app.py

import gradio as gr
import io
import contextlib
import traceback


# ---------- Python runner ----------

def run_python(code: str) -> str:
    """
    Execute user-provided Python code and capture stdout / errors.
    NOTE: This is for teaching demos; do NOT use this pattern in
    a multi-user production environment without sandboxing.
    """
    stdout_buffer = io.StringIO()
    try:
        # Provide a very simple, mostly empty environment
        local_env = {}
        global_env = {"__builtins__": __builtins__}

        with contextlib.redirect_stdout(stdout_buffer):
            exec(code, global_env, local_env)

        output = stdout_buffer.getvalue()
        if not output.strip():
            output = "[No output produced]"
        return output
    except Exception:
        error_text = stdout_buffer.getvalue()
        error_text += "\n" + traceback.format_exc()
        return error_text


# ---------- Course content ----------

lessons = [
    {
        "title": "Lesson 1: Setup & Simple Apps",
        "description": """
### Lesson 1: Setting Up Python and Developing a Simple Application

**Topics**
- Topic A: Set Up the Development Environment  
- Topic B: Write Python Statements  
- Topic C: Create a Python Application  
- Topic D: Prevent Errors  

**You’ll practice:**
- Using `print()` and variables
- Reading user input with `input()`
- Building a tiny interactive console app

**Mini-project idea:**  
Create a **“Profile Card”** script that asks for your name, age, and hobby, then prints a nicely formatted profile.
""",
        "starter_code": '''# Lesson 1: Simple Hello & Input

print("👋 Welcome to Lesson 1: Setup & Simple Apps")

name = input("What is your name? ")
age = input("How old are you? ")

print(f"Hello, {name}! You are {age} years old.")

# Try:
# 1. Ask for a favorite color and food and add them to the message.
# 2. Create a small "profile card" printed with multiple lines, e.g.:
#    Name: ...
#    Age: ...
#    Favorite color: ...
'''
    },
    {
        "title": "Lesson 2: Simple Data Types",
        "description": """
### Lesson 2: Processing Simple Data Types

**Topics**
- Topic A: Process Strings and Integers  
- Topic B: Process Decimals, Floats, and Mixed Number Types  

**You’ll practice:**
- Combining strings
- Doing arithmetic with integers and floats
- Using `round()` and basic numeric conversions

**Mini-project idea:**  
Create a **BMI & Health Stats** script that asks for height, weight, and age, calculates BMI, and prints a short health summary.
""",
        "starter_code": '''# Lesson 2: Strings, Integers, Floats

print("✨ Lesson 2: Simple Data Types")

first_name = "Alice"
last_name = "Smith"
age = 30
height_m = 1.70
weight_kg = 65.0

full_name = first_name + " " + last_name
bmi = weight_kg / (height_m ** 2)

print("Full name:", full_name)
print("Age next year:", age + 1)
print("BMI (unrounded):", bmi)
print("BMI (rounded to 2 decimals):", round(bmi, 2))

# Try:
# 1. Ask the user for their name and birth year; compute their age.
# 2. Convert a temperature from Fahrenheit to Celsius:
#       celsius = (f - 32) * 5/9
# 3. Ask for two prices and print the subtotal, tax, and total.
'''
    },
    {
        "title": "Lesson 3: Data Structures",
        "description": """
### Lesson 3: Processing Data Structures

**Topics**
- Topic A: Process Ordered Data Structures (lists, tuples)  
- Topic B: Process Unordered Data Structures (sets, dictionaries)  

**You’ll practice:**
- Storing groups of values in lists and tuples
- Using sets to deduplicate data
- Using dictionaries to store labeled data

**Mini-project idea:**  
Build a tiny **“Student Gradebook”** using a dictionary of names and scores. Compute averages and print a report.
""",
        "starter_code": '''# Lesson 3: Lists, Tuples, Sets, Dictionaries

print("📚 Lesson 3: Data Structures")

# Ordered: lists and tuples
fruits = ["apple", "banana", "cherry"]
scores = (88, 92, 79)

print("Fruits:", fruits)
print("First fruit:", fruits[0])
print("Scores:", scores)
print("Average score:", sum(scores) / len(scores))

# Unordered: sets and dictionaries
numbers_with_duplicates = [1, 2, 2, 3, 3, 3]
unique_numbers = set(numbers_with_duplicates)

print("Original numbers:", numbers_with_duplicates)
print("Unique numbers:", unique_numbers)

student = {
    "name": "Alice",
    "age": 20,
    "grade": "A"
}

print("Student name:", student["name"])

print("\nAll student key/value pairs:")
for key, value in student.items():
    print(f"{key}: {value}")

