lang: Add module imports and more

This enables imports in mcl code, and is one of last remaining blockers
to using mgmt. Now we can start writing standalone modules, and adding
standard library functions as needed. There's still lots to do, but this
was a big missing piece. It was much harder to get right than I had
expected, but I think it's solid!

This unfortunately large commit is the result of some wild hacking I've
been doing for the past little while. It's the result of a rebase that
broke many "wip" commits that tracked my private progress, into
something that's not gratuitously messy for our git logs. Since this was
a learning and discovery process for me, I've "erased" the confusing git
history that wouldn't have helped. I'm happy to discuss the dead-ends,
and a small portion of that code was even left in for possible future
use.

This patch includes:

* A change to the cli interface:
You now specify the front-end explicitly, instead of leaving it up to
the front-end to decide when to "activate". For example, instead of:

mgmt run --lang code.mcl

we now do:

mgmt run lang --lang code.mcl

We might rename the --lang flag in the future to avoid the awkward word
repetition. Suggestions welcome, but I'm considering "input". One
side-effect of this change, is that flags which are "engine" specific
now must be specified with "run" before the front-end name. Eg:

mgmt run --tmp-prefix lang --lang code.mcl

instead of putting --tmp-prefix at the end. We also changed the GAPI
slightly, but I've patched all code that used it. This also makes things
consistent with the "deploy" command.

* The deploys are more robust and let you deploy after a run
This has been vastly improved and let's mgmt really run as a smart
engine that can handle different workloads. If you don't want to deploy
when you've started with `run` or if one comes in, you can use the
--no-watch-deploy option to block new deploys.

* The import statement exists and works!
We now have a working `import` statement. Read the docs, and try it out.
I think it's quite elegant how it fits in with `SetScope`. Have a look.
As a result, we now have some built-in functions available in modules.
This also adds the metadata.yaml entry-point for all modules. Have a
look at the examples or the tests. The bulk of the patch is to support
this.

* Improved lang input parsing code:
I re-wrote the parsing that determined what ran when we passed different
things to --lang. Deciding between running an mcl file or raw code is
now handled in a more intelligent, and re-usable way. See the inputs.go
file if you want to have a look. One casualty is that you can't stream
code from stdin *directly* to the front-end, it's encapsulated into a
deploy first. You can still use stdin though! I doubt anyone will notice
this change.

* The scope was extended to include functions and classes:
Go forth and import lovely code. All these exist in scopes now, and can
be re-used!

* Function calls actually use the scope now. Glad I got this sorted out.

* There is import cycle detection for modules!
Yes, this is another dag. I think that's #4. I guess they're useful.

* A ton of tests and new test infra was added!
This should make it much easier to add new tests that run mcl code. Have
a look at TestAstFunc1 to see how to add more of these.

As usual, I'll try to keep these commits smaller in the future!

