from manim import *

def area_rect(mob):
    height = np.linalg.norm(mob.get_right()[1] - mob.get_right()[0])
    width = np.linalg.norm(mob.get_right()[2] - mob.get_right()[1])
    s = height * width
    return s

def counter(mob):
    S = area_rect(mob[0])
    for i in range(len(mob)):
        s = area_rect(mob = mob[i])
        S += s
    return S

class GraphAreaPlot(Scene):
    def construct(self):
        ax = Axes(
            x_range=[-3, 3],
            y_range=[-1.5, 1.5],
            x_axis_config={
                "numbers_to_include": [-1, 1],
                "tip_width": 0.15,
                "tip_height": 0.15,
                "tick_size": 0.08
                },
            y_axis_config={
                "tip_width": 0.15,
                "tip_height": 0.15,
                "tick_size": 0.08
                }
        )
        labels = ax.get_axis_labels()
        # график функции
        graph = ax.plot(lambda x: np.cos(x), x_range=[-3, 3], color=BLUE_B)
        # Разбиения
        dx = ValueTracker(0.3)
        riemann_area = always_redraw(lambda:
            ax.get_riemann_rectangles(
                graph,
                x_range=[0, 0.5 * PI],
                dx=dx.get_value(),
                color=TEAL_A,
                fill_opacity=0.9,
                stroke_width=0.2,
                input_sample_type="right"
            )
        )
        # счетчик разбиений
        num = always_redraw(
            lambda: MathTex("n =", str(round(len(riemann_area), 0))
            ).to_edge(UR)
        )
        num[1].add_updater(
            lambda num: num.become(Tex(str(round(len(riemann_area), 0))).next_to(num[0], RIGHT, buff = 0.05)))

        # счетчик площади
        num_S = always_redraw(
            lambda: MathTex(
                "S =",
                str(round(counter(riemann_area), 2)
            )
        ).next_to(num, DOWN, aligned_edge=RIGHT))
        num_S[1].add_updater(
            lambda num: num.become(Tex(str(round(counter(riemann_area), 2))).next_to(num[0], RIGHT, buff = 0.05)))
        #
        area = ax.get_area(
            graph,
            [0, 0.5 * PI],
            color=(YELLOW, YELLOW),
            opacity=1,
            stroke_width=0
        )

        # анимации
        self.add(ax, labels)
        self.add(graph, riemann_area, num, num_S)
        self.play(dx.animate.set_value(0.2), run_time = 10)
        self.wait()
        # self.play(Create(graph), run_time = 1.5)
        # self.play(DrawBorderThenFill(riemann_area), run_time = 2.5, lag_ratio = 0.2)
        # self.play(FadeIn(num), FadeIn(num_S))
        # self.play(dx.animate.set_value(0.03), run_time = 10)
        # self.wait()
        # self.play(FadeOut(num, shift = DOWN), FadeOut(num_S, shift = DOWN))
        # self.play(ReplacementTransform(riemann_area, area), run_time = 2)
        # self.add(area)
        # self.remove(riemann_area)
        # self.wait(2)