<?php
/**
 * @link http://www.yiiframework.com/
 * @copyright Copyright (c) 2008 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

namespace yii\redis;
use yii\base\InvalidParamException;
use yii\base\NotSupportedException;
use yii\db\ActiveQueryInterface;
use yii\db\ActiveQueryTrait;
use yii\db\QueryTrait;

/**
 * ActiveQuery represents a query associated with an Active Record class.
 *
 * ActiveQuery instances are usually created by [[ActiveRecord::find()]]
 * and [[ActiveRecord::count()]].
 *
 * ActiveQuery mainly provides the following methods to retrieve the query results:
 *
 * - [[one()]]: returns a single record populated with the first row of data.
 * - [[all()]]: returns all records based on the query results.
 * - [[count()]]: returns the number of records.
 * - [[sum()]]: returns the sum over the specified column.
 * - [[average()]]: returns the average over the specified column.
 * - [[min()]]: returns the min over the specified column.
 * - [[max()]]: returns the max over the specified column.
 * - [[scalar()]]: returns the value of the first column in the first row of the query result.
 * - [[exists()]]: returns a value indicating whether the query result has data or not.
 *
 * You can use query methods, such as [[where()]], [[limit()]] and [[orderBy()]] to customize the query options.
 *
 * ActiveQuery also provides the following additional query options:
 *
 * - [[with()]]: list of relations that this query should be performed with.
 * - [[indexBy()]]: the name of the column by which the query result should be indexed.
 * - [[asArray()]]: whether to return each record as an array.
 *
 * These options can be configured using methods of the same name. For example:
 *
 * ~~~
 * $customers = Customer::find()->with('orders')->asArray()->all();
 * ~~~
 *
 * @author Carsten Brandt <mail@cebe.cc>
 * @since 2.0
 */
class ActiveQuery extends \yii\base\Component implements ActiveQueryInterface
{
	use QueryTrait;
	use ActiveQueryTrait;

	/**
	 * Executes the query and returns all results as an array.
	 * @param Connection $db the database connection used to execute the query.
	 * If this parameter is not given, the `db` application component will be used.
	 * @return array|ActiveRecord[] the query results. If the query results in nothing, an empty array will be returned.
	 */
	public function all($db = null)
	{
		// TODO add support for orderBy
		$data = $this->executeScript($db, 'All');
		$rows = [];
		foreach($data as $dataRow) {
			$row = [];
			$c = count($dataRow);
			for($i = 0; $i < $c; ) {
				$row[$dataRow[$i++]] = $dataRow[$i++];
			}
			$rows[] = $row;
		}
		if (!empty($rows)) {
			$models = $this->createModels($rows);
			if (!empty($this->with)) {
				$this->findWith($this->with, $models);
			}
			if (!$this->asArray) {
				foreach($models as $model) {
					$model->afterFind();
				}
			}
			return $models;
		} else {
			return [];
		}
	}

	/**
	 * Executes the query and returns a single row of result.
	 * @param Connection $db the database connection used to execute the query.
	 * If this parameter is not given, the `db` application component will be used.
	 * @return ActiveRecord|array|null a single row of query result. Depending on the setting of [[asArray]],
	 * the query result may be either an array or an ActiveRecord object. Null will be returned
	 * if the query results in nothing.
	 */
	public function one($db = null)
	{
		// TODO add support for orderBy
		$data = $this->executeScript($db, 'One');
		if (empty($data)) {
			return null;
		}
		$row = [];
		$c = count($data);
		for($i = 0; $i < $c; ) {
			$row[$data[$i++]] = $data[$i++];
		}
		if ($this->asArray) {
			$model = $row;
		} else {
			/** @var ActiveRecord $class */
			$class = $this->modelClass;
			$model = $class::instantiate($row);
			$class::populateRecord($model, $row);
		}
		if (!empty($this->with)) {
			$models = [$model];
			$this->findWith($this->with, $models);
			$model = $models[0];
		}
		if (!$this->asArray) {
			$model->afterFind();
		}
		return $model;
	}

