Add hover to rule

langserver/hover.go

@@ -0,0 +1,36 @@
+package langserver
+
+import (
+	"context"
+	"encoding/json"
+
+	"github.com/sourcegraph/go-lsp"
+	"github.com/sourcegraph/jsonrpc2"
+)
+
+func (h *handler) handleTextDocumentHover(ctx context.Context, conn *jsonrpc2.Conn, req *jsonrpc2.Request) (result interface{}, err error) {
+	if req.Params == nil {
+		return nil, &jsonrpc2.Error{Code: jsonrpc2.CodeInvalidParams}
+	}
+
+	var params lsp.TextDocumentPositionParams
+	if err := json.Unmarshal(*req.Params, &params); err != nil {
+		return nil, err
+	}
+
+	return h.documentIdent(ctx, params.TextDocument.URI, params.Position)
+}
+
+func (h *handler) documentIdent(ctx context.Context, uri lsp.DocumentURI, position lsp.Position) (lsp.Hover, error) {
+	loc := h.toOPALocation(position, uri)
+	documentResults, err := h.project.TermDocument(loc)
+	if err != nil {
+		return lsp.Hover{}, err
+	}
+
+	result := make([]lsp.MarkedString, len(documentResults))
+	for i, d := range documentResults {
+		result[i] = lsp.MarkedString{Language: d.Language, Value: d.Content}
+	}
+	return lsp.Hover{Contents: result}, nil
+}

langserver/initialize.go

@@ -35,6 +35,7 @@ func (h *handler) handleInitialize(ctx context.Context, conn *jsonrpc2.Conn, req
 			},
 			DocumentFormattingProvider: true,
 			DefinitionProvider:         true,
+			HoverProvider:              true,
 			CompletionProvider: &lsp.CompletionOptions{
 				TriggerCharacters: []string{"*"},
 				ResolveProvider:   true,

langserver/internal/source/completion.go

@@ -32,12 +32,6 @@ const (
 	ImportItem
 )
 
-const (
-	BuiltinDetail = `built-in function
-
-See https://www.openpolicyagent.org/docs/latest/policy-reference/#built-in-functions`
-)
-
 func (p *Project) ListCompletionItems(location *ast.Location) ([]CompletionItem, error) {
 	term, err := p.SearchTargetTerm(location)
 	if err != nil {
@@ -267,11 +261,9 @@ func (p *Project) listBuiltinFunction(term *ast.Term) []CompletionItem {
 				continue
 			}
 			result = append(result, CompletionItem{
-				Label: b.Name,
-				Kind:  BuiltinFunctionItem,
-				Detail: fmt.Sprintf(`%s%s
-
-%s`, b.Name, b.Decl.FuncArgs().String(), BuiltinDetail),
+				Label:      b.Name,
+				Kind:       BuiltinFunctionItem,
+				Detail:     createDocForBuiltinFunction(b),
 				InsertText: fmt.Sprintf("%s%s", b.Name, b.Decl.FuncArgs().String()),
 			})
 		}
@@ -286,11 +278,9 @@ func (p *Project) listBuiltinFunction(term *ast.Term) []CompletionItem {
 		if strings.HasPrefix(b.Name, fmt.Sprintf("%s.", val.Value.String())) {
 			name := strings.TrimLeft(b.Name, fmt.Sprintf("%s.", val.Value.String()))
 			result = append(result, CompletionItem{
-				Label: name,
-				Kind:  BuiltinFunctionItem,
-				Detail: fmt.Sprintf(`%s%s
-
-%s`, b.Name, b.Decl.FuncArgs().String(), BuiltinDetail),
+				Label:      name,
+				Kind:       BuiltinFunctionItem,
+				Detail:     createDocForBuiltinFunction(b),
 				InsertText: fmt.Sprintf("%s%s", name, b.Decl.FuncArgs().String()),
 			})
 		}
@@ -403,15 +393,16 @@ func (p *Project) createRuleCompletionItem(rule *ast.Rule) CompletionItem {
 		itemKind = VariableItem
 	}
 
-	detail := string(rule.Loc().Text)
-	if detail == "default" {
-		detail = rule.String()
-	}
-
 	return CompletionItem{
 		Label:      rule.Head.Name.String(),
 		Kind:       itemKind,
 		InsertText: insertText.String(),
-		Detail:     detail,
+		Detail:     createDocForRule(rule),
 	}
 }
+
+func createDocForBuiltinFunction(builtin *ast.Builtin) string {
+	return fmt.Sprintf(`%s%s
+
+%s`, builtin.Name, builtin.Decl.FuncArgs().String(), BuiltinDetail)
+}

