import math
import operator
from llvmlite import ir
from numba.core import types, typing, utils
from numba.core.imputils import Registry
from numba.types import float32, float64, int64, uint64
from numba.cuda import libdevice

registry = Registry()
lower = registry.lower


booleans = []
booleans += [('isnand', 'isnanf', math.isnan)]
booleans += [('isinfd', 'isinff', math.isinf)]
booleans += [('isfinited', 'finitef', math.isfinite)]

unarys = []
unarys += [('ceil', 'ceilf', math.ceil)]
unarys += [('floor', 'floorf', math.floor)]
unarys += [('fabs', 'fabsf', math.fabs)]
unarys += [('exp', 'expf', math.exp)]
unarys += [('expm1', 'expm1f', math.expm1)]
unarys += [('erf', 'erff', math.erf)]
unarys += [('erfc', 'erfcf', math.erfc)]
unarys += [('tgamma', 'tgammaf', math.gamma)]
unarys += [('lgamma', 'lgammaf', math.lgamma)]
unarys += [('sqrt', 'sqrtf', math.sqrt)]
unarys += [('log', 'logf', math.log)]
unarys += [('log2', 'log2f', math.log2)]
unarys += [('log10', 'log10f', math.log10)]
unarys += [('log1p', 'log1pf', math.log1p)]
unarys += [('acosh', 'acoshf', math.acosh)]
unarys += [('acos', 'acosf', math.acos)]
unarys += [('cos', 'cosf', math.cos)]
unarys += [('cosh', 'coshf', math.cosh)]
unarys += [('asinh', 'asinhf', math.asinh)]
unarys += [('asin', 'asinf', math.asin)]
unarys += [('sin', 'sinf', math.sin)]
unarys += [('sinh', 'sinhf', math.sinh)]
unarys += [('atan', 'atanf', math.atan)]
unarys += [('atanh', 'atanhf', math.atanh)]
unarys += [('tan', 'tanf', math.tan)]
unarys += [('tanh', 'tanhf', math.tanh)]

unarys_fastmath = {}
unarys_fastmath['cosf'] = 'fast_cosf'
unarys_fastmath['sinf'] = 'fast_sinf'
unarys_fastmath['tanf'] = 'fast_tanf'
unarys_fastmath['expf'] = 'fast_expf'
unarys_fastmath['log2f'] = 'fast_log2f'
unarys_fastmath['log10f'] = 'fast_log10f'
unarys_fastmath['logf'] = 'fast_logf'

binarys = []
binarys += [('copysign', 'copysignf', math.copysign)]
binarys += [('atan2', 'atan2f', math.atan2)]
binarys += [('pow', 'powf', math.pow)]
binarys += [('fmod', 'fmodf', math.fmod)]
binarys += [('hypot', 'hypotf', math.hypot)]
if utils.PYVERSION >= (3, 7):
    binarys += [('remainder', 'remainderf', math.remainder)]

binarys_fastmath = {}
binarys_fastmath['powf'] = 'fast_powf'


@lower(math.isinf, types.Integer)
@lower(math.isnan, types.Integer)
def math_isinf_isnan_int(context, builder, sig, args):
    return context.get_constant(types.boolean, 0)


@lower(math.isfinite, types.Integer)
def math_isfinite_int(context, builder, sig, args):
    return context.get_constant(types.boolean, 1)


def impl_boolean(key, ty, libfunc):
    def lower_boolean_impl(context, builder, sig, args):
        libfunc_impl = context.get_function(libfunc,
                                            typing.signature(types.int32, ty))
        result = libfunc_impl(builder, args)
        return context.cast(builder, result, types.int32, types.boolean)

    lower(key, ty)(lower_boolean_impl)


def impl_unary(key, ty, libfunc):
    def lower_unary_impl(context, builder, sig, args):
        actual_libfunc = libfunc
        fast_replacement = None
        if ty == float32 and context.fastmath:
            fast_replacement = unarys_fastmath.get(libfunc.__name__)

        if fast_replacement is not None:
            actual_libfunc = getattr(libdevice, fast_replacement)

        libfunc_impl = context.get_function(actual_libfunc,
                                            typing.signature(ty, ty))
        return libfunc_impl(builder, args)

    lower(key, ty)(lower_unary_impl)


def impl_unary_int(key, ty, libfunc):
    def lower_unary_int_impl(context, builder, sig, args):
        if sig.args[0] == int64:
            convert = builder.sitofp
        elif sig.args[0] == uint64:
            convert = builder.uitofp
        else:
            m = 'Only 64-bit integers are supported for generic unary int ops'
            raise TypeError(m)

        arg = convert(args[0], ir.DoubleType())
        sig = typing.signature(float64, float64)
        libfunc_impl = context.get_function(libfunc, sig)
        return libfunc_impl(builder, [arg])

    lower(key, ty)(lower_unary_int_impl)


def impl_binary(key, ty, libfunc):
    def lower_binary_impl(context, builder, sig, args):
        actual_libfunc = libfunc
        fast_replacement = None
        if ty == float32 and context.fastmath:
            fast_replacement = binarys_fastmath.get(libfunc.__name__)

