<?php

namespace Core\API {

  use Core\Driver\SQL\Expression\Count;
  use Core\Objects\Context;
  use Core\Objects\DatabaseEntity\Group;
  use Core\Objects\DatabaseEntity\User;

  abstract class GroupsAPI extends Request {

    public function __construct(Context $context, bool $externalCall = false, array $params = array()) {
      parent::__construct($context, $externalCall, $params);
    }

    protected function groupExists($name): bool {
      $sql = $this->context->getSQL();
      $res = $sql->select(new Count())
        ->from("Group")
        ->whereEq("name", $name)
        ->execute();

      $this->success = ($res !== FALSE);
      $this->lastError = $sql->getLastError();
      return $this->success && $res[0]["count"] > 0;
    }

    protected function getGroup(int $groupId): Group|false {
      $sql = $this->context->getSQL();
      $group = Group::find($sql, $groupId);
      if ($group === false) {
        return $this->createError("Error fetching group: " . $sql->getLastError());
      } else if ($group === null) {
        return $this->createError("This group does not exist.");
      }

      return $group;
    }

    protected function getUser(int $userId): User|false {
      $sql = $this->context->getSQL();
      $user = User::find($sql, $userId, true);
      if ($user === false) {
        return $this->createError("Error fetching user: " . $sql->getLastError());
      } else if ($user === null) {
        return $this->createError("This user does not exist.");
      }

      return $user;
    }
  }
}

namespace Core\API\Groups {

  use Core\API\GroupsAPI;
  use Core\API\Parameter\ArrayType;
  use Core\API\Parameter\Parameter;
  use Core\API\Parameter\RegexType;
  use Core\API\Parameter\StringType;
  use Core\API\Traits\Pagination;
  use Core\Driver\SQL\Column\Column;
  use Core\Driver\SQL\Condition\Compare;
  use Core\Driver\SQL\Condition\CondIn;
  use Core\Driver\SQL\Condition\CondLike;
  use Core\Driver\SQL\Condition\CondNot;
  use Core\Driver\SQL\Expression\Alias;
  use Core\Driver\SQL\Expression\Count;
  use Core\Driver\SQL\Join\InnerJoin;
  use Core\Objects\Context;
  use Core\Objects\DatabaseEntity\Group;
  use Core\Objects\DatabaseEntity\User;

  class Fetch extends GroupsAPI {

    use Pagination;

    private int $groupCount;

    public function __construct(Context $context, $externalCall = false) {
      parent::__construct($context, $externalCall,
        self::getPaginationParameters(['id', 'name', 'memberCount'])
      );

      $this->groupCount = 0;
    }

    public function _execute(): bool {

      $sql = $this->context->getSQL();
      if (!$this->initPagination($sql, Group::class)) {
        return false;
      }

      $nmTable = User::getHandler($sql)->getNMRelation("groups")->getTableName();
      $memberCount = new Alias($sql->select(new Count())
        ->from($nmTable)
        ->whereEq("group_id", new Column("Group.id")), "memberCount");

      $groupsQuery = $this->createPaginationQuery($sql, [$memberCount]);
      $groups = $groupsQuery->execute();
      if ($groups !== false && $groups !== null) {
        $this->result["groups"] = [];

        foreach ($groups as $group) {
          $groupData = $group->jsonSerialize();
          $groupData["memberCount"] = $group["memberCount"];
          $this->result["groups"][] = $groupData;
        }
      } else {
        return $this->createError("Error fetching groups: " . $sql->getLastError());
      }

      return $this->success;
    }

    public static function getDescription(): string {
      return "Allows users to fetch available groups";
    }

    public static function getDefaultPermittedGroups(): array {
      return [Group::ADMIN, Group::SUPPORT];
    }
  }

  class Search extends GroupsAPI {
    public function __construct(Context $context, bool $externalCall = false) {
      parent::__construct($context, $externalCall, [
        "query" => new StringType("query", -1, true, NULL),
        "exclude" => new ArrayType("exclude", Parameter::TYPE_INT, true, true, [])
      ]);
    }

    protected function _execute(): bool {
      $sql = $this->context->getSQL();
      $query = $this->getParam("query");
      $exclude = array_unique($this->getParam("exclude"));

