<?php
/**
 * Groups component
 * 
 * @author Pierre HUBERT
 */

class GroupsComponent {

    /**
     * Groups list table
     */
    const GROUPS_LIST_TABLE = DBprefix . "groups";

    /**
     * Groups members table
     */
    const GROUPS_MEMBERS_TABLE = DBprefix."groups_members";

    /**
     * Create a new group
     * 
     * @param NewGroup $newGroup Information about the new group
     * to create
     * @return int The ID of the created group / -1 in case of failure
     */
    public function create(NewGroup $newGroup) : int {

        //Insert the group in the database
        db()->addLine(self::GROUPS_LIST_TABLE, array(
            "time_create" => $newGroup->get_time_sent(),
            "userid_create" => $newGroup->get_userID(),
            "name" => $newGroup->get_name()
        ));

        //Get the ID of the last inserted group
        $groupID = db()->getLastInsertedID();

        //Check for errors
        if(!$groupID > 0)
            return -1;

        //Register the user who created the group as an admin of the group
        $member = new GroupMember;
        $member->set_group_id($groupID);
        $member->set_userID($newGroup->get_userID());
        $member->set_time_sent($newGroup->get_time_sent());
        $member->set_level(GroupMember::ADMINISTRATOR);
        $this->insertMember($member);

        return $groupID;
    }

    /**
     * Check whether a group exists or not
     * 
     * @param int $id The ID of the target group
     * @return bool TRUE if the group exists / FALSE else
     */
    public function exists(int $id) : bool {

        return db()->count(
            self::GROUPS_LIST_TABLE,
            "WHERE id = ?",
            array($id)
        ) > 0;

    }

    /**
     * Get the visibility level of a group
     * 
     * @param int $id The ID of the target group
     * @return int The visibility level of the group
     */
    public function getVisiblity(int $id) : int {
        $data = db()->select(
            self::GROUPS_LIST_TABLE,
            "WHERE id = ?",
            array($id),
            array("visibility")
        );

        if(count($data) < 1)
            throw new Exception("Group " + $id + " does not exists!");
        
        return $data[0]["visibility"];
    }

    /**
     * Get and return information about a group
     * 
     * @param int $id The ID of the target group
     * @return GroupInfo Information about the group / invalid
     * object in case of failure
     */
    public function get_info(int $id) : GroupInfo {

        //Query the database
        $info = db()->select(self::GROUPS_LIST_TABLE, "WHERE id = ?", array($id));

        //Check for results
        if(count($info) == 0)
            return new GroupInfo(); //Return invalid object
        
        //Create and fill GroupInfo object with database entry
        return $this->dbToGroupInfo($info[0]);
    }

    /**
     * Get and return advanced information about a group
     * 
     * @param int $id The ID of the target group
     * @return GroupInfo Information about the group / invalid
     * object in case of failure
     */
    public function get_advanced_info(int $id) : AdvancedGroupInfo {

        //Query the database
        $info = db()->select(self::GROUPS_LIST_TABLE, "WHERE id = ?", array($id));

        //Check for results
        if(count($info) == 0)
            return new AdvancedGroupInfo(); //Return invalid object
        
        //Create and fill GroupInfo object with database entry
        return $this->dbToAdvancedGroupInfo($info[0]);
    }

    /**
     * Get a group settings
     * 
     * @param int $id The ID of the target group
     * @return GroupSettings The settings of the group / invalid
     * GroupSettings object in case of failure
     */
    public function get_settings(int $id) : GroupSettings {

        //Query the database
        $info = db()->select(self::GROUPS_LIST_TABLE, "WHERE id = ?", array($id));

        //Check for results
        if(count($info) == 0)
            return new GroupSettings(); //Return invalid object
        
        //Create and fill GroupInfo object with database entry
        return $this->dbToGroupSettings($info[0]);

    }

    /**
     * Set (update) group settings
     * 
     * @param GroupSettings $settings The settings to update
     * @return bool TRUE for a success / FALSE
     */
    public function set_settings(GroupSettings $settings) : bool {
        
