# utils/plot_utils.py
import matplotlib.pyplot as plt
import numpy as np

def plot_beam_shape(span_lengths, supports, load_type):
    fig, ax = plt.subplots(figsize=(10, 2))
    ax.plot([0, sum(span_lengths)], [0, 0], color='black', lw=4)

    current_position = 0
    for i, length in enumerate(span_lengths):
        ax.plot([current_position + length, current_position + length], [0, 1], color='blue', lw=2)
        current_position += length

    for i, support in enumerate(supports):
        ax.text(i * 10, 0.5, support, ha='center', fontsize=12)

    ax.set_title("Beam Shape")
    ax.axis('off')
    plt.show()

def plot_sfd(shear_forces, span_lengths):
    fig, ax = plt.subplots(figsize=(10, 6))
    x = np.linspace(0, sum(span_lengths), len(shear_forces))
    y = shear_forces
    ax.plot(x, y, label='Shear Force', color='red', lw=2)
    ax.set_title("Shear Force Diagram (SFD)")
    ax.set_xlabel("Beam Length (ft)")
    ax.set_ylabel("Shear Force (kN)")
    ax.grid(True)
    plt.show()

def plot_bmd(bending_moments, span_lengths):
    fig, ax = plt.subplots(figsize=(10, 6))
    x = np.linspace(0, sum(span_lengths), len(bending_moments))
    y = bending_moments
    ax.plot(x, y, label='Bending Moment', color='blue', lw=2)
    ax.set_title("Bending Moment Diagram (BMD)")
    ax.set_xlabel("Beam Length (ft)")
    ax.set_ylabel("Bending Moment (kNm)")
    ax.grid(True)
    plt.show()