langserver/internal/source/document.go

@@ -0,0 +1,93 @@
+package source
+
+import (
+	"strings"
+
+	"github.com/open-policy-agent/opa/ast"
+)
+
+const (
+	BuiltinDetail = `built-in function
+
+See https://www.openpolicyagent.org/docs/latest/policy-reference/#built-in-functions`
+)
+
+type Document struct {
+	Content  string
+	Language string
+}
+
+func (p *Project) TermDocument(loc *ast.Location) ([]Document, error) {
+	term, err := p.SearchTargetTerm(loc)
+	if err != nil {
+		return nil, err
+	}
+	if term == nil {
+		return nil, nil
+	}
+
+	return p.findTermDocument(term), nil
+}
+
+func (p *Project) findTermDocument(term *ast.Term) []Document {
+	rule := p.findRuleForTerm(term.Loc())
+	if rule != nil {
+		target := p.findDefinitionInRule(term, rule)
+		if target != nil {
+			return nil
+		}
+
+		for _, b := range ast.DefaultBuiltins {
+			if b.Infix != "" {
+				continue
+			}
+			if b.Name == term.String() {
+				return []Document{
+					{
+						Content:  b.Name + b.Decl.FuncArgs().String(),
+						Language: "rego",
+					},
+					{
+						Content:  BuiltinDetail,
+						Language: "markdown",
+					},
+				}
+			}
+		}
+	}
+	return p.findTermDocumentInModule(term)
+}
+
+func (p *Project) findTermDocumentInModule(term *ast.Term) []Document {
+	searchPackageName := p.findPolicyRef(term)
+	searchPolicies := p.cache.FindPolicies(searchPackageName)
+	if len(searchPolicies) == 0 {
+		return nil
+	}
+
+	word := term.String()
+	if strings.Contains(word, ".") {
+		word = word[strings.Index(word, ".")+1:]
+	}
+
+	result := make([]Document, 0)
+	for _, mod := range searchPolicies {
+		for _, rule := range mod.Rules {
+			if rule.Head.Name.String() == word {
+				result = append(result, Document{
+					Content:  createDocForRule(rule),
+					Language: "rego",
+				})
+			}
+		}
+	}
+	return result
+}
+
+func createDocForRule(rule *ast.Rule) string {
+	detail := string(rule.Loc().Text)
+	if detail == "default" {
+		return rule.String()
+	}
+	return detail
+}

langserver/internal/source/document_test.go

@@ -0,0 +1,152 @@
+package source_test
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/kitagry/regols/langserver/internal/source"
+	"github.com/open-policy-agent/opa/ast"
+)
+
+func TestProject_TermDocument(t *testing.T) {
+	tests := map[string]struct {
+		files      map[string]source.File
+		location   *ast.Location
+		expectDocs []source.Document
+	}{
+		"document in same file method": {
+			files: map[string]source.File{
+				"src.rego": {
+					RowText: `package src
+
+violation[msg] {
+	method(msg)
+}
+
+method(msg) {
+	msg == "hello"
+}`,
+				},
+			},
+			location: &ast.Location{
+				Row: 4,
+				Col: 2,
+				Offset: len("package src\n\nviolation[msg] {	m"),
+				Text: []byte("m"),
+				File: "src.rego",
+			},
+			expectDocs: []source.Document{
+				{
+					Content: `method(msg) {
+	msg == "hello"
+}`,
+					Language: "rego",
+				},
+			},
+		},
+		"default can show all": {
+			files: map[string]source.File{
+				"src.rego": {
+					RowText: `package src
+
+violation[msg] {
+	item
+}
+
+default item = "hello"`,
+				},
+			},
+			location: &ast.Location{
+				Row: 4,
+				Col: 2,
+				Offset: len("package src\n\nviolation[msg] {	i"),
+				Text: []byte("i"),
+				File: "src.rego",
+			},
+			expectDocs: []source.Document{
+				{
+					Content:  `default item = "hello"`,
+					Language: "rego",
+				},
+			},
+		},
+		"builtin function": {
+			files: map[string]source.File{
+				"src.rego": {
+					RowText: `package src
+
+violation[msg] {
+	sprintf("msg: %s", [msg])
+}`,
+				},
+			},
+			location: &ast.Location{
+				Row: 4,
+				Col: 2,
+				Offset: len("package src\n\nviolation[msg] {	s"),
+				Text: []byte("s"),
+				File: "src.rego",
+			},
+			expectDocs: []source.Document{
+				{
+					Content:  "sprintf(string, array[any])",
+					Language: "rego",
+				},
+				{
+					Content: `built-in function
+
+See https://www.openpolicyagent.org/docs/latest/policy-reference/#built-in-functions`,
+					Language: "markdown",
+				},
+			},
+		},
+		"builtin function with ref": {
+			files: map[string]source.File{
+				"src.rego": {
+					RowText: `package src
+
+violation[msg] {
+	json.is_valid("{}")
+}`,
+				},
+			},
+			location: &ast.Location{
+				Row: 4,
+				Col: 7,
+				Offset: len("package src\n\nviolation[msg] {	json.i"),
+				Text: []byte("i"),
+				File: "src.rego",
+			},
+			expectDocs: []source.Document{
+				{
+					Content:  "json.is_valid(string)",
+					Language: "rego",
+				},
+				{
+					Content: `built-in function
+
+See https://www.openpolicyagent.org/docs/latest/policy-reference/#built-in-functions`,
+					Language: "markdown",
+				},
+			},
+		},
+	}
+
+	for n, tt := range tests {
+		t.Run(n, func(t *testing.T) {
+			project, err := source.NewProjectWithFiles(tt.files)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			docs, err := project.TermDocument(tt.location)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			if diff := cmp.Diff(tt.expectDocs, docs); diff != "" {
+				t.Errorf("TermDocument result diff (-expect, +got)\n%s", diff)
+			}
+		})
+	}
+}

langserver/langserver.go

@@ -55,6 +55,8 @@ func (h *handler) handle(ctx context.Context, conn *jsonrpc2.Conn, req *jsonrpc2
 		return h.handleTextDocumentDefinition(ctx, conn, req)
 	case "textDocument/completion":
 		return h.handleTextDocumentCompletion(ctx, conn, req)
+	case "textDocument/hover":
+		return h.handleTextDocumentHover(ctx, conn, req)
 	}
 	return nil, &jsonrpc2.Error{Code: jsonrpc2.CodeMethodNotFound, Message: fmt.Sprintf("method not supported: %s", req.Method)}
 }