Support repo license (#24872)

Close #278
Close #24076

## Solutions:
- Use
[google/licenseclassifier](https://github.com/google/licenseclassifier/)
Test result between
[google/licensecheck](https://github.com/google/licensecheck) and
[go-license-detector](https://github.com/go-enry/go-license-detector):
https://github.com/go-gitea/gitea/pull/24872#issuecomment-1560361167
Test result between
[google/licensecheck](https://github.com/google/licensecheck) and
[google/licenseclassifier](https://github.com/google/licenseclassifier/):
https://github.com/go-gitea/gitea/pull/24872#issuecomment-1576092178
- Generate License Convert Name List to avoid import license templates
with same contents
Gitea automatically get latest license data from[
spdx/license-list-data](https://github.com/spdx/license-list-data).
But unfortunately, some license templates have same contents. #20915
[click here to see the
list](https://github.com/go-gitea/gitea/pull/24872#issuecomment-1584141684)
So we will generate a list of these license templates with same contents
and create a new file to save the result when using `make
generate-license`. (Need to decide the save path)
- Save License info into a new table `repo_license`
Can easily support searching repo by license in the future.

## Screen shot
Single License:

![image](https://github.com/go-gitea/gitea/assets/18380374/41260bd7-0b4c-4038-8592-508706cffa9f)

Multiple Licenses:

![image](https://github.com/go-gitea/gitea/assets/18380374/34ce2f73-7e18-446b-9b96-ecc4fb61bd70)

Triggers:
- [x] Push commit to default branch
- [x] Create repo
- [x] Mirror repo
- [x] When Default Branch is changed, licenses should be updated

Todo:
- [x] Save Licenses info in to DB when there's a change to license file
in the commit
- [x] DB Migration
- [x] A nominal test?
- [x] Select which library to
use(https://github.com/go-gitea/gitea/pull/24872#issuecomment-1560361167)
- [x] API Support
- [x] Add repo license table
- ~Select license in settings if there are several licenses(Not
recommended)~
- License board(later, not in this PR)

![image](https://github.com/go-gitea/gitea/assets/18380374/2c3c3bf8-bcc2-4c6d-8ce0-81d1a9733878)

---------

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: Denys Konovalov <kontakt@denyskon.de>
Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: KN4CK3R <admin@oldschoolhack.me>
Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: 6543 <m.huber@kithara.com>
Co-authored-by: a1012112796 <1012112796@qq.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.com>

models/fixtures/repo_license.yml

@@ -0,0 +1 @@
+[] # empty

models/fixtures/repository.yml

@@ -26,7 +26,7 @@
   fork_id: 0
   is_template: false
   template_id: 0
-  size: 7597
+  size: 8478
   is_fsck_enabled: true
   close_issues_via_commit_in_any_branch: false
 

models/migrations/migrations.go

@@ -500,7 +500,7 @@ var migrations = []Migration{
 	// v259 -> v260
 	NewMigration("Convert scoped access tokens", v1_20.ConvertScopedAccessTokens),
 
-	// Gitea 1.20.0 ends at 260
+	// Gitea 1.20.0 ends at v260
 
 	// v260 -> v261
 	NewMigration("Drop custom_labels column of action_runner table", v1_21.DropCustomLabelsColumnOfActionRunner),
@@ -601,6 +601,8 @@ var migrations = []Migration{
 	NewMigration("Add metadata column for comment table", v1_23.AddCommentMetaDataColumn),
 	// v304 -> v305
 	NewMigration("Add index for release sha1", v1_23.AddIndexForReleaseSha1),
+	// v305 -> v306
+	NewMigration("Add Repository Licenses", v1_23.AddRepositoryLicenses),
 }
 
