# Example of why virtual environments matter
"""
Project A needs:
- requests==2.25.1
- pandas==1.3.0

Project B needs:
- requests==2.28.0
- pandas==1.5.0

Without virtual environments: CONFLICT!
With virtual environments: Each project has its own dependencies ✅
"""

# Check current Python environment
import sys
import os

print(f"Python executable: {sys.executable}")
print(f"Python version: {sys.version}")
print(f"Current working directory: {os.getcwd()}")

# Show some environment info
if hasattr(sys, 'prefix'):
    print(f"Python prefix: {sys.prefix}")

# Commands you would run in terminal (simulated here)
"""
# 1. Create a new virtual environment
python -m venv myproject_env

# 2. Activate the environment
# Windows:
myproject_env\Scripts\activate
# Mac/Linux:
source myproject_env/bin/activate

# 3. Install packages
pip install requests pandas

# 4. Check installed packages
pip list

# 5. Save dependencies
pip freeze > requirements.txt

# 6. Deactivate when done
deactivate
"""

# Checking if we're in a virtual environment
import sys
import os

def check_virtual_env():
    # Check if we're in a virtual environment
    in_venv = hasattr(sys, 'real_prefix') or (
        hasattr(sys, 'base_prefix') and sys.base_prefix != sys.prefix
    )
    
    if in_venv:
        return "Running in virtual environment"
    else:
        return "Running in system Python"

env_status = check_virtual_env()
print(f"Environment status: {env_status}")

# Example requirements.txt content
requirements_content = """
# Core dependencies
requests==2.28.2
pandas==1.5.3
numpy==1.24.2

# Development dependencies
pytest==7.2.1
black==23.1.0
flake8==6.0.0

# Optional dependencies
matplotlib>=3.6.0
seaborn>=0.11.0
"""

print("Example requirements.txt:")
print(requirements_content)

# How to work with requirements files
"""
# Install from requirements file:
pip install -r requirements.txt

# Update requirements file:
pip freeze > requirements.txt

# Install specific versions:
pip install requests==2.28.2

# Install latest version:
pip install pandas
"""

# Recommended project structure
project_structure = """
my_project/
├── myproject_env/          # Virtual environment (don't commit to git)
│   ├── Scripts/            # Windows: Scripts, Mac/Linux: bin
│   ├── Lib/
│   └── Include/
├── src/                    # Your source code
│   ├── main.py
│   └── utils.py
├── tests/                  # Test files
│   └── test_main.py
├── requirements.txt        # Dependencies
├── .gitignore             # Ignore venv directory
├── README.md              # Project documentation
└── setup.py               # Package configuration (optional)
"""

print("Recommended project structure:")
print(project_structure)

# .gitignore content for Python projects
gitignore_content = """
# Virtual environments
venv/
env/
myproject_env/
.env

# Python
__pycache__/
*.pyc
*.pyo
*.pyd
.Python
build/
develop-eggs/
dist/
downloads/
eggs/
.eggs/
lib/
lib64/
parts/
sdist/
var/
wheels/
*.egg-info/
.installed.cfg
*.egg
"""

print("\nExample .gitignore for Python:")
print(gitignore_content[:200] + "...")

# Virtual environment naming strategies
naming_examples = {
    "project_based": "myproject_env",
    "version_based": "python39_env", 
    "purpose_based": "data_analysis_env",
    "client_based": "client_webapp_env"
}

# Multiple environments for different purposes
environments_structure = """
~/environments/
├── web_development/        # Django/Flask projects
├── data_science/          # Pandas/NumPy/Jupyter
├── machine_learning/      # TensorFlow/PyTorch
└── testing/              # Pytest/Coverage tools
"""

print("Environment naming examples:")
for strategy, example in naming_examples.items():
    print(f"  {strategy}: {example}")

print("\nMultiple environments structure:")
print(environments_structure)

# Package management workflow
def demonstrate_package_workflow():
    workflow_steps = [
        "1. Create virtual environment",
        "2. Activate environment", 
        "3. Install core packages first",
        "4. Test your code",
        "5. Add more packages as needed",
        "6. Update requirements.txt regularly",
        "7. Use specific versions for production"
    ]
    
    return workflow_steps

# Package installation strategies
installation_strategies = {
    "development": [
        "pip install package_name",  # Latest version
        "Test and develop",
        "pip freeze > requirements.txt"  # Save working versions
    ],
    "production": [
        "pip install -r requirements.txt",  # Exact versions
        "pip install --no-deps package",    # Skip dependencies if needed
        "pip check"  # Verify no conflicts
    ]
}

print("Package management workflow:")
for step in demonstrate_package_workflow():
    print(f"  {step}")

print("\nInstallation strategies:")
for env_type, strategy in installation_strategies.items():
    print(f"\n{env_type.title()}:")
    for step in strategy:
        print(f"  - {step}")

# Creating activation shortcuts (examples)
activation_scripts = {
    "Windows batch file (.bat)": """
@echo off
cd /d "C:\\path\\to\\your\\project"
call myproject_env\\Scripts\\activate
echo Environment activated for MyProject
cmd /k
""",
    
    "Mac/Linux shell script (.sh)": """
#!/bin/bash
cd ~/path/to/your/project
source myproject_env/bin/activate
echo "Environment activated for MyProject"
exec "$SHELL"
""",
    
    "Python script": """
import subprocess
import os

def activate_project_env():
    project_path = "/path/to/project"
    env_path = os.path.join(project_path, "myproject_env")
    
    if os.path.exists(env_path):
        print(f"Activating environment: {env_path}")
        # Platform-specific activation would go here
        return True
    else:
        print("Environment not found!")
        return False
"""
}

print("Activation script examples:")
for script_type, content in activation_scripts.items():
    print(f"\n{script_type}:")
    print(content[:100] + "..." if len(content) > 100 else content)

# Common virtual environment issues and solutions
common_issues = {
    "Environment won't activate": [
        "Check if activation script exists",
        "Try using full path to activate script", 
        "On Windows: Check execution policy",
        "Recreate environment if corrupted"
    ],
    
    "Package installation fails": [
        "Update pip: python -m pip install --upgrade pip",
        "Check internet connection",
        "Clear pip cache: pip cache purge",
        "Install from wheel files if needed"
    ],
    
    "Wrong Python version": [
        "Specify Python version: python3.9 -m venv env",
        "Check PATH environment variable",
        "Use full path to Python executable",
        "Update system Python if needed"
    ],
    
    "Import errors after activation": [
        "Verify environment is activated (check prompt)",
        "Reinstall packages in environment",
        "Check PYTHONPATH environment variable",
        "Restart terminal/IDE"
    ]
}

print("Common virtual environment troubleshooting:")
for issue, solutions in common_issues.items():
    print(f"\n{issue}:")
    for solution in solutions:
        print(f"  • {solution}")