<?php
/**
 * Part of the Joomla Framework Data Package
 *
 * @copyright  Copyright (C) 2005 - 2021 Open Source Matters, Inc. All rights reserved.
 * @license    GNU General Public License version 2 or later; see LICENSE
 */

namespace Joomla\Data;

/**
 * DataSet is a collection class that allows the developer to operate on a set of DataObjects as if they were in a typical PHP array.
 *
 * @since  1.0
 */
class DataSet implements DumpableInterface, \ArrayAccess, \Countable, \Iterator
{
	/**
	 * The current position of the iterator.
	 *
	 * @var    integer
	 * @since  1.0
	 */
	private $current = false;

	/**
	 * The iterator objects.
	 *
	 * @var    DataObject[]
	 * @since  1.0
	 */
	private $objects = [];

	/**
	 * The class constructor.
	 *
	 * @param   DataObject[]  $objects  An array of DataObject objects to bind to the data set.
	 *
	 * @since   1.0
	 * @throws  \InvalidArgumentException if an object is not a DataObject.
	 */
	public function __construct(array $objects = [])
	{
		// Set the objects.
		$this->initialise($objects);
	}

	/**
	 * The magic call method is used to call object methods using the iterator.
	 *
	 * Example: $array = $objectList->foo('bar');
	 *
	 * The object list will iterate over its objects and see if each object has a callable 'foo' method.
	 * If so, it will pass the argument list and assemble any return values. If an object does not have
	 * a callable method no return value is recorded.
	 * The keys of the objects and the result array are maintained.
	 *
	 * @param   string  $method     The name of the method called.
	 * @param   array   $arguments  The arguments of the method called.
	 *
	 * @return  array   An array of values returned by the methods called on the objects in the data set.
	 *
	 * @since   1.0
	 */
	public function __call($method, $arguments = [])
	{
		$return = [];

		// Iterate through the objects.
		foreach ($this->objects as $key => $object)
		{
			// Create the object callback.
			$callback = [$object, $method];

			// Check if the callback is callable.
			if (\is_callable($callback))
			{
				// Call the method for the object.
				$return[$key] = \call_user_func_array($callback, $arguments);
			}
		}

		return $return;
	}

	/**
	 * The magic get method is used to get a list of properties from the objects in the data set.
	 *
	 * Example: $array = $dataSet->foo;
	 *
	 * This will return a column of the values of the 'foo' property in all the objects
	 * (or values determined by custom property setters in the individual DataObject's).
	 * The result array will contain an entry for each object in the list (compared to __call which may not).
	 * The keys of the objects and the result array are maintained.
	 *
	 * @param   string  $property  The name of the data property.
	 *
	 * @return  array  An associative array of the values.
	 *
	 * @since   1.0
	 */
	public function __get($property)
	{
		$return = [];

		// Iterate through the objects.
		foreach ($this->objects as $key => $object)
		{
			// Get the property.
			$return[$key] = $object->$property;
		}

		return $return;
	}

	/**
	 * The magic isset method is used to check the state of an object property using the iterator.
	 *
	 * Example: $array = isset($objectList->foo);
	 *
	 * @param   string  $property  The name of the property.
	 *
	 * @return  boolean  True if the property is set in any of the objects in the data set.
	 *
	 * @since   1.0
	 */
	public function __isset($property)
	{
		$return = [];

		// Iterate through the objects.
		foreach ($this->objects as $object)
		{
			// Check the property.
			$return[] = isset($object->$property);
		}

		return \in_array(true, $return, true);
	}

	/**
	 * The magic set method is used to set an object property using the iterator.
	 *
	 * Example: $objectList->foo = 'bar';
	 *
	 * This will set the 'foo' property to 'bar' in all of the objects
	 * (or a value determined by custom property setters in the DataObject).
	 *
	 * @param   string  $property  The name of the property.
	 * @param   mixed   $value     The value to give the data property.
	 *
	 * @return  void
	 *
	 * @since   1.0
	 */
	public function __set($property, $value)
	{
		// Iterate through the objects.
		foreach ($this->objects as $object)
		{
			// Set the property.
			$object->$property = $value;
		}
	}

	/**
	 * The magic unset method is used to unset an object property using the iterator.
	 *
	 * Example: unset($objectList->foo);
	 *
	 * This will unset all of the 'foo' properties in the list of DataObject's.
	 *
	 * @param   string  $property  The name of the property.
	 *
	 * @return  void
	 *
	 * @since   1.0
	 */
	public function __unset($property)
	{
		// Iterate through the objects.
		foreach ($this->objects as $object)
		{
			unset($object->$property);
		}
	}

