feat: absolute imports (#63)

* feat: go-like import style

jb now creates a directory structure inside of vendor/ that is similar to how go
does (github.com/grafana/jsonnet-libs). This is reflected in the final import
paths, which means they will be go-like

* refactor(spec/deps): named regexs

* feat: make goImportStyle configurable

Defaults to off, can be enabled in `jsonnetfile.json`

* fix: integration test

* doc: license headers

* fix(deps): remove GO_IMPORT_STYLE

not an option anymore, will always do so and symlink

* feat: symlink to legacy location

* feat: allow to disable legacy links

* fix(test): legacyImports in integration tests

* fix(spec): test

* fix: respect legacyName aliases

It was possible to alias packages by changing `name` previously.

While names are now absolute (and computed), legacy links should still respect
old aliases to avoid breaking code.

* fix(test): integration

* fix(init): keep legacyImports enabled for now

* feat: rewrite imports

adds a command to automatically rewrite imports from legacy to absolute style

* fix(tool): rewrite confused by prefixing packages

When a package was a prefix of another one, it broke.
Fixed that by using a proper regular expression. Added a test to make sure it
works as expected

* Update cmd/jb/init.go

* fix: exclude local packages from legacy linking

They actually still use the old style, which is fine. LegacyLinking
messed them up, but from now on it just ignores symlinks that match a localPackage.

spec/deps/dependencies.go

@@ -0,0 +1,106 @@
+// 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 deps
+
+import (
+	"os"
+	"path/filepath"
+)
+
+type Dependency struct {
+	Source  Source `json:"source"`
+	Version string `json:"version"`
+	Sum     string `json:"sum,omitempty"`
+
+	// older schema used to have `name`. We still need that data for
+	// `LegacyName`
+	LegacyNameCompat string `json:"name,omitempty"`
+}
+
+func Parse(dir, uri string) *Dependency {
+	if uri == "" {
+		return nil
+	}
+
+	if d := parseGit(uri); d != nil {
+		return d
+	}
+
+	return parseLocal(dir, uri)
+}
+
+func (d Dependency) Name() string {
+	return d.Source.Name()
+}
+
+func (d Dependency) LegacyName() string {
+	if d.LegacyNameCompat != "" {
+		return d.LegacyNameCompat
+	}
+	return d.Source.LegacyName()
+}
+
+type Source struct {
+	GitSource   *Git   `json:"git,omitempty"`
+	LocalSource *Local `json:"local,omitempty"`
+}
+
+func (s Source) Name() string {
+	switch {
+	case s.GitSource != nil:
+		return s.GitSource.Name()
+	case s.LocalSource != nil:
+		return s.LegacyName()
+	default:
+		return ""
+	}
+}
+
+func (s Source) LegacyName() string {
+	switch {
+	case s.GitSource != nil:
+		return s.GitSource.LegacyName()
+	case s.LocalSource != nil:
+		return filepath.Base(s.LocalSource.Directory)
+	default:
+		return ""
+	}
+}
+
+type Local struct {
+	Directory string `json:"directory"`
+}
+
+func parseLocal(dir, p string) *Dependency {
+	clean := filepath.Clean(p)
+	abs := filepath.Join(dir, clean)
+
+	info, err := os.Stat(abs)
+	if err != nil {
+		return nil
+	}
+
+	if !info.IsDir() {
+		return nil
+	}
+
+	return &Dependency{
+		Source: Source{
+			LocalSource: &Local{
+				Directory: clean,
+			},
+		},
+		Version: "",
+	}
+}