from math import floor

from voronoiview.colors import Color
from voronoiview.exceptions import ExceededWindowBoundsError


class Point():
    """
    A class representing a point. A point
    has a point_size bounding box around
    it.
    """

    def __init__(self, x, y, color, point_size,
                 viewport_width, viewport_height, weight=1.0):
        """
        Initializes a new point with a point_size bounding box, viewport
        awareness, and a color.

        Initialized with additional viewport data to make sure the
        move function refuses to move a point outside the screen.

        @param x The x-coordinate.
        @param y The y-coordinate.
        @param color The color of the point.
        @param point_size The size of the point in pixels.
        @param viewport_width The width of the viewport.
        @param viewport_height The height of the viewport.
        """

        if not isinstance(color, Color):
            raise ValueError("Point must be initialized with a color of " +
                             "type Color.")

        self._point_size = point_size

        # Unfortunately, it appears decorated property methods are not
        # inheirited and instead of redoing everything we will just repeat
        # the properties here.
        self._x = x
        self._y = y
        self._weight = weight

        self._color = color

        self._viewport_width = viewport_width
        self._viewport_height = viewport_height

        self._calculate_hitbox()

        self._check_window_bounds(x, y)

        self._selected = False

        self._attributes = []

    @property
    def x(self):
        return self._x

    @property
    def y(self):
        return self._y

    @property
    def array(self):
        """
        Returns an array representation of the point for use in generating a voronoi diagram.
        """
        return [self._x, self._y]

    @property
    def weight(self):
        return self._weight

    @weight.setter
    def weight(self, weight):
        self._weight = weight

    @property
    def point_size(self):
        return self._point_size

    @property
    def selected(self):
        return self._selected

    @property
    def color(self):
        return self._color

    @color.setter
    def color(self, color):
        if not isinstance(color, Color):
            raise ValueError('Point color must be of type Color.')

        self._color = color

    @property
    def attributes(self):
        return self._attributes

    def add_attribute(self, attr):
        self._attributes.append(attr)

    def _calculate_hitbox(self):
        """
        Calculates the hit box for the point given the current
        position (center) and the point size.
        """
        half_point = floor(self.point_size / 2.0)

        self._top_left_corner = (self._x - half_point,
                                 self._y + half_point)

        self._bottom_right_corner = (self._x + half_point,
                                     self._y - half_point)

    def _check_window_bounds(self, x, y):
        """
        Simple window bound check that raises an exception when
        the point (x, y) exceeds the known viewport bounds.

        @param x The x-coordinate under test.
        @param y The y-coordinate under test.
        @raises ExceededWindowBoundsError If the viewport bounds are exceeded.
        """
        half_point = floor(self.point_size / 2.0)

        # Screen size in pixels is always positive
        # We need to include the half point here because
        # the (x, y) for a point is the center of the square and we
        # do not want the EDGES to exceed the viewport bounds.
        if (x > self._viewport_width - half_point or
                y > self._viewport_height - half_point or
                x < half_point or
                y < half_point):

            raise ExceededWindowBoundsError

    def move(self, dx, dy):
        """
        Adds the deltas dx and dy to the point.

        @param dx The delta in the x direction.
        @param dy The delta in the y direction.
        """

        self._check_window_bounds(self._x + dx, self._y + dy)

        self._x += dx
        self._y += dy

        # It's important to note as we move the point we need to
        # make sure we are constantly updating it's hitbox.
        self._calculate_hitbox()

    def __eq__(self, other):
        """
        Override for class equality.

        @param other The other object.
        """
        return (self._x == other.x and
                self._y == other.y and
                self._color == other.color and
                self._attributes == other.attributes and
                self._point_size == other.point_size)

    def __repr__(self):

        # For some reason I had to split this instead of using one giant
        # string chained with `+` inside of `()`.
        s = "<POINT "
        s += f"X: {self._x} | Y: {self._y} | "
        s += f"SIZE: {self._point_size} | "
        s += f"COLOR: {self._color} | "
        s += f"WEIGHT: {self._weight} | "
        s += f"VIEWPORT_WIDTH: {self._viewport_width} | "
        s += f"VIEWPORT_HEIGHT: {self._viewport_height}"
        s += ">"

        return s

    def select(self):
        """
        Selects the point.
        """
        self._selected = True

    def unselect(self):
        """
        Unselects the point.
        """
        self._selected = False

    def hit(self, x, y):
        """
        Determines if the point was hit inside of it's bounding box.

