feat(spec): version field (#85)

Adds a `version` field to the `jsonnetfile.json`, so that `jb` can automatically recognize too old / too new schema versions, instead of panicking.

spec/v1/spec.go

@@ -0,0 +1,90 @@
+// Copyright 2018 jsonnet-bundler authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package spec
+
+import (
+	"encoding/json"
+	"sort"
+
+	"github.com/jsonnet-bundler/jsonnet-bundler/spec/v1/deps"
+)
+
+const Version uint = 1
+
+// JsonnetFile is the structure of a `.json` file describing a set of jsonnet
+// dependencies. It is used for both, the jsonnetFile and the lockFile.
+type JsonnetFile struct {
+	// List of dependencies
+	Dependencies map[string]deps.Dependency
+
+	// Symlink files to old location
+	LegacyImports bool
+}
+
+// New returns a new JsonnetFile with the dependencies map initialized
+func New() JsonnetFile {
+	return JsonnetFile{
+		Dependencies:  make(map[string]deps.Dependency),
+		LegacyImports: true,
+	}
+}
+
+// jsonFile is the json representation of a JsonnetFile, which is different for
+// compatibility reasons.
+type jsonFile struct {
+	Version       uint              `json:"version"`
+	Dependencies  []deps.Dependency `json:"dependencies"`
+	LegacyImports bool              `json:"legacyImports"`
+}
+
+// UnmarshalJSON unmarshals a `jsonFile`'s json into a JsonnetFile
+func (jf *JsonnetFile) UnmarshalJSON(data []byte) error {
+	var s jsonFile
+	s.LegacyImports = jf.LegacyImports // adpot default
+
+	if err := json.Unmarshal(data, &s); err != nil {
+		return err
+	}
+
+	jf.Dependencies = make(map[string]deps.Dependency)
+	for _, d := range s.Dependencies {
+		jf.Dependencies[d.Name()] = d
+	}
+
+	jf.LegacyImports = s.LegacyImports
+
+	return nil
+}
+
+// MarshalJSON serializes a JsonnetFile into json of the format of a `jsonFile`
+func (jf JsonnetFile) MarshalJSON() ([]byte, error) {
+	var s jsonFile
+
+	s.Version = Version
+
+	for _, d := range jf.Dependencies {
+		s.Dependencies = append(s.Dependencies, d)
+	}
+
+	sort.SliceStable(s.Dependencies, func(i int, j int) bool {
+		return s.Dependencies[i].Name() < s.Dependencies[j].Name()
+	})
+
+	if s.Dependencies == nil {
+		s.Dependencies = make([]deps.Dependency, 0, 0)
+	}
+
+	return json.Marshal(s)
+}