import pygame
import math

# FONT = pygame.font.SysFont("dejavu", 16)

WIDTH, HEIGHT = 800, 800

class Planet():
    # Astronomical unit (~ dist Earth - Sun)
    AU = 149.6e6 * 1000
    G = 6.67428e-11
    SCALE = 250 / AU # 1 AU = 100 px
    TIMESTEP = 3600 * 24 # 1 day

    def __init__(self, x, y, radius, color, mass, isSun = False) -> None:
        self.x = x
        self.y = y
        self.radius = radius
        self.color = color
        self.mass = mass

        self.orbit = []
        self.isSun = isSun
        self.distance_to_sun = 0

        self.x_vel = 0
        self.y_vel = 0
    
    def draw(self, win):
        x = self.x * self.SCALE + WIDTH / 2
        y = self.y * self.SCALE + HEIGHT / 2

        if len(self. orbit) > 2:
            updated_points = []
            for point in self.orbit:
                x, y = point
                x = x * self.SCALE + WIDTH / 2
                y = y * self.SCALE + HEIGHT / 2
                updated_points.append((x, y))
            pygame.draw.lines(win, self.color, False, updated_points, 2)

        pygame.draw.circle(win, self.color, (x, y), self.radius)

        # if not self.isSun:
        #     distance_text = FONT.render(f"{round(self.distance_to_sun / 1000, 1)}km", 1, (255, 255, 255))
        #     win.blit(distance_text, (x - distance_text.get_width() / 2, y - distance_text.get_height() / 2))

    def attraction(self, other):
        other_x, other_y = other.x, other.y
        distance_x = other_x - self.x
        distance_y = other_y - self.y
        distance = math.sqrt(distance_x**2 + distance_y**2)

        if other.isSun: self.distance_to_sun = distance

        force = self.G * self.mass * other.mass / distance**2

        theta = math.atan2(distance_y, distance_x)
        force_x = math.cos(theta) * force
        force_y = math.sin(theta) * force

        return force_x, force_y

    def update_position(self, planets):
        total_fx = total_fy = 0
        for planet in planets:
            if self == planet: continue
            fx, fy = self.attraction(planet)
            total_fx += fx
            total_fy += fy
        self.x_vel += total_fx / self.mass * self.TIMESTEP
        self.y_vel += total_fy / self.mass * self.TIMESTEP

        self.x += self.x_vel * self.TIMESTEP
        self.y += self.y_vel * self.TIMESTEP

        self.orbit.append((self.x, self.y))