      $groupsQuery = Group::createBuilder($sql, false)
        ->limit(5);

      if (!empty($query)) {
        $groupsQuery->where(new CondLike(new Column("name"), "%$query%"));
      }

      if (!empty($exclude)) {
        $groupsQuery->where(new CondNot(new CondIn(new Column("id"), $exclude)));
      }

      $groups = Group::findBy($groupsQuery);
      if ($groups === false) {
        return $this->createError($sql->getLastError());
      }

      $this->result["groups"] = $groups;
      return true;
    }

    public static function getDescription(): string {
      return "Returns a list of groups matching the search criteria";
    }

    public static function getDefaultPermittedGroups(): array {
      return [Group::ADMIN, Group::SUPPORT];
    }
  }

  class Get extends GroupsAPI {
    public function __construct(Context $context, bool $externalCall = false) {
      parent::__construct($context, $externalCall, [
        "id" => new Parameter("id", Parameter::TYPE_INT)
      ]);
    }

    protected function _execute(): bool {
      $groupId = $this->getParam("id");
      $group = $this->getGroup($groupId);
      if ($group) {
        $this->result["group"] = $group->jsonSerialize();
      }

      return true;
    }

    public static function getDescription(): string {
      return "Allows users to get details about a group";
    }

    public static function getDefaultPermittedGroups(): array {
      return [Group::ADMIN, Group::SUPPORT];
    }
  }

  class GetMembers extends GroupsAPI {

    use Pagination;

    public function __construct(Context $context, bool $externalCall = false) {
      $paginationParams = self::getPaginationParameters(["id", "name", "fullName"]);
      $paginationParams["id"] = new Parameter("id", Parameter::TYPE_INT);
      parent::__construct($context, $externalCall, $paginationParams);
    }

    protected function _execute(): bool {
      $sql = $this->context->getSQL();
      $nmTable = User::getHandler($sql)->getNMRelation("groups")->getTableName();
      $condition = new Compare("group_id", $this->getParam("id"));
      $nmJoin = new InnerJoin($nmTable, "$nmTable.user_id", "User.id");
      if (!$this->initPagination($sql, User::class, $condition, [$nmJoin])) {
        return false;
      }

      $userQuery = $this->createPaginationQuery($sql, null, [$nmJoin]);
      $users = $userQuery->execute();
      if ($users !== false && $users !== null) {
        $this->result["members"] = [];

        foreach ($users as $user) {
          $this->result["users"][] = $user->jsonSerialize(["id", "name", "fullName", "profilePicture"]);
        }
      } else {
        return $this->createError("Error fetching group members: " . $sql->getLastError());
      }

      return true;
    }

    public static function getDescription(): string {
      return "Allows users to fetch members of a group";
    }

    public static function getDefaultPermittedGroups(): array {
      return [Group::ADMIN, Group::SUPPORT];
    }
  }

  class Create extends GroupsAPI {
    public function __construct(Context $context, $externalCall = false) {
      parent::__construct($context, $externalCall, [
        'name' => new RegexType('name', "[a-zA-Z][a-zA-Z0-9_-]{0,31}"),
        'color' => new RegexType('color', "#[a-fA-F0-9]{3,6}"),
      ]);
    }

    public function _execute(): bool {
      $name = $this->getParam("name");
      $color = $this->getParam("color");
      $exists = $this->groupExists($name);
      if (!$this->success) {
        return false;
      } else if ($exists) {
        return $this->createError("A group with this name already exists");
      }

      $sql = $this->context->getSQL();

      $group = new Group(null, $name, $color);
      $this->success = ($group->save($sql) !== FALSE);
      $this->lastError = $sql->getLastError();

      if ($this->success) {
        $this->result["id"] = $group->getId();
      }

      return $this->success;
    }

    public static function getDescription(): string {
      return "Allows users to create a new group";
    }

    public static function getDefaultPermittedGroups(): array {
      return [Group::ADMIN];
    }
  }

  class Update extends GroupsAPI {
    public function __construct(Context $context, $externalCall = false) {
      parent::__construct($context, $externalCall, [
        "id" => new Parameter("id", Parameter::TYPE_INT),
        "name" => new RegexType("name", "[a-zA-Z][a-zA-Z0-9_-]{0,31}"),
        "color" => new RegexType("color", "#[a-fA-F0-9]{3,6}"),
      ]);
    }

    public function _execute(): bool {
      $sql = $this->context->getSQL();
      $groupId = $this->getParam("id");
      $name = $this->getParam("name");
      $color = $this->getParam("color");

