WIP - graph visualization

.changes/unreleased/ENHANCEMENTS-20251209-175542.yaml

@@ -0,0 +1,6 @@
+kind: ENHANCEMENTS
+body: Terraform Graph Visualization in VS Code Extension
+time: 2025-12-09T17:55:42.954862+05:30
+custom:
+    Issue: "2056"
+    Repository: terraform-ls

go.mod

@@ -14,7 +14,7 @@ require (
 	github.com/hashicorp/go-uuid v1.0.3
 	github.com/hashicorp/go-version v1.7.0
 	github.com/hashicorp/hc-install v0.9.2
-	github.com/hashicorp/hcl-lang v0.0.0-20250613065305-ef4e1a57cead
+	github.com/hashicorp/hcl-lang v0.0.0-20251223113758-c9e9d0ec101a
 	github.com/hashicorp/hcl/v2 v2.24.0
 	github.com/hashicorp/terraform-exec v0.24.0
 	github.com/hashicorp/terraform-json v0.27.2

go.sum

@@ -116,8 +116,8 @@ github.com/hashicorp/golang-lru v0.5.4 h1:YDjusn29QI/Das2iO9M0BHnIbxPeyuCHsjMW+l
 github.com/hashicorp/golang-lru v0.5.4/go.mod h1:iADmTwqILo4mZ8BN3D2Q6+9jd8WM5uGBxy+E8yxSoD4=
 github.com/hashicorp/hc-install v0.9.2 h1:v80EtNX4fCVHqzL9Lg/2xkp62bbvQMnvPQ0G+OmtO24=
 github.com/hashicorp/hc-install v0.9.2/go.mod h1:XUqBQNnuT4RsxoxiM9ZaUk0NX8hi2h+Lb6/c0OZnC/I=
-github.com/hashicorp/hcl-lang v0.0.0-20250613065305-ef4e1a57cead h1:Nthdz3YLW98zGxDKgkBj6lTXWKhp1tWDg8ecyLkYe94=
-github.com/hashicorp/hcl-lang v0.0.0-20250613065305-ef4e1a57cead/go.mod h1:lUY+oHKrbuViZqM+HHqmKE/18umUBPLAIoVT0WSZjKE=
+github.com/hashicorp/hcl-lang v0.0.0-20251223113758-c9e9d0ec101a h1:k8sRuiYS612tDfIGZiAsAXYcjRsfnkaW2u47IoL/6JU=
+github.com/hashicorp/hcl-lang v0.0.0-20251223113758-c9e9d0ec101a/go.mod h1:2SQEYnpcouuNOR8bjKyWuh82bawbZgoesfHZgqVSTjg=
 github.com/hashicorp/hcl/v2 v2.24.0 h1:2QJdZ454DSsYGoaE6QheQZjtKZSUs9Nh2izTWiwQxvE=
 github.com/hashicorp/hcl/v2 v2.24.0/go.mod h1:oGoO1FIQYfn/AgyOhlg9qLC6/nOJPX3qGbkZpYAcqfM=
 github.com/hashicorp/terraform-exec v0.24.0 h1:mL0xlk9H5g2bn0pPF6JQZk5YlByqSqrO5VoaNtAf8OE=

