class UserManager extends Listenable {
	constructor() {
		super();

		this.users = { };
		this.roles = { };
		
		this.loadUsersRequest = new Request(OnTime.REQUEST_URI + "Users", Request.GET, this.loadedUsers.bind(this), this.userLoadingError.bind(this));
		this.loadUsersInterval = setInterval(this.loadUsers.bind(this), 60000);
		this.loadUsers();

		this.deleteUserRequest = new Request(OnTime.REQUEST_URI + "User/Delete", Request.POST, this.deletedUser.bind(this), this.userDeletionError.bind(this));
		this.createUserRequest = new Request(OnTime.REQUEST_URI + "User/Create", Request.POST, this.createdUser.bind(this), this.userCreationError.bind(this));
		this.updateUserRequest = new Request(OnTime.REQUEST_URI + "User", Request.POST, this.updatedUser.bind(this), this.userUpdatingError.bind(this));

		this.deleteRoleRequest = new Request(OnTime.REQUEST_URI + "Role/Delete", Request.POST, this.deletedRole.bind(this), this.roleDeletionError.bind(this));
		this.createRoleRequest = new Request(OnTime.REQUEST_URI + "Role/Create", Request.POST, this.createdRole.bind(this), this.roleCreationError.bind(this));
		this.updateRoleRequest = new Request(OnTime.REQUEST_URI + "Role", Request.POST, this.updatedRole.bind(this), this.roleUpdatingError.bind(this));
	}

	performInitialCalls(eventType, callback) {
		if (eventType == "roleadded") {
			for (var roleKey in this.roles) {
				var addedRole = this.roles[roleKey];

				var roleAddedEvent = new Event("roleadded");
				roleAddedEvent.role = addedRole;
				callback(roleAddedEvent);
			}
		}
		else if (eventType == "useradded") {
			for (var email in this.users) {
				var addedUser = this.users[email];

				var userAddedEvent = new Event("useradded");
				userAddedEvent.user = addedUser;
				callback(userAddedEvent);
			}
		}
	}

	/**
	 * Shows or hides the elements on the page depending on whether the user has access to them or not.
	 * This is done via CSS classes.
	 */
	applyPermissionsToInterface() {
		//Do nothing if there is no logged in user.
		if (!this.sessionUser) {
			return;
		}

		var allPermissions = [ "accounts", "user_role", "user_role_grant", "user", "user_samerole", "user_all", "card", "card_category", "project", "report_project", "period", "multiuser", "project_user" ];

		var permissions = this.roles[this.sessionUser.role_key].permissions;

		//Re-enable all elements that were be disabled because of the lack of permission in the last update.
		if (this.elementsDisabledBecauseOfLackingPermissions) {
			for (var i = 0; i < this.elementsDisabledBecauseOfLackingPermissions.length; i++) {
				if (this.elementsDisabledBecauseOfLackingPermissions[i].hasAttribute("disabled")) {
					this.elementsDisabledBecauseOfLackingPermissions[i].removeAttribute("disabled");
				}
			}
		}

		//Disable all elements that this user has no access to.
		this.elementsDisabledBecauseOfLackingPermissions = [ ];
		for (var i = 0; i < allPermissions.length; i++) {
			var permission = allPermissions[i];

			var readElements = document.body.querySelectorAll(".available__" + permission);
			var writeElements = document.body.querySelectorAll(".available_w__" + permission);

			if (!permission in permissions) {
				for (var j = 0; j < readElements.length; j++) {
					this.elementsDisabledBecauseOfLackingPermissions.push(readElements[j]);
				}
			}
			if ((!permission in permissions) || permissions[permission] == "r") {
				for (var j = 0; j < writeElements.length; j++) {
					this.elementsDisabledBecauseOfLackingPermissions.push(writeElements[j]);
				}
			}
		}

		for (var i = 0; i < this.elementsDisabledBecauseOfLackingPermissions.length; i++) {
			this.elementsDisabledBecauseOfLackingPermissions[i].setAttribute("disabled", "true");
		}

		for (var permission in permissions) {
			document.body.classList.add("enable__" + permission);

			if (permissions[permission] == "w") {
				document.body.classList.add("enable_w__" + permission);
			}
		}
	}

	/**
	 * Returns the permissions of the logged in user.
	 */
	getPermissions() {
		if (!this.sessionUser) {
			return { };
		}

		return this.roles[this.sessionUser.role_key].permissions;
	}

	/**
	 * Checks whether the logged in user has the required access ("w" or "r") on the given resource or not and returns this information.
	 * @return true if the resource is available to the user, false if not.
	 */
	isResourceAvailable(permission, type) {
		var permissions = this.getPermissions();

		if (permission in permissions && (permissions[permission] == type || (type == "r" && permissions[permission] == "w"))) {
			return true;
		}

		return false;
	}

	loadUsers() {
		if (this.loadUsersRequest.ready) {
			this.loadUsersRequest.send();
		}
	}

	loadedUsers(roles) {
		//Check for deleted and updated roles.
		for (var roleKey in this.roles) {
			if (!(roleKey in roles)) {
				//The role does no longer exist.
				var roleRemovedEvent = new Event("roleremoved");
				roleRemovedEvent.role = this.roles[roleKey];
				this.dispatchEvent(roleRemovedEvent);
				continue;
			}

			if (!Object.equals(roles[roleKey], this.roles[roleKey])) {
				//The role has changed.
				var roleChangedEvent = new Event("rolechanged");
				roleChangedEvent.role = roles[roleKey];
				this.dispatchEvent(roleChangedEvent);
			}
		}

