import pytest


pytest.importorskip("xarray")
pytestmark = pytest.mark.filterwarnings("error")

import inspect
import re
from copy import deepcopy

import numpy as np
from xarray import DataArray

import pytensor.tensor.random as ptr
import pytensor.xtensor.random as pxr
from pytensor import config, function, shared
from pytensor.graph import rewrite_graph
from pytensor.graph.basic import equal_computations
from pytensor.tensor import broadcast_arrays, tensor
from pytensor.tensor.random.op import RandomVariable
from pytensor.tensor.random.type import random_generator_type
from pytensor.xtensor import as_xtensor, xtensor
from pytensor.xtensor.random import (
    categorical,
    multinomial,
    multivariate_normal,
    normal,
)
from pytensor.xtensor.vectorization import XRV
from tests.xtensor.util import check_vectorization


def lower_rewrite(vars):
    return rewrite_graph(
        vars,
        include=(
            "lower_xtensor",
            "canonicalize",
        ),
    )


def test_all_basic_rvs_are_wrapped():
    # This ignores wrapper functions
    pxr_members = {name for name, _ in inspect.getmembers(pxr)}
    for name, op in inspect.getmembers(ptr.basic):
        if name in "_gamma":
            name = "gamma"
        if isinstance(op, RandomVariable) and name not in pxr_members:
            raise NotImplementedError(f"Variable {name} not implemented as XRV")


def test_updates():
    rng = shared(np.random.default_rng(40))
    next_rng, draws = normal(0, 1, rng=rng).owner.outputs
    fn = function([], [draws], updates=[(rng, next_rng)])
    res1, res2 = fn(), fn()

    rng = np.random.default_rng(40)
    expected_res1, expected_res2 = rng.normal(0, 1), rng.normal(0, 1)
    np.testing.assert_allclose(res1, expected_res1)
    np.testing.assert_allclose(res2, expected_res2)


def test_zero_inputs():
    class ZeroInputRV(RandomVariable):
        signature = "->()"
        dtype = "floatX"
        name = "ZeroInputRV"

        @classmethod
        def rng_fn(cls, rng, size=None):
            return rng.random(size=size)

    zero_input_rv = ZeroInputRV()
    zero_input_xrv = XRV(zero_input_rv, core_dims=((), ()), extra_dims=["a"])

    rng = random_generator_type("rng")
    a_size = xtensor("a_size", dims=(), dtype=int)
    rv = zero_input_xrv(rng, a_size)
    assert rv.type.dims == ("a",)
    assert rv.type.shape == (None,)

    rng_test = np.random.default_rng(12345)
    a_size_val = np.array(5)
    np.testing.assert_allclose(
        rv.eval({rng: rng_test, a_size: a_size_val}),
        rng_test.random(size=(a_size_val,)),
    )


def test_output_dim_does_not_map_from_input_dims():
    class NewDimRV(RandomVariable):
        signature = "()->(p)"
        dtype = "floatX"
        name = "NewDimRV"

        @classmethod
        def rng_fn(cls, rng, n, size=None):
            r = np.stack([n, n + 1], axis=-1)
            if size is None:
                return r
            return np.broadcast_to(r, (*size, 2))

        def _supp_shape_from_params(self, dist_params, param_shapes=None):
            return (2,)

    new_dim_rv = NewDimRV()
    new_dim_xrv = XRV(new_dim_rv, core_dims=(((),), ("p",)), extra_dims=["a"])

    a_size = xtensor("a_size", dims=(), dtype=int)
    rv = new_dim_xrv(None, a_size, 1)
    assert rv.type.dims == ("a", "p")
    assert rv.type.shape == (None, 2)

    a_size_val = np.array(5)
    np.testing.assert_allclose(
        rv.eval({a_size: a_size_val}), np.broadcast_to((1, 2), (a_size_val, 2))
    )


def test_dtype():
    x = normal(0, 1)
    assert x.type.dtype == config.floatX

    with config.change_flags(floatX="float64"):
        x = normal(0, 1)
    assert x.type.dtype == "float64"