internal/langserver/handlers/command/display_graph.go

@@ -0,0 +1,201 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package command
+
+import (
+	"context"
+	"fmt"
+	"path/filepath"
+	"sort"
+
+	"github.com/creachadair/jrpc2"
+	"github.com/hashicorp/hcl-lang/decoder"
+	"github.com/hashicorp/hcl-lang/lang"
+	"github.com/hashicorp/hcl/v2"
+	"github.com/hashicorp/hcl/v2/hclsyntax"
+	"github.com/hashicorp/terraform-ls/internal/langserver/cmd"
+	ilsp "github.com/hashicorp/terraform-ls/internal/lsp"
+	lsp "github.com/hashicorp/terraform-ls/internal/protocol"
+	"github.com/hashicorp/terraform-ls/internal/uri"
+)
+
+const displayGraphVersion = 0
+
+type displayGraphResponse struct {
+	FormatVersion int    `json:"v"`
+	Nodes         []node `json:"nodes"`
+	Edges         []edge `json:"edges"`
+}
+
+type node struct {
+	ID int `json:"id"`
+	lsp.Location
+	Type   string   `json:"type"`
+	Labels []string `json:"labels"`
+}
+
+type edge struct {
+	From int `json:"from"`
+	To   int `json:"to"`
+}
+
+type blockInfo struct {
+	filename string
+	block    *hclsyntax.Block
+}
+
+func (h *CmdHandler) DisplayGraphHandler(ctx context.Context, args cmd.CommandArgs) (interface{}, error) {
+	response := newDisplayGraphResponse()
+
+	docUri, ok := args.GetString("uri")
+	if !ok || docUri == "" {
+		return response, fmt.Errorf("%w: expected uri argument to be set", jrpc2.InvalidParams.Err())
+	}
+
+	dh := ilsp.HandleFromDocumentURI(lsp.DocumentURI(uri.FromPath(docUri)))
+	doc, err := h.StateStore.DocumentStore.GetDocument(dh)
+	if err != nil {
+		return response, err
+	}
+
+	// Wait for incomplete jobs to ensure references are computed
+	jobIds, err := h.StateStore.JobStore.ListIncompleteJobsForDir(dh.Dir)
+	if err != nil {
+		return response, err
+	}
+	h.StateStore.JobStore.WaitForJobs(ctx, jobIds...)
+
+	path := lang.Path{
+		Path:       dh.Dir.Path(),
+		LanguageID: doc.LanguageID,
+	}
+
+	pathDecoder, err := h.Decoder.Path(path)
+	if err != nil {
+		return response, err
+	}
+
+	nodes, nodeMap, err := getNodes(pathDecoder, path)
+	if err != nil {
+		return response, err
+	}
+
+	edges, err := getEdges(pathDecoder, path, h.Decoder, nodeMap)
+	if err != nil {
+		return response, err
+	}
+
+	response.Nodes = nodes
+	response.Edges = edges
+	return response, nil
+}
+
+func newDisplayGraphResponse() displayGraphResponse {
+	return displayGraphResponse{
+		FormatVersion: displayGraphVersion,
+		Nodes:         make([]node, 0),
+		Edges:         make([]edge, 0),
+	}
+}
+
+func getNodes(pathDecoder *decoder.PathDecoder, path lang.Path) ([]node, map[string]int, error) {
+	var blocks []blockInfo
+	for _, file := range pathDecoder.Files() {
+		body := file.Body.(*hclsyntax.Body)
+		for _, block := range body.Blocks {
+			blocks = append(blocks, blockInfo{
+				filename: block.DefRange().Filename,
+				block:    block,
+			})
+		}
+	}
+
+	sort.Slice(blocks, func(i, j int) bool {
+		if blocks[i].filename != blocks[j].filename {
+			return blocks[i].filename < blocks[j].filename
+		}
+		return blocks[i].block.DefRange().Start.Line < blocks[j].block.DefRange().Start.Line
+	})
+
+	nodes := make([]node, 0)
+	nodeMap := make(map[string]int)
+	idCounter := 0
+	for _, bi := range blocks {
+		loc := pathRangetoLocation(path, bi.block.DefRange())
+		key := locationKey(loc)
+		nodeMap[key] = idCounter
+		nodes = append(nodes,
+			node{
+				ID:       idCounter,
+				Location: loc,
+				Type:     bi.block.Type,
+				Labels:   bi.block.Labels,
+			})
+		idCounter++
+	}
+	return nodes, nodeMap, nil
+}
+
+func getEdges(pathDecoder *decoder.PathDecoder, path lang.Path, decoder *decoder.Decoder, nodeMap map[string]int) ([]edge, error) {
+	edges := make([]edge, 0)
+	refTargets := pathDecoder.RefTargets()
+	seen := make(map[string]bool)
+
+	for _, refTarget := range refTargets {
+		if refTarget.RootBlockRange != nil {
+			fromLoc := pathRangetoLocation(path, *refTarget.RootBlockRange)
+			fromKey := locationKey(fromLoc)
+			fromID, fromExists := nodeMap[fromKey]
+			if !fromExists {
+				continue
+			}
+			origins := decoder.ReferenceOriginsByTargetInPath(context.Background(), refTarget, path, path)
+			for _, refOrigin := range origins {
+				toLoc := pathRangetoLocation(path, refOrigin.RootBlockRange)
+				toKey := locationKey(toLoc)
+				toID, toExists := nodeMap[toKey]
+				if !toExists {
+					continue
+				}
+				edge := edge{
+					From: fromID,
+					To:   toID,
+				}
+				edgeKey := edgeKey(edge)
+				if isASelfEdge(edge) || isSeenEdge(&seen, edgeKey) {
+					continue
+				}
+
+				edges = append(edges, edge)
+				seen[edgeKey] = true
+			}
+
+		}
+	}
+	return edges, nil
+}
+
+func edgeKey(e edge) string {
+	return fmt.Sprintf("%d->%d", e.From, e.To)
+}
+
+func locationKey(loc lsp.Location) string {
+	return fmt.Sprintf("%s#%d:%d#%d:%d", loc.URI, loc.Range.Start.Line, loc.Range.Start.Character, loc.Range.End.Line, loc.Range.End.Character)
+}
+
+func isSeenEdge(seen *map[string]bool, edgeKey string) bool {
+	_, ok := (*seen)[edgeKey]
+	return ok
+}
+
+func isASelfEdge(edge edge) bool {
+	return edge.From == edge.To
+}
+
+func pathRangetoLocation(path lang.Path, rng hcl.Range) lsp.Location {
+	return lsp.Location{
+		URI:   lsp.DocumentURI(uri.FromPath(filepath.Join(path.Path, rng.Filename))),
+		Range: ilsp.HCLRangeToLSP(rng),
+	}
+}