lang/lexparse_test.go

@@ -2090,13 +2090,14 @@ func TestLexParseWithOffsets1(t *testing.T) {
 
 func TestImportParsing0(t *testing.T) {
 	type test struct { // an individual test
-		name   string
-		fail   bool
-		alias  string
-		system bool
-		local  bool
-		path   string
-		url    string
+		name     string
+		fail     bool
+		alias    string
+		isSystem bool
+		isLocal  bool
+		isFile   bool
+		path     string
+		url      string
 	}
 	testCases := []test{}
 	testCases = append(testCases, test{ // index: 0
@@ -2108,70 +2109,70 @@ func TestImportParsing0(t *testing.T) {
 		fail: true, // can't be root
 	})
 	testCases = append(testCases, test{
-		name:  "git://example.com/purpleidea/mgmt",
-		alias: "mgmt",
-		local: false,
-		path:  "example.com/purpleidea/mgmt/",
-		url:   "git://example.com/purpleidea/mgmt",
+		name:    "git://example.com/purpleidea/mgmt",
+		alias:   "mgmt",
+		isLocal: false,
+		path:    "example.com/purpleidea/mgmt/",
+		url:     "git://example.com/purpleidea/mgmt",
 	})
 	testCases = append(testCases, test{
-		name:  "git://example.com/purpleidea/mgmt/",
-		alias: "mgmt",
-		local: false,
-		path:  "example.com/purpleidea/mgmt/",
-		url:   "git://example.com/purpleidea/mgmt/",
+		name:    "git://example.com/purpleidea/mgmt/",
+		alias:   "mgmt",
+		isLocal: false,
+		path:    "example.com/purpleidea/mgmt/",
+		url:     "git://example.com/purpleidea/mgmt/",
 	})
 	testCases = append(testCases, test{
-		name:  "git://example.com/purpleidea/mgmt/foo/bar/",
-		alias: "bar",
-		local: false,
-		path:  "example.com/purpleidea/mgmt/foo/bar/",
+		name:    "git://example.com/purpleidea/mgmt/foo/bar/",
+		alias:   "bar",
+		isLocal: false,
+		path:    "example.com/purpleidea/mgmt/foo/bar/",
 		// TODO: change this to be more clever about the clone URL
 		//url: "git://example.com/purpleidea/mgmt/",
 		// TODO: also consider changing `git` to `https` ?
 		url: "git://example.com/purpleidea/mgmt/foo/bar/",
 	})
 	testCases = append(testCases, test{
-		name:  "git://example.com/purpleidea/mgmt-foo",
-		alias: "foo", // prefix is magic
-		local: false,
-		path:  "example.com/purpleidea/mgmt-foo/",
-		url:   "git://example.com/purpleidea/mgmt-foo",
+		name:    "git://example.com/purpleidea/mgmt-foo",
+		alias:   "foo", // prefix is magic
+		isLocal: false,
+		path:    "example.com/purpleidea/mgmt-foo/",
+		url:     "git://example.com/purpleidea/mgmt-foo",
 	})
 	testCases = append(testCases, test{
-		name:  "git://example.com/purpleidea/foo-bar",
-		alias: "foo_bar",
-		local: false,
-		path:  "example.com/purpleidea/foo-bar/",
-		url:   "git://example.com/purpleidea/foo-bar",
+		name:    "git://example.com/purpleidea/foo-bar",
+		alias:   "foo_bar",
+		isLocal: false,
+		path:    "example.com/purpleidea/foo-bar/",
+		url:     "git://example.com/purpleidea/foo-bar",
 	})
 	testCases = append(testCases, test{
-		name:  "git://example.com/purpleidea/FOO-bar",
-		alias: "foo_bar",
-		local: false,
-		path:  "example.com/purpleidea/FOO-bar/",
-		url:   "git://example.com/purpleidea/FOO-bar",
+		name:    "git://example.com/purpleidea/FOO-bar",
+		alias:   "foo_bar",
+		isLocal: false,
+		path:    "example.com/purpleidea/FOO-bar/",
+		url:     "git://example.com/purpleidea/FOO-bar",
 	})
 	testCases = append(testCases, test{
-		name:  "git://example.com/purpleidea/foo-BAR",
-		alias: "foo_bar",
-		local: false,
-		path:  "example.com/purpleidea/foo-BAR/",
-		url:   "git://example.com/purpleidea/foo-BAR",
+		name:    "git://example.com/purpleidea/foo-BAR",
+		alias:   "foo_bar",
+		isLocal: false,
+		path:    "example.com/purpleidea/foo-BAR/",
+		url:     "git://example.com/purpleidea/foo-BAR",
 	})
 	testCases = append(testCases, test{
-		name:  "git://example.com/purpleidea/foo-BAR-baz",
-		alias: "foo_bar_baz",
-		local: false,
-		path:  "example.com/purpleidea/foo-BAR-baz/",
-		url:   "git://example.com/purpleidea/foo-BAR-baz",
+		name:    "git://example.com/purpleidea/foo-BAR-baz",
+		alias:   "foo_bar_baz",
+		isLocal: false,
+		path:    "example.com/purpleidea/foo-BAR-baz/",
+		url:     "git://example.com/purpleidea/foo-BAR-baz",
 	})
 	testCases = append(testCases, test{
-		name:  "git://example.com/purpleidea/Module-Name",
-		alias: "module_name",
-		local: false,
-		path:  "example.com/purpleidea/Module-Name/",
-		url:   "git://example.com/purpleidea/Module-Name",
+		name:    "git://example.com/purpleidea/Module-Name",
+		alias:   "module_name",
+		isLocal: false,
+		path:    "example.com/purpleidea/Module-Name/",
+		url:     "git://example.com/purpleidea/Module-Name",
 	})
 	testCases = append(testCases, test{
 		name: "git://example.com/purpleidea/foo-",
@@ -2185,74 +2186,114 @@ func TestImportParsing0(t *testing.T) {
 		name:  "/var/lib/mgmt",
 		alias: "mgmt",
 		fail:  true, // don't allow absolute paths
-		//local: true,
+		//isLocal: true,
 		//path: "/var/lib/mgmt",
 	})
 	testCases = append(testCases, test{
 		name:  "/var/lib/mgmt/",
