<?php

    namespace VWA;

    class Database
    {
        private $system, $host, $port, $name, $user, $pass, $pdo;

        public function __construct($system, $host, $port, $name, $user, $pass)
        {
            $this->system = $system;
            $this->host = $host;
            $this->port = $port;
            $this->name = $name;
            $this->user = $user;
            $this->pass = $pass;
            $this->pdo = new \PDO($system.':host='.$host.';port='.$port.';dbname='.$name.';', $user, $pass);
        }

        public function getPDO() { return $this->pdo; }
        public function getSystem() { return $this->system; }

        public static function createParameterList($count)
        {
            if ($count == 0)
            {
                return '';
            }
            else if ($count == 1)
            {
                return '?';
            }
            else
            {
                $output = '?';
                for ($i = 1; $i < $count; $i++)
                {
                    $output .= ', ?';
                }

                return $output;
            }
        }

        public function execute($query, $parameters = [])
        {
            $statement = $this->pdo->prepare($query);

            if (count($parameters) > 0)
            {
                $statement->execute($parameters);
            }
            else
            {
                $statement->execute();
            }

            echo '<br>';
            echo $query;
            echo '<br>';

            return $statement;
        }

        public function select($table, $columns, $condition = '', $parameters = [])
        {
            $query = 'SELECT ';

            $first = true;
            foreach ($columns as $column)
            {
                if ($first)
                {
                    $query .= $column;
                    $first = false;
                }
                else
                {
                    $query .= ', '.$column;
                }
            }

            $query .= ' FROM '.$table;

            if ($condition != '')
            {
                $query .= ' WHERE '.$condition;
            }

            return $this->execute($query, $parameters)->fetchAll(\PDO::FETCH_ASSOC);
        }

        public function selectUnique($table, $columns, $targetColumn, $parameter)
        {
            $result = $this->database->select('users', ['*'], $targetColumn.' = ?', [$parameter]);
            if (count($result) == 0)
            {
                return null;
            }
            else
            {
                return $result[0];
            }
        }

        public function insert($table, $columns, $parameters = [])
        {
            return $this->insertMany($table, $columns, [$parameters]);
        }

        public function insertMany($table, $columns, $rows = [[]])
        {
            $query = 'INSERT INTO '.$table.' (';

            $first = true;
            foreach ($columns as $column)
            {
                if ($first)
                {
                    $query .= $column;
                    $first = false;
                }
                else
                {
                    $query .= ', '.$column;
                }
            }

            $query .= ') VALUES ';

            $outputRow = function($row)
            {
                $output = '(';
                $first = true;
                foreach ($row as $value)
                {
                    if ($first)
                    {
                        $output .= '?';
                        $first = false;
                    }
                    else
                    {
                        $output .= ', ?';
                    }
                }

                $output .= ')';

                return $output;
            };

            $parameters = [];
            $first = true;
            foreach ($rows as $row)
            {
                if ($first)
                {
                    $query .= $outputRow($row);
                    $first = false;
                }
                else
                {
                    $query .= ', '.$outputRow($row);
                }

                foreach ($row as $value)
                {
                    $parameters[] = $value;
                }
            }

            echo '<br>START<br>';

            echo $query;
            echo '<br>';
            print_r($parameters);

            $this->execute($query, $parameters);
            return $this->pdo->lastInsertId();
        }
    }

    class DataCache
    {
        private $fullCreate, $fullGet, $fullGetKey, $objects, $attachedCaches;

        public function __construct($fullCreate, $fullGet, $fullGetKey = null)
        {
            if ($fullGetKey == null)
            {
                $this->fullGetKey = function($object) { return $object->getID(); };
            }
            else
            {
                $this->fullGetKey = $fullGetKey;
            }

            $this->fullCreate = $fullCreate;
            $this->fullGet = $fullGet;
            $this->objects = [];
            $this->attachedCaches = [];
        }

        public function attach($caches)
        {
            foreach ($caches as $cache)
            {
                $this->attachedCaches[] = $cache;
            }
        }

        public function getKey($object)
        {
            return call_user_func($this->fullGetKey, $object);
        }

        public function get($key)
        {
            return $this->getFirstOrNull($this->getMultiple([$key]));
        }

        public function getMultiple($keys)
        {
            $objects = [];
            $uncachedKeys = [];
            foreach ($keys as $key)
            {
                if (array_key_exists($key, $this->objects))
                {
                    $objects[] = $this->objects[$key];
                }
                else
                {
                    $uncachedKeys[] = $key;
                }
            }

            if (count($uncachedKeys) > 0)
            {
                $loadedObjects = call_user_func($this->fullGet, $keys);
                $this->putInCache($loadedObjects);
                $objects = array_merge($objects, $loadedObjects);
            }

            return $objects;
        }

        public function create($args)
        {
            return $this->getFirstOrNull($this->createMultiple([$args]));
        }

        public function createMultiple($argLists)
        {
            $objects = call_user_func($this->fullCreate, $argLists);
            $this->putInCache($objects);
            return $objects;
        }