		//Process new roles.
		for (var roleKey in roles) {
			if (!(roleKey in this.roles)) {
				var roleAddedEvent = new Event("roleadded");
				roleAddedEvent.role = roles[roleKey];
				this.dispatchEvent(roleAddedEvent);
			}
		}

		this.roles = roles;

		//Collect all users and process them as well.
		var users = { };
		for (var roleKey in roles) {
			for (var email in roles[roleKey].users) {
				users[email] = roles[roleKey].users[email];

				if (users[email].is_session_user) {
					this.sessionUser = users[email];

					//Apply the new permissions if they have changed.
					if (!Object.equals(this.permissions, this.roles[this.sessionUser.role_key].permissions)) {
						this.permissions = this.roles[this.sessionUser.role_key].permissions;
						this.applyPermissionsToInterface();
					}
				}
			}
		}

		//Check for deleted and updated users.
		for (var email in this.users) {
			if (!(email in users)) {
				//The user does no longer exist.
				var userRemovedEvent = new Event("userremoved");
				userRemovedEvent.user = this.users[email];
				this.dispatchEvent(userRemovedEvent);
				continue;
			}

			if (!Object.equals(users[email], this.users[email])) {
				//The user has changed.
				var userChangedEvent = new Event("userchanged");
				userChangedEvent.user = users[email];
				this.dispatchEvent(userChangedEvent);
			}
		}

		//Process new users.
		for (var email in users) {
			if (!(email in this.users)) {
				var userAddedEvent = new Event("useradded");
				userAddedEvent.user = users[email];
				this.dispatchEvent(userAddedEvent);
			}
		}

		this.users = users;
	}

	userLoadingError(request, status, error) {
		alert("Error during the loading of the users:\r\n\r\n" + JSON.stringify(error, true));
	}

	/**
	 * Attempts to delete the given user on the server side.
	 */
	deleteUser(user) {
		this.deleteUserRequest.send(user);
	}

	deletedUser(response) {
		var userRemovedEvent = new Event("userremoved");
		userRemovedEvent.user = response;
		this.dispatchEvent(userRemovedEvent);

		//Log out if the currently logged in user was deleted.
		if (response.email == this.sessionUser.email) {
			this.sessionUser = null;
			localStorage.removeItem("session");
		}

		delete this.users[response.email];
	}

	userDeletionError(request, status, error) {
		alert("Error during the deletion of the user:\r\n\r\n" + JSON.stringify(error, true));
	}

	/**
	 * Attempts to create a user with the given data on the server side.
	 */
	createUser(user) {
		this.createUserRequest.send(user);
	}

	createdUser(response) {
		this.users[response.email] = response;
		this.roles[response.role_key].users[response.email] = response;

		var userAddedEvent = new Event("useradded");
		userAddedEvent.user = response;
		this.dispatchEvent(userAddedEvent);
	}

	userCreationError(request, status, error) {
		alert("Error during the creation of the user:\r\n\r\n" + JSON.stringify(error, true));
	}

	/**
	 * Attempts to save the given user data on the server.
	 */
	updateUser(user) {
		this.updateUserRequest.send(user);
	}

	updatedUser(response) {
		delete this.users[response.email];

		var newEmailAddress = response.new_email;
		var oldEmailAddress = response.email;
		delete response.new_email;
		response.email = newEmailAddress;

		this.users[newEmailAddress] = response;

		response.old_email = oldEmailAddress;

		var userChangedEvent = new Event("userchanged");
		userChangedEvent.user = response;
		this.dispatchEvent(userChangedEvent);
	}

	userUpdatingError(request, status, error) {
		alert("Error while updating the user:\r\n\r\n" + JSON.stringify(error, true));
	}

	/**
	 * Attempts to delete the given role on the server side.
	 */
	deleteRole(role) {
		this.deleteRoleRequest.send(role);
	}

	deletedRole(response) {
		var roleRemovedEvent = new Event("roleremoved");
		roleRemovedEvent.role = response;
		this.dispatchEvent(roleRemovedEvent);

		delete this.roles[response.role_key];
	}

	roleDeletionError(request, status, error) {
		alert("Error during the deletion of the role:\r\n\r\n" + JSON.stringify(error, true));
	}

	/**
	 * Attempts to create a role with the given data on the server side.
	 */
	createRole(role) {
		this.createRoleRequest.send(role);
	}

	createdRole(response) {
		this.roles[response.role_key] = response;

		var roleAddedEvent = new Event("roleadded");
		roleAddedEvent.role = response;
		this.dispatchEvent(roleAddedEvent);
	}

	roleCreationError(request, status, error) {
		alert("Error during the creation of the role:\r\n\r\n" + JSON.stringify(error, true));
	}

	/**
	 * Attempts to save the given role data on the server.
	 */
	updateRole(role) {
		this.updateRoleRequest.send(role);
	}

	updatedRole(response) {
		this.roles[response.role_key] = response;

		var roleChangedEvent = new Event("rolechanged");
		roleChangedEvent.role = response;
		this.dispatchEvent(roleChangedEvent);
	}

	roleUpdatingError(request, status, error) {
		alert("Error while updating the role:\r\n\r\n" + JSON.stringify(error, true));
	}
}