	/**
	 * Returns the number of records.
	 * @param string $q the COUNT expression. This parameter is ignored by this implementation.
	 * @param Connection $db the database connection used to execute the query.
	 * If this parameter is not given, the `db` application component will be used.
	 * @return integer number of records
	 */
	public function count($q = '*', $db = null)
	{
		if ($this->where === null) {
			/** @var ActiveRecord $modelClass */
			$modelClass = $this->modelClass;
			if ($db === null) {
				$db = $modelClass::getDb();
			}
			return $db->executeCommand('LLEN', [$modelClass::keyPrefix()]);
		} else {
			return $this->executeScript($db, 'Count');
		}
	}

	/**
	 * Returns a value indicating whether the query result contains any row of data.
	 * @param Connection $db the database connection used to execute the query.
	 * If this parameter is not given, the `db` application component will be used.
	 * @return boolean whether the query result contains any row of data.
	 */
	public function exists($db = null)
	{
		return $this->one($db) !== null;
	}

	/**
	 * Executes the query and returns the first column of the result.
	 * @param string $column name of the column to select
	 * @param Connection $db the database connection used to execute the query.
	 * If this parameter is not given, the `db` application component will be used.
	 * @return array the first column of the query result. An empty array is returned if the query results in nothing.
	 */
	public function column($column, $db = null)
	{
		// TODO add support for orderBy
		return $this->executeScript($db, 'Column', $column);
	}

	/**
	 * Returns the number of records.
	 * @param string $column the column to sum up
	 * @param Connection $db the database connection used to execute the query.
	 * If this parameter is not given, the `db` application component will be used.
	 * @return integer number of records
	 */
	public function sum($column, $db = null)
	{
		return $this->executeScript($db, 'Sum', $column);
	}

	/**
	 * Returns the average of the specified column values.
	 * @param string $column the column name or expression.
	 * Make sure you properly quote column names in the expression.
	 * @param Connection $db the database connection used to execute the query.
	 * If this parameter is not given, the `db` application component will be used.
	 * @return integer the average of the specified column values.
	 */
	public function average($column, $db = null)
	{
		return $this->executeScript($db, 'Average', $column);
	}

	/**
	 * Returns the minimum of the specified column values.
	 * @param string $column the column name or expression.
	 * Make sure you properly quote column names in the expression.
	 * @param Connection $db the database connection used to execute the query.
	 * If this parameter is not given, the `db` application component will be used.
	 * @return integer the minimum of the specified column values.
	 */
	public function min($column, $db = null)
	{
		return $this->executeScript($db, 'Min', $column);
	}

	/**
	 * Returns the maximum of the specified column values.
	 * @param string $column the column name or expression.
	 * Make sure you properly quote column names in the expression.
	 * @param Connection $db the database connection used to execute the query.
	 * If this parameter is not given, the `db` application component will be used.
	 * @return integer the maximum of the specified column values.
	 */
	public function max($column, $db = null)
	{
		return $this->executeScript($db, 'Max', $column);
	}

	/**
	 * Returns the query result as a scalar value.
	 * The value returned will be the specified attribute in the first record of the query results.
	 * @param string $attribute name of the attribute to select
	 * @param Connection $db the database connection used to execute the query.
	 * If this parameter is not given, the `db` application component will be used.
	 * @return string the value of the specified attribute in the first record of the query result.
	 * Null is returned if the query result is empty.
	 */
	public function scalar($attribute, $db = null)
	{
		$record = $this->one($db);
		if ($record !== null) {
			return $record->hasAttribute($attribute) ? $record->$attribute : null;
		} else {
			return null;
		}
	}


	/**
	 * Executes a script created by [[LuaScriptBuilder]]
	 * @param Connection $db the database connection used to execute the query.
	 * If this parameter is not given, the `db` application component will be used.
	 * @param string $type the type of the script to generate
	 * @param string $columnName
	 * @return array|bool|null|string
	 */
	protected function executeScript($db, $type, $columnName = null)
	{
		if (!empty($this->orderBy)) {
			throw new NotSupportedException('orderBy is currently not supported by redis ActiveRecord.');
		}

