rb_hash_aset(hCast, numo_cInt32,    numo_mDFloatMath);
    rb_hash_aset(hCast, numo_cInt16,    numo_mDFloatMath);
    rb_hash_aset(hCast, numo_cInt8,     numo_mDFloatMath);
    rb_hash_aset(hCast, numo_cUInt64,   numo_mDFloatMath);
    rb_hash_aset(hCast, numo_cUInt32,   numo_mDFloatMath);
    rb_hash_aset(hCast, numo_cUInt16,   numo_mDFloatMath);
    rb_hash_aset(hCast, numo_cUInt8,    numo_mDFloatMath);
    rb_hash_aset(hCast, numo_cDFloat,   numo_mDFloatMath);
    rb_hash_aset(hCast, numo_cDFloat,   numo_mDFloatMath);
    rb_hash_aset(hCast, numo_cDComplex, numo_mDComplexMath);
    rb_hash_aset(hCast, numo_cSFloat,   numo_mSFloatMath);
    rb_hash_aset(hCast, numo_cSComplex, numo_mSComplexMath);
#ifdef RUBY_INTEGER_UNIFICATION
    rb_hash_aset(hCast, rb_cInteger, rb_mMath);
#else
    rb_hash_aset(hCast, rb_cFixnum,  rb_mMath);
    rb_hash_aset(hCast, rb_cBignum,  rb_mMath);
#endif
    rb_hash_aset(hCast, rb_cFloat,   rb_mMath);
    rb_hash_aset(hCast, rb_cComplex, numo_mDComplexMath);

    id_send     = rb_intern("send");
    id_UPCAST   = rb_intern("UPCAST");
    id_DISPATCH = rb_intern("DISPATCH");
    id_extract  = rb_intern("extract");
}