<?

// First Example: Address Validation
class Address { 
  function __construct(string $emailAddress) {
     // String validation on Address class violates SRP
     $this->validateEmail($emailAddress);
     // ...
   }

  private function validateEmail(string $emailAddress) {
    $regex = "/[a-zA-Z0-9_-.+]+@[a-zA-Z0-9-]+.[a-zA-Z]+/";
    // Regex is a sample / It might be wrong
    // Emails and Urls should be first class objects

    if (!preg_match($regex, $emailAddress))
    {
      throw new Exception('Invalid email address ' . emailAddress);
    }    
  }
}

// Second Example: Wordle

class Wordle { 
  function validateWord(string $wordleword) {
    // Wordle word should be a real world entity. Not a subset of strings
  }
 }

<?

//First Example: Address Validation
class Address { 
  function __construct(EmailAddress $emailAddress) {
     // Email is always valid / Code is cleaner
     // ...
   }
}

class EmailAddress { 
  // We can reuse this object many times avoiding copy-pasting
  string $address; 
  private function __construct(string $emailAddress) {
    $regex = "/[a-zA-Z0-9_-.+]+@[a-zA-Z0-9-]+.[a-zA-Z]+/";
    // Regex is a sample / It might be wrong
    // Emails and Urls are first class objects

    if (!preg_match($regex, $emailAddress))
    {
      throw new Exception('Invalid email address ' . emailAddress);
    }   
    $this->address = $emailAddress;
  }
}

// Second Example: Wordle

class Wordle { 
  function validateWord(WordleWord $wordleword) {
    // Wordle word is a real world entity. Not a subset of string
  }
 }

class WordleWord { 
  function __construct(string $emailAddress) {
    // Avoid building invalid world words
    // For example length != 5
  }
 }

// Samples borrowed with permission from
// https://towardsdev.com/why-a-host-is-not-a-string-and-a-port-is-not-an-integer-595c182d817c

var port = 8080;

var in = open("example.org", port);
var uri = urifromPort("example.org", port);
var address = addressFromPort("example.org", port);
var path = pathFromPort("example.org", port);

// Samples borrowed with permission from
// https://towardsdev.com/why-a-host-is-not-a-string-and-a-port-is-not-an-integer-595c182d817c

const server = Port.parse(this, "www.kivakit.org:8080");
// Port is a smallobject with responsibilities and protocol

let in = port.open(this);
const uri = port.asUri(this);
const address = port.asInetSocketAddress();
const path = port.path(this, "/index.html");

class Workflow {
    moveToNextTransition() {
        // We couple the business rule with the accidental implementation
        if (this.stepWork.hasPendingTasks) {
            throw new Exception('Preconditions are not met yet..');
        } else {
            this.moveToNextStep();
        }
    }
}

class Workflow {
    moveToNextTransition() {
        if (!this.canWeMoveOn()) {
            throw new Exception('Preconditions are not met yet..');
        } else {
            this.moveToNextStep();
        }
    }

    canWeMoveOn() {
        // We hide accidental implementation 'the how'
        // under the 'what'
        return !this.stepWork.hasPendingTasks();
    }
}

class Webpage {

  renderHTML() {
    renderDocType();
    renderTitle();
    renderRssHeader();
    renderRssTitle();
    renderRssDescription();
   // ...
  }
  // HTML render can change

  renderRssDescription() {
   // ...
  }

  renderRssTitle() {
   // ...
  }

  renderRssPubDate() {
   // ...
  }
  // RSS Format might change

}

class Webpage {

  renderHTML() {
    this.renderDocType();
    this.renderTitle();
    (new RSSFeed()).render();
    this.renderRssTitle();
    this.renderRssDescription();
   // ...
  }
  // HTML render can change
}

class RSSFeed {
  render() {
    this.renderDescription();
    this.renderTitle();
    this.renderPubDate();
    // ...
  }  
  // RSS Format might change
  // Might have unitary tests
  // etc
}

// If you made Square derive from Rectangle, 
// then a Square should be usable anywhere you expect a rectangle

#include <iostream>

Rectangle::Rectangle(const unsigned width, const unsigned height):
    m_width(width),
    m_height(height)
{
}

unsigned Rectangle::getWidth() const
{
    return m_width;
}

void Rectangle::setWidth(const unsigned width)
{
  /* Width and Height are independent */
    m_width = width;
}

unsigned Rectangle::getHeight() const
{
    return m_height;
}

void Rectangle::setHeight(const unsigned height)
{
    m_height = height;
}

unsigned Rectangle::area() const
{
  /*Valid for both Rectangles and Squares*/
    return m_height * m_width;
}

Square::Square(const unsigned size)
    : Rectangle(size, size)
{
}

// OK for squares, bad for rectangles
// Protocol is bad, width and height are not relevant on squares
void Square::setWidth(const unsigned size)
{
    m_height = size;
    m_width = size;
}

// OK for squares, bad for rectangles
// Protocol is bad, width and height are not relevant on squares
void Square::setHeight(const unsigned size)
{
    m_height = size;
    m_width = size;
}

void process(Rectangle& r)
{
    unsigned h = 10;
    auto w = r.getWidth();
    r.setHeight(h);

    std::cout << "Expected area: " << (w*h) << ", got " << r.area() << "n";
    // area is not well defined in squares
    // every square IS-A rectangle, but does not behave-like a rectangle
}

int main()
{
    Rectangle rectangle{3,4};
    Square square{5};
    process(rectangle);
    process(square);
}

// If you made Square derive from Rectangle, 
// then a Square should be usable anywhere you expect a rectangle

#include <iostream>

Rectangle::Rectangle(const unsigned width, const unsigned height):
    m_width(width),
    m_height(height)
{
}

void Rectangle:changeWidth(const unsigned width)
{
  /* Width and Height are independant */
    m_width = width;
    // We should discuss if it is good to mutate 
    // and not create a new Figure
}

void Rectangle::changeHeight(const unsigned height)
{
    m_height = height;
}

unsigned Rectangle::area() const
{ 
    return m_height * m_width;
}

// No inheritance
Square::Square(const unsigned size):
    m_size(size)
{
}

unsigned Square::area() const
{ 
    return m_size * m_size;
}

void Square::changeSize(const unsigned size)
{
    m_size = size; 
}

void testRectangleChange(Rectangle& r)
{
    unsigned h = 10;
    auto w = r.getWidth();
    r.setHeight(h);

    std::cout << "Expected area: " << (w*h) << ", got " << r.area() << "n";
    // area is not well defined in squares
    // every square IS-A rectangle, but does not behave-like a rectangle
}

int main()
{
    Rectangle rectangle{3,4};
    Square square{5};
    testRectangleChange(rectangle);
    testRectangleChange(square);
}