    with config.change_flags(floatX="float32"):
        x = normal(0, 1)
    assert x.type.dtype == "float32"


def test_normal():
    rng = random_generator_type("rng")
    c_size = tensor("c_size", shape=(), dtype=int)
    mu = tensor("mu", shape=(3,))
    sigma = tensor("sigma", shape=(2,))

    mu_val = np.array([-10, 0.0, 10.0])
    sigma_val = np.array([1.0, 10.0])
    c_size_val = np.array(5)
    rng_val = np.random.default_rng(12345)

    c_size_xr = as_xtensor(c_size, name="c_size_xr")
    mu_xr = as_xtensor(mu, dims=("mu_dim",), name="mu_xr")
    sigma_xr = as_xtensor(sigma, dims=("sigma_dim",), name="sigma_xr")

    out = normal(mu_xr, sigma_xr, rng=rng)
    assert out.type.dims == ("mu_dim", "sigma_dim")
    assert out.type.shape == (3, 2)
    assert equal_computations(
        [lower_rewrite(out.values)],
        [rewrite_graph(ptr.normal(mu[:, None], sigma[None, :], rng=rng))],
    )

    out_eval = out.eval(
        {
            mu: mu_val,
            sigma: sigma_val,
            rng: rng_val,
        }
    )
    out_expected = deepcopy(rng_val).normal(mu_val[:, None], sigma_val[None, :])
    np.testing.assert_allclose(out_eval, out_expected)

    # Test with batch dimension
    out = normal(mu_xr, sigma_xr, extra_dims=dict(c_dim=c_size_xr), rng=rng)
    assert out.type.dims == ("c_dim", "mu_dim", "sigma_dim")
    assert out.type.shape == (None, 3, 2)
    lowered_size = (c_size, *broadcast_arrays(mu[:, None], sigma[None, :])[0].shape)
    assert equal_computations(
        [lower_rewrite(out.values)],
        [
            rewrite_graph(
                ptr.normal(mu[:, None], sigma[None, :], size=lowered_size, rng=rng)
            )
        ],
    )
    out_eval = out.eval(
        {
            mu: mu_val,
            sigma: sigma_val,
            c_size: c_size_val,
            rng: rng_val,
        }
    )
    out_expected = deepcopy(rng_val).normal(
        mu_val[:, None],
        sigma_val[None, :],
        size=(c_size_val, mu_val.shape[0], sigma_val.shape[0]),
    )
    np.testing.assert_allclose(out_eval, out_expected)

    # Test invalid core_dims
    with pytest.raises(
        ValueError,
        match=re.escape("normal needs 0 core_dims, but got 1"),
    ):
        normal(mu_xr, sigma_xr, core_dims=("a",), rng=rng)

    # Test Invalid extra_dims (conflicting with existing batch dims)
    with pytest.raises(
        ValueError,
        match=re.escape(
            "Size dimensions ['mu_dim'] conflict with parameter dimensions. They should be unique."
        ),
    ):
        pxr.normal(mu_xr, sigma_xr, extra_dims=dict(mu_dim=c_size_xr), rng=rng)


def test_categorical():
    rng = random_generator_type("rng")
    p = tensor("p", shape=(2, 3))
    c_size = tensor("c", shape=(), dtype=int)

    p_xr = as_xtensor(p, dims=("p", "batch_dim"), name="p_xr")
    c_size_xr = as_xtensor(c_size, name="c_size_xr")

    out = categorical(p_xr, core_dims=("p",), rng=rng)
    assert out.type.dims == ("batch_dim",)
    assert out.type.shape == (3,)
    assert equal_computations(
        [lower_rewrite(out.values)], [ptr.categorical(p.T, rng=rng)]
    )
    np.testing.assert_allclose(
        out.eval(
            {
                p: np.array([[1.0, 0], [0, 1.0], [1.0, 0]]).T,
                rng: np.random.default_rng(),
            }
        ),
        np.array([0, 1, 0]),
    )