		/** @var ActiveRecord $modelClass */
		$modelClass = $this->modelClass;

		if ($db === null) {
			$db = $modelClass::getDb();
		}

		// find by primary key if possible. This is much faster than scanning all records
		if (is_array($this->where) && !isset($this->where[0]) && $modelClass::isPrimaryKey(array_keys($this->where))) {
			return $this->findByPk($db, $type, $columnName);
		}

		$method = 'build' . $type;
		$script = $db->getLuaScriptBuilder()->$method($this, $columnName);
		return $db->executeCommand('EVAL', [$script, 0]);
	}

	/**
	 * Fetch by pk if possible as this is much faster
	 * @param Connection $db the database connection used to execute the query.
	 * If this parameter is not given, the `db` application component will be used.
	 * @param string $type the type of the script to generate
	 * @param string $columnName
	 * @return array|bool|null|string
	 * @throws \yii\base\InvalidParamException
	 * @throws \yii\base\NotSupportedException
	 */
	private function findByPk($db, $type, $columnName = null)
	{
		if (count($this->where) == 1) {
			$pks = (array) reset($this->where);
		} else {
			foreach($this->where as $values) {
				if (is_array($values)) {
					// TODO support composite IN for composite PK
					throw new NotSupportedException('Find by composite PK is not supported by redis ActiveRecord.');
				}
			}
			$pks = [$this->where];
		}

		/** @var ActiveRecord $modelClass */
		$modelClass = $this->modelClass;

		if ($type == 'Count') {
			$start = 0;
			$limit = null;
		} else {
			$start = $this->offset === null ? 0 : $this->offset;
			$limit = $this->limit;
		}
		$i = 0;
		$data = [];
		foreach($pks as $pk) {
			if (++$i > $start && ($limit === null || $i <= $start + $limit)) {
				$key = $modelClass::keyPrefix() . ':a:' . $modelClass::buildKey($pk);
				$result = $db->executeCommand('HGETALL', [$key]);
				if (!empty($result)) {
					$data[] = $result;
					if ($type === 'One' && $this->orderBy === null) {
						break;
					}
				}
			}
		}
		// TODO support orderBy

		switch($type) {
			case 'All':
				return $data;
			case 'One':
				return reset($data);
			case 'Count':
				return count($data);
			case 'Column':
				$column = [];
				foreach($data as $dataRow) {
					$row = [];
					$c = count($dataRow);
					for($i = 0; $i < $c; ) {
						$row[$dataRow[$i++]] = $dataRow[$i++];
					}
					$column[] = $row[$columnName];
				}
				return $column;
			case 'Sum':
				$sum = 0;
				foreach($data as $dataRow) {
					$c = count($dataRow);
					for($i = 0; $i < $c; ) {
						if ($dataRow[$i++] == $columnName) {
							$sum += $dataRow[$i];
							break;
						}
					}
				}
				return $sum;
			case 'Average':
				$sum = 0;
				$count = 0;
				foreach($data as $dataRow) {
					$count++;
					$c = count($dataRow);
					for($i = 0; $i < $c; ) {
						if ($dataRow[$i++] == $columnName) {
							$sum += $dataRow[$i];
							break;
						}
					}
				}
				return $sum / $count;
			case 'Min':
				$min = null;
				foreach($data as $dataRow) {
					$c = count($dataRow);
					for($i = 0; $i < $c; ) {
						if ($dataRow[$i++] == $columnName && ($min == null || $dataRow[$i] < $min)) {
							$min = $dataRow[$i];
							break;
						}
					}
				}
				return $min;
			case 'Max':
				$max = null;
				foreach($data as $dataRow) {
					$c = count($dataRow);
					for($i = 0; $i < $c; ) {
						if ($dataRow[$i++] == $columnName && ($max == null || $dataRow[$i] > $max)) {
							$max = $dataRow[$i];
							break;
						}
					}
				}
				return $max;
		}
		throw new InvalidParamException('Unknown fetch type: ' . $type);
	}
}
