# Copyright (C) 2002, Thomas Hamelryck (thamelry@binf.ku.dk)
#
# This file is part of the Biopython distribution and governed by your
# choice of the "Biopython License Agreement" or the "BSD 3-Clause License".
# Please see the LICENSE file that should have been included as part of this
# package.
"""Base class for Residue, Chain, Model and Structure classes.

It is a simple container class, with list and dictionary like properties.
"""

import warnings
from collections import deque
from copy import copy
from typing import Any
from typing import Generic
from typing import Optional
from typing import TYPE_CHECKING
from typing import TypeVar
from typing import Union

import numpy as np

from Bio import BiopythonWarning
from Bio.PDB.PDBExceptions import PDBConstructionException

if TYPE_CHECKING:
    from Bio.PDB.Atom import Atom

_Child = TypeVar("_Child", bound=Union["Entity", "Atom"])
_Parent = TypeVar("_Parent", bound=Optional["Entity"])
_Self = TypeVar("_Self", bound="Entity[Any, Any]")


class Entity(Generic[_Parent, _Child]):
    """Basic container object for PDB hierarchy.

    Structure, Model, Chain and Residue are subclasses of Entity.
    It deals with storage and lookup.
    """

    parent: Optional[_Parent]
    child_list: list[_Child]
    child_dict: dict[Any, _Child]
    level: str

    def __init__(self, id):
        """Initialize the class."""
        self._id = id
        self.full_id = None
        self.parent = None
        self.child_list = []
        self.child_dict = {}
        # Dictionary that keeps additional properties
        self.xtra = {}

    # Special methods

    def __len__(self):
        """Return the number of children."""
        return len(self.child_list)

    def __getitem__(self, id):
        """Return the child with given id."""
        return self.child_dict[id]

    def __delitem__(self, id):
        """Remove a child."""
        return self.detach_child(id)

    def __contains__(self, id):
        """Check if there is a child element with the given id."""
        return id in self.child_dict

    def __iter__(self):
        """Iterate over children."""
        yield from self.child_list

    # Generic id-based comparison methods considers all parents as well as children
    # Works for all Entities - Atoms have comparable custom operators
    def __eq__(self, other):
        """Test for equality. This compares full_id including the IDs of all parents."""
        if isinstance(other, type(self)):
            if self.parent is None:
                return self.id == other.id
            else:
                return self.full_id[1:] == other.full_id[1:]
        else:
            return NotImplemented

    def __ne__(self, other):
        """Test for inequality."""
        if isinstance(other, type(self)):
            if self.parent is None:
                return self.id != other.id
            else:
                return self.full_id[1:] != other.full_id[1:]
        else:
            return NotImplemented

    def __gt__(self, other):
        """Test greater than."""
        if isinstance(other, type(self)):
            if self.parent is None:
                return self.id > other.id
            else:
                return self.full_id[1:] > other.full_id[1:]
        else:
            return NotImplemented

    def __ge__(self, other):
        """Test greater or equal."""
        if isinstance(other, type(self)):
            if self.parent is None:
                return self.id >= other.id
            else:
                return self.full_id[1:] >= other.full_id[1:]
        else:
            return NotImplemented

    def __lt__(self, other):
        """Test less than."""
        if isinstance(other, type(self)):
            if self.parent is None:
                return self.id < other.id
            else:
                return self.full_id[1:] < other.full_id[1:]
        else:
            return NotImplemented

    def __le__(self, other):
        """Test less or equal."""
        if isinstance(other, type(self)):
            if self.parent is None:
                return self.id <= other.id
            else:
                return self.full_id[1:] <= other.full_id[1:]
        else:
            return NotImplemented

    def __hash__(self):
        """Hash method to allow uniqueness (set)."""
        return hash(self.full_id)

    # Private methods

    def _reset_full_id(self):
        """Reset the full_id (PRIVATE).

        Resets the full_id of this entity and
        recursively of all its children based on their ID.
        """
        for child in self:
            try:
                child._reset_full_id()
            except AttributeError:
                pass  # Atoms do not cache their full ids.
        self.full_id = self._generate_full_id()

    def _generate_full_id(self):
        """Generate full_id (PRIVATE).

        Generate the full_id of the Entity based on its
        Id and the IDs of the parents.
        """
        entity_id = self.get_id()
        parts = [entity_id]
        parent = self.get_parent()
        while parent is not None:
            entity_id = parent.get_id()
            parts.append(entity_id)
            parent = parent.get_parent()
        parts.reverse()
        return tuple(parts)

    # Public methods

    @property
    def id(self):
        """Return identifier."""
        return self._id

    @id.setter
    def id(self, value):
        """Change the id of this entity.

        This will update the child_dict of this entity's parent
        and invalidate all cached full ids involving this entity.

