<?php

namespace SilverStripe\Core;

use BadMethodCallException;
use InvalidArgumentException;

/**
 * Allows an object to declare a set of custom methods
 */
trait CustomMethods
{

    /**
     * Custom method sources
     *
     * @var array
     */
    protected static $extra_methods = array();

    /**
     * Name of methods to invoke by defineMethods for this instance
     *
     * @var array
     */
    protected $extra_method_registers = array();

    /**
     * Non-custom methods
     *
     * @var array
     */
    protected static $built_in_methods = array();

    /**
     * Attempts to locate and call a method dynamically added to a class at runtime if a default cannot be located
     *
     * You can add extra methods to a class using {@link Extensions}, {@link Object::createMethod()} or
     * {@link Object::addWrapperMethod()}
     *
     * @param string $method
     * @param array $arguments
     * @return mixed
     * @throws BadMethodCallException
     */
    public function __call($method, $arguments)
    {
        // If the method cache was cleared by an an Object::add_extension() / Object::remove_extension()
        // call, then we should rebuild it.
        $class = get_class($this);
        if (!array_key_exists($class, self::$extra_methods)) {
            $this->defineMethods();
        }

        $config = $this->getExtraMethodConfig($method);
        if (empty($config)) {
            throw new BadMethodCallException(
                "Object->__call(): the method '$method' does not exist on '$class'"
            );
        }

        switch (true) {
            case isset($config['property']) : {
                $obj = $config['index'] !== null ?
                    $this->{$config['property']}[$config['index']] :
                    $this->{$config['property']};

                if ($obj) {
                    if (!empty($config['callSetOwnerFirst'])) {
                        /** @var Extension $obj */
                        $obj->setOwner($this);
                    }
                    $retVal = call_user_func_array(array($obj, $method), $arguments);
                    if (!empty($config['callSetOwnerFirst'])) {
                        /** @var Extension $obj */
                        $obj->clearOwner();
                    }
                    return $retVal;
                }

                if (!empty($this->destroyed)) {
                    throw new BadMethodCallException(
                        "Object->__call(): attempt to call $method on a destroyed $class object"
                    );
                } else {
                    throw new BadMethodCallException(
                        "Object->__call(): $class cannot pass control to $config[property]($config[index])."
                        . ' Perhaps this object was mistakenly destroyed?'
                    );
                }
            }
            case isset($config['wrap']):
                array_unshift($arguments, $config['method']);
                return call_user_func_array(array($this, $config['wrap']), $arguments);

                case isset($config['function']):
                return $config['function']($this, $arguments);

                default:
                throw new BadMethodCallException(
                    "Object->__call(): extra method $method is invalid on $class:"
                        . var_export($config, true)
                );
        }
    }

    /**
     * Adds any methods from {@link Extension} instances attached to this object.
     * All these methods can then be called directly on the instance (transparently
     * mapped through {@link __call()}), or called explicitly through {@link extend()}.
     *
     * @uses addMethodsFrom()
     */
    protected function defineMethods()
    {
        // Define from all registered callbacks
        foreach ($this->extra_method_registers as $callback) {
            call_user_func($callback);
        }
    }

    /**
     * Register an callback to invoke that defines extra methods
     *
     * @param string $name
     * @param callable $callback
     */
    protected function registerExtraMethodCallback($name, $callback)
    {
        if (!isset($this->extra_method_registers[$name])) {
            $this->extra_method_registers[$name] = $callback;
        }
    }

    // --------------------------------------------------------------------------------------------------------------

    /**
     * Return TRUE if a method exists on this object
     *
     * This should be used rather than PHP's inbuild method_exists() as it takes into account methods added via
     * extensions
     *
     * @param string $method
     * @return bool
     */
    public function hasMethod($method)
    {
        return method_exists($this, $method) || $this->getExtraMethodConfig($method);
    }

    /**
     * Get meta-data details on a named method
     *
     * @param array $method
     * @return array List of custom method details, if defined for this method
     */
    protected function getExtraMethodConfig($method)
    {
        $class = get_class($this);
        if (isset(self::$extra_methods[$class][strtolower($method)])) {
            return self::$extra_methods[$class][strtolower($method)];
        }
        return null;
    }