        //Generate database entry
        $modif = $this->GroupSettingsToDB($settings);

        //Apply update
        return db()->updateDB(
            self::GROUPS_LIST_TABLE, 
            "id = ?",
            $modif,
            array($settings->get_id()));

    }

    /**
     * Insert a new group member
     * 
     * @param GroupMember $member Information about the member to insert
     * @return bool TRUE for a success / FALSE else
     */
    private function insertMember(GroupMember $member) : bool {
        return db()->addLine(self::GROUPS_MEMBERS_TABLE, array(
            "groups_id" => $member->get_group_id(),
            "user_id" => $member->get_userID(),
            "time_create" => $member->get_time_sent(),
            "level" => $member->get_level()
        ));
    }

    /**
     * Check whether a user has already a saved membership in a group or not
     * 
     * @param int $userID The ID of the target user
     * @param int $groupID The ID of the target group
     * @return bool TRUE if the database includes a membership for the user / FALSE else
     */
    private function hasMembership(int $userID, int $groupID) : bool {
        return db()->count(
            self::GROUPS_MEMBERS_TABLE,
            "WHERE groups_id = ? AND user_id = ?", 
            array($groupID, $userID)) > 0;
    }

    /**
     * Get the membership level of a user to a group
     * 
     * @param int $userID The ID of the queried user
     * @param int $groupID The ID of the target group
     * @return int The membership level of the user
     */
    public function getMembershipLevel(int $userID, int $groupID) : int {

        //Check for membership
        if(!$this->hasMembership($userID, $groupID))
            return GroupMember::VISITOR;
        
        //Fetch the database to get membership
        $results = db()->select(
            self::GROUPS_MEMBERS_TABLE,
            "WHERE groups_id = ? AND user_id = ?",
            array($groupID, $userID),
            array("level")
        );

        //Check for results
        if(count($results) < 0)
            return GroupMember::VISITOR; //Security first
        
        return $results[0]["level"];
    }

    /**
     * Check whether a user is an administrator of a group
     * or not
     * 
     * @param int $userID Requested user ID to check
     * @param int $groupID Requested group to check
     * @return bool TRUE if the user is an admin / FALSE else
     */
    public function isAdmin(int $userID, int $groupID) : bool {
        return $this->getMembershipLevel($userID, $groupID)
             == GroupMember::ADMINISTRATOR;
    }

    /**
     * Check whether a group is open or not
     * 
     * @param int $groupID The ID of the target group
     * @return bool TRUE if the group is open / FALSE else
     */
    public function isOpen(int $groupID) : bool {
        return db()->count(
            self::GROUPS_LIST_TABLE,
            "WHERE id = ? AND visibility = ?",
            array($groupID, GroupInfo::OPEN_GROUP)) > 0;
    }

    /**
     * Check whether a group is secret or not
     * 
     * @param int $groupID The ID of the target group
     * @return bool TRUE if the group is open / FALSE else
     */
    public function isSecret(int $groupID) : bool {
        return db()->count(
            self::GROUPS_LIST_TABLE,
            "WHERE id = ? AND visibility = ?",
            array($groupID, GroupInfo::SECRET_GROUP)) > 0;
    }

    /**
     * Count the number of members of a group
     * 
     * @param int $id The ID of the target group
     * @return int The number of members of the group
     */
    private function countMembers(int $id) : int {
        return db()->count(self::GROUPS_MEMBERS_TABLE, 
            "WHERE groups_id = ?",
            array($id));
    }

    /**
     * Get and return the access level of a user over a group
     * 
     * @param int $groupID The ID of the target group
     * @param int $userID The ID of the user
     * @return int The visiblity access level of the user
     */
    public function getAccessLevel(int $groupID, int $userID) : int {

        if($userID > 0)
            //Get the membership level of the user
            $membership_level = $this->getMembershipLevel($userID, $groupID);
        
        else
            $membership_level = GroupInfo::VISITOR; //Signed out users are all visitors

