api: add blueprint freeze route

The blueprint freeze route returns the blueprint info but each
package will be the package selected by depsolving. So, instead of the
version being the version number with optional wildcards as
/blueprints/info would provide, the version is of the form
`Version-Release.Arch`.

internal/weldr/api.go

@@ -7,6 +7,7 @@ import (
 	"log"
 	"net"
 	"net/http"
+	"sort"
 	"strings"
 
 	"github.com/google/uuid"
@@ -68,6 +69,7 @@ func New(rpmmd rpmmd.RPMMD, repo rpmmd.RepoConfig, logger *log.Logger, store *st
 	api.router.GET("/api/v0/blueprints/list", api.blueprintsListHandler)
 	api.router.GET("/api/v0/blueprints/info/*blueprints", api.blueprintsInfoHandler)
 	api.router.GET("/api/v0/blueprints/depsolve/*blueprints", api.blueprintsDepsolveHandler)
+	api.router.GET("/api/v0/blueprints/freeze/*blueprints", api.blueprintsFreezeHandler)
 	api.router.GET("/api/v0/blueprints/diff/:blueprint/:from/:to", api.blueprintsDiffHandler)
 	api.router.GET("/api/v0/blueprints/changes/*blueprints", api.blueprintsChangesHandler)
 	api.router.POST("/api/v0/blueprints/new", api.blueprintsNewHandler)
@@ -689,6 +691,83 @@ func (api *API) blueprintsDepsolveHandler(writer http.ResponseWriter, request *h
 	})
 }
 
+func (api *API) blueprintsFreezeHandler(writer http.ResponseWriter, request *http.Request, params httprouter.Params) {
+	type blueprintFrozen struct {
+		Blueprint blueprint.Blueprint `json:"blueprint"`
+	}
+
+	type reply struct {
+		Blueprints []blueprintFrozen `json:"blueprints"`
+		Errors     []responseError   `json:"errors"`
+	}
+
+	names := strings.Split(params.ByName("blueprints"), ",")
+	if names[0] == "/" {
+		errors := responseError{
+			Code: http.StatusNotFound,
+			ID:   "HTTPError",
+			Msg:  "Not Found",
+		}
+		statusResponseError(writer, http.StatusNotFound, errors)
+		return
+	}
+
+	blueprints := []blueprintFrozen{}
+	errors := []responseError{}
+	for i, name := range names {
+		// remove leading / from first name
+		if i == 0 {
+			name = name[1:]
+		}
+		var blueprint blueprint.Blueprint
+		var changed bool
+		if !api.store.GetBlueprint(name, &blueprint, &changed) {
+			err := responseError{
+				ID:  "UnknownBlueprint",
+				Msg: fmt.Sprintf("%s: blueprint_not_found", name),
+			}
+			errors = append(errors, err)
+			return
+		}
+
+		specs := make([]string, len(blueprint.Packages))
+		for i, pkg := range blueprint.Packages {
+			specs[i] = pkg.Name
+			// If a package has version "*" the package name suffix must be equal to "-*-*.*"
+			// Using just "-*" would find any other package containing the package name
+			if pkg.Version != "" && pkg.Version != "*" {
+				specs[i] += "-" + pkg.Version
+			} else if pkg.Version == "*" {
+				specs[i] += "-*-*.*"
+			}
+		}
+
+		var repos []rpmmd.RepoConfig
+		repos = append(repos, api.repo)
+		for _, source := range api.store.GetAllSources() {
+			repos = append(repos, rpmmd.SourceToRepo(source))
+		}
+
+		dependencies, _ := api.rpmmd.Depsolve(specs, repos)
+
+		for pkgIndex, pkg := range blueprint.Packages {
+			i := sort.Search(len(dependencies), func(i int) bool {
+				return dependencies[i].Name >= pkg.Name
+			})
+			if i < len(dependencies) && dependencies[i].Name == pkg.Name {
+				blueprint.Packages[pkgIndex].Version = dependencies[i].Version + "-" + dependencies[i].Release + "." + dependencies[i].Arch
+			}
+		}
+
+		blueprints = append(blueprints, blueprintFrozen{blueprint})
+	}
+
+	json.NewEncoder(writer).Encode(reply{
+		Blueprints: blueprints,
+		Errors:     errors,
+	})
+}
+
 func (api *API) blueprintsDiffHandler(writer http.ResponseWriter, request *http.Request, params httprouter.Params) {
 	type pack struct {
 		Package blueprint.Package `json:"Package"`