 		alias: "mgmt",
 		fail:  true, // don't allow absolute paths
-		//local: true,
+		//isLocal: true,
 		//path: "/var/lib/mgmt/",
 	})
 	testCases = append(testCases, test{
-		name:  "git://example.com/purpleidea/Module-Name?foo=bar&baz=42",
-		alias: "module_name",
-		local: false,
-		path:  "example.com/purpleidea/Module-Name/",
-		url:   "git://example.com/purpleidea/Module-Name",
+		name:    "git://example.com/purpleidea/Module-Name?foo=bar&baz=42",
+		alias:   "module_name",
+		isLocal: false,
+		path:    "example.com/purpleidea/Module-Name/",
+		url:     "git://example.com/purpleidea/Module-Name",
 	})
 	testCases = append(testCases, test{
-		name:  "git://example.com/purpleidea/Module-Name/?foo=bar&baz=42",
-		alias: "module_name",
-		local: false,
-		path:  "example.com/purpleidea/Module-Name/",
-		url:   "git://example.com/purpleidea/Module-Name/",
+		name:    "git://example.com/purpleidea/Module-Name/?foo=bar&baz=42",
+		alias:   "module_name",
+		isLocal: false,
+		path:    "example.com/purpleidea/Module-Name/",
+		url:     "git://example.com/purpleidea/Module-Name/",
 	})
 	testCases = append(testCases, test{
-		name:  "git://example.com/purpleidea/Module-Name/?sha1=25ad05cce36d55ce1c55fd7e70a3ab74e321b66e",
-		alias: "module_name",
-		local: false,
-		path:  "example.com/purpleidea/Module-Name/",
-		url:   "git://example.com/purpleidea/Module-Name/",
+		name:    "git://example.com/purpleidea/Module-Name/?sha1=25ad05cce36d55ce1c55fd7e70a3ab74e321b66e",
+		alias:   "module_name",
+		isLocal: false,
+		path:    "example.com/purpleidea/Module-Name/",
+		url:     "git://example.com/purpleidea/Module-Name/",
 		// TODO: report the query string info as an additional param
 	})
 	testCases = append(testCases, test{
-		name:  "git://example.com/purpleidea/Module-Name/subpath/foo",
-		alias: "foo",
-		local: false,
-		path:  "example.com/purpleidea/Module-Name/subpath/foo/",
-		url:   "git://example.com/purpleidea/Module-Name/subpath/foo",
+		name:    "git://example.com/purpleidea/Module-Name/subpath/foo",
+		alias:   "foo",
+		isLocal: false,
+		path:    "example.com/purpleidea/Module-Name/subpath/foo/",
+		url:     "git://example.com/purpleidea/Module-Name/subpath/foo",
 	})
 	testCases = append(testCases, test{
-		name:  "foo/",
-		alias: "foo",
-		local: true,
-		path:  "foo/",
+		name:    "foo/",
+		alias:   "foo",
+		isLocal: true,
+		path:    "foo/",
 	})
 	testCases = append(testCases, test{
-		name:   "foo/bar",
-		alias:  "bar",
-		system: true, // system because not a dir (no trailing slash)
-		local:  true, // not really used, but this is what we return
+		// import foo.mcl # import a file next to me
+		name:     "foo.mcl",
+		alias:    "foo",
+		isSystem: false,
+		isLocal:  true,
+		isFile:   true,
+		path:     "foo.mcl",
 	})
 	testCases = append(testCases, test{
-		name:   "foo/bar/baz",
-		alias:  "baz",
-		system: true, // system because not a dir (no trailing slash)
-		local:  true, // not really used, but this is what we return
+		// import server/foo.mcl # import a file in a dir next to me
+		name:     "server/foo.mcl",
+		alias:    "foo",
+		isSystem: false,
+		isLocal:  true,
+		isFile:   true,
+		path:     "server/foo.mcl",
 	})
 	testCases = append(testCases, test{
-		name:   "fmt",
-		alias:  "fmt",
-		system: true,
-		local:  true, // not really used, but this is what we return
+		// import a deeper file (not necessarily a good idea)
+		name:     "server/vars/blah.mcl",
+		alias:    "blah",
+		isSystem: false,
+		isLocal:  true,
+		isFile:   true,
+		path:     "server/vars/blah.mcl",
 	})
 	testCases = append(testCases, test{
-		name:   "blah",
-		alias:  "blah",
-		system: true, // even modules that don't exist return true here
-		local:  true,
+		name:     "foo/bar",
+		alias:    "bar",
+		isSystem: true, // system because not a dir (no trailing slash)
+		isLocal:  true, // not really used, but this is what we return
+	})
+	testCases = append(testCases, test{
+		name:     "foo/bar/baz",
+		alias:    "baz",
+		isSystem: true, // system because not a dir (no trailing slash)
+		isLocal:  true, // not really used, but this is what we return
+	})
+	testCases = append(testCases, test{
+		name:     "fmt",
+		alias:    "fmt",
+		isSystem: true,
+		isLocal:  true, // not really used, but this is what we return
+	})
+	testCases = append(testCases, test{
+		name:     "blah",
+		alias:    "blah",
+		isSystem: true, // even modules that don't exist return true here
+		isLocal:  true,
+	})
+	testCases = append(testCases, test{
+		name:     "git:///home/james/code/mgmt-example1/",
+		alias:    "example1",
+		isSystem: false,
+		isLocal:  false,
+		// FIXME: do we want to have a special "local" imports dir?
+		path: "home/james/code/mgmt-example1/",
+		url:  "git:///home/james/code/mgmt-example1/",
+	})
+	testCases = append(testCases, test{
+		name: "git:////home/james/code/mgmt-example1/",
+		fail: true, // don't allow double root slash
 	})
 