      $group = $this->getGroup($groupId);
      if ($group === false) {
        return false;
      }

      $otherGroup = Group::findBy(Group::createBuilder($sql, true)
        ->whereNeq("id", $groupId)
        ->whereEq("name", $name)
        ->first());

      if ($otherGroup) {
        return $this->createError("This name is already in use");
      }

      $group->name = $name;
      $group->color = $color;
      $this->success = ($group->save($sql) !== FALSE);
      $this->lastError = $sql->getLastError();

      return $this->success;
    }

    public static function getDescription(): string {
      return "Allows users to update existing groups";
    }

    public static function getDefaultPermittedGroups(): array {
      return [Group::ADMIN];
    }
  }

  class Delete extends GroupsAPI {
    public function __construct(Context $context, $externalCall = false) {
      parent::__construct($context, $externalCall, array(
        'id' => new Parameter('id', Parameter::TYPE_INT)
      ));
    }

    public function _execute(): bool {
      $id = $this->getParam("id");
      if (in_array($id, array_keys(Group::GROUPS))) {
        return $this->createError("You cannot delete a default group.");
      }

      $sql = $this->context->getSQL();
      $group = $this->getGroup($id);
      if ($group) {
        $this->success = ($group->delete($sql) !== FALSE);
        $this->lastError = $sql->getLastError();
      }

      return $this->success;
    }

    public static function getDescription(): string {
      return "Allows users to delete a group";
    }

    public static function getDefaultPermittedGroups(): array {
      return [Group::ADMIN];
    }
  }

  class AddMember extends GroupsAPI {
    public function __construct(Context $context, bool $externalCall = false) {
      parent::__construct($context, $externalCall, [
        "id" => new Parameter("id", Parameter::TYPE_INT),
        "userId" => new Parameter("userId", Parameter::TYPE_INT)
      ]);
    }

    protected function _execute(): bool {
      $groupId = $this->getParam("id");
      $group = $this->getGroup($groupId);
      if ($group === false) {
        return false;
      }

      $userId = $this->getParam("userId");
      $currentUser = $this->context->getUser();
      $user = $this->getUser($userId);
      if ($user === false) {
        return false;
      } else if (isset($user->getGroups()[$groupId])) {
        return $this->createError("This user is already member of this group.");
      } else if ($groupId === Group::ADMIN && !$currentUser->hasGroup(Group::ADMIN)) {
        return $this->createError("You cannot add the administrator group to other users.");
      }

      $user->groups[$groupId] = $group;
      $sql = $this->context->getSQL();
      $this->success = $user->save($sql, ["groups"], true);
      if (!$this->success) {
        return $this->createError("Error saving user: " . $sql->getLastError());
      } else {
        return true;
      }
    }

    public static function getDescription(): string {
      return "Allows users to add members to a group";
    }

    public static function getDefaultPermittedGroups(): array {
      return [Group::ADMIN];
    }
  }

  class RemoveMember extends GroupsAPI {
    public function __construct(Context $context, bool $externalCall = false) {
      parent::__construct($context, $externalCall, [
        "id" => new Parameter("id", Parameter::TYPE_INT),
        "userId" => new Parameter("userId", Parameter::TYPE_INT)
      ]);
    }

    protected function _execute(): bool {
      $groupId = $this->getParam("id");
      $group = $this->getGroup($groupId);
      if ($group === false) {
        return false;
      }

      $userId = $this->getParam("userId");
      $currentUser = $this->context->getUser();
      $user = $this->getUser($userId);
      if ($user === false) {
        return false;
      } else if (!isset($user->getGroups()[$groupId])) {
        return $this->createError("This user is not member of this group.");
      } else if ($userId === $currentUser->getId() && $groupId === Group::ADMIN) {
        return $this->createError("Cannot remove Administrator group from own user.");
      }

      unset($user->groups[$groupId]);
      $sql = $this->context->getSQL();
      $this->success = $user->save($sql, ["groups"], true);
      if (!$this->success) {
        return $this->createError("Error saving user: " . $sql->getLastError());
      } else {
        return true;
      }
    }

    public static function getDescription(): string {
      return "Allows users to remove members from a group";
    }

    public static function getDefaultPermittedGroups(): array {
      return [Group::ADMIN];
    }
  }
}