Add CRAN package registry (#22331)

This PR adds a [CRAN](https://cran.r-project.org/) package registry.

![grafik](https://user-images.githubusercontent.com/1666336/210450039-d6fa6f77-20cd-4741-89a8-1624def267f7.png)

models/packages/cran/search.go

@@ -0,0 +1,90 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package cran
+
+import (
+	"context"
+	"strconv"
+	"strings"
+
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/models/packages"
+	cran_module "code.gitea.io/gitea/modules/packages/cran"
+
+	"xorm.io/builder"
+)
+
+type SearchOptions struct {
+	OwnerID  int64
+	FileType string
+	Platform string
+	RVersion string
+	Filename string
+}
+
+func (opts *SearchOptions) toConds() builder.Cond {
+	var cond builder.Cond = builder.Eq{
+		"package.type":                packages.TypeCran,
+		"package.owner_id":            opts.OwnerID,
+		"package_version.is_internal": false,
+	}
+
+	if opts.Filename != "" {
+		cond = cond.And(builder.Eq{"package_file.lower_name": strings.ToLower(opts.Filename)})
+	}
+
+	var propsCond builder.Cond = builder.Eq{
+		"package_property.ref_type": packages.PropertyTypeFile,
+	}
+	propsCond = propsCond.And(builder.Expr("package_property.ref_id = package_file.id"))
+
+	count := 1
+	propsCondBlock := builder.Eq{"package_property.name": cran_module.PropertyType}.And(builder.Eq{"package_property.value": opts.FileType})
+
+	if opts.Platform != "" {
+		count += 2
+		propsCondBlock = propsCondBlock.
+			Or(builder.Eq{"package_property.name": cran_module.PropertyPlatform}.And(builder.Eq{"package_property.value": opts.Platform})).
+			Or(builder.Eq{"package_property.name": cran_module.PropertyRVersion}.And(builder.Eq{"package_property.value": opts.RVersion}))
+	}
+
+	propsCond = propsCond.And(propsCondBlock)
+
+	cond = cond.And(builder.Eq{
+		strconv.Itoa(count): builder.Select("COUNT(*)").Where(propsCond).From("package_property"),
+	})
+
+	return cond
+}
+
+func SearchLatestVersions(ctx context.Context, opts *SearchOptions) ([]*packages.PackageVersion, error) {
+	sess := db.GetEngine(ctx).
+		Table("package_version").
+		Select("package_version.*").
+		Join("LEFT", "package_version pv2", builder.Expr("package_version.package_id = pv2.package_id AND pv2.is_internal = ? AND (package_version.created_unix < pv2.created_unix OR (package_version.created_unix = pv2.created_unix AND package_version.id < pv2.id))", false)).
+		Join("INNER", "package", "package.id = package_version.package_id").
+		Join("INNER", "package_file", "package_file.version_id = package_version.id").
+		Where(opts.toConds().And(builder.Expr("pv2.id IS NULL"))).
+		Asc("package.name")
+
+	pvs := make([]*packages.PackageVersion, 0, 10)
+	return pvs, sess.Find(&pvs)
+}
+
+func SearchFile(ctx context.Context, opts *SearchOptions) (*packages.PackageFile, error) {
+	sess := db.GetEngine(ctx).
+		Table("package_version").
+		Select("package_file.*").
+		Join("INNER", "package", "package.id = package_version.package_id").
+		Join("INNER", "package_file", "package_file.version_id = package_version.id").
+		Where(opts.toConds())
+
+	pf := &packages.PackageFile{}
+	if has, err := sess.Get(pf); err != nil {
+		return nil, err
+	} else if !has {
+		return nil, packages.ErrPackageFileNotExist
+	}
+	return pf, nil
+}

models/packages/descriptor.go

@@ -19,6 +19,7 @@ import (
 	"code.gitea.io/gitea/modules/packages/conan"
 	"code.gitea.io/gitea/modules/packages/conda"
 	"code.gitea.io/gitea/modules/packages/container"
+	"code.gitea.io/gitea/modules/packages/cran"
 	"code.gitea.io/gitea/modules/packages/debian"
 	"code.gitea.io/gitea/modules/packages/helm"
 	"code.gitea.io/gitea/modules/packages/maven"
@@ -151,6 +152,8 @@ func GetPackageDescriptor(ctx context.Context, pv *PackageVersion) (*PackageDesc
 		metadata = &conda.VersionMetadata{}
 	case TypeContainer:
 		metadata = &container.Metadata{}
+	case TypeCran:
+		metadata = &cran.Metadata{}
 	case TypeDebian:
 		metadata = &debian.Metadata{}
 	case TypeGeneric:

models/packages/package.go

@@ -37,6 +37,7 @@ const (
 	TypeConan     Type = "conan"
 	TypeConda     Type = "conda"
 	TypeContainer Type = "container"
+	TypeCran      Type = "cran"
 	TypeDebian    Type = "debian"
 	TypeGeneric   Type = "generic"
 	TypeGo        Type = "go"
@@ -60,6 +61,7 @@ var TypeList = []Type{
 	TypeConan,
 	TypeConda,
 	TypeContainer,
+	TypeCran,
 	TypeDebian,
 	TypeGeneric,
 	TypeGo,
@@ -92,6 +94,8 @@ func (pt Type) Name() string {
 		return "Conda"
 	case TypeContainer:
 		return "Container"
+	case TypeCran:
+		return "CRAN"
 	case TypeDebian:
 		return "Debian"
 	case TypeGeneric:
@@ -139,6 +143,8 @@ func (pt Type) SVGName() string {
 		return "gitea-conda"
 	case TypeContainer:
 		return "octicon-container"
+	case TypeCran:
+		return "gitea-cran"
 	case TypeDebian:
 		return "gitea-debian"
 	case TypeGeneric: