Add team member invite by email (#20307)

Allows to add (not registered) team members by email.

related #5353

Invite by mail:

![grafik](https://user-images.githubusercontent.com/1666336/178154779-adcc547f-c0b7-4a2a-a131-4e41a3d9d3ad.png)

Pending invitations:

![grafik](https://user-images.githubusercontent.com/1666336/178154882-9d739bb8-2b04-46c1-a025-c1f4be26af98.png)

Email:

![grafik](https://user-images.githubusercontent.com/1666336/178164716-f2f90893-7ba6-4a5e-a3db-42538a660258.png)

Join form:

![grafik](https://user-images.githubusercontent.com/1666336/178154840-aaab983a-d922-4414-b01a-9b1a19c5cef7.png)

Co-authored-by: Jack Hay <jjphay@gmail.com>

models/organization/team_invite.go

@@ -0,0 +1,162 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package organization
+
+import (
+	"context"
+	"fmt"
+
+	"code.gitea.io/gitea/models/db"
+	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/timeutil"
+	"code.gitea.io/gitea/modules/util"
+
+	"xorm.io/builder"
+)
+
+type ErrTeamInviteAlreadyExist struct {
+	TeamID int64
+	Email  string
+}
+
+func IsErrTeamInviteAlreadyExist(err error) bool {
+	_, ok := err.(ErrTeamInviteAlreadyExist)
+	return ok
+}
+
+func (err ErrTeamInviteAlreadyExist) Error() string {
+	return fmt.Sprintf("team invite already exists [team_id: %d, email: %s]", err.TeamID, err.Email)
+}
+
+func (err ErrTeamInviteAlreadyExist) Unwrap() error {
+	return util.ErrAlreadyExist
+}
+
+type ErrTeamInviteNotFound struct {
+	Token string
+}
+
+func IsErrTeamInviteNotFound(err error) bool {
+	_, ok := err.(ErrTeamInviteNotFound)
+	return ok
+}
+
+func (err ErrTeamInviteNotFound) Error() string {
+	return fmt.Sprintf("team invite was not found [token: %s]", err.Token)
+}
+
+func (err ErrTeamInviteNotFound) Unwrap() error {
+	return util.ErrNotExist
+}
+
+// ErrUserEmailAlreadyAdded represents a "user by email already added to team" error.
+type ErrUserEmailAlreadyAdded struct {
+	Email string
+}
+
+// IsErrUserEmailAlreadyAdded checks if an error is a ErrUserEmailAlreadyAdded.
+func IsErrUserEmailAlreadyAdded(err error) bool {
+	_, ok := err.(ErrUserEmailAlreadyAdded)
+	return ok
+}
+
+func (err ErrUserEmailAlreadyAdded) Error() string {
+	return fmt.Sprintf("user with email already added [email: %s]", err.Email)
+}
+
+func (err ErrUserEmailAlreadyAdded) Unwrap() error {
+	return util.ErrAlreadyExist
+}
+
+// TeamInvite represents an invite to a team
+type TeamInvite struct {
+	ID          int64              `xorm:"pk autoincr"`
+	Token       string             `xorm:"UNIQUE(token) INDEX NOT NULL DEFAULT ''"`
+	InviterID   int64              `xorm:"NOT NULL DEFAULT 0"`
+	OrgID       int64              `xorm:"INDEX NOT NULL DEFAULT 0"`
+	TeamID      int64              `xorm:"UNIQUE(team_mail) INDEX NOT NULL DEFAULT 0"`
+	Email       string             `xorm:"UNIQUE(team_mail) NOT NULL DEFAULT ''"`
+	CreatedUnix timeutil.TimeStamp `xorm:"INDEX created"`
+	UpdatedUnix timeutil.TimeStamp `xorm:"INDEX updated"`
+}
+
+func CreateTeamInvite(ctx context.Context, doer *user_model.User, team *Team, email string) (*TeamInvite, error) {
+	has, err := db.GetEngine(ctx).Exist(&TeamInvite{
+		TeamID: team.ID,
+		Email:  email,
+	})
+	if err != nil {
+		return nil, err
+	}
+	if has {
+		return nil, ErrTeamInviteAlreadyExist{
+			TeamID: team.ID,
+			Email:  email,
+		}
+	}
+
+	// check if the user is already a team member by email
+	exist, err := db.GetEngine(ctx).
+		Where(builder.Eq{
+			"team_user.org_id":  team.OrgID,
+			"team_user.team_id": team.ID,
+			"`user`.email":      email,
+		}).
+		Join("INNER", "`user`", "`user`.id = team_user.uid").
+		Table("team_user").
+		Exist()
+	if err != nil {
+		return nil, err
+	}
+
+	if exist {
+		return nil, ErrUserEmailAlreadyAdded{
+			Email: email,
+		}
+	}
+
+	token, err := util.CryptoRandomString(25)
+	if err != nil {
+		return nil, err
+	}
+
+	invite := &TeamInvite{
+		Token:     token,
+		InviterID: doer.ID,
+		OrgID:     team.OrgID,
+		TeamID:    team.ID,
+		Email:     email,
+	}
+
+	return invite, db.Insert(ctx, invite)
+}
+
+func RemoveInviteByID(ctx context.Context, inviteID, teamID int64) error {
+	_, err := db.DeleteByBean(ctx, &TeamInvite{
+		ID:     inviteID,
+		TeamID: teamID,
+	})
+	return err
+}
+
+func GetInvitesByTeamID(ctx context.Context, teamID int64) ([]*TeamInvite, error) {
+	invites := make([]*TeamInvite, 0, 10)
+	return invites, db.GetEngine(ctx).
+		Where("team_id=?", teamID).
+		Find(&invites)
+}
+
+func GetInviteByToken(ctx context.Context, token string) (*TeamInvite, error) {
+	invite := &TeamInvite{}
+
+	has, err := db.GetEngine(ctx).Where("token=?", token).Get(invite)
+	if err != nil {
+		return nil, err
+	}
+	if !has {
+		return nil, ErrTeamInviteNotFound{Token: token}
+	}
+	return invite, nil
+}