        private function getFirstOrNull($collection)
        {
            if (count($collection) == 0)
            {
                return null;
            }
            else
            {
                return $collection[0];
            }
        }

        private function putInCache($objects)
        {
            foreach ($objects as $object)
            {
                $this->objects[$this->getKey($object)] = $object;
                foreach ($this->attachedCaches as $cache)
                {
                    $cache->objects[$cache->getKey($object)] = $object;
                }
            }
        }
    }

    abstract class DataSource
    {
        public function accessUsers() { return $this->users; }
        public function accessUsersByEmail() { return $this->usersByEmail; }
        public function createUser($name, $email, $pass) { return $this->users->create(['name' => $name, 'email' => $email, 'pass' => $pass]); }
        protected abstract function createUsers($argLists);
        protected abstract function getUsers($ids);
        protected abstract function getUsersByEmail($emails);
        private $users, $usersByEmail;

        public function accessTypes() { return $this->types; }
        public function createType($name) { return $this->types->create(['name' => $name]); }
        protected abstract function createTypes($argLists);
        protected abstract function getTypes($ids);
        private $types;

        public function accessFields() { return $this->fields; }
        public function createField($typeID, $name, $fieldType) { return $this->fields->create(['typeID' => $typeID, 'name' => $name, 'fieldType' => $fieldType]); }
        protected abstract function createFields($argLists);
        protected abstract function getFields($ids);
        private $fields;

        public function accessViews() { return $this->views; }
        public function createView($typeID, $name) { return $this->views->create(['typeID' => $typeID, 'name' => $name]); }
        protected abstract function createViews($argLists);
        protected abstract function getViews($ids);
        private $views;

        protected function initialize()
        {
            $this->users = new DataCache(function($argLists) { return $this->createUsers($argLists); }, function($ids) { return $this->getUsers($ids); });
            $this->usersByEmail = new DataCache(function($argLists) { return $this->createUsers($argLists); }, function($emails) { return $this->getUsersByEmail($emails); }, function($user) { return $user->getEmail(); });

            $this->users->attach([$this->usersByEmail]);
            $this->usersByEmail->attach([$this->users]);

            $this->types = new DataCache(function($argLists) { return $this->createTypes($argLists); }, function($ids) { return $this->getTypes($ids); });

            $this->fields = new DataCache(function($argLists) { return $this->createFields($argLists); }, function($ids) { return $this->getFields($ids); });
        }
    }

    class TemporaryDataSource extends DataSource
    {
        public function __construct()
        {
            $this->initialize();
        }

        private $userCount = 1;

        protected function createUsers($argLists)
        {
            $users = [];
            foreach ($argLists as $argList)
            {
                $users[] = new User($this->userCount++, $argList['name'], $argList['email'], password_hash($argList['pass'], \PASSWORD_BCRYPT, ['cost' => 12]));
            }

            return $users;
        }

        protected function getUsers($ids) { return []; }

        protected function getUsersByEmail($emails) { return []; }

        private $typeCount = 1;

        protected function createTypes($argLists)
        {
            $types = [];
            foreach ($argLists as $argList)
            {
                $types[] = new Type($this->typeCount++, $argList['name']);
            }

            return $types;
        }

        protected function getTypes($ids) { return []; }

        private $fieldCount = 1;

        protected function createFields($argLists)
        {
            $fields = [];
            foreach ($argLists as $argList)
            {
                $field = new Field($argList['typeID'], $this->fieldCount++, $argList['name'], $argList['fieldType']);
                Type::fromID($argList['typeID'])->_addFieldID($field->getID());
                $fields[] = $field;
            }

            return $fields;
        }

        protected function getFields($ids) { return []; }
    }

    /*class DatabaseDataSource extends DataSource
    {
        private $database;

        public function __construct($database)
        {
            $this->initialize();
            $this->database = $database;
        }

        protected function loadUsersByID($ids)
        {
            $result = $this->database->select('users', ['name', 'email', 'pass'], 'id = IN('.createParameterList(count($ids)).')', $ids);
            if ($result == null)
            {
                return null;
            }
            else
            {
                return ['key' => $id, 'object' => new User($id, $result['name'], $result['email'], $result['pass'])];
            }
        }

        protected function loadUsersByEmail($emails)
        {
            $result = $this->database->selectUnique('users', ['id', 'name', 'pass'], 'email', $email);
            if ($result == null)
            {
                return null;
            }
            else
            {
                return ['key' => $email, 'object' => new User($result['id'], $result['name'], $email, $result['pass'])];
            }
        }

        protected function loadClassesByID($ids)
        {
            $result = $this->database->selectUnique('classes', ['name'], 'id', $id);
            if ($result == null)
            {
                return null;
            }

            $class = new WebClass($result[0]['id'], $name);

