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_22/v286.go

@@ -0,0 +1,108 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+package v1_22
+
+import (
+	"errors"
+	"fmt"
+
+	"gitea.dev/modelmigration/base"
+	"gitea.dev/modules/log"
+	"gitea.dev/modules/setting"
+
+	"xorm.io/xorm"
+)
+
+func expandHashReferencesToSha256(x base.EngineMigration) error {
+	alteredTables := [][2]string{
+		{"commit_status", "context_hash"},
+		{"comment", "commit_sha"},
+		{"pull_request", "merge_base"},
+		{"pull_request", "merged_commit_id"},
+		{"review", "commit_id"},
+		{"review_state", "commit_sha"},
+		{"repo_archiver", "commit_id"},
+		{"release", "sha1"},
+		{"repo_indexer_status", "commit_sha"},
+	}
+
+	db := x.NewSession()
+	defer db.Close()
+
+	if err := db.Begin(); err != nil {
+		return err
+	}
+
+	if !setting.Database.Type.IsSQLite3() {
+		if setting.Database.Type.IsMSSQL() {
+			// drop indexes that need to be re-created afterwards
+			droppedIndexes := []string{
+				"DROP INDEX [IDX_commit_status_context_hash] ON [commit_status]",
+				"DROP INDEX [UQE_review_state_pull_commit_user] ON [review_state]",
+				"DROP INDEX [UQE_repo_archiver_s] ON [repo_archiver]",
+			}
+			for _, s := range droppedIndexes {
+				_, err := db.Exec(s)
+				if err != nil {
+					return errors.New(s + " " + err.Error())
+				}
+			}
+		}
+
+		for _, alts := range alteredTables {
+			var err error
+			if setting.Database.Type.IsMySQL() {
+				_, err = db.Exec(fmt.Sprintf("ALTER TABLE `%s` MODIFY COLUMN `%s` VARCHAR(64)", alts[0], alts[1]))
+			} else if setting.Database.Type.IsMSSQL() {
+				_, err = db.Exec(fmt.Sprintf("ALTER TABLE [%s] ALTER COLUMN [%s] NVARCHAR(64)", alts[0], alts[1]))
+			} else {
+				_, err = db.Exec(fmt.Sprintf("ALTER TABLE `%s` ALTER COLUMN `%s` TYPE VARCHAR(64)", alts[0], alts[1]))
+			}
+			if err != nil {
+				return fmt.Errorf("alter column '%s' of table '%s' failed: %w", alts[1], alts[0], err)
+			}
+		}
+
+		if setting.Database.Type.IsMSSQL() {
+			recreateIndexes := []string{
+				"CREATE INDEX IDX_commit_status_context_hash ON commit_status(context_hash)",
+				"CREATE UNIQUE INDEX UQE_review_state_pull_commit_user ON review_state(user_id, pull_id, commit_sha)",
+				"CREATE UNIQUE INDEX UQE_repo_archiver_s ON repo_archiver(repo_id, type, commit_id)",
+			}
+			for _, s := range recreateIndexes {
+				_, err := db.Exec(s)
+				if err != nil {
+					return errors.New(s + " " + err.Error())
+				}
+			}
+		}
+	}
+	log.Debug("Updated database tables to hold SHA256 git hash references")
+
+	return db.Commit()
+}
+
+func addObjectFormatNameToRepository(x base.EngineMigration) error {
+	type Repository struct {
+		ObjectFormatName string `xorm:"VARCHAR(6) NOT NULL DEFAULT 'sha1'"`
+	}
+
+	if _, err := x.SyncWithOptions(xorm.SyncOptions{
+		IgnoreIndices:    true,
+		IgnoreConstrains: true,
+	}, new(Repository)); err != nil {
+		return err
+	}
+
+	// Here to catch weird edge-cases where column constraints above are
+	// not applied by the DB backend
+	_, err := x.Exec("UPDATE `repository` set `object_format_name` = 'sha1' WHERE `object_format_name` = '' or `object_format_name` IS NULL")
+	return err
+}
+
+func AdjustDBForSha256(x base.EngineMigration) error {
+	if err := expandHashReferencesToSha256(x); err != nil {
+		return err
+	}
+	return addObjectFormatNameToRepository(x)
+}