Children Utilities

/**
 * Maps over children array with optional context binding
 * @param children - Array of child elements to map over
 * @param fn - Function to apply to each child
 * @param ctx - Optional context to bind the function to
 * @returns Array of mapped results
 */
map<T, U>(
  children: T[],
  fn: (child: T, index: number) => U,
  ctx?: any
): U[];

import { Children, createElement } from "inferno-compat";

function ButtonGroup({ children }) {
  // Add click handlers to all child buttons
  const enhancedChildren = Children.map(children, (child, index) => {
    if (child.type === 'button') {
      return cloneElement(child, {
        onClick: () => console.log(`Button ${index} clicked`),
        key: index
      });
    }
    return child;
  });
  
  return createElement('div', { className: 'button-group' }, enhancedChildren);
}

// With context binding
function ListRenderer({ children, formatter }) {
  const formattedChildren = Children.map(
    children,
    function(child, index) {
      return this.formatChild(child, index);
    },
    formatter // Context object with formatChild method
  );
  
  return createElement('ul', null, formattedChildren);
}

// Handling null/undefined children
function SafeMap({ children }) {
  // Children.map gracefully handles null/undefined
  const mapped = Children.map(children, (child, index) => {
    return createElement('li', { key: index }, child);
  });
  
  return createElement('ul', null, mapped || []);
}

/**
 * Iterates over children array with optional context binding
 * @param children - Array of child elements to iterate over
 * @param fn - Function to call for each child
 * @param ctx - Optional context to bind the function to
 */
forEach<T>(
  children: T[],
  fn: (child: T, index: number) => void,
  ctx?: any
): void;

import { Children, createElement, Component } from "inferno-compat";

class FormValidator extends Component {
  constructor(props) {
    super(props);
    this.state = { errors: [] };
  }
  
  validateChildren = () => {
    const errors = [];
    
    Children.forEach(this.props.children, (child, index) => {
      if (child.type === 'input' && child.props.required && !child.props.value) {
        errors.push(`Field ${index + 1} is required`);
      }
    });
    
    this.setState({ errors });
  }
  
  render() {
    const { children } = this.props;
    const { errors } = this.state;
    
    return createElement('form', null,
      children,
      errors.length > 0 && createElement('div', { className: 'errors' },
        errors.map((error, index) => 
          createElement('p', { key: index }, error)
        )
      )
    );
  }
}

// Context usage for method binding
class ComponentInspector extends Component {
  inspectChild(child, index) {
    console.log(`Child ${index}:`, {
      type: child.type,
      props: Object.keys(child.props || {}),
      hasChildren: !!child.children
    });
  }
  
  componentDidMount() {
    Children.forEach(
      this.props.children,
      this.inspectChild,
      this // Bind to component instance
    );
  }
  
  render() {
    return createElement('div', null, this.props.children);
  }
}

/**
 * Returns the number of children in a children array
 * @param children - Array of child elements to count
 * @returns Number of children in the array
 */
count(children: any[]): number;

import { Children, createElement } from "inferno-compat";

function TabContainer({ children, activeTab = 0 }) {
  const childCount = Children.count(children);
  
  return createElement('div', { className: 'tab-container' },
    // Tab headers
    createElement('div', { className: 'tab-headers' },
      Array.from({ length: childCount }, (_, index) =>
        createElement('button', {
          key: index,
          className: index === activeTab ? 'active' : '',
          onClick: () => setActiveTab(index)
        }, `Tab ${index + 1}`)
      )
    ),
    // Active tab content
    Children.toArray(children)[activeTab]
  );
}

function ConditionalRenderer({ children, maxChildren = 5 }) {
  const count = Children.count(children);
  
  if (count === 0) {
    return createElement('p', null, 'No content available');
  }
  
  if (count > maxChildren) {
    return createElement('div', null,
      createElement('p', null, `Showing first ${maxChildren} of ${count} items`),
      Children.toArray(children).slice(0, maxChildren)
    );
  }
  
  return createElement('div', null, children);
}

// Edge cases handling
function SafeCounter({ children }) {
  const count = Children.count(children); // Handles null/undefined gracefully
  
  return createElement('div', null,
    createElement('p', null, `Child count: ${count}`),
    children
  );
}

/**
 * Returns the single child element, throws error if not exactly one child
 * @param children - Children array that should contain exactly one element
 * @returns The single child element
 * @throws Error if children count is not exactly 1
 */
only(children: any[]): any;

import { Children, createElement, cloneElement } from "inferno-compat";

function SingleChildWrapper({ children, className }) {
  // Ensure exactly one child is provided
  const child = Children.only(children);
  
  // Add wrapper class to the single child
  return cloneElement(child, {
    className: `${child.props.className || ''} ${className}`.trim()
  });
}

// Usage - this works
const wrapped = createElement(SingleChildWrapper, { className: 'highlight' },
  createElement('p', null, 'Single paragraph')
);

// This would throw an error - multiple children
try {
  const invalid = createElement(SingleChildWrapper, { className: 'highlight' },
    createElement('p', null, 'First paragraph'),
    createElement('p', null, 'Second paragraph')
  );
} catch (error) {
  console.error(error.message); // "Children.only() expects only one child."
}

function ModalContent({ children }) {
  try {
    const content = Children.only(children);
    return createElement('div', { className: 'modal-content' }, content);
  } catch (error) {
    return createElement('div', { className: 'modal-error' },
      createElement('p', null, 'Modal requires exactly one child element')
    );
  }
}

// Higher-order component that requires single child
function withEnhancement(WrappedComponent) {
  return function EnhancedComponent(props) {
    return createElement(WrappedComponent, {
      ...props,
      children: Children.only(props.children) // Ensure single child
    });
  };
}

/**
 * Converts children to a flattened array
 * @param children - Children to convert (can be arrays, single elements, null, etc.)
 * @returns Flattened array of children
 */
toArray(children: any[]): any[];

import { Children, createElement } from "inferno-compat";

function FlexibleList({ children }) {
  const childArray = Children.toArray(children);
  
  return createElement('ul', null,
    childArray.map((child, index) =>
      createElement('li', { key: index }, child)
    )
  );
}

// Handles various input types
const list = createElement(FlexibleList, null,
  'Simple string',
  createElement('span', null, 'Element'),
  ['Nested', 'Array'],
  null, // Ignored
  undefined, // Ignored
  42 // Number
);

function NavigationBreadcrumbs({ children }) {
  const items = Children.toArray(children);
  
  return createElement('nav', { className: 'breadcrumbs' },
    items.map((item, index) => 
      createElement('span', { key: index },
        item,
        index < items.length - 1 && 
          createElement('span', { className: 'separator' }, ' > ')
      )
    )
  );
}

// Complex nesting example
function DeepNestingHandler({ children }) {
  const flattened = Children.toArray(children);
  
  console.log('Original structure:', children);
  console.log('Flattened array:', flattened);
  
  return createElement('div', null, flattened);
}

const complex = createElement(DeepNestingHandler, null,
  [
    ['deeply', 'nested'],
    'array',
    [['structure'], 'here']
  ]
);
// Results in: ['deeply', 'nested', 'array', 'structure', 'here']

interface Children {
  map<T, U>(children: T[], fn: (child: T, index: number) => U, ctx?: any): U[];
  forEach<T>(children: T[], fn: (child: T, index: number) => void, ctx?: any): void;
  count(children: any[]): number;
  only(children: any[]): any;
  toArray(children: any[]): any[];
}