        //Check if the user is a confirmed member of group
        if($membership_level == GroupInfo::ADMINISTRATOR)
            return GroupInfo::ADMIN_ACCESS;
        if($membership_level == GroupInfo::MODERATOR)
            return GroupInfo::MODERATOR_ACCESS;
        if($membership_level == GroupInfo::MEMBER)
            return GroupInfo::MEMBER_ACCESS;
        
        //Get the visibility level of the group
        $group_visibility_level = $this->getVisiblity($groupID);

        //If the group is open, everyone has view access
        if($group_visibility_level == GroupInfo::OPEN_GROUP)
            return GroupInfo::VIEW_ACCESS;

        //Else, all pending membership gives limited access
        if($membership_level == GroupInfo::PENDING)
            return GroupInfo::LIMITED_ACCESS;

        //Private groups gives limited access
        if($group_visibility_level == GroupInfo::PRIVATE_GROUP)
            return GroupInfo::LIMITED_ACCESS;
        
        //Else the user can not see the group
        return GroupInfo::NO_ACCESS;
    }

    /**
     * Delete current group logo (if any)
     * 
     * @param int $id The ID of the target group
     * @return bool TRUE if the logo was deleted / FALSE else
     */
    public function deleteLogo(int $id) : bool {

        //Get the current settings of the group
		$settings = $this->get_settings($id);

		//Check if the group has currently an group logo or not
		if($settings->has_logo()){
			
			//Delete the previous logo
			if(file_exists($settings->get_logo_sys_path()))
				if(!unlink($settings->get_logo_sys_path()))
                    return FALSE;
            
            //Save new information
            $settings->set_logo("null");
            return $this->set_settings($settings);
        }
        
        //Success (nothing to be done)
        return TRUE;
    }

    /**
     * Turn a database entry into a GroupInfo object
     * 
     * @param array $data Database entry
     * @param GroupInfo $group The object to fill with the information (optionnal)
     * @return GroupInfo Generated object
     */
    private function dbToGroupInfo(array $data, GroupInfo $info = null) : GroupInfo {

        if($info == null)
            $info = new GroupInfo();

        $info->set_id($data["id"]);
        $info->set_name($data["name"]);
        $info->set_number_members($this->countMembers($info->get_id()));
        $info->set_membership_level($this->getMembershipLevel(userID, $info->get_id()));
        $info->set_visibility($data["visibility"]);

        if($data["path_logo"] != null && $data["path_logo"] != "" && $data["path_logo"] != "null")
            $info->set_logo($data["path_logo"]);

        return $info;

    }

    /**
     * Turn a database group entry into AdvancedGroupInfo object entry
     * 
     * @param array $data Database entry
     * @param AdvancedGroupInfo $info Optionnal, fill an existing object
     * instead of creating a new one
     * @return AdvancedGroupInfo Advanced information about the group
     */
    private function dbToAdvancedGroupInfo(array $data, AdvancedGroupInfo $info = null) : AdvancedGroupInfo {

        if($info == null)
            $info = new AdvancedGroupInfo();

        //Parse basical information about the group
        $this->dbToGroupInfo($data, $info);

        //Parse advanced information
        $info->set_time_create($data["time_create"]);

        return $info;

    }

    /**
     * Turn a database group entry into GroupSettings object
     * 
     * @param array $data Database entry
     * @return GroupSettings The settings of the group
     */
    private function dbToGroupSettings(array $data) : GroupSettings {

        //Parse advanced settings about the group
        $info = new GroupSettings();
        $this->dbToAdvancedGroupInfo($data, $info);

        return $info;

    }

    /**
     * Turn a GroupSettings object into a database entry
     * 
     * @param GroupSettings $settings The object to convert
     * @return array Generated database entry
     */
    private function GroupSettingsToDB(GroupSettings $settings) : array {
        $data = array();

        if($settings->has_name())
            $data["name"] = $settings->get_name();

        if($settings->has_logo())
            $data["path_logo"] = $settings->get_logo();

        if($settings->has_visibility())
            $data["visibility"] = $settings->get_visibility();

        return $data;
    }
}

//Register component
Components::register("groups", new GroupsComponent());