        if fast_replacement is not None:
            actual_libfunc = getattr(libdevice, fast_replacement)

        libfunc_impl = context.get_function(actual_libfunc,
                                            typing.signature(ty, ty, ty))
        return libfunc_impl(builder, args)

    lower(key, ty, ty)(lower_binary_impl)


def impl_binary_int(key, ty, libfunc):
    def lower_binary_int_impl(context, builder, sig, args):
        if sig.args[0] == int64:
            convert = builder.sitofp
        elif sig.args[0] == uint64:
            convert = builder.uitofp
        else:
            m = 'Only 64-bit integers are supported for generic binary int ops'
            raise TypeError(m)

        args = [convert(arg, ir.DoubleType()) for arg in args]
        sig = typing.signature(float64, float64, float64)
        libfunc_impl = context.get_function(libfunc, sig)
        return libfunc_impl(builder, args)

    lower(key, ty, ty)(lower_binary_int_impl)


for fname64, fname32, key in booleans:
    impl32 = getattr(libdevice, fname32)
    impl64 = getattr(libdevice, fname64)
    impl_boolean(key, float32, impl32)
    impl_boolean(key, float64, impl64)


for fname64, fname32, key in unarys:
    impl32 = getattr(libdevice, fname32)
    impl64 = getattr(libdevice, fname64)
    impl_unary(key, float32, impl32)
    impl_unary(key, float64, impl64)
    impl_unary_int(key, int64, impl64)
    impl_unary_int(key, uint64, impl64)


for fname64, fname32, key in binarys:
    impl32 = getattr(libdevice, fname32)
    impl64 = getattr(libdevice, fname64)
    impl_binary(key, float32, impl32)
    impl_binary(key, float64, impl64)
    impl_binary_int(key, int64, impl64)
    impl_binary_int(key, uint64, impl64)


def impl_pow_int(ty, libfunc):
    def lower_pow_impl_int(context, builder, sig, args):
        powi_sig = typing.signature(ty, ty, types.int32)
        libfunc_impl = context.get_function(libfunc, powi_sig)
        return libfunc_impl(builder, args)

    lower(math.pow, ty, types.int32)(lower_pow_impl_int)


impl_pow_int(types.float32, libdevice.powif)
impl_pow_int(types.float64, libdevice.powi)


def impl_modf(ty, libfunc):
    retty = types.UniTuple(ty, 2)

    def lower_modf_impl(context, builder, sig, args):
        modf_sig = typing.signature(retty, ty)
        libfunc_impl = context.get_function(libfunc, modf_sig)
        return libfunc_impl(builder, args)

    lower(math.modf, ty)(lower_modf_impl)


impl_modf(types.float32, libdevice.modff)
impl_modf(types.float64, libdevice.modf)


def impl_frexp(ty, libfunc):
    retty = types.Tuple((ty, types.int32))

    def lower_frexp_impl(context, builder, sig, args):
        frexp_sig = typing.signature(retty, ty)
        libfunc_impl = context.get_function(libfunc, frexp_sig)
        return libfunc_impl(builder, args)

    lower(math.frexp, ty)(lower_frexp_impl)


impl_frexp(types.float32, libdevice.frexpf)
impl_frexp(types.float64, libdevice.frexp)


def impl_ldexp(ty, libfunc):
    def lower_ldexp_impl(context, builder, sig, args):
        ldexp_sig = typing.signature(ty, ty, types.int32)
        libfunc_impl = context.get_function(libfunc, ldexp_sig)
        return libfunc_impl(builder, args)

    lower(math.ldexp, ty, types.int32)(lower_ldexp_impl)


impl_ldexp(types.float32, libdevice.ldexpf)
impl_ldexp(types.float64, libdevice.ldexp)


# Complex power implementations - translations of _Py_c_pow from CPython
# https://github.com/python/cpython/blob/a755410e054e1e2390de5830befc08fe80706c66/Objects/complexobject.c#L123-L151
#
# The complex64 variant casts all constants and some variables to ensure that
# as much computation is done in single precision as possible. A small number
# of operations are still done in 64-bit, but these come from libdevice code.

def cpow_implement(fty, cty):
    def core(context, builder, sig, args):
        def cpow_internal(a, b):

            if b.real == fty(0.0) and b.imag == fty(0.0):
                return cty(1.0) + cty(0.0j)
            elif a.real == fty(0.0) and b.real == fty(0.0):
                return cty(0.0) + cty(0.0j)

            vabs = math.hypot(a.real, a.imag)
            len = math.pow(vabs, b.real)
            at = math.atan2(a.imag, a.real)
            phase = at * b.real
            if b.imag != fty(0.0):
                len /= math.exp(at * b.imag)
                phase += b.imag * math.log(vabs)

            return len * (cty(math.cos(phase)) +
                          cty(math.sin(phase) * cty(1.0j)))

        return context.compile_internal(builder, cpow_internal, sig, args)

    lower(operator.pow, cty, cty)(core)
    lower(operator.ipow, cty, cty)(core)
    lower(pow, cty, cty)(core)


cpow_implement(types.float32, types.complex64)
cpow_implement(types.float64, types.complex128)
