lsp/eval: Load capabilities and config into eval (#1217)

When developing Regal rules it's useful to be able to access the
server's capabilities and configuration. This change adds these to the
rego evaluation context.

Signed-off-by: Charlie Egan <charlie@styra.com>

internal/lsp/eval.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"os"
 	"strings"
 
 	"github.com/anderseknert/roast/pkg/encoding"
@@ -18,6 +19,7 @@ import (
 	"github.com/styrainc/regal/internal/lsp/log"
 	"github.com/styrainc/regal/internal/lsp/uri"
 	"github.com/styrainc/regal/pkg/builtins"
+	"github.com/styrainc/regal/pkg/config"
 )
 
 func (l *LanguageServer) Eval(
@@ -74,7 +76,12 @@ func (l *LanguageServer) Eval(
 		allBundles["regal"] = rbundle.LoadedBundle
 	}
 
-	regoArgs := prepareRegoArgs(ast.MustParseBody(query), allBundles, printHook)
+	regoArgs := prepareRegoArgs(
+		ast.MustParseBody(query),
+		allBundles,
+		printHook,
+		l.getLoadedConfig(),
+	)
 
 	pq, err := rego.New(regoArgs...).PrepareForEval(ctx)
 	if err != nil {
@@ -138,21 +145,57 @@ func (l *LanguageServer) EvalWorkspacePath(
 	return EvalPathResult{Value: res, PrintOutput: hook.Output}, nil
 }
 
-func prepareRegoArgs(query ast.Body, bundles map[string]bundle.Bundle, printHook print.Hook) []func(*rego.Rego) {
+func prepareRegoArgs(
+	query ast.Body,
+	bundles map[string]bundle.Bundle,
+	printHook print.Hook,
+	cfg *config.Config,
+) []func(*rego.Rego) {
 	bundleArgs := make([]func(*rego.Rego), 0, len(bundles))
 	for key, b := range bundles {
 		bundleArgs = append(bundleArgs, rego.ParsedBundle(key, &b))
 	}
 
-	baseArgs := []func(*rego.Rego){
+	args := []func(*rego.Rego){
 		rego.ParsedQuery(query),
 		rego.Function2(builtins.RegalParseModuleMeta, builtins.RegalParseModule),
 		rego.Function1(builtins.RegalLastMeta, builtins.RegalLast),
 		rego.EnablePrintStatements(true),
 		rego.PrintHook(printHook),
 	}
 
-	return append(baseArgs, bundleArgs...)
+	args = append(args, bundleArgs...)
+
+	var caps *config.Capabilities
+	if cfg != nil && cfg.Capabilities != nil {
+		caps = cfg.Capabilities
+	} else {
+		caps = config.CapabilitiesForThisVersion()
+	}
+
+	var evalConfig config.Config
+	if cfg != nil {
+		evalConfig = *cfg
+	}
+
+	internalBundle := &bundle.Bundle{
+		Manifest: bundle.Manifest{
+			Roots:    &[]string{"internal"},
+			Metadata: map[string]any{"name": "internal"},
+		},
+		Data: map[string]any{
+			"internal": map[string]any{
+				"combined_config": config.ToMap(evalConfig),
+				"capabilities":    caps,
+			},
+		},
+	}
+
+	fmt.Fprintln(os.Stderr, "Loaded internal bundle")
+
+	args = append(args, rego.ParsedBundle("internal", internalBundle))
+
+	return args
 }
 
 type PrintHook struct {

internal/lsp/eval_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"io"
 	"os"
+	"slices"
 	"strings"
 	"testing"
 
@@ -60,6 +61,46 @@ func TestEvalWorkspacePath(t *testing.T) {
 	}
 }
 
+func TestEvalWorkspacePathInternalData(t *testing.T) {
+	t.Parallel()
+
+	logger := newTestLogger(t)
+
+	ls := NewLanguageServer(
+		context.Background(),
+		&LanguageServerOptions{LogWriter: logger, LogLevel: log.LevelDebug},
+	)
+
+	res, err := ls.EvalWorkspacePath(context.TODO(), "object.keys(data.internal)", strings.NewReader("{}"))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	val, ok := res.Value.([]any)
+	if !ok {
+		t.Fatalf("expected []any, got %T", res.Value)
+	}
+
+	valStr := make([]string, 0, len(val))
+
+	for _, v := range val {
+		str, ok := v.(string)
+		if !ok {
+			t.Fatalf("expected string, got %T", v)
+		}
+
+		valStr = append(valStr, str)
+	}
+
+	slices.Sort(valStr)
+
+	exp := []string{"capabilities", "combined_config"}
+
+	if !slices.Equal(valStr, exp) {
+		t.Fatalf("expected %v, got %v", exp, valStr)
+	}
+}
+
 func TestFindInput(t *testing.T) {
 	t.Parallel()