    /**
     * Return the names of all the methods available on this object
     *
     * @param bool $custom include methods added dynamically at runtime
     * @return array
     */
    public function allMethodNames($custom = false)
    {
        $class = get_class($this);
        if (!isset(self::$built_in_methods[$class])) {
            self::$built_in_methods[$class] = array_map('strtolower', get_class_methods($this));
        }

        if ($custom && isset(self::$extra_methods[$class])) {
            return array_merge(self::$built_in_methods[$class], array_keys(self::$extra_methods[$class]));
        } else {
            return self::$built_in_methods[$class];
        }
    }

    /**
     * @param object $extension
     * @return array
     */
    protected function findMethodsFromExtension($extension)
    {
        if (method_exists($extension, 'allMethodNames')) {
            if ($extension instanceof Extension) {
                $extension->setOwner($this);
            }
            $methods = $extension->allMethodNames(true);
            if ($extension instanceof Extension) {
                $extension->clearOwner();
            }
        } else {
            if (!isset(self::$built_in_methods[$extension->class])) {
                self::$built_in_methods[$extension->class] = array_map('strtolower', get_class_methods($extension));
            }
            $methods = self::$built_in_methods[$extension->class];
        }

        return $methods;
    }

    /**
     * Add all the methods from an object property (which is an {@link Extension}) to this object.
     *
     * @param string $property the property name
     * @param string|int $index an index to use if the property is an array
     * @throws InvalidArgumentException
     */
    protected function addMethodsFrom($property, $index = null)
    {
        $class = get_class($this);
        $extension = ($index !== null) ? $this->{$property}[$index] : $this->$property;

        if (!$extension) {
            throw new InvalidArgumentException(
                "Object->addMethodsFrom(): could not add methods from {$class}->{$property}[$index]"
            );
        }

        $methods = $this->findMethodsFromExtension($extension);
        if ($methods) {
            $methodInfo = array(
                'property' => $property,
                'index'    => $index,
                'callSetOwnerFirst' => $extension instanceof Extension,
            );

            $newMethods = array_fill_keys($methods, $methodInfo);

            if (isset(self::$extra_methods[$class])) {
                self::$extra_methods[$class] =
                    array_merge(self::$extra_methods[$class], $newMethods);
            } else {
                self::$extra_methods[$class] = $newMethods;
            }
        }
    }

    /**
     * Add all the methods from an object property (which is an {@link Extension}) to this object.
     *
     * @param string $property the property name
     * @param string|int $index an index to use if the property is an array
     */
    protected function removeMethodsFrom($property, $index = null)
    {
        $extension = ($index !== null) ? $this->{$property}[$index] : $this->$property;
        $class = get_class($this);

        if (!$extension) {
            throw new InvalidArgumentException(
                "Object->removeMethodsFrom(): could not remove methods from {$class}->{$property}[$index]"
            );
        }

        $methods = $this->findMethodsFromExtension($extension);
        if ($methods) {
            foreach ($methods as $method) {
                $methodInfo = self::$extra_methods[$class][$method];

                if ($methodInfo['property'] === $property && $methodInfo['index'] === $index) {
                    unset(self::$extra_methods[$class][$method]);
                }
            }

            if (empty(self::$extra_methods[$class])) {
                unset(self::$extra_methods[$class]);
            }
        }
    }

    /**
     * Add a wrapper method - a method which points to another method with a different name. For example, Thumbnail(x)
     * can be wrapped to generateThumbnail(x)
     *
     * @param string $method the method name to wrap
     * @param string $wrap the method name to wrap to
     */
    protected function addWrapperMethod($method, $wrap)
    {
        $class = get_class($this);
        self::$extra_methods[$class][strtolower($method)] = array (
            'wrap'   => $wrap,
            'method' => $method
        );
    }

    /**
     * Add an extra method using raw PHP code passed as a string
     *
     * @param string $method the method name
     * @param string $code the PHP code - arguments will be in an array called $args, while you can access this object
     *        by using $obj. Note that you cannot call protected methods, as the method is actually an external
     *        function
     */
    protected function createMethod($method, $code)
    {
        $class = get_class($this);
        self::$extra_methods[$class][strtolower($method)] = array (
            'function' => create_function('$obj, $args', $code)
        );
    }
}