Problem 1.6 - Internal Reactions

[Problem adapted from © Chris Galitz CC BY NC-SA 4.0]

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from shiny import App, render, ui, reactive
import random
import asyncio
import io
import math
import string
from datetime import datetime
from pathlib import Path

def generate_random_letters(length):
    # Generate a random string of letters of specified length
    return "".join(random.choice(string.ascii_lowercase) for _ in range(length))

problem_ID = "646"
P = reactive.Value("__")
theta = reactive.Value("__")
attempts = ["Timestamp,Attempt,Answer1,Answer2,Answer3,Feedback\n"]

app_ui = ui.page_fluid(
    ui.markdown("**Please enter your ID number from your instructor and click to generate your problem**"),
    ui.input_text("ID", "", placeholder="Enter ID Number Here"),
    ui.input_action_button("generate_problem", "Generate Problem", class_="btn-primary"),
    ui.markdown("**Problem Statement**"),
    ui.output_ui("ui_problem_statement"),
    ui.input_text("answer1", "Your normal force in units of lb", placeholder="Please enter your shear force"),
    ui.input_text("answer2", "Your shear force in units of lb", placeholder="Please enter your normal force"),
    ui.input_text("answer3", "Your bending moment in units of lb-in", placeholder="Please enter your bending moment"),

    ui.input_action_button("submit", "Submit Answers", class_="btn-primary"),
    ui.download_button("download", "Download File to Submit", class_="btn-success"),
)

def server(input, output, session):
    # Initialize a counter for attempts
    attempt_counter = reactive.Value(0)

    @output
    @render.ui
    def ui_problem_statement():
        return [
            ui.markdown(
                f"A gear shift, once engaged, can be modeled as the bent cantilever beam shown. If a force, P = {P()} lb at angle Θ = {theta()}, was used to engage the shifter, determine the magnitude of the internal normal force, N, shear force, V, and bending moment, M, at point B."
            )
        ]

    @reactive.Effect
    @reactive.event(input.generate_problem)
    def randomize_vars():
        random.seed(input.ID())
        P.set(random.randrange(20,75,1))
        theta.set(random.randrange(10,25,1))

    @reactive.Effect
    @reactive.event(input.submit)
    def _():
        attempt_counter.set(
            attempt_counter() + 1
        )  # Increment the attempt counter on each submission.

        # Calculate the instructor's answer and determine if the user's answer is correct.
        instr1 = abs(P()*math.cos((70+theta())*math.pi/180))
        instr2 = abs(P()*math.sin((70+theta())*math.pi/180))
        instr3 = abs(P()*math.sin((70+theta())*math.pi/180)*(15+14*math.cos(70*math.pi/180))-P()*math.cos((70+theta())*math.pi/180)*14*math.sin(70*math.pi/180))

        correct1 = math.isclose(float(input.answer1()), instr1, rel_tol=0.01)
        correct2 = math.isclose(float(input.answer2()), instr2, rel_tol=0.01)
        correct3 = math.isclose(float(input.answer3()), instr3, rel_tol=0.01)

        if correct1 and correct2 and correct3:
            check = "All answers are correct."
        else:
            conditions = []
            for i, correct in enumerate([correct1, correct2, correct3], start=1):
                if correct:
                    conditions.append(f"correct for answer {i}")
                else:
                    conditions.append(f"incorrect for answer {i}")
            check = "; ".join(conditions) + "."
        
        correct_indicator = "JL" if correct1 and correct2 and correct3 else "JG"

        random_start = generate_random_letters(4)
        random_middle = generate_random_letters(4)
        random_end = generate_random_letters(4)
        encoded_attempt = f"{random_start}{problem_ID}-{random_middle}{attempt_counter()}{correct_indicator}-{random_end}{input.ID()}"

        session.encoded_attempt = reactive.Value(encoded_attempt)
        attempts.append(f"{datetime.now()}, {attempt_counter()}, {input.answer1()}, {input.answer2()}, {check}\n")

        feedback = ui.markdown(f"Your answers of {input.answer1()}, {input.answer2()}, and {input.answer3()} are {check}")
        m = ui.modal(feedback, title="Feedback", easy_close=True)
        ui.modal_show(m)

    @session.download(filename=lambda: f"Problem_Log-{problem_ID}-{input.ID()}.csv")
    async def download():
        final_encoded = session.encoded_attempt() if session.encoded_attempt is not None else "No attempts"
        yield f"{final_encoded}\n\n"
        yield "Timestamp,Attempt,Answer1,Answer2,Feedback\n"
        for attempt in attempts[1:]:
            await asyncio.sleep(0.25)
            yield attempt

app = App(app_ui, server)