        @raises: ValueError
        """
        if value == self._id:
            return
        if self.parent is not None:
            if value in self.parent.child_dict:
                # See issue 1551 for details on the downgrade.
                warnings.warn(
                    f"The id `{value}` is already used for a sibling of this entity. "
                    f"Changing id from `{self._id}` to `{value}` might create access "
                    "inconsistencies to children of the parent entity.",
                    BiopythonWarning,
                )
            del self.parent.child_dict[self._id]
            self.parent.child_dict[value] = self

        self._id = value
        self._reset_full_id()

    def strictly_equals(
        self: _Self, other: _Self, compare_coordinates: bool = False
    ) -> bool:
        """Compare this entity to the other entity for equality.

        Recursively compare the children of this entity to the other entity's children.
        Compare most properties including names and IDs.

        :param other: The entity to compare this entity with
        :type other: Entity
        :param compare_coordinates: Whether to compare atomic coordinates
        :type compare_coordinates: bool
        :return: Whether the two entities are strictly equal
        :rtype: bool
        """
        if not isinstance(other, type(self)):
            return False

        if self.id != other.id:
            return False

        if len(self.child_list) != len(other.child_list):
            return False

        for left_child, right_child in zip(self.child_list, other.child_list):
            assert hasattr(left_child, "strictly_equals")
            if not left_child.strictly_equals(right_child, compare_coordinates):
                return False

        return True

    def get_level(self):
        """Return level in hierarchy.

        A - atom
        R - residue
        C - chain
        M - model
        S - structure
        """
        return self.level

    def set_parent(self, entity: _Parent):
        """Set the parent Entity object."""
        self.parent = entity
        self._reset_full_id()

    def detach_parent(self):
        """Detach the parent."""
        self.parent = None

    def detach_child(self, id):
        """Remove a child."""
        child = self.child_dict[id]
        child.detach_parent()
        del self.child_dict[id]
        self.child_list.remove(child)

    def add(self, entity: _Child):
        """Add a child to the Entity."""
        entity_id = entity.get_id()
        if self.has_id(entity_id):
            raise PDBConstructionException(f"{entity_id} defined twice")
        entity.set_parent(self)
        self.child_list.append(entity)
        self.child_dict[entity_id] = entity

    def insert(self, pos: int, entity: _Child):
        """Add a child to the Entity at a specified position."""
        entity_id = entity.get_id()
        if self.has_id(entity_id):
            raise PDBConstructionException(f"{entity_id} defined twice")
        entity.set_parent(self)
        self.child_list[pos:pos] = [entity]
        self.child_dict[entity_id] = entity

    def get_iterator(self):
        """Return iterator over children."""
        yield from self.child_list

    def get_list(self):
        """Return a copy of the list of children."""
        return copy(self.child_list)

    def has_id(self, id):
        """Check if a child with given id exists."""
        return id in self.child_dict

    def get_parent(self):
        """Return the parent Entity object."""
        return self.parent

    def get_id(self):
        """Return the id."""
        return self.id

    def get_full_id(self):
        """Return the full id.

        The full id is a tuple containing all id's starting from
        the top object (Structure) down to the current object. A full id for
        a Residue object e.g. is something like:

        ("1abc", 0, "A", (" ", 10, "A"))

        This corresponds to:

        Structure with id "1abc"
        Model with id 0
        Chain with id "A"
        Residue with id (" ", 10, "A")

        The Residue id indicates that the residue is not a hetero-residue
        (or a water) because it has a blank hetero field, that its sequence
        identifier is 10 and its insertion code "A".
        """
        if self.full_id is None:
            self.full_id = self._generate_full_id()
        return self.full_id

    def transform(self, rot, tran):
        """Apply rotation and translation to the atomic coordinates.

        :param rot: A right multiplying rotation matrix
        :type rot: 3x3 NumPy array

        :param tran: the translation vector
        :type tran: size 3 NumPy array

        Examples
        --------
        This is an incomplete but illustrative example::

            from numpy import pi, array
            from Bio.PDB.vectors import Vector, rotmat
            rotation = rotmat(pi, Vector(1, 0, 0))
            translation = array((0, 0, 1), 'f')
            entity.transform(rotation, translation)

        """
        for o in self.get_list():
            o.transform(rot, tran)

    def center_of_mass(self, geometric=False):
        """Return the center of mass of the Entity as a numpy array.

        If geometric is True, returns the center of geometry instead.
        """
        # Recursively iterate through children until we get all atom coordinates

        if not len(self):
            raise ValueError(f"{self} does not have children")

        maybe_disordered = {"R", "C"}  # to know when to use get_unpacked_list
        only_atom_level = {"A"}

        entities = deque([self])  # start with [self] to avoid auto-unpacking
        while True:
            e = entities.popleft()
            if e.level in maybe_disordered:
                entities += e.get_unpacked_list()
            else:
                entities += e.child_list

            elevels = {e.level for e in entities}
            if elevels == only_atom_level:
                break  # nothing else to unpack

        coords = np.asarray([a.coord for a in entities], dtype=np.float32)
        if geometric:
            masses = None
        else:
            masses = np.asarray([a.mass for a in entities], dtype=np.float32)

        return np.average(coords, axis=0, weights=masses)

    def copy(self):
        """Copy entity recursively."""
        shallow = copy(self)

        shallow.child_list = []
        shallow.child_dict = {}
        shallow.xtra = copy(self.xtra)

        shallow.detach_parent()

        for child in self.child_list:
            shallow.add(child.copy())
        return shallow


class DisorderedEntityWrapper:
    """Wrapper class to group equivalent Entities.