	/**
	 * Gets an array of keys, existing in objects
	 *
	 * @param   string  $type  Selection type 'all' or 'common'
	 *
	 * @return  array   Array of keys
	 *
	 * @since   1.2.0
	 * @throws  \InvalidArgumentException
	 */
	public function getObjectsKeys($type = 'all')
	{
		$keys = null;

		if ($type == 'all')
		{
			$function = 'array_merge';
		}
		elseif ($type == 'common')
		{
			$function = 'array_intersect_key';
		}
		else
		{
			throw new \InvalidArgumentException("Unknown selection type: $type");
		}

		foreach ($this->objects as $object)
		{
			$objectVars = json_decode(json_encode($object), true);

			$keys = ($keys === null) ? $objectVars : $function($keys, $objectVars);
		}

		return array_keys($keys);
	}

	/**
	 * Gets all objects as an array
	 *
	 * @param   boolean  $associative  Option to set return mode: associative or numeric array.
	 * @param   string   ...$keys      Unlimited optional property names to extract from objects.
	 *
	 * @return  array  Returns an array according to defined options.
	 *
	 * @since   1.2.0
	 */
	public function toArray($associative = true, ...$keys)
	{
		if (empty($keys))
		{
			$keys = $this->getObjectsKeys();
		}

		$return = [];

		$i = 0;

		foreach ($this->objects as $key => $object)
		{
			$arrayItem = [];

			$key = ($associative) ? $key : $i++;

			$j = 0;

			foreach ($keys as $property)
			{
				$propertyKey             = ($associative) ? $property : $j++;
				$arrayItem[$propertyKey] = $object->$property ?? null;
			}

			$return[$key] = $arrayItem;
		}

		return $return;
	}

	/**
	 * Gets the number of data objects in the set.
	 *
	 * @return  integer  The number of objects.
	 *
	 * @since   1.0
	 */
	public function count()
	{
		return \count($this->objects);
	}

	/**
	 * Clears the objects in the data set.
	 *
	 * @return  DataSet  Returns itself to allow chaining.
	 *
	 * @since   1.0
	 */
	public function clear()
	{
		$this->objects = [];
		$this->rewind();

		return $this;
	}

	/**
	 * Get the current data object in the set.
	 *
	 * @return  DataObject|false  The current object, or false if the array is empty or the pointer is beyond the end of the elements.
	 *
	 * @since   1.0
	 */
	public function current()
	{
		return is_scalar($this->current) ? $this->objects[$this->current] : false;
	}

	/**
	 * Dumps the data object in the set, recursively if appropriate.
	 *
	 * @param   integer            $depth   The maximum depth of recursion (default = 3).
	 *                                      For example, a depth of 0 will return a stdClass with all the properties in native
	 *                                      form. A depth of 1 will recurse into the first level of properties only.
	 * @param   \SplObjectStorage  $dumped  An array of already serialized objects that is used to avoid infinite loops.
	 *
	 * @return  array  An associative array of the data objects in the set, dumped as a simple PHP stdClass object.
	 *
	 * @see     DataObject::dump()
	 * @since   1.0
	 */
	public function dump($depth = 3, \SplObjectStorage $dumped = null)
	{
		// Check if we should initialise the recursion tracker.
		if ($dumped === null)
		{
			$dumped = new \SplObjectStorage;
		}

		// Add this object to the dumped stack.
		$dumped->attach($this);

		$objects = [];

		// Make sure that we have not reached our maximum depth.
		if ($depth > 0)
		{
			// Handle JSON serialization recursively.
			foreach ($this->objects as $key => $object)
			{
				$objects[$key] = $object->dump($depth, $dumped);
			}
		}

		return $objects;
	}

	/**
	 * Gets the data set in a form that can be serialised to JSON format.
	 *
	 * Note that this method will not return an associative array, otherwise it would be encoded into an object.
	 * JSON decoders do not consistently maintain the order of associative keys, whereas they do maintain the order of arrays.
	 *
	 * @return  array
	 *
	 * @since   1.0
	 */
	public function jsonSerialize()
	{
		$return = [];

		// Iterate through the objects.
		foreach ($this->objects as $object)
		{
			// Call the method for the object.
			$return[] = $object;
		}

		return $return;
	}

	/**
	 * Gets the key of the current object in the iterator.
	 *
	 * @return  integer|false  The object key on success; false on failure.
	 *
	 * @since   1.0
	 */
	public function key()
	{
		return $this->current;
	}

	/**
	 * Gets the array of keys for all the objects in the iterator (emulates array_keys).
	 *
	 * @return  array  The array of keys
	 *
	 * @since   1.0
	 */
	public function keys()
	{
		return array_keys($this->objects);
	}

