from manim import *
from manim import GrowFromCenter as Grow
from geom_func import *

def split_segment(A, B, k):
    """ Координаты точки, которая делит отрезок AB в отношении k:1, считая от A """
    N = np.array(
        [
            (A[0] + B[0] * k) / (1 + k),
            (A[1] + B[1] * k) / (1 + k),
            0
        ]
    )
    return N


def extend_segment(A, B, k):
    """ Координаты точки, лежащей на продолжении отрезка AB за точку B через k единиц """
    dAB = distance(A, B)
    vAB = direction_vector(A, B) / dAB
    C = B + vAB * k
    return C

config.background_color = WHITE

LINE_BLUE = '#006699'
LINE_ORANGE = '#ff6600'
DOT_BLUE = '#0099ff'


class Cheva_s_Theorem(Scene):
    def construct(self):
        DashedLine.set_default(dash_length = DEFAULT_DASH_LENGTH*2, dashed_ratio=0.6)
        MathTex.set_default(color=BLACK)
        # Треугольник
        A = 6 * LEFT + 2 * DOWN
        B = 4 * LEFT + 3 * UP
        C = 0.5 * LEFT + 2 * DOWN
        kwargs = {
            "radius": 0.045,
            "stroke_width": 0.75,
            "stroke_color": '#000',
            "z_index": 1,
            "stroke_opacity": 1,
            "fill_color": DOT_BLUE,
        }
        pA, pB, pC = [Dot(p, **kwargs) for p in [A, B, C]]
        ABC = always_redraw(lambda:
            Polygon(
                pA.get_center(),
                pB.get_center(),
                pC.get_center(),
                stroke_width=2.5,
                stroke_color=LINE_BLUE,
            )
        )
        # отметки на сторонах
        c1, a1 = (ValueTracker(i) for i in [0.5, 0.7])
        dots = VGroup()
        for i in [(pA, pB, c1), (pB, pC, a1)]:
            dot = always_redraw(lambda i=i: Dot(
                split_segment(i[0].get_center(), i[1].get_center(), i[2].get_value()),
                **kwargs
                )
            )
            dots.add(dot)
        C1, A1 = dots

        pK = always_redraw(lambda:
            Dot(
                line_intersection(
                    [pA.get_center(), A1.get_center()],
                    [pC.get_center(), C1.get_center()]),
                    **kwargs
            )
        )
        B1 = always_redraw(lambda:
            Dot(
                line_intersection(
                    [pA.get_center(), pC.get_center()],
                    [pB.get_center(), extend_segment(pB.get_center(), pK.get_center(), 5)]),
                    **kwargs
            )
        )
        dots.add(B1)
        # чевианы
        lines = VGroup()
        for d in [(pA, A1), (pB, B1), (pC, C1)]:
            line = always_redraw(lambda d=d:
                Line(d[0].get_center(), d[1].get_center()).set_stroke(LINE_ORANGE, 2.5)
            )
            lines.add(line)

        # лейблы
        # labels = VGroup()
        # num = ["A", "B", "C", "A_1", "B_1", "C_1"]
        # for i, s in enumerate([pA, pB, pC, A1, B1, C1]):
        #     vec = normalize(s.get_center() - pK.get_center())
        #     label = always_redraw(lambda i=i:
        #         MathTex(f"{num[i]}").scale(0.6).next_to(s, vec, buff = 0.1)
        #     )
        #     labels.add(label)

        labels = MathTex('A', 'B', 'C', 'A_1', 'B_1', 'C_1').scale(0.6).set_color(BLACK).set_z_index(3)
        for i, s in enumerate([pA, pB, pC, A1, B1, C1]):
            vec = normalize(s.get_center() - pK.get_center())
            labels[i].add_updater(lambda i: i.next_to(s, vec, buff = 0.1))

        # анимации
        self.add(pA, pB, pC, ABC, dots, lines, pK, labels)
        pairs = [(a1, 2.5), (c1, 1.5)]
        anims = [v.animate.set_value(t) for v, t in pairs]
        anims_kwargs = {"run_time": 8, "rate_func": there_and_back}
        self.play(*anims, **anims_kwargs)
        self.wait()