    This class is a simple wrapper class that groups a number of equivalent
    Entities and forwards all method calls to one of them (the currently selected
    object). DisorderedResidue and DisorderedAtom are subclasses of this class.

    E.g.: A DisorderedAtom object contains a number of Atom objects,
    where each Atom object represents a specific position of a disordered
    atom in the structure.
    """

    def __init__(self, id):
        """Initialize the class."""
        self.id = id
        self.child_dict = {}
        self.selected_child = None
        self.parent = None

    # Special methods

    def __getattr__(self, method):
        """Forward the method call to the selected child."""
        if method == "__setstate__":
            # Avoid issues with recursion when attempting deepcopy
            raise AttributeError
        if not hasattr(self, "selected_child"):
            # Avoid problems with pickling
            # Unpickling goes into infinite loop!
            raise AttributeError
        return getattr(self.selected_child, method)

    def __getitem__(self, id):
        """Return the child with the given id."""
        return self.selected_child[id]

    # XXX Why doesn't this forward to selected_child?
    # (NB: setitem was here before getitem, iter, len, sub)
    def __setitem__(self, id, child):
        """Add a child, associated with a certain id."""
        self.child_dict[id] = child

    def __contains__(self, id):
        """Check if the child has the given id."""
        return id in self.selected_child

    def __iter__(self):
        """Return the number of children."""
        return iter(self.selected_child)

    def __len__(self):
        """Return the number of children."""
        return len(self.selected_child)

    def __sub__(self, other):
        """Subtraction with another object."""
        return self.selected_child - other

    # Sorting
    # Directly compare the selected child
    def __gt__(self, other):
        """Return if child is greater than other."""
        return self.selected_child > other

    def __ge__(self, other):
        """Return if child is greater or equal than other."""
        return self.selected_child >= other

    def __lt__(self, other):
        """Return if child is less than other."""
        return self.selected_child < other

    def __le__(self, other):
        """Return if child is less or equal than other."""
        return self.selected_child <= other

    # Public methods
    def copy(self):
        """Copy disorderd entity recursively."""
        shallow = copy(self)
        shallow.child_dict = {}
        shallow.detach_parent()

        for child in self.disordered_get_list():
            shallow.disordered_add(child.copy())

        return shallow

    def get_id(self):
        """Return the id."""
        return self.id

    def strictly_equals(
        self, other: "DisorderedEntityWrapper", compare_coordinates: bool = False
    ) -> bool:
        """Compare this entity to the other entity using a strict definition of equality.

        Recursively compare the children of this entity to the other entity's children.
        Compare most properties including the selected child, names, and IDs.

        :param other: The entity to compare this entity with
        :type other: DisorderedEntityWrapper
        :param compare_coordinates: Whether to compare atomic coordinates
        :type compare_coordinates: bool
        :return: Whether the two entities are strictly equal
        :rtype: bool
        """
        if not isinstance(other, type(self)):
            return False

        if self.id != other.id:
            return False

        if not self.selected_child.get_id() == other.selected_child.get_id():
            return False

        # Check that the children dictionaries have the same keys
        if self.child_dict.keys() != other.child_dict.keys():
            return False

        # Compare the children using strictly_equals
        for key in self.child_dict.keys():
            if not self.child_dict[key].strictly_equals(
                other.child_dict[key], compare_coordinates
            ):
                return False

        return True

    def disordered_has_id(self, id):
        """Check if there is an object present associated with this id."""
        return id in self.child_dict

    def detach_parent(self):
        """Detach the parent."""
        self.parent = None
        for child in self.disordered_get_list():
            child.detach_parent()

    def get_parent(self):
        """Return parent."""
        return self.parent

    def set_parent(self, parent):
        """Set the parent for the object and its children."""
        self.parent = parent
        for child in self.disordered_get_list():
            child.set_parent(parent)

    def disordered_select(self, id):
        """Select the object with given id as the currently active object.

        Uncaught method calls are forwarded to the selected child object.
        """
        self.selected_child = self.child_dict[id]

    def disordered_add(self, child):
        """Add disordered entry.

        This is implemented by DisorderedAtom and DisorderedResidue.
        """
        raise NotImplementedError

    def disordered_remove(self, child):
        """Remove disordered entry.

        This is implemented by DisorderedAtom and DisorderedResidue.
        """
        raise NotImplementedError

    def is_disordered(self):
        """Return 2, indicating that this Entity is a collection of Entities."""
        return 2

    def disordered_get_id_list(self):
        """Return a list of id's."""
        # sort id list alphabetically
        return sorted(self.child_dict)

    def disordered_get(self, id=None):
        """Get the child object associated with id.

        If id is None, the currently selected child is returned.
        """
        if id is None:
            return self.selected_child
        return self.child_dict[id]

    def disordered_get_list(self):
        """Return list of children."""
        return list(self.child_dict.values())