	/**
	 * Applies a function to every object in the set (emulates array_walk).
	 *
	 * @param   callable  $funcname  Callback function.
	 *
	 * @return  boolean
	 *
	 * @since   1.2.0
	 * @throws  \InvalidArgumentException
	 */
	public function walk(callable $funcname)
	{
		foreach ($this->objects as $key => $object)
		{
			$funcname($object, $key);
		}

		return true;
	}

	/**
	 * Advances the iterator to the next object in the iterator.
	 *
	 * @return  void
	 *
	 * @since   1.0
	 */
	public function next()
	{
		// Get the object offsets.
		$keys = $this->keys();

		// Check if _current has been set to false but offsetUnset.
		if ($this->current === false && isset($keys[0]))
		{
			// This is a special case where offsetUnset was used in a foreach loop and the first element was unset.
			$this->current = $keys[0];
		}
		else
		{
			// Get the current key.
			$position = array_search($this->current, $keys);

			// Check if there is an object after the current object.
			if ($position !== false && isset($keys[$position + 1]))
			{
				// Get the next id.
				$this->current = $keys[$position + 1];
			}
			else
			{
				// That was the last object or the internal properties have become corrupted.
				$this->current = null;
			}
		}
	}

	/**
	 * Checks whether an offset exists in the iterator.
	 *
	 * @param   mixed  $offset  The object offset.
	 *
	 * @return  boolean
	 *
	 * @since   1.0
	 */
	public function offsetExists($offset)
	{
		return isset($this->objects[$offset]);
	}

	/**
	 * Gets an offset in the iterator.
	 *
	 * @param   mixed  $offset  The object offset.
	 *
	 * @return  DataObject|null
	 *
	 * @since   1.0
	 */
	public function offsetGet($offset)
	{
		return $this->objects[$offset] ?? null;
	}

	/**
	 * Sets an offset in the iterator.
	 *
	 * @param   mixed       $offset  The object offset.
	 * @param   DataObject  $object  The object object.
	 *
	 * @return  void
	 *
	 * @since   1.0
	 * @throws  \InvalidArgumentException if an object is not an instance of DataObject.
	 */
	public function offsetSet($offset, $object)
	{
		if (!($object instanceof DataObject))
		{
			throw new \InvalidArgumentException(
				sprintf(
					'The $object argument must be an instance of "%s", a %s was given.',
					DataObject::class,
					\gettype($object) === 'object' ? \get_class($object) : \gettype($object)
				)
			);
		}

		// Set the offset.
		if ($offset === null)
		{
			$this->objects[] = $object;
		}
		else
		{
			$this->objects[$offset] = $object;
		}
	}

	/**
	 * Unsets an offset in the iterator.
	 *
	 * @param   mixed  $offset  The object offset.
	 *
	 * @return  void
	 *
	 * @since   1.0
	 */
	public function offsetUnset($offset)
	{
		if (!isset($this[$offset]))
		{
			// Do nothing if the offset does not exist.
			return;
		}

		// Check for special handling of unsetting the current position.
		if ($offset == $this->current)
		{
			// Get the current position.
			$keys     = $this->keys();
			$position = array_search($this->current, $keys);

			// Check if there is an object before the current object.
			if ($position > 0)
			{
				// Move the current position back one.
				$this->current = $keys[$position - 1];
			}
			else
			{
				// We are at the start of the keys AND let's assume we are in a foreach loop and `next` is going to be called.
				$this->current = false;
			}
		}

		unset($this->objects[$offset]);
	}

	/**
	 * Rewinds the iterator to the first object.
	 *
	 * @return  void
	 *
	 * @since   1.0
	 */
	public function rewind()
	{
		// Set the current position to the first object.
		if (empty($this->objects))
		{
			$this->current = false;
		}
		else
		{
			$keys          = $this->keys();
			$this->current = array_shift($keys);
		}
	}

	/**
	 * Validates the iterator.
	 *
	 * @return  boolean
	 *
	 * @since   1.0
	 */
	public function valid()
	{
		// Check the current position.
		if (!is_scalar($this->current) || !isset($this->objects[$this->current]))
		{
			return false;
		}

		return true;
	}

	/**
	 * Initialises the list with an array of objects.
	 *
	 * @param   array  $input  An array of objects.
	 *
	 * @return  void
	 *
	 * @since   1.0
	 * @throws  \InvalidArgumentException if an object is not a DataObject.
	 */
	private function initialise(array $input = [])
	{
		foreach ($input as $key => $object)
		{
			if ($object !== null)
			{
				$this[$key] = $object;
			}
		}

		$this->rewind();
	}
}
