# app.py
import gradio as gr
import numpy as np
import matplotlib.pyplot as plt
from io import BytesIO
from calculator import (
    deflection_simply_supported_point_load,
    deflection_simply_supported_udl,
    deflection_cantilever_point_load,
    deflection_cantilever_udl,
    generate_deflection_curve,
)

plt.switch_backend("Agg")  # safe for non-interactive environments (Spaces)


def plot_deflection(x, y, L):
    fig, ax = plt.subplots(figsize=(8, 3))
    ax.plot(x, y)
    ax.axhline(0, linewidth=0.8)
    ax.set_xlabel("x (m)")
    ax.set_ylabel("Deflection (m)")
    ax.set_title("Beam Deflection Curve")
    ax.grid(True)
    ax.set_xlim(0, L)
    fig.tight_layout()
    buf = BytesIO()
    fig.savefig(buf, format="png")
    buf.seek(0)
    plt.close(fig)
    return buf


def run(beam_type, L, load_type, load_value, load_pos, E, I, num_points):
    # convert inputs
    L = float(L)
    E = float(E)
    I = float(I)
    load_value = float(load_value)
    num_points = int(num_points)

    # For point load use load_pos (a). For UDL, load_pos ignored.
    a = float(load_pos) if load_type == "Point Load" else None

    x, y = generate_deflection_curve(
        beam_type=beam_type,
        load_type=load_type,
        L=L,
        load_value=load_value,
        a=a,
        E=E,
        I=I,
        num=num_points,
    )

    # find maximum deflection magnitude and its x location
    # deflections are returned as signed values (downwards negative)
    abs_y = np.abs(y)
    idx = np.argmax(abs_y)
    max_defl = float(y[idx])
    max_x = float(x[idx])

    buf = plot_deflection(x, y, L)

    # Return nicely formatted outputs
    return (
        f"{max_defl:.6e} m",
        f"{max_x:.4f} m",
        buf,
        f"x sample: {np.round(x[:6], 6).tolist()} ...",
        f"y sample: {np.round(y[:6], 9).tolist()} ...",
    )


title = "Beam Deflection Calculator"
desc = "Calculate beam deflections for common beam/load cases and view the deflection curve."

with gr.Blocks() as demo:
    gr.Markdown(f"# {title}\n\n{desc}")

    with gr.Row():
        with gr.Column():
            beam_type = gr.Radio(
                ["Simply Supported", "Cantilever"],
                label="Beam Type",
                value="Simply Supported",
            )
            L = gr.Number(label="Length L (m)", value=1.0)
            load_type = gr.Radio(
                ["Point Load", "Uniformly Distributed Load"],
                label="Load Type",
                value="Point Load",
            )
            load_value = gr.Number(label="Load (N or N/m)", value=100.0)
            load_pos = gr.Number(
                label="Load position a (m) — for point load (from left / fixed end)",
                value=0.5,
            )
            E = gr.Number(label="Elastic modulus E (Pa)", value=2.1e11)
            I = gr.Number(label="Moment of inertia I (m^4)", value=1e-6)
            num_points = gr.Slider(50, 2000, value=400, step=10, label="Points for curve")
            run_btn = gr.Button("Calculate")

        with gr.Column():
            max_defl_out = gr.Textbox(label="Max deflection", interactive=False)
            max_x_out = gr.Textbox(label="Location of max deflection", interactive=False)
            plot_out = gr.Image(label="Deflection curve")
            x_sample = gr.Textbox(label="x sample", interactive=False)
            y_sample = gr.Textbox(label="y sample", interactive=False)

    run_btn.click(
        run,
        inputs=[beam_type, L, load_type, load_value, load_pos, E, I, num_points],
        outputs=[max_defl_out, max_x_out, plot_out, x_sample, y_sample],
    )

if __name__ == "__main__":
    demo.launch()