    out = categorical(
        p_xr, core_dims=("p",), extra_dims=dict(cp1=c_size_xr + 1, c=c_size_xr), rng=rng
    )
    assert out.type.dims == ("cp1", "c", "batch_dim")
    assert out.type.shape == (None, None, 3)
    assert equal_computations(
        [lower_rewrite(out.values)],
        [
            rewrite_graph(
                ptr.categorical(
                    p.T, size=(1 + c_size, c_size, p[0].shape.squeeze()), rng=rng
                )
            )
        ],
    )
    np.testing.assert_allclose(
        out.eval(
            {
                p: np.array([[1.0, 0.0], [0.0, 1.0], [1.0, 0.0]]).T,
                c_size: np.array(5),
                rng: np.random.default_rng(),
            }
        ),
        np.broadcast_to([0, 1, 0], shape=(6, 5, 3)),
    )

    # Test invaild core dims
    with pytest.raises(
        ValueError, match="categorical needs 1 core_dims to be specified"
    ):
        categorical(p_xr, rng=rng)

    with pytest.raises(
        ValueError,
        match=re.escape(
            "At least one core dim=('px',) missing from input p_xr with dims=('p', 'batch_dim')"
        ),
    ):
        categorical(p_xr, core_dims=("px",), rng=rng)


def test_multinomial():
    rng = random_generator_type("rng")
    n = tensor("n", shape=(2,))
    p = tensor("p", shape=(3, None))
    c_size = tensor("c", shape=(), dtype=int)
    n_xr = as_xtensor(n, dims=("a",), name="a_xr")
    p_xr = as_xtensor(p, dims=("p", "a"), name="p_xr")
    c_size_xr = as_xtensor(c_size, name="c_size_xr")
    a_size_xr = n_xr.sizes["a"]

    out = multinomial(n_xr, p_xr, core_dims=("p",), rng=rng)
    assert out.type.dims == ("a", "p")
    assert out.type.shape == (2, 3)
    assert equal_computations(
        [lower_rewrite(out.values)],
        [ptr.multinomial(n, p.T, size=None, rng=rng)],
    )
    # Test we can actually evaluate it
    np.testing.assert_allclose(
        out.eval(
            {
                n: [5, 10],
                p: np.array([[1.0, 0, 0], [0, 0, 1.0]]).T,
                rng: np.random.default_rng(),
            }
        ),
        np.array([[5, 0, 0], [0, 0, 10]]),
    )

    out = multinomial(
        n_xr, p_xr, core_dims=("p",), extra_dims=dict(c=c_size_xr), rng=rng
    )
    assert out.type.dims == ("c", "a", "p")
    assert equal_computations(
        [lower_rewrite(out.values)],
        [rewrite_graph(ptr.multinomial(n, p.T, size=(c_size, n.shape[0]), rng=rng))],
    )

    # Test we can actually evaluate it with extra_dims
    np.testing.assert_allclose(
        out.eval(
            {
                n: [5, 10],
                p: np.array([[1.0, 0, 0], [0, 0, 1.0]]).T,
                c_size: 5,
                rng: np.random.default_rng(),
            }
        ),
        np.broadcast_to(
            [[5, 0, 0], [0, 0, 10]],
            shape=(5, 2, 3),
        ),
    )

    # Test invalid core_dims
    with pytest.raises(
        ValueError, match="multinomial needs 1 core_dims to be specified"
    ):
        multinomial(n_xr, p_xr, rng=rng)

    with pytest.raises(ValueError, match="multinomial needs 1 core_dims, but got 2"):
        multinomial(n_xr, p_xr, core_dims=("p1", "p2"), rng=rng)

    with pytest.raises(
        ValueError, match=re.escape("Parameter a_xr has invalid core dimensions ['a']")
    ):
        # n cannot have a core dimension
        multinomial(n_xr, p_xr, core_dims=("a",), rng=rng)

    with pytest.raises(
        ValueError,
        match=re.escape(
            "At least one core dim=('px',) missing from input p_xr with dims=('p', 'a')"
        ),
    ):
        multinomial(n_xr, p_xr, core_dims=("px",), rng=rng)

