from dataclasses import dataclass
from typing import Generator
from abc import ABC, abstractmethod

import pygame as pg
from transform import Transform

@dataclass
class Face:
    begin: pg.Vector2
    end: pg.Vector2

    @property
    def normal(self) -> pg.Vector2:
        return (self.end-self.begin).rotate(-90).normalize()
    
@dataclass
class ColliderContact:
    __slots__ = ["points", "normal", "penetration"]
    points: list[pg.Vector2]
    normal: pg.Vector2
    penetration: float

@dataclass(frozen=True)
class PolygonalHull:
    _vertices: list[pg.Vector2]

    def get_vertex_at_index(self, key: int) -> pg.Vector2:
        return self._vertices[key]

    def get_face_at_index(self, key: int) -> Face:
        return Face(self._vertices[key], self._vertices[(key + 1) % len(self._vertices)])
    
    def vertices(self) -> Generator[pg.Vector2, None, None]:
        for v in self._vertices:
            yield v
    
    def faces(self) -> Generator[Face, None, None]:
        for i in range(len(self._vertices)):
            yield self.get_face_at_index(i)

    def project(self, axis: pg.Vector2) -> tuple[float, float]:
        projections = [v.dot(axis) for v in self._vertices]
        return (min(projections), max(projections))


class BaseCollider(ABC):

    @abstractmethod
    def moment_of_inertia(self, mass: float) -> float:
        pass

class ConvexCollider(BaseCollider):

    @abstractmethod
    def hull(self, transform: Transform) -> PolygonalHull:
        pass
    
@dataclass
class CircleCollider(BaseCollider):

    radius: float

    def moment_of_inertia(self, mass: float) -> float:
        return 0.5 * self.radius ** 2 * mass

@dataclass
class LineCollider(ConvexCollider):

    length: float

    def hull(self, transform: Transform) -> PolygonalHull:
        return PolygonalHull([
            transform.global_position - pg.Vector2(self.length / 2.0, 0).rotate(transform.global_degrees) * transform.global_scale,
            transform.global_position + pg.Vector2(self.length / 2.0, 0).rotate(transform.global_degrees) * transform.global_scale
        ])
    
    def moment_of_inertia(self, mass):
        return 1.0 / 12.0 * mass * self.length**2


@dataclass
class RectCollider(ConvexCollider):

    dimensions: tuple[float, float]

    @property
    def width(self):
        return self.dimensions[0]
    
    @property
    def height(self):
        return self.dimensions[1]

    def hull(self, transform: Transform) -> PolygonalHull:
        return PolygonalHull([
            transform.global_position - pg.Vector2(self.width / 2.0, self.height / 2.0).rotate(transform.global_degrees) * transform.global_scale,
            transform.global_position - pg.Vector2(-self.width / 2.0, self.height / 2.0).rotate(transform.global_degrees) * transform.global_scale,
            transform.global_position - pg.Vector2(-self.width / 2.0, -self.height / 2.0).rotate(transform.global_degrees) * transform.global_scale,
            transform.global_position - pg.Vector2(self.width / 2.0, -self.height / 2.0).rotate(transform.global_degrees) * transform.global_scale
        ])

    def moment_of_inertia(self, mass: float) -> float:
        return (1.0 / 12.0) * mass * (self.width ** 2 + self.height ** 2)