<?php

use SilverStripe\ORM\SS_List;
use SilverStripe\ORM\SS_Map;

/**
 * Represents a field that allows users to select one or more items from a list
 */
abstract class SelectField extends FormField {

	/**
	 * Associative or numeric array of all dropdown items,
	 * with array key as the submitted field value, and the array value as a
	 * natural language description shown in the interface element.
	 *
	 * @var array|ArrayAccess
	 */
	protected $source;

	/**
	 * The values for items that should be disabled (greyed out) in the dropdown.
	 * This is a non-associative array
	 *
	 * @var array
	 */
	protected $disabledItems = array();

	/**
	 * @param string $name The field name
	 * @param string $title The field title
	 * @param array|ArrayAccess $source A map of the dropdown items
	 * @param mixed $value The current value
	 */
	public function __construct($name, $title = null, $source = array(), $value = null) {
		$this->setSource($source);
		if(!isset($title)) {
			$title = $name;
		}
		parent::__construct($name, $title, $value);
	}

	public function getSchemaStateDefaults() {
		$data = parent::getSchemaStateDefaults();
		$disabled = $this->getDisabledItems();

		// Add options to 'data'
		$source = $this->getSource();
		$data['source'] = (is_array($source))
			? array_map(function ($value, $title) use ($disabled) {
				return [
					'value' => $value,
					'title' => $title,
					'disabled' => in_array($value, $disabled),
				];
			}, array_keys($source), $source)
			: [];

		return $data;
	}

	/**
	 * Mark certain elements as disabled,
	 * regardless of the {@link setDisabled()} settings.
	 *
	 * These should be items that appear in the source list, not in addition to them.
	 *
	 * @param array|SS_List $items Collection of values or items
	 * @return $this
	 */
	public function setDisabledItems($items){
		$this->disabledItems = $this->getListValues($items);
		return $this;
	}

	/**
	 * Non-associative list of disabled item values
	 *
	 * @return array
	 */
	public function getDisabledItems(){
		return $this->disabledItems;
	}

	/**
	 * Check if the given value is disabled
	 *
	 * @param string $value
	 * @return bool
	 */
	protected function isDisabledValue($value) {
		if($this->isDisabled()) {
			return true;
		}
		return in_array($value, $this->getDisabledItems());
	}

	public function getAttributes() {
		return array_merge(
			parent::getAttributes(),
			array('type' => null, 'value' => null)
		);
	}

	/**
	 * Retrieve all values in the source array
	 *
	 * @return array
	 */
	protected function getSourceValues() {
		return array_keys($this->getSource());
	}

	/**
	 * Gets all valid values for this field.
	 *
	 * Does not include "empty" value if specified
	 *
	 * @return array
	 */
	public function getValidValues() {
		$valid = array_diff($this->getSourceValues(), $this->getDisabledItems());
		// Renumber indexes from 0
		return array_values($valid);
	}

	/**
	 * Gets the source array not including any empty default values.
	 *
	 * @return array|ArrayAccess
	 */
	public function getSource() {
		return $this->source;
	}

	/**
	 * Set the source for this list
	 *
	 * @param mixed $source
	 * @return $this
	 */
	public function setSource($source) {
		$this->source = $this->getListMap($source);
		return $this;
	}

	/**
	 * Given a list of values, extract the associative map of id => title
	 *
	 * @param mixed $source
	 * @return array Associative array of ids and titles
	 */
	protected function getListMap($source) {
		// Extract source as an array
		if($source instanceof SS_List) {
			$source = $source->map();
		}
		if($source instanceof SS_Map) {
			$source = $source->toArray();
		}
		if(!is_array($source) && !($source instanceof ArrayAccess)) {
			user_error('$source passed in as invalid type', E_USER_ERROR);
		}

		return $source;
	}

	/**
	 * Given a non-array collection, extract the non-associative list of ids
	 * If passing as array, treat the array values (not the keys) as the ids
	 *
	 * @param mixed $values
	 * @return array Non-associative list of values
	 */
	protected function getListValues($values) {
		// Empty values
		if(empty($values)) {
			return array();
		}

		// Direct array
		if(is_array($values)) {
			return array_values($values);
		}

		// Extract lists
		if($values instanceof SS_List) {
			return $values->column('ID');
		}

		return array(trim($values));
	}

	/**
	 * Determine if the current value of this field matches the given option value
	 *
	 * @param mixed $dataValue The value as extracted from the source of this field (or empty value if available)
	 * @param mixed $userValue The value as submitted by the user
	 * @return boolean True if the selected value matches the given option value
	 */
	public function isSelectedValue($dataValue, $userValue) {
		if($dataValue === $userValue) {
			return true;
		}

		// Allow null to match empty strings
		if($dataValue === '' && $userValue === null) {
			return true;
		}

		// Safety check against casting arrays as strings in PHP>5.4
 		if(is_array($dataValue) || is_array($userValue)) {
			return false;
		}

		// For non-falsey values do loose comparison
		if($dataValue) {
			return $dataValue == $userValue;
		}

		// For empty values, use string comparison to perform visible value match
		return ((string) $dataValue) === ((string) $userValue);
	}

	public function performReadonlyTransformation() {
		/** @var LookupField $field */
		$field = $this->castedCopy('LookupField');
		$field->setSource($this->getSource());
		$field->setReadonly(true);

		return $field;
	}

	public function performDisabledTransformation() {
		$clone = clone $this;
		$clone->setDisabled(true);
		return $clone;
	}

	/**
	 * Returns another instance of this field, but "cast" to a different class.
	 *
	 * @see FormField::castedCopy()
	 *
	 * @param String $classOrCopy
	 * @return FormField
	 */
	public function castedCopy($classOrCopy) {
		$field = parent::castedCopy($classOrCopy);
		if($field instanceof SelectField) {
			$field->setSource($this->getSource());
		}
		return $field;
	}
}