refactor: prepare to decouple the "model migration" package and "models" package (#38533)

Migrations should never use model structs directly, because the model
structs can be different in different releases. e.g. if one migration uses
"User" model, it works in the early releases, then one day, when the
User model changes, the migration breaks because it will use the
new (incorrect) User model, it should only use the old User model.

The same to "modules/structs".

---------

Signed-off-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: delvh <dev.lh@web.de>

modelmigration/v1_16/v189.go

@@ -0,0 +1,109 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package v1_16
+
+import (
+	"encoding/binary"
+	"fmt"
+
+	"gitea.dev/modelmigration/base"
+	"gitea.dev/modules/json"
+)
+
+func UnwrapLDAPSourceCfg(x base.EngineMigration) error {
+	jsonUnmarshalHandleDoubleEncode := func(bs []byte, v any) error {
+		err := json.Unmarshal(bs, v)
+		if err != nil {
+			ok := true
+			rs := []byte{}
+			temp := make([]byte, 2)
+			for _, rn := range string(bs) {
+				if rn > 0xffff {
+					ok = false
+					break
+				}
+				binary.LittleEndian.PutUint16(temp, uint16(rn))
+				rs = append(rs, temp...)
+			}
+			if ok {
+				if rs[0] == 0xff && rs[1] == 0xfe {
+					rs = rs[2:]
+				}
+				err = json.Unmarshal(rs, v)
+			}
+		}
+		if err != nil && len(bs) > 2 && bs[0] == 0xff && bs[1] == 0xfe {
+			err = json.Unmarshal(bs[2:], v)
+		}
+		return err
+	}
+
+	// LoginSource represents an external way for authorizing users.
+	type LoginSource struct {
+		ID        int64 `xorm:"pk autoincr"`
+		Type      int
+		IsActived bool   `xorm:"INDEX NOT NULL DEFAULT false"`
+		IsActive  bool   `xorm:"INDEX NOT NULL DEFAULT false"`
+		Cfg       string `xorm:"TEXT"`
+	}
+
+	const ldapType = 2
+	const dldapType = 5
+
+	type WrappedSource struct {
+		Source map[string]any
+	}
+
+	// change lower_email as unique
+	if err := x.Sync(new(LoginSource)); err != nil {
+		return err
+	}
+
+	sess := x.NewSession()
+	defer sess.Close()
+
+	const batchSize = 100
+	for start := 0; ; start += batchSize {
+		sources := make([]*LoginSource, 0, batchSize)
+		if err := sess.Limit(batchSize, start).Where("`type` = ? OR `type` = ?", ldapType, dldapType).Find(&sources); err != nil {
+			return err
+		}
+		if len(sources) == 0 {
+			break
+		}
+
+		for _, source := range sources {
+			wrapped := &WrappedSource{
+				Source: map[string]any{},
+			}
+			err := jsonUnmarshalHandleDoubleEncode([]byte(source.Cfg), &wrapped)
+			if err != nil {
+				return fmt.Errorf("failed to unmarshal %s: %w", source.Cfg, err)
+			}
+			if len(wrapped.Source) > 0 {
+				bs, err := json.Marshal(wrapped.Source)
+				if err != nil {
+					return err
+				}
+				source.Cfg = string(bs)
+				if _, err := sess.ID(source.ID).Cols("cfg").Update(source); err != nil {
+					return err
+				}
+			}
+		}
+	}
+
+	if _, err := x.SetExpr("is_active", "is_actived").Update(&LoginSource{}); err != nil {
+		return fmt.Errorf("SetExpr Update failed:  %w", err)
+	}
+
+	if err := sess.Begin(); err != nil {
+		return err
+	}
+	if err := base.DropTableColumns(sess, "login_source", "is_actived"); err != nil {
+		return err
+	}
+
+	return sess.Commit()
+}