 	t.Logf("ModuleMagicPrefix: %s", ModuleMagicPrefix)
@@ -2264,7 +2305,7 @@ func TestImportParsing0(t *testing.T) {
 		}
 		names = append(names, tc.name)
 		t.Run(fmt.Sprintf("test #%d (%s)", index, tc.name), func(t *testing.T) {
-			name, fail, alias, system, local, path, url := tc.name, tc.fail, tc.alias, tc.system, tc.local, tc.path, tc.url
+			name, fail, alias, isSystem, isLocal, isFile, path, url := tc.name, tc.fail, tc.alias, tc.isSystem, tc.isLocal, tc.isFile, tc.path, tc.url
 
 			output, err := ParseImportName(name)
 			if !fail && err != nil {
@@ -2275,6 +2316,7 @@ func TestImportParsing0(t *testing.T) {
 			if fail && err == nil {
 				t.Errorf("test #%d: FAIL", index)
 				t.Errorf("test #%d: ParseImportName expected error, not nil", index)
+				t.Logf("test #%d: output: %+v", index, output)
 				return
 			}
 			if fail { // we failed as expected, don't continue...
@@ -2288,21 +2330,26 @@ func TestImportParsing0(t *testing.T) {
 				t.Logf("test #%d:  alias: %s", index, alias)
 				return
 			}
-			if system != output.System {
-				t.Errorf("test #%d: unexpected value for: `System`", index)
+			if isSystem != output.IsSystem {
+				t.Errorf("test #%d: unexpected value for: `IsSystem`", index)
 				//t.Logf("test #%d:  input: %s", index, name)
-				t.Logf("test #%d: output: %+v", index, output)
-				t.Logf("test #%d: system: %t", index, system)
+				t.Logf("test #%d:   output: %+v", index, output)
+				t.Logf("test #%d: isSystem: %t", index, isSystem)
 				return
-
 			}
-			if local != output.Local {
-				t.Errorf("test #%d: unexpected value for: `Local`", index)
+			if isLocal != output.IsLocal {
+				t.Errorf("test #%d: unexpected value for: `IsLocal`", index)
+				//t.Logf("test #%d:  input: %s", index, name)
+				t.Logf("test #%d:  output: %+v", index, output)
+				t.Logf("test #%d: isLocal: %t", index, isLocal)
+				return
+			}
+			if isFile != output.IsFile {
+				t.Errorf("test #%d: unexpected value for: `isFile`", index)
 				//t.Logf("test #%d:  input: %s", index, name)
 				t.Logf("test #%d: output: %+v", index, output)
-				t.Logf("test #%d:  local: %t", index, local)
+				t.Logf("test #%d: isFile: %t", index, isFile)
 				return
-
 			}
 			if path != output.Path {
 				t.Errorf("test #%d: unexpected value for: `Path`", index)
@@ -2310,15 +2357,23 @@ func TestImportParsing0(t *testing.T) {
 				t.Logf("test #%d: output: %+v", index, output)
 				t.Logf("test #%d:   path: %s", index, path)
 				return
-
 			}
 			if url != output.URL {
 				t.Errorf("test #%d: unexpected value for: `URL`", index)
 				//t.Logf("test #%d:  input: %s", index, name)
 				t.Logf("test #%d: output: %+v", index, output)
-				t.Logf("test #%d:   url: %s", index, url)
+				t.Logf("test #%d:    url: %s", index, url)
 				return
+			}
 
+			// add some additional sanity checking:
+			if strings.HasPrefix(path, "/") {
+				t.Errorf("test #%d: the path value starts with a / (it should be relative)", index)
+			}
+			if !isSystem {
+				if !strings.HasSuffix(path, "/") && !strings.HasSuffix(path, interfaces.DotFileNameExtension) {
+					t.Errorf("test #%d: the path value should be a directory or a code file", index)
+				}
 			}
 		})
 	}