        The condition for hit is simple - consider the following
        bounding box:
                 -------------
                |              |
                |    (x,y)     |
                |              |
                 -------------

        Where the clicked location is in the center. Then the top
        left corner is defined as (x - half_point_size, y + half_point_size)
        and the bottom corner is (x + half_point_size, y - half_point_size)

        So long as x and y are greater than the top left and less than the
        top right it is considered a hit.

        This function is necessary for properly deleting and selecting points.
        """

        return (x >= self._top_left_corner[0] and
                x <= self._bottom_right_corner[0] and
                y <= self._top_left_corner[1] and
                y >= self._bottom_right_corner[1])


class Attribute:

    def __init__(self, name, value):
        """
        Initializes an attribute.
        """
        self._name = name
        self._value = value


class PointSet:
    """
    Useful container for points. Since points are not hashable (they are
    modified in place by move) we are forced to back the PointSet with an
    array. However, it is still a "set" in the "uniqueness among all points"
    sense because `add_point` will reject a point with a duplicate center.
    """

    def __init__(self, point_size, viewport_width, viewport_height):
        """
        Initializes a point container with points of size point_size.

        @param point_size The size of the points.
        @param viewport_width The width of the viewport for bounds
               calculations.
        @param viewport_height The height of the viewport for bounds
               calculations.
        """
        self._points = []
        self._point_size = point_size
        self._viewport_width = viewport_width
        self._viewport_height = viewport_height

    def __eq__(self, other):
        other_points = list(other.points)

        return (self._points == other_points and
                self._point_size == other.point_size and
                self._viewport_width == other.viewport_width and
                self._viewport_height == other.viewport_height)

    def __repr__(self):
        s = []

        for p in self._points:
            s.append(str(p))

        return ",".join(s)

    def clear(self):
        self._points = []

    @property
    def points(self):
        """
        Getter for points. Returns a generator for
        looping.
        """
        for point in self._points:
            yield point

    def clear_points(self):
        self._points = []

    @property
    def point_size(self):
        return self._point_size

    @property
    def viewport_height(self):
        return self._viewport_height

    @property
    def viewport_width(self):
        return self._viewport_width

    @viewport_height.setter
    def viewport_height(self, height):
        self._viewport_height = height

    @viewport_width.setter
    def viewport_width(self, width):
        self._viewport_width = width

    def empty(self):
        return len(self._points) == 0

    def clear_selection(self):
        """
        Handy helper function to clear all selected points.
        """
        for p in self._points:
            p.unselect()

    def add_point(self, x, y, color, weight=1.0, attrs=[]):
        """
        Adds a point in screen coordinates and an optional attribute to
        the list.

        @param x The x-coordinate.
        @param y The y-coordinate.
        @param color The color of the point.
        @param weight The point weight.
        @param attr An optional attribute.
        @raises ExceededWindowBoundsError If the point could not be constructed
                                          because it would be outside the
                                          window bounds.
        """

        if attrs != [] and not all(isinstance(x, Attribute) for x in attrs):
            raise ValueError("Attributes in add_point must be an " +
                             "attribute array.")

        if not isinstance(color, Color):
            raise ValueError("Point color must be a Color enum.")

        if not isinstance(weight, float):
            raise ValueError("Point weight must be a float.")

        point = Point(x, y, color, self._point_size,
                      self._viewport_width, self._viewport_height, weight)

        for attr in attrs:
            point.add_attribute(attr)

        if point in self._points:
            # Silently reject a duplicate point (same center).
            return

        self._points.append(point)

    def remove_point(self, x, y):
        """
        Removes a point from the point set based on a bounding
        box calculation.

        Removing a point is an exercise is determining which points
        have been hit, and then pulling them out of the list.

        If two points have a section overlapping, and the user clicks
        the overlapped section, both points will be removed.

        Currently O(n).

        @param x The x-coordinate.
        @param y The y-coordinate.
        """
        for p in self._points:
            if p.hit(x, y):
                self._points.remove(p)

    def groups(self):
        """
        Returns a map from color to point representing each point's group
        membership based on color.
        """
        g = {}

        for p in self._points:
            if p.color not in g:
                # Create the key for the group color since it does
                # not exist.
                g[p.color] = []

            g[p.color].append(p)

        return g