# Try:
# 1. Add a new key "major" to the student dictionary, then print it.
# 2. Create a list of 5 movies and print the first and last.
# 3. Create a "gradebook" dict: student_name -> list of scores,
#    then print each student's average.
'''
    },
    {
        "title": "Lesson 4: Conditionals & Loops",
        "description": """
### Lesson 4: Writing Conditional Statements and Loops

**Topics**
- Topic A: Write a Conditional Statement (`if`, `elif`, `else`)  
- Topic B: Write a Loop (`for`, `while`)  

**You’ll practice:**
- Making decisions in code
- Repeating actions until some condition is met
- Combining `if` with loops for basic logic

**Mini-project idea:**  
Create a **“Number Guessing Game”** that picks a random number and gives the user several attempts with hints (too high / too low).
""",
        "starter_code": '''# Lesson 4: Conditionals & Loops

print("🔁 Lesson 4: Conditionals and Loops")

# Conditional example
score = int(input("Enter a score between 0 and 100: "))

if score >= 90:
    grade = "A"
elif score >= 80:
    grade = "B"
elif score >= 70:
    grade = "C"
elif score >= 60:
    grade = "D"
else:
    grade = "F"

print(f"Your grade is: {grade}")

# Loop example: print even numbers 2-20
print("\nEven numbers from 2 to 20:")
for n in range(2, 21, 2):
    print(n, end=" ")

print()  # newline

# Try:
# 1. Use a while loop to ask for a password until it is 'secret'.
# 2. Write an if/elif/else to classify a number as positive, negative, or zero.
# 3. (Challenge) Make a number guessing game (1-20) that tells the user if
#    their guess is too high or too low.
'''
    },
    {
        "title": "Lesson 5: Functions, Classes, Modules",
        "description": """
### Lesson 5: Structuring Code for Reuse

**Topics**
- Topic A: Define and Call a Function  
- Topic B: Define and Instantiate a Class  
- Topic C: Import and Use a Module  

**You’ll practice:**
- Creating functions with parameters and return values
- Creating simple classes with attributes and methods
- Using built-in modules like `math`, `random`

**Mini-project idea:**  
Create a **“Banking Simulator”** with a `BankAccount` class that supports deposit, withdraw, and showing balance.
""",
        "starter_code": '''# Lesson 5: Functions, Classes, and Modules

print("🧩 Lesson 5: Reusable Code")

# --- Functions ---

def add(a, b):
    """Return the sum of a and b."""
    return a + b

result = add(10, 5)
print("10 + 5 =", result)


# --- Classes ---

class Car:
    def __init__(self, make, model, year):
        self.make = make
        self.model = model
        self.year = year

    def description(self):
        return f"{self.year} {self.make} {self.model}"

my_car = Car("Toyota", "Corolla", 2022)
print("My car:", my_car.description())


# --- Modules ---

import math
import random

print("Square root of 16:", math.sqrt(16))
print("Random integer from 1 to 6:", random.randint(1, 6))

# Try:
# 1. Write a function is_even(n) that returns True if n is even.
# 2. Create a BankAccount class with deposit and withdraw methods,
#    and test it with a few transactions.
# 3. Use random.randint to simulate rolling two dice and print their sum.
'''
    },
    {
        "title": "Lesson 6: Files & Directories",
        "description": """
### Lesson 6: Writing Code to Process Files and Directories

**Topics**
- Topic A: Write to a Text File  
- Topic B: Read from a Text File  
- Topic C: Get the Contents of a Directory  
- Topic D: Manage Files and Directories  

⚠️ In a hosted environment, file access is temporary and sandboxed,
but the patterns you learn here transfer directly to your local machine.

**You’ll practice:**
- Creating directories and files
- Reading and writing text data
- Listing directory contents

**Mini-project idea:**  
Create a simple **“Log Writer”** that appends timestamped messages to a log file, then reads and prints the last N lines.
""",
        "starter_code": '''# Lesson 6: Files & Directories

print("📂 Lesson 6: Files and Directories")

from pathlib import Path

# Create a folder
folder = Path("demo_folder")
folder.mkdir(exist_ok=True)

# Write to a file
file_path = folder / "example.txt"
file_path.write_text("Hello from Lesson 6!\\nThis is a test file.")

print("Wrote file:", file_path)

