gopls/internal: implement Packages command

Implements the `gopls.packages` command.

Updates golang/go#59445

Change-Id: Ia72a971b7aac9baa964c8cf5eee8b332b3125fa4
Reviewed-on: https://go-review.googlesource.com/c/tools/+/600355
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Robert Findley <rfindley@google.com>

gopls/internal/server/command.go

@@ -143,8 +143,85 @@ func (h *commandHandler) Modules(ctx context.Context, args command.ModulesArgs)
 	return result, nil
 }
 
-func (h *commandHandler) Packages(context.Context, command.PackagesArgs) (command.PackagesResult, error) {
-	panic("unimplemented")
+func (h *commandHandler) Packages(ctx context.Context, args command.PackagesArgs) (command.PackagesResult, error) {
+	wantTests := args.Mode&command.NeedTests != 0
+	result := command.PackagesResult{
+		Module: make(map[string]command.Module),
+	}
+
+	keepPackage := func(pkg *metadata.Package) bool {
+		for _, file := range pkg.GoFiles {
+			for _, arg := range args.Files {
+				if file == arg || file.Dir() == arg {
+					return true
+				}
+				if args.Recursive && arg.Encloses(file) {
+					return true
+				}
+			}
+		}
+		return false
+	}
+
+	buildPackage := func(snapshot *cache.Snapshot, meta *metadata.Package) (command.Package, command.Module) {
+		if wantTests {
+			// These will be used in the next CL to query tests
+			_, _ = ctx, snapshot
+			panic("unimplemented")
+		}
+
+		pkg := command.Package{
+			Path: string(meta.PkgPath),
+		}
+		if meta.Module == nil {
+			return pkg, command.Module{}
+		}
+
+		mod := command.Module{
+			Path:    meta.Module.Path,
+			Version: meta.Module.Version,
+			GoMod:   protocol.URIFromPath(meta.Module.GoMod),
+		}
+		pkg.ModulePath = mod.Path
+		return pkg, mod
+	}
+
+	err := h.run(ctx, commandConfig{
+		progress: "Packages",
+	}, func(ctx context.Context, _ commandDeps) error {
+		for _, view := range h.s.session.Views() {
+			snapshot, release, err := view.Snapshot()
+			if err != nil {
+				return err
+			}
+			defer release()
+
+			metas, err := snapshot.WorkspaceMetadata(ctx)
+			if err != nil {
+				return err
+			}
+
+			for _, meta := range metas {
+				if meta.IsIntermediateTestVariant() {
+					continue
+				}
+				if !keepPackage(meta) {
+					continue
+				}
+
+				pkg, mod := buildPackage(snapshot, meta)
+				result.Packages = append(result.Packages, pkg)
+
+				// Overwriting is ok
+				if mod.Path != "" {
+					result.Module[mod.Path] = mod
+				}
+			}
+		}
+
+		return nil
+	})
+	return result, err
 }
 
 func (h *commandHandler) MaybePromptForTelemetry(ctx context.Context) error {

gopls/internal/test/integration/workspace/packages_test.go

@@ -0,0 +1,139 @@
+// Copyright 2024 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package workspace
+
+import (
+	"sort"
+	"strings"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"golang.org/x/tools/gopls/internal/protocol"
+	"golang.org/x/tools/gopls/internal/protocol/command"
+	. "golang.org/x/tools/gopls/internal/test/integration"
+)
+
+func TestPackages(t *testing.T) {
+	const goModView = `
+-- go.mod --
+module foo
+
+-- foo.go --
+package foo
+func Foo()
+
+-- bar/bar.go --
+package bar
+func Bar()
+
+-- baz/go.mod --
+module baz
+
+-- baz/baz.go --
+package baz
+func Baz()
+`
+
+	t.Run("file", func(t *testing.T) {
+		Run(t, goModView, func(t *testing.T, env *Env) {
+			checkPackages(t, env, []protocol.DocumentURI{env.Editor.DocumentURI("foo.go")}, false, []command.Package{
+				{
+					Path:       "foo",
+					ModulePath: "foo",
+				},
+			}, map[string]command.Module{
+				"foo": {
+					Path:  "foo",
+					GoMod: env.Editor.DocumentURI("go.mod"),
+				},
+			})
+		})
+	})
+
+	t.Run("package", func(t *testing.T) {
+		Run(t, goModView, func(t *testing.T, env *Env) {
+			checkPackages(t, env, []protocol.DocumentURI{env.Editor.DocumentURI("bar")}, false, []command.Package{
+				{
+					Path:       "foo/bar",
+					ModulePath: "foo",
+				},
+			}, map[string]command.Module{
+				"foo": {
+					Path:  "foo",
+					GoMod: env.Editor.DocumentURI("go.mod"),
+				},
+			})
+		})
+	})
+
+	t.Run("workspace", func(t *testing.T) {
+		Run(t, goModView, func(t *testing.T, env *Env) {
+			checkPackages(t, env, []protocol.DocumentURI{env.Editor.DocumentURI("")}, true, []command.Package{
+				{
+					Path:       "foo",
+					ModulePath: "foo",
+				},
+				{
+					Path:       "foo/bar",
+					ModulePath: "foo",
+				},
+			}, map[string]command.Module{
+				"foo": {
+					Path:  "foo",
+					GoMod: env.Editor.DocumentURI("go.mod"),
+				},
+			})
+		})
+	})
+
+	t.Run("nested module", func(t *testing.T) {
+		Run(t, goModView, func(t *testing.T, env *Env) {
+			// Load the nested module
+			env.OpenFile("baz/baz.go")
+
+			// Request packages using the URI of the nested module _directory_
+			checkPackages(t, env, []protocol.DocumentURI{env.Editor.DocumentURI("baz")}, true, []command.Package{
+				{
+					Path:       "baz",
+					ModulePath: "baz",
+				},
+			}, map[string]command.Module{
+				"baz": {
+					Path:  "baz",
+					GoMod: env.Editor.DocumentURI("baz/go.mod"),
+				},
+			})
+		})
+	})
+}
+
+func checkPackages(t testing.TB, env *Env, files []protocol.DocumentURI, recursive bool, wantPkg []command.Package, wantModule map[string]command.Module) {
+	t.Helper()
+
+	cmd, err := command.NewPackagesCommand("Packages", command.PackagesArgs{Files: files, Recursive: recursive})
+	if err != nil {
+		t.Fatal(err)
+	}
+	var result command.PackagesResult
+	env.ExecuteCommand(&protocol.ExecuteCommandParams{
+		Command:   command.Packages.String(),
+		Arguments: cmd.Arguments,
+	}, &result)
+
+	// The ordering of packages is undefined so sort the results to ensure
+	// consistency
+	sort.Slice(result.Packages, func(i, j int) bool {
+		a, b := result.Packages[i], result.Packages[j]
+		return strings.Compare(a.Path, b.Path) < 0
+	})
+
+	if diff := cmp.Diff(wantPkg, result.Packages); diff != "" {
+		t.Errorf("Packages(%v) returned unexpected packages (-want +got):\n%s", files, diff)
+	}
+
+	if diff := cmp.Diff(wantModule, result.Module); diff != "" {
+		t.Errorf("Packages(%v) returned unexpected modules (-want +got):\n%s", files, diff)
+	}
+}