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>

4 files changed, 70 insertions, 0 deletions

diff --git a/routers/api/v1/api.go b/routers/api/v1/api.go
index 1244676508..5aa8ad44e5 100644
--- a/routers/api/v1/api.go
+++ b/routers/api/v1/api.go
@@ -1327,6 +1327,7 @@ func Routes() *web.Router {
 				m.Get("/issue_config", context.ReferencesGitRepo(), repo.GetIssueConfig)
 				m.Get("/issue_config/validate", context.ReferencesGitRepo(), repo.ValidateIssueConfig)
 				m.Get("/languages", reqRepoReader(unit.TypeCode), repo.GetLanguages)
+				m.Get("/licenses", reqRepoReader(unit.TypeCode), repo.GetLicenses)
 				m.Get("/activities/feeds", repo.ListRepoActivityFeeds)
 				m.Get("/new_pin_allowed", repo.AreNewIssuePinsAllowed)
 				m.Group("/avatar", func() {
diff --git a/routers/api/v1/repo/license.go b/routers/api/v1/repo/license.go
new file mode 100644
index 0000000000..8a6bdfd42f
--- /dev/null
+++ b/routers/api/v1/repo/license.go
@@ -0,0 +1,51 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package repo
+
+import (
+	"net/http"
+
+	repo_model "code.gitea.io/gitea/models/repo"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/services/context"
+)
+
+// GetLicenses returns licenses
+func GetLicenses(ctx *context.APIContext) {
+	// swagger:operation GET /repos/{owner}/{repo}/licenses repository repoGetLicenses
+	// ---
+	// summary: Get repo licenses
+	// produces:
+	//   - application/json
+	// parameters:
+	// - name: owner
+	//   in: path
+	//   description: owner of the repo
+	//   type: string
+	//   required: true
+	// - name: repo
+	//   in: path
+	//   description: name of the repo
+	//   type: string
+	//   required: true
+	// responses:
+	//   "404":
+	//     "$ref": "#/responses/notFound"
+	//   "200":
+	//     "$ref": "#/responses/LicensesList"
+
+	licenses, err := repo_model.GetRepoLicenses(ctx, ctx.Repo.Repository)
+	if err != nil {
+		log.Error("GetRepoLicenses failed: %v", err)
+		ctx.InternalServerError(err)
+		return
+	}
+
+	resp := make([]string, len(licenses))
+	for i := range licenses {
+		resp[i] = licenses[i].License
+	}
+
+	ctx.JSON(http.StatusOK, resp)
+}
diff --git a/routers/api/v1/repo/repo.go b/routers/api/v1/repo/repo.go
index 1bcec8fcf7..6c1a94ee16 100644
--- a/routers/api/v1/repo/repo.go
+++ b/routers/api/v1/repo/repo.go
@@ -731,6 +731,7 @@ func updateBasicProperties(ctx *context.APIContext, opts api.EditRepoOption) err
 	}
 
 	// Default branch only updated if changed and exist or the repository is empty
+	updateRepoLicense := false
 	if opts.DefaultBranch != nil && repo.DefaultBranch != *opts.DefaultBranch && (repo.IsEmpty || ctx.Repo.GitRepo.IsBranchExist(*opts.DefaultBranch)) {
 		if !repo.IsEmpty {
 			if err := gitrepo.SetDefaultBranch(ctx, ctx.Repo.Repository, *opts.DefaultBranch); err != nil {
@@ -739,6 +740,7 @@ func updateBasicProperties(ctx *context.APIContext, opts api.EditRepoOption) err
 					return err
 				}
 			}
+			updateRepoLicense = true
 		}
 		repo.DefaultBranch = *opts.DefaultBranch
 	}
@@ -748,6 +750,15 @@ func updateBasicProperties(ctx *context.APIContext, opts api.EditRepoOption) err
 		return err
 	}
 
+	if updateRepoLicense {
+		if err := repo_service.AddRepoToLicenseUpdaterQueue(&repo_service.LicenseUpdaterOptions{
+			RepoID: ctx.Repo.Repository.ID,
+		}); err != nil {
+			ctx.Error(http.StatusInternalServerError, "AddRepoToLicenseUpdaterQueue", err)
+			return err
+		}
+	}
+
 	log.Trace("Repository basic settings updated: %s/%s", owner.Name, repo.Name)
 	return nil
 }
diff --git a/routers/api/v1/swagger/repo.go b/routers/api/v1/swagger/repo.go
index 345835f9a5..b9d2a0217c 100644
--- a/routers/api/v1/swagger/repo.go
+++ b/routers/api/v1/swagger/repo.go
@@ -359,6 +359,13 @@ type swaggerLanguageStatistics struct {
 	Body map[string]int64 `json:"body"`
 }
 
+// LicensesList
+// swagger:response LicensesList
+type swaggerLicensesList struct {
+	// in: body
+	Body []string `json:"body"`
+}
+
 // CombinedStatus
 // swagger:response CombinedStatus
 type swaggerCombinedStatus struct {