// Vikunja is a to-do list application to facilitate your life.
// Copyright 2018-2021 Vikunja and contributors. All rights reserved.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public Licensee as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public Licensee for more details.
//
// You should have received a copy of the GNU Affero General Public Licensee
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

package models

import (
	"code.vikunja.io/web"
	"xorm.io/builder"
	"xorm.io/xorm"
)

// CanWrite checks if a user has write access to a namespace
func (n *Namespace) CanWrite(s *xorm.Session, a web.Auth) (bool, error) {
	can, _, err := n.checkRight(s, a, RightWrite, RightAdmin)
	return can, err
}

// IsAdmin returns true or false if the user is admin on that namespace or not
func (n *Namespace) IsAdmin(s *xorm.Session, a web.Auth) (bool, error) {
	is, _, err := n.checkRight(s, a, RightAdmin)
	return is, err
}

// CanRead checks if a user has read access to that namespace
func (n *Namespace) CanRead(s *xorm.Session, a web.Auth) (bool, int, error) {
	return n.checkRight(s, a, RightRead, RightWrite, RightAdmin)
}

// CanUpdate checks if the user can update the namespace
func (n *Namespace) CanUpdate(s *xorm.Session, a web.Auth) (bool, error) {
	return n.IsAdmin(s, a)
}

// CanDelete checks if the user can delete a namespace
func (n *Namespace) CanDelete(s *xorm.Session, a web.Auth) (bool, error) {
	return n.IsAdmin(s, a)
}

// CanCreate checks if the user can create a new namespace
func (n *Namespace) CanCreate(s *xorm.Session, a web.Auth) (bool, error) {
	if _, is := a.(*LinkSharing); is {
		return false, nil
	}

	// This is currently a dummy function, later on we could imagine global limits etc.
	return true, nil
}

func (n *Namespace) checkRight(s *xorm.Session, a web.Auth, rights ...Right) (bool, int, error) {

	// If the auth is a link share, don't do anything
	if _, is := a.(*LinkSharing); is {
		return false, 0, nil
	}

	// Get the namespace and check the right
	nn, err := getNamespaceSimpleByID(s, n.ID)
	if err != nil {
		return false, 0, err
	}

	if a.GetID() == nn.OwnerID ||
		nn.ID == SharedListsPseudoNamespace.ID ||
		nn.ID == FavoritesPseudoNamespace.ID ||
		nn.ID == SavedFiltersPseudoNamespace.ID {
		return true, int(RightAdmin), nil
	}

	/*
		The following loop creates an sql condition like this one:

		namespaces.owner_id = 1 OR
		(users_namespaces.user_id = 1 AND users_namespaces.right = 1) OR
		(team_members.user_id = 1 AND team_namespaces.right = 1) OR


		for each passed right. That way, we can check with a single sql query (instead if 8)
		if the user has the right to see the list or not.
	*/

	var conds []builder.Cond
	conds = append(conds, builder.Eq{"namespaces.owner_id": a.GetID()})
	for _, r := range rights {
		// User conditions
		// If the namespace was shared directly with the user and the user has the right
		conds = append(conds, builder.And(
			builder.Eq{"users_namespaces.user_id": a.GetID()},
			builder.Eq{"users_namespaces.right": r},
		))

		// Team rights
		// If the namespace was shared directly with the team and the team has the right
		conds = append(conds, builder.And(
			builder.Eq{"team_members.user_id": a.GetID()},
			builder.Eq{"team_namespaces.right": r},
		))
	}

	type allRights struct {
		UserNamespace NamespaceUser `xorm:"extends"`
		TeamNamespace TeamNamespace `xorm:"extends"`
	}

	var maxRights = 0
	r := &allRights{}
	exists, err := s.
		Select("*").
		Table("namespaces").
		// User stuff
		Join("LEFT", "users_namespaces", "users_namespaces.namespace_id = namespaces.id").
		// Teams stuff
		Join("LEFT", "team_namespaces", "namespaces.id = team_namespaces.namespace_id").
		Join("LEFT", "team_members", "team_members.team_id = team_namespaces.team_id").
		// The actual condition
		Where(builder.And(
			builder.Or(
				conds...,
			),
			builder.Eq{"namespaces.id": n.ID},
		)).
		Exist(r)

	// Figure out the max right and return it
	if int(r.UserNamespace.Right) > maxRights {
		maxRights = int(r.UserNamespace.Right)
	}
	if int(r.TeamNamespace.Right) > maxRights {
		maxRights = int(r.TeamNamespace.Right)
	}

	return exists, maxRights, err
}