# Read from a file
content = file_path.read_text()
print("\\nFile contents:")
print(content)

# List directory contents
print("\\nContents of demo_folder:")
for item in folder.iterdir():
    print(" -", item.name)

# Try:
# 1. Add another file with different text.
# 2. Read both files and print their contents.
# 3. Add a timestamp to each line you write into a 'log.txt' file.
'''
    },
    {
        "title": "Lesson 7: Exceptions",
        "description": """
### Lesson 7: Dealing with Exceptions

**Topics**
- Topic A: Handle Exceptions  
- Topic B: Raise Exceptions  

**You’ll practice:**
- Wrapping risky code in `try/except`
- Catching specific errors like `ValueError` and `ZeroDivisionError`
- Raising your own exceptions when inputs are invalid

**Mini-project idea:**  
Create a **“Safe Calculator”** that:
- Accepts user input for operations
- Handles invalid inputs gracefully
- Prevents divide-by-zero errors
""",
        "starter_code": '''# Lesson 7: Exceptions

print("⚠️ Lesson 7: Exceptions")

def safe_divide(a, b):
    try:
        return a / b
    except ZeroDivisionError:
        print("Error: cannot divide by zero!")
        return None

x = float(input("Enter numerator: "))
y = float(input("Enter denominator: "))
result = safe_divide(x, y)

print("Result:", result)

# Raising your own exception
def set_age(age):
    if age < 0 or age > 120:
        raise ValueError("Age must be between 0 and 120.")
    return age

try:
    age_value = int(input("Enter an age (0-120): "))
    print("Valid age:", set_age(age_value))
except ValueError as e:
    print("Invalid age:", e)

# Try:
# 1. Wrap more user input in try/except to catch ValueError.
# 2. Write a function that raises ValueError if a discount is
#    not between 0 and 100.
# 3. Build a small "safe calculator" that handles bad input gracefully.
'''
    },
]

appendix_markdown = """
## 📎 References & Appendices

This tab consolidates extra reference material for the course.

---

### Appendix A: Major Differences Between Python 2 and 3

Modern development uses **Python 3**, but here are some historical differences:

- `print`  
  - Python 2: `print "Hello"`  
  - Python 3: `print("Hello")`
- Integer division  
  - Python 2: `5/2` → `2` (integer when both are ints)  
  - Python 3: `5/2` → `2.5`, use `5//2` for integer division.
- Text and bytes  
  - Python 2: `str` (bytes) vs `unicode`.  
  - Python 3: `str` is Unicode by default; `bytes` is a separate type.
- `input()`  
  - Python 2: `input()` evaluates, `raw_input()` returns string.  
  - Python 3: `input()` always returns a string.
- Standard library layout  
  - Some modules reorganized (e.g., `urllib` family).

If you’re starting now, you almost never need Python 2, but you might see old code in the wild.

---

### Appendix B: Mini Python Style Guide (PEP 8 Highlights)

Follow these conventions to keep your code clean and readable:

**Indentation**
- Use **4 spaces** per indentation level.
- Avoid mixing tabs and spaces.

**Naming**
- Variables / functions: `snake_case` (e.g., `total_price`, `calculate_bmi`).  
- Classes: `CapWords` (e.g., `BankAccount`).  
- Constants: `UPPER_CASE` (e.g., `PI = 3.14159`).

**Spacing**
- Around operators: `x = a + b`, not `x=a+b`.  
- After commas: `func(a, b, c)`.

**Imports**
- At the **top** of the file.  
- One import per line is preferred.

**Comments & Docstrings**
- Use `#` for short explanations above a line or block.  
- Use triple-quoted strings for docstrings, for example:
  `\"\"\"This is a multi-line docstring.\"\"\"`.

**Structure**
- Break large scripts into functions and classes.  
- For larger programs, use:

```python
if __name__ == "__main__":
    main()

with gr.Tabs():
    # Main lesson tabs
    for lesson in lessons:
        with gr.Tab(lesson["title"]):
            gr.Markdown(lesson["description"])

            code = gr.Code(
                value=lesson["starter_code"],
                language="python",
                label="✏️ Edit and run your Python code here",
                interactive=True,
            )

            with gr.Row():
                run_button = gr.Button("▶️ Run code", variant="primary")
                clear_button = gr.Button("🧹 Clear output")

            output = gr.Textbox(
                label="📤 Output (stdout and errors)",
                lines=14,
                show_copy_button=True,
            )

            # Bind buttons
            run_button.click(run_python, inputs=code, outputs=output)
            clear_button.click(lambda: "", outputs=output)

    # References / Appendices tab
    with gr.Tab("References & Appendices"):
        gr.Markdown(appendix_markdown)

gr.Markdown(
    """