            $result = $this->database->select('fields', ['id', 'name', 'type'], 'class = ?', [$class->getID()]);
            foreach ($result as $row)
            {
                $class->internalAddField(new Field($class, $row['id'], $row['name'], $row['type']));
            }

            return $class;
        }

        protected function constructClasses($names)
        {

        }
    }*/

    class Core
    {
        private static $instance;

        public static function getInstance()
        {
            return Core::$instance;
        }

        private $data;

        public function __construct($data)
        {
            Core::$instance = $this;
            $this->data = $data;
        }

        public function getData()
        {
            return $this->data;
        }

        public function login($email, $pass)
        {
            $user = User::fromEmail($email);
            if ($user == null)
            {
                return LoginResponse::UnknownEmail;
            }
            else if (!password_verify($pass, $user->getPassHash()))
            {
                return LoginResponse::InvalidPass;
            }
            else
            {
                session_destroy();
                session_start();
                $_SESSION['userID'] = $user->getID();
                return LoginResponse::Success;
            }
        }

        public function logout()
        {
            session_destroy();
            $_SESSION = [];
        }

        public function getCurrentUser()
        {
            if (!isset($_SESSION['userID']))
            {
                return null;
            }
            else
            {
                return User::fromID($_SESSION['userID']);
            }
        }
    }

    abstract class LoginResponse
    {
        const UnknownEmail = 0;
        const InvalidPass = 1;
        const Success = 2;
    }

    class User
    {
        public static function fromID($id)
        {
            return Core::getInstance()->getData()->accessUsers()->get($id);
        }

        public static function fromEmail($email)
        {
            return Core::getInstance()->getData()->accessUsersByEmail()->get($email);
        }

        public static function create($name, $email, $pass)
        {
            return Core::getInstance()->getData()->createUser($name, $email, $pass);
        }

        private $id, $name, $email, $passHash;

        public function __construct($id, $name, $email, $passHash)
        {
            $this->id = $id;
            $this->name = $name;
            $this->email = $email;
            $this->passHash = $passHash;
        }

        public function getID() { return $this->id; }
        public function getName() { return $this->name; }
        public function getEmail() { return $this->email; }
        public function getPassHash() { return $this->passHash; }
    }

    class Type
    {
        public static function fromID($id)
        {
            return Core::getInstance()->getData()->accessTypes()->get($id);
        }

        public static function create($name)
        {
            return Core::getInstance()->getData()->createType($name);
        }

        private $id, $name, $fields, $fieldIDs;

        public function __construct($id, $name, $fieldIDs)
        {
            $this->id = $id;
            $this->name = $name;
            $this->fieldIDs = $fieldIDs;
        }

        public function getID() { return $this->id; }
        public function getName() { return $this->name; }
        public function getFieldIDs() { return $this->fieldIDs; }

        public function getFields()
        {
            $fields = [];
            foreach ($this->fieldIDs as $fieldID)
            {
                $fields[] = Field::fromID($fieldID);
            }

            return $fields;
        }

        public function _addFieldID($fieldID)
        {
            $this->fieldIDs[] = $fieldID;
        }

        public function _removeFieldID($fieldID)
        {
            array_splice($this->fieldIDs, array_search($fieldID, $this->fieldIDs), 1);
        }
    }

    class Field
    {
        public static function fromID($id)
        {
            return Core::getInstance()->getData()->accessFields()->get($id);
        }

        public static function create($typeID, $name, $fieldType)
        {
            return Core::getInstance()->getData()->createField($typeID, $name, $fieldType);
        }

        private $typeID, $id, $name, $fieldType;

        public function __construct($typeID, $id, $name, $fieldType)
        {
            $this->typeID = $typeID;
            $this->id = $id;
            $this->name = $name;
            $this->fieldType = $fieldType;
        }

        public function getTypeID() { return $this->typeID; }
        public function getType() { return Type::fromID($this->typeID); }
        public function getID() { return $this->id; }
        public function getName() { return $this->name; }
        public function getFieldType() { return $this->fieldType; }
    }

    abstract class FieldType
    {
        const Boolean = 0;
        const Integer = 1;
        const BigInteger = 2;
        const Number = 3;
        const PreciseNumber = 4;
        const Text = 5;
        const Enumeration = 6;
        const Object = 7;
    }

    class View
    {
        public static function fromID($id)
        {
            return Core::getInstance()->getData()->accessFields()->get($id);
        }

        public static function create($typeID, $name, $fieldType)
        {
            return Core::getInstance()->getData()->createField($typeID, $name, $fieldType);
        }

        private $typeID, $id, $name;

        public function __construct($typeID, $id, $name)
        {
            $this->typeID = $typeID;
            $this->id = $id;
            $this->name = $name;
        }

        public function getTypeID() { return $this->typeID; }
        public function getType() { return Type::fromID($this->typeID); }
        public function getID() { return $this->id; }
        public function getName() { return $this->name; }
    }

    class Entity
    {
        private $typeID, $id, $fields;

        public function __construct($typeID, $id)
        {
            $this->typeID = $typeID;
            $this->id = $id;
            $this->fields = [];
        }

        public function getTypeID() { return $this->typeID; }
        public function getType() { return Type::fromID($this->typeID); }
        public function getID() { return $this->id; }
        public function getFields() { return $this->fields; }
    }

?>