    # Test invalid extra_dims
    with pytest.raises(
        ValueError,
        match=re.escape(
            "Size dimensions ['a'] conflict with parameter dimensions. They should be unique."
        ),
    ):
        multinomial(
            n_xr,
            p_xr,
            core_dims=("p",),
            extra_dims=dict(c=c_size_xr, a=a_size_xr),
            rng=rng,
        )


def test_multivariate_normal():
    rng = random_generator_type("rng")
    mu = tensor("mu", shape=(4, 2))
    cov = tensor("cov", shape=(2, 3, 2, 4))

    mu_xr = as_xtensor(mu, dims=("b1", "rows"), name="mu_xr")
    cov_xr = as_xtensor(cov, dims=("cols", "b2", "rows", "b1"), name="cov_xr")

    out = multivariate_normal(mu_xr, cov_xr, core_dims=("rows", "cols"), rng=rng)
    assert out.type.dims == ("b1", "b2", "rows")
    assert out.type.shape == (4, 3, 2)
    assert equal_computations(
        [lower_rewrite(out.values)],
        [ptr.multivariate_normal(mu[:, None], cov.transpose(3, 1, 2, 0), rng=rng)],
    )

    # Order of core_dims doesn't matter
    out = multivariate_normal(mu_xr, cov_xr, core_dims=("cols", "rows"), rng=rng)
    assert out.type.dims == ("b1", "b2", "rows")
    assert out.type.shape == (4, 3, 2)
    assert equal_computations(
        [lower_rewrite(out.values)],
        [ptr.multivariate_normal(mu[:, None], cov.transpose(3, 1, 2, 0), rng=rng)],
    )

    # Test method
    out = multivariate_normal(
        mu_xr, cov_xr, core_dims=("rows", "cols"), rng=rng, method="svd"
    )
    assert equal_computations(
        [lower_rewrite(out.values)],
        [
            ptr.multivariate_normal(
                mu[:, None], cov.transpose(3, 1, 2, 0), rng=rng, method="svd"
            )
        ],
    )

    # Test invalid core_dims
    with pytest.raises(
        TypeError,
        match=re.escape(
            "multivariate_normal() missing 1 required keyword-only argument: 'core_dims'"
        ),
    ):
        multivariate_normal(mu_xr, cov_xr)

    with pytest.raises(
        ValueError, match="multivariate_normal requires 2 core_dims, got 3"
    ):
        multivariate_normal(mu_xr, cov_xr, core_dims=("b1", "rows", "cols"))

    with pytest.raises(
        ValueError, match=re.escape("Operand has repeated dims ('rows', 'rows')")
    ):
        multivariate_normal(mu_xr, cov_xr, core_dims=("rows", "rows"))

    with pytest.raises(
        ValueError,
        match=re.escape("Parameter mu_xr has invalid core dimensions ['b1']"),
    ):
        # mu cannot have two core_dims
        multivariate_normal(mu_xr, cov_xr, core_dims=("rows", "b1"))

    with pytest.raises(
        ValueError,
        match=re.escape(
            "At least one core dim=('rows', 'missing_cols') missing from input cov_xr with dims=('cols', 'b2', 'rows', 'b1')"
        ),
    ):
        # cov must have both core_dims
        multivariate_normal(mu_xr, cov_xr, core_dims=("rows", "missing_cols"))


def test_xrv_vectorize():
    # Note: We only need to test a couple Ops, since the vectorization logic is not Op specific

    n = xtensor("n", dims=("n",), shape=(3,), dtype=int)
    pna = xtensor("p", dims=("p", "n", "a"), shape=(5, 3, 2))
    out = multinomial(n, pna, core_dims=("p",), extra_dims={"extra": 5})
    check_vectorization(
        [n, pna],
        [out],
        input_vals=[
            DataArray([3, 5, 10], dims=("n",)),
            DataArray(
                np.random.multinomial(n=1, pvals=np.ones(5) / 5, size=(2, 3)).T,
                dims=("p", "n", "a"),
            ),
        ],
    )


def test_xrv_batch_extra_dim_vectorize():
    # TODO: Check it raises NotImplementedError when we try to batch the extra_dim of an xrv
    pass