 // GetCurrentDBVersion returns the current db version

models/migrations/v1_23/v305.go

@@ -0,0 +1,23 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package v1_23 //nolint
+
+import (
+	"code.gitea.io/gitea/modules/timeutil"
+
+	"xorm.io/xorm"
+)
+
+func AddRepositoryLicenses(x *xorm.Engine) error {
+	type RepoLicense struct {
+		ID          int64 `xorm:"pk autoincr"`
+		RepoID      int64 `xorm:"UNIQUE(s) NOT NULL"`
+		CommitID    string
+		License     string             `xorm:"VARCHAR(255) UNIQUE(s) NOT NULL"`
+		CreatedUnix timeutil.TimeStamp `xorm:"INDEX CREATED"`
+		UpdatedUnix timeutil.TimeStamp `xorm:"INDEX UPDATED"`
+	}
+
+	return x.Sync(new(RepoLicense))
+}

models/repo/license.go

@@ -0,0 +1,120 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package repo
+
+import (
+	"context"
+
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/modules/timeutil"
+)
+
+func init() {
+	db.RegisterModel(new(RepoLicense))
+}
+
+type RepoLicense struct { //revive:disable-line:exported
+	ID          int64 `xorm:"pk autoincr"`
+	RepoID      int64 `xorm:"UNIQUE(s) NOT NULL"`
+	CommitID    string
+	License     string             `xorm:"VARCHAR(255) UNIQUE(s) NOT NULL"`
+	CreatedUnix timeutil.TimeStamp `xorm:"INDEX CREATED"`
+	UpdatedUnix timeutil.TimeStamp `xorm:"INDEX UPDATED"`
+}
+
+// RepoLicenseList defines a list of repo licenses
+type RepoLicenseList []*RepoLicense //revive:disable-line:exported
+
+func (rll RepoLicenseList) StringList() []string {
+	var licenses []string
+	for _, rl := range rll {
+		licenses = append(licenses, rl.License)
+	}
+	return licenses
+}
+
+// GetRepoLicenses returns the license statistics for a repository
+func GetRepoLicenses(ctx context.Context, repo *Repository) (RepoLicenseList, error) {
+	licenses := make(RepoLicenseList, 0)
+	if err := db.GetEngine(ctx).Where("`repo_id` = ?", repo.ID).Asc("`license`").Find(&licenses); err != nil {
+		return nil, err
+	}
+	return licenses, nil
+}
+
+// UpdateRepoLicenses updates the license statistics for repository
+func UpdateRepoLicenses(ctx context.Context, repo *Repository, commitID string, licenses []string) error {
+	oldLicenses, err := GetRepoLicenses(ctx, repo)
+	if err != nil {
+		return err
+	}
+	for _, license := range licenses {
+		upd := false
+		for _, o := range oldLicenses {
+			// Update already existing license
+			if o.License == license {
+				if _, err := db.GetEngine(ctx).ID(o.ID).Cols("`commit_id`").Update(o); err != nil {
+					return err
+				}
+				upd = true
+				break
+			}
+		}
+		// Insert new license
+		if !upd {
+			if err := db.Insert(ctx, &RepoLicense{
+				RepoID:   repo.ID,
+				CommitID: commitID,
+				License:  license,
+			}); err != nil {
+				return err
+			}
+		}
+	}
+	// Delete old licenses
+	licenseToDelete := make([]int64, 0, len(oldLicenses))
+	for _, o := range oldLicenses {
+		if o.CommitID != commitID {
+			licenseToDelete = append(licenseToDelete, o.ID)
+		}
+	}
+	if len(licenseToDelete) > 0 {
+		if _, err := db.GetEngine(ctx).In("`id`", licenseToDelete).Delete(&RepoLicense{}); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// CopyLicense Copy originalRepo license information to destRepo (use for forked repo)
+func CopyLicense(ctx context.Context, originalRepo, destRepo *Repository) error {
+	repoLicenses, err := GetRepoLicenses(ctx, originalRepo)
+	if err != nil {
+		return err
+	}
+	if len(repoLicenses) > 0 {
+		newRepoLicenses := make(RepoLicenseList, 0, len(repoLicenses))
+
+		for _, rl := range repoLicenses {
+			newRepoLicense := &RepoLicense{
+				RepoID:   destRepo.ID,
+				CommitID: rl.CommitID,
+				License:  rl.License,
+			}
+			newRepoLicenses = append(newRepoLicenses, newRepoLicense)
+		}
+		if err := db.Insert(ctx, &newRepoLicenses); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// CleanRepoLicenses will remove all license record of the repo
+func CleanRepoLicenses(ctx context.Context, repo *Repository) error {
+	return db.DeleteBeans(ctx, &RepoLicense{
+		RepoID: repo.ID,
+	})
+}