"""Base types and utilities for Graph Bolt."""

from dataclasses import dataclass

import torch
from torch.utils.data import functional_datapipe
from torchdata.datapipes.iter import IterDataPipe

from ..utils import recursive_apply

__all__ = [
    "CANONICAL_ETYPE_DELIMITER",
    "ORIGINAL_EDGE_ID",
    "etype_str_to_tuple",
    "etype_tuple_to_str",
    "CopyTo",
    "isin",
    "CSCFormatBase",
    "seed",
]

CANONICAL_ETYPE_DELIMITER = ":"
ORIGINAL_EDGE_ID = "_ORIGINAL_EDGE_ID"


def seed(val):
    """Set the random seed of Graphbolt.

    Parameters
    ----------
    val : int
        The seed.
    """
    torch.ops.graphbolt.set_seed(val)


def isin(elements, test_elements):
    """Tests if each element of elements is in test_elements. Returns a boolean
    tensor of the same shape as elements that is True for elements in
    test_elements and False otherwise.

    Parameters
    ----------
    elements : torch.Tensor
        A 1D tensor represents the input elements.
    test_elements : torch.Tensor
        A 1D tensor represents the values to test against for each input.

    Examples
    --------
    >>> isin(torch.tensor([1, 2, 3, 4]), torch.tensor([2, 3]))
    tensor([[False,  True,  True,  False]])
    """
    assert elements.dim() == 1, "Elements should be 1D tensor."
    assert test_elements.dim() == 1, "Test_elements should be 1D tensor."
    return torch.ops.graphbolt.isin(elements, test_elements)


def etype_tuple_to_str(c_etype):
    """Convert canonical etype from tuple to string.

    Examples
    --------
    >>> c_etype = ("user", "like", "item")
    >>> c_etype_str = _etype_tuple_to_str(c_etype)
    >>> print(c_etype_str)
    "user:like:item"
    """
    assert isinstance(c_etype, tuple) and len(c_etype) == 3, (
        "Passed-in canonical etype should be in format of (str, str, str). "
        f"But got {c_etype}."
    )
    return CANONICAL_ETYPE_DELIMITER.join(c_etype)


def etype_str_to_tuple(c_etype):
    """Convert canonical etype from string to tuple.

    Examples
    --------
    >>> c_etype_str = "user:like:item"
    >>> c_etype = _etype_str_to_tuple(c_etype_str)
    >>> print(c_etype)
    ("user", "like", "item")
    """
    if isinstance(c_etype, tuple):
        return c_etype
    ret = tuple(c_etype.split(CANONICAL_ETYPE_DELIMITER))
    assert len(ret) == 3, (
        "Passed-in canonical etype should be in format of 'str:str:str'. "
        f"But got {c_etype}."
    )
    return ret


def apply_to(x, device):
    """Apply `to` function to object x only if it has `to`."""

    return x.to(device) if hasattr(x, "to") else x


@functional_datapipe("copy_to")
class CopyTo(IterDataPipe):
    """DataPipe that transfers each element yielded from the previous DataPipe
    to the given device. For MiniBatch, only the related attributes
    (automatically inferred) will be transferred by default. If you want to
    transfer any other attributes, indicate them in the `extra_attrs`.

    Functional name: :obj:`copy_to`.

    This is equivalent to

    .. code:: python

       for data in datapipe:
           yield data.to(device)

    Parameters
    ----------
    datapipe : DataPipe
        The DataPipe.
    device : torch.device
        The PyTorch CUDA device.
    extra_attrs: List[string]
        The extra attributes in the MiniBatch you want to be carried to the
        specific device.
    """

    def __init__(self, datapipe, device, extra_attrs=None):
        super().__init__()
        self.datapipe = datapipe
        self.device = device
        self.extra_attrs = extra_attrs

    def __iter__(self):
        for data in self.datapipe:
            data = recursive_apply(data, apply_to, self.device)
            if self.extra_attrs is not None:
                for attr in self.extra_attrs:
                    setattr(
                        data,
                        attr,
                        recursive_apply(
                            getattr(data, attr), apply_to, self.device
                        ),
                    )
            yield data


@dataclass
class CSCFormatBase:
    r"""Basic class representing data in Compressed Sparse Column (CSC) format.

    Examples
    --------
    >>> indptr = torch.tensor([0, 1, 3])
    >>> indices = torch.tensor([1, 4, 2])
    >>> csc_foramt_base = CSCFormatBase(indptr=indptr, indices=indices)
    >>> print(csc_format_base.indptr)
    ... torch.tensor([0, 1, 3])
    >>> print(csc_foramt_base)
    ... torch.tensor([1, 4, 2])
    """
    indptr: torch.Tensor = None
    indices: torch.Tensor = None

    def __init__(self, indptr: torch.Tensor, indices: torch.Tensor):
        self.indptr = indptr
        self.indices = indices
        if not indptr.is_cuda:
            assert self.indptr[-1] == len(
                self.indices
            ), "The last element of indptr should be the same as the length of indices."

    def __repr__(self) -> str:
        return _csc_format_base_str(self)

    def to(self, device: torch.device) -> None:  # pylint: disable=invalid-name
        """Copy `CSCFormatBase` to the specified device using reflection."""

        for attr in dir(self):
            # Only copy member variables.
            if not callable(getattr(self, attr)) and not attr.startswith("__"):
                setattr(
                    self,
                    attr,
                    recursive_apply(
                        getattr(self, attr), lambda x: apply_to(x, device)
                    ),
                )

        return self


def _csc_format_base_str(csc_format_base: CSCFormatBase) -> str:
    final_str = "CSCFormatBase("

    def _add_indent(_str, indent):
        lines = _str.split("\n")
        lines = [lines[0]] + [" " * indent + line for line in lines[1:]]
        return "\n".join(lines)

    final_str += (
        f"indptr={_add_indent(str(csc_format_base.indptr), 21)},\n" + " " * 14
    )
    final_str += (
        f"indices={_add_indent(str(csc_format_base.indices), 22)},\n" + ")"
    )
    return final_str
