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<?php
    /**
     * CzProject Innu DB
     *
     * @author      Jan Pecha, <janpecha@email.cz>
     */

    namespace Cz\InnuDb;
    use Nette;

    class Collection extends Nette\Object implements \Iterator
    {
        const ASC = 'ASC',
            DESC = 'DESC';

        /** @var  array */
        private $data;

        /** @var  int|NULL */
        private $limit;

        /** @var  int */
        private $offset = 0;

        /** @var  array|NULL  [column => sorting] */
        private $sorting = NULL;

        /** @var  array  [column => value] */
        private $conditions = array();

        /** @var  int|NULL */
        private $count;

        /** @var  array  @internal */
        private $filtredData;

        /** @var  int|string  @internal */
        private $iteratorKey;

        /** @var  array  [column => cmp => [values]] */
        private $formattedConditions;



        public function __construct(array $data)
        {
            $this->data = $data;
        }



        /**
         * @return  array
         */
        public function getData()
        {
            if($this->filtredData === NULL)
            {
                // where
                $data = $this->applyConditions($this->data);

                // limit & offset
                if(is_int($this->limit))
                {
                    $data = array_slice($data, $this->offset, $this->limit, TRUE /*preserve keys*/);
                }

                // sorting
                $this->filtredData = $this->sorting($data);
            }

            return $this->filtredData;
        }



        /**
         * @return  int
         */
        public function getCount()
        {
            if($this->count === NULL)
            {
                $this->count = count($this->getData());
            }

            return $this->count;
        }



        /**
         * @param   string|id
         * @return  mixed|FALSE
         */
        public function find($id)
        {
            $data = $this->getData();

            if(isset($data[$id]))
            {
                return $data[$id];
            }

            return FALSE;
        }



        public function fetch()
        {
            $item = $this->current();
            $this->next();
            return $item;
        }



        /**
         * @param   int|NULL
         * @param   int
         * @return  Collection  fluent interface
         */
        public function limit($limit, $offset = 0)
        {
            $this->reset();
            $this->limit = $limit !== NULL ? (int) $limit : NULL;
            $this->offset = (int) $offset;
            return $this;
        }



        /**
         * @param   array  [column => ASC, column => DESC]
         * @return  Collection
         */
        public function sort($sorting, $sort = NULL)
        {
            $this->reset();
            if(!is_array($sorting))
            {
                $sorting = array(
                    $sorting => $sort !== NULL ? $sort : 'ASC',
                );
            }

            if($this->sorting === NULL)
            {
                $this->sorting = $sorting;
            }
            else
            {
                $this->sorting = array_merge($this->sorting, $sorting);
            }

            return $this;
        }



        /**
         * Alias for sort()
         * @param   array  [column => ASC, column => DESC]
         * @return  Collection
         */
        public function order($sorting, $sort = NULL)
        {
            return $this->sort($sorting, $sort);
        }



        /**
         * @param   array  [column => value, ...]
         * @return  Collection
         */
        public function where($column, $value = NULL)
        {
            $this->reset();
            if(!is_array($column))
            {
                $args = func_num_args();

                if($args === 1) // only column
                {
                    throw new CollectionException("Missing parameter value, called only where('$column') without value");
                }

                $column = array(
                    $column => $value,
                );
            }

            $this->conditions = array_merge($this->conditions, $column);
            return $this;
        }



        /**
         * @param   array  [column => ASC, column => DESC]
         * @return  array
         */
        protected function sorting($data)
        {
            if($this->sorting === NULL)
            {
                return $data;
            }

            uasort($data, array($this, '_sortCmp'));
            return $data;
        }



        /**
         * @param   mixed
         * @param   mixed
         * @return  int
         */
        protected function _sortCmp($a, $b)
        {
            // -1   a < b
            //  0   a = b
            //  1   a > b

            foreach((array) $this->sorting as $column => $sorting)
            {
                if(!isset($a[$column]) || !isset($b[$column]))
                {
                    throw new CollectionException("Sort: column '{$column}' is missing in first or second item.");
                }

                $sort = 0; // a = b

                if(is_string($a[$column]))
                {
                    $sort = strcmp($a[$column], $b[$column]);
                }
                elseif($a[$column] < $b[$column])
                {
                    $sort = -1;
                }
                elseif($a[$column] > $b[$column])
                {
                    $sort = 1;
                }

                if($sort) // sort != 0
                {
                    return ($sorting !== self::ASC) ? ($sort * -1) : $sort;
                }
            }

            return 0; // a = b, TODO: return -1 ? A < B ???
        }



        /**
         * @return  array
         */
        protected function applyConditions(array $data)
        {
            $this->formattedConditions = array();
            $hasConditions = FALSE;

            foreach($this->conditions as $cond => $value)
            {
                $hasConditions = TRUE;
                // >, <, =, <=, >=
                $column = $cond = trim($cond);
                $op = '=';
                $chars = substr($cond, -2, 2);
                if($chars === '>=' || $chars === '<=')
                {
                    $op = $chars;
                    $column = rtrim(substr($cond, 0, -2));
                }
                elseif($chars[1] === '=' || $chars[1] === '<' || $chars[1] === '>')
                {
                    $op = $chars[1];
                    $column = rtrim(substr($cond, 0, -1));
                }

                $this->formattedConditions[$column][$op][] = $value;
            }

            if(!$hasConditions)
            {
                return $data;
            }

            return array_filter($data, array($this, '_conditionCmp'));
        }



        /**
         * @param   mixed
         * @return  bool
         */
        protected function _conditionCmp($item)
        {
            foreach($this->formattedConditions as $column => $ops)
            {
                if(!array_key_exists($column, $item))
                {
                    throw new CollectionException("Where: column '$column' missing in item");
                }

                foreach($ops as $op => $values)
                {
                    foreach($values as $value)
                    {
                        // TODO: value is callback -> return $callback($item, $op);
                        // TODO: value is array -> item[column] in_array $value for =, etc.
                        if($op === '=')
                        {
                            if($item[$column] !== $value)
                            {
                                return FALSE;
                            }
                        }
                        elseif($op === '<')
                        {
                            if(!($item[$column] < $value))
                            {
                                return FALSE;
                            }
                        }
                        elseif($op === '>')
                        {
                            if(!($item[$column] > $value))
                            {
                                return FALSE;
                            }
                        }
                        elseif($op === '<=')
                        {
                            if(!($item[$column] <= $value))
                            {
                                return FALSE;
                            }
                        }
                        elseif($op === '>=')
                        {
                            if(!($item[$column] >= $value))
                            {
                                return FALSE;
                            }
                        }
                    }
                }
            }

            return TRUE;
        }



        /**
         * Resets count & filtredData.
         * @internal
         * @return  void
         */
        protected function reset()
        {
            $this->count = NULL;
            $this->filtredData = NULL;
        }



        /************************ Iterator methods **************************/
        public function rewind()
        {
            $this->getData();
            reset($this->filtredData);
            $this->iteratorKey = key($this->filtredData);
        }



        public function current()
        {
            $this->getData();
            $item = current($this->filtredData);
            $this->iteratorKey = key($this->filtredData);
            return $item;
        }



        public function key()
        {
            return key($this->filtredData);
        }



        public function next()
        {
            $this->getData();
            next($this->filtredData);
            $this->iteratorKey = key($this->filtredData);
        }



        public function valid()
        {
            $data = $this->getData();
            return isset($data[$this->iteratorKey]);
        }
    }



    class CollectionException extends \RuntimeException
    {
    }