<?php

namespace Kirby\Toolkit;

use ArgumentCountError;
use Kirby\Exception\Exception;
use Kirby\Exception\InvalidArgumentException;
use TypeError;

/**
 * Vue-like components
 *
 * @package   Kirby Toolkit
 * @author    Bastian Allgeier <bastian@getkirby.com>
 * @link      https://getkirby.com
 * @copyright Bastian Allgeier GmbH
 * @license   https://opensource.org/licenses/MIT
 */
class Component
{
    /**
     * Registry for all component mixins
     *
     * @var array
     */
    public static $mixins = [];

    /**
     * Registry for all component types
     *
     * @var array
     */
    public static $types = [];

    /**
     * An array of all passed attributes
     *
     * @var array
     */
    protected $attrs = [];

    /**
     * An array of all computed properties
     *
     * @var array
     */
    protected $computed = [];

    /**
     * An array of all registered methods
     *
     * @var array
     */
    protected $methods = [];

    /**
     * An array of all component options
     * from the component definition
     *
     * @var array
     */
    protected $options = [];

    /**
     * An array of all resolved props
     *
     * @var array
     */
    protected $props = [];

    /**
     * The component type
     *
     * @var string
     */
    protected $type;

    /**
     * Magic caller for defined methods and properties
     *
     * @param string $name
     * @param array $arguments
     * @return mixed
     */
    public function __call(string $name, array $arguments = [])
    {
        if (array_key_exists($name, $this->computed) === true) {
            return $this->computed[$name];
        }

        if (array_key_exists($name, $this->props) === true) {
            return $this->props[$name];
        }

        if (array_key_exists($name, $this->methods) === true) {
            return $this->methods[$name]->call($this, ...$arguments);
        }

        return $this->$name;
    }

    /**
     * Creates a new component for the given type
     *
     * @param string $type
     * @param array $attrs
     */
    public function __construct(string $type, array $attrs = [])
    {
        if (isset(static::$types[$type]) === false) {
            throw new InvalidArgumentException('Undefined component type: ' . $type);
        }

        $this->attrs   = $attrs;
        $this->options = $options = $this->setup($type);
        $this->methods = $methods = $options['methods'] ?? [];

        foreach ($attrs as $attrName => $attrValue) {
            $this->$attrName = $attrValue;
        }

        if (isset($options['props']) === true) {
            $this->applyProps($options['props']);
        }

        if (isset($options['computed']) === true) {
            $this->applyComputed($options['computed']);
        }

        $this->attrs   = $attrs;
        $this->methods = $methods;
        $this->options = $options;
        $this->type    = $type;
    }

    /**
     * Improved `var_dump` output
     *
     * @return array
     */
    public function __debugInfo(): array
    {
        return $this->toArray();
    }

    /**
     * Fallback for missing properties to return
     * null instead of an error
     *
     * @param string $attr
     * @return null
     */
    public function __get(string $attr)
    {
        return null;
    }

    /**
     * A set of default options for each component.
     * This can be overwritten by extended classes
     * to define basic options that should always
     * be applied.
     *
     * @return array
     */
    public static function defaults(): array
    {
        return [];
    }

    /**
     * Register all defined props and apply the
     * passed values.
     *
     * @param array $props
     * @return void
     */
    protected function applyProps(array $props): void
    {
        foreach ($props as $propName => $propFunction) {
            if (is_a($propFunction, 'Closure') === true) {
                if (isset($this->attrs[$propName]) === true) {
                    try {
                        $this->$propName = $this->props[$propName] = $propFunction->call($this, $this->attrs[$propName]);
                    } catch (TypeError $e) {
                        throw new TypeError('Invalid value for "' . $propName . '"');
                    }
                } else {
                    try {
                        $this->$propName = $this->props[$propName] = $propFunction->call($this);
                    } catch (ArgumentCountError $e) {
                        throw new ArgumentCountError('Please provide a value for "' . $propName . '"');
                    }
                }
            } else {
                $this->$propName = $this->props[$propName] = $propFunction;
            }
        }
    }

    /**
     * Register all computed properties and calculate their values.
     * This must happen after all props are registered.
     *
     * @param array $computed
     * @return void
     */
    protected function applyComputed(array $computed): void
    {
        foreach ($computed as $computedName => $computedFunction) {
            if (is_a($computedFunction, 'Closure') === true) {
                $this->$computedName = $this->computed[$computedName] = $computedFunction->call($this);
            }
        }
    }

    /**
     * Load a component definition by type
     *
     * @param string $type
     * @return array
     */
    public static function load(string $type): array
    {
        $definition = static::$types[$type];

        // load definitions from string
        if (is_string($definition) === true) {
            if (is_file($definition) !== true) {
                throw new Exception('Component definition ' . $definition . ' does not exist');
            }

            static::$types[$type] = $definition = F::load($definition);
        }

        return $definition;
    }

    /**
     * Loads all options from the component definition
     * mixes in the defaults from the defaults method and
     * then injects all additional mixins, defined in the
     * component options.
     *
     * @param string $type
     * @return array
     */
    public static function setup(string $type): array
    {
        // load component definition
        $definition = static::load($type);

        if (isset($definition['extends']) === true) {
            // extend other definitions
            $options = array_replace_recursive(static::defaults(), static::load($definition['extends']), $definition);
        } else {
            // inject defaults
            $options = array_replace_recursive(static::defaults(), $definition);
        }

        // inject mixins
        if (isset($options['mixins']) === true) {
            foreach ($options['mixins'] as $mixin) {
                if (isset(static::$mixins[$mixin]) === true) {
                    $options = array_replace_recursive(static::$mixins[$mixin], $options);
                }
            }
        }

        return $options;
    }

    /**
     * Converts all props and computed props to an array
     *
     * @return array
     */
    public function toArray(): array
    {
        if (is_a($this->options['toArray'] ?? null, 'Closure') === true) {
            return $this->options['toArray']->call($this);
        }

        $array = array_merge($this->attrs, $this->props, $this->computed);

        ksort($array);

        return $array;
    }
}