import gradio as gr
import numpy as np
import matplotlib.pyplot as plt

def polynomial_plot(coeffs, x_power, y_power):
    try:
        coeffs = [float(c.strip()) for c in coeffs.split(",")]
    except:
        return "❌ 請輸入正確的係數 (逗號分隔)", None
    
    x = np.linspace(-10, 10, 400)
    y = np.zeros_like(x)

    # 建立 f(x)
    for i, coef in enumerate(coeffs):
        y += coef * (x**i)

    # 應用 x 的最高次方限制
    if x_power < len(coeffs):
        y = sum(coeffs[i] * (x**i) for i in range(x_power+1))

    # y 的次方 (例如 y^2 = f(x))
    if y_power != 1:
        # 避免負數開根
        y = np.sign(y) * (np.abs(y))**(1.0/y_power)

    fig, ax = plt.subplots()
    ax.plot(x, y, label=f"Polynomial (deg={x_power}), y^{y_power}")
    ax.axhline(0, color="black", linewidth=0.8)
    ax.axvline(0, color="black", linewidth=0.8)
    ax.set_xlabel("x")
    ax.set_ylabel("y")
    ax.legend()
    ax.grid(True)

    return "✅ 繪圖完成", fig

with gr.Blocks() as demo:
    gr.Markdown("## 📈 多項式繪圖器 (Polynomial Plotter)")
    gr.Markdown("輸入係數，指定 x 與 y 的次方")

    coeffs = gr.Textbox(label="係數列表 (由常數到高次，例如: 1, -3, 2 代表 1 - 3x + 2x²)", value="1,-3,2")
    x_power = gr.Slider(1, 10, value=2, step=1, label="x 的最高次方 (degree)")
    y_power = gr.Slider(1, 5, value=1, step=1, label="y 的次方 (例如 2 表示 y² = f(x))")

    plot_btn = gr.Button("繪圖")
    status = gr.Textbox(label="狀態", interactive=False)
    plot = gr.Plot(label="圖形")

    plot_btn.click(fn=polynomial_plot, inputs=[coeffs, x_power, y_power], outputs=[status, plot])

demo.launch()