(GH-327) Format on save code action

This adds a code action to format a file based on the `editor.codeActionsOnSave` setting. This can either be a global setting or one specific to the terraform language.

internal/langserver/handlers/code_action.go

@@ -0,0 +1,78 @@
+package handlers
+
+import (
+	"context"
+	"fmt"
+
+	lsp "github.com/hashicorp/terraform-ls/internal/protocol"
+)
+
+func (h *logHandler) TextDocumentCodeAction(ctx context.Context, params lsp.CodeActionParams) ([]lsp.CodeAction, error) {
+	var ca []lsp.CodeAction
+	var wanted map[lsp.CodeActionKind]bool
+
+	// TODO: get this from initialize
+	supported := map[lsp.CodeActionKind]bool{
+		`source`:                        true,
+		`source.fixAll`:                 true,
+		`source.formatAll`:              true,
+		`source.formatAll.terraform-ls`: true,
+	}
+
+	// return early if we don't support any code actions
+	if len(supported) == 0 {
+		return nil, nil
+	}
+
+	// if Only is empty, assume that the client wants all code actions
+	// else build mapping of requested and determine if supported
+	if len(params.Context.Only) == 0 {
+		wanted = supported
+	} else {
+		wanted = make(map[lsp.CodeActionKind]bool)
+		for _, only := range params.Context.Only {
+			wanted[only] = supported[only]
+		}
+	}
+
+	if len(wanted) == 0 {
+		return nil, fmt.Errorf("could not find a supported code action to execute for %s, wanted %v",
+			params.TextDocument.URI, params.Context.Only)
+	}
+
+	for action, _ := range wanted {
+		switch action {
+		case lsp.Source, lsp.SourceFixAll, `source.formatAll`, `source.formatAll.terraform-ls`:
+			c, err := terraformFmt(ctx, h, params.TextDocument.URI)
+			if err != nil {
+				continue
+			}
+			ca = append(ca, c)
+		}
+	}
+
+	return ca, nil
+}
+
+func terraformFmt(ctx context.Context, h *logHandler, uri lsp.DocumentURI) (lsp.CodeAction, error) {
+	var ca lsp.CodeAction
+
+	edits, err := formatDocument(ctx, h, uri)
+	if err != nil {
+		return ca, err
+	}
+
+	we := lsp.WorkspaceEdit{
+		Changes: map[string][]lsp.TextEdit{
+			string(uri): edits,
+		},
+	}
+
+	x := lsp.CodeAction{
+		Title:       "Format Document",
+		Kind:        lsp.SourceFixAll,
+		IsPreferred: false,
+		Edit:        we,
+	}
+	return x, nil
+}

internal/langserver/handlers/formatting.go

@@ -14,12 +14,23 @@ import (
 func (h *logHandler) TextDocumentFormatting(ctx context.Context, params lsp.DocumentFormattingParams) ([]lsp.TextEdit, error) {
 	var edits []lsp.TextEdit
 
+	edits, err := formatDocument(ctx, h, params.TextDocument.URI)
+	if err != nil {
+		return edits, err
+	}
+
+	return edits, nil
+}
+
+func formatDocument(ctx context.Context, h *logHandler, uri lsp.DocumentURI) ([]lsp.TextEdit, error) {
+	var edits []lsp.TextEdit
+
 	fs, err := lsctx.DocumentStorage(ctx)
 	if err != nil {
 		return edits, err
 	}
 
-	fh := ilsp.FileHandlerFromDocumentURI(params.TextDocument.URI)
+	fh := ilsp.FileHandlerFromDocumentURI(uri)
 
 	tfExec, err := module.TerraformExecutorForModule(ctx, fh.Dir())
 	if err != nil {
@@ -45,5 +56,7 @@ func (h *logHandler) TextDocumentFormatting(ctx context.Context, params lsp.Docu
 
 	changes := hcl.Diff(file, original, formatted)
 
-	return ilsp.TextEditsFromDocumentChanges(changes), nil
+	edits = ilsp.TextEditsFromDocumentChanges(changes)
+
+	return edits, nil
 }

internal/langserver/handlers/handlers_test.go

@@ -42,6 +42,9 @@ func initializeResponse(t *testing.T, commandPrefix string) string {
 				"definitionProvider": true,
 				"referencesProvider": true,
 				"documentSymbolProvider": true,
+				"codeActionProvider": {
+					"codeActionKinds": ["source", "source.fixAll"]
+				},
 				"codeLensProvider": {},
 				"documentLinkProvider": {},
 				"workspaceSymbolProvider": true,

internal/langserver/handlers/initialize.go

@@ -25,6 +25,15 @@ func (svc *service) Initialize(ctx context.Context, params lsp.InitializeParams)
 				ResolveProvider:   false,
 				TriggerCharacters: []string{".", "["},
 			},
+			CodeActionProvider: lsp.CodeActionOptions{
+				CodeActionKinds: []lsp.CodeActionKind{
+					lsp.Source,       // "source"
+					lsp.SourceFixAll, // "source.fixAll"
+					"source.formatAll",
+					"source.formatAll.terraform-ls",
+				},
+				ResolveProvider: false,
+			},
 			DeclarationProvider:        lsp.DeclarationOptions{},
 			DefinitionProvider:         true,
 			CodeLensProvider:           lsp.CodeLensOptions{},

internal/langserver/handlers/service.go

@@ -231,6 +231,19 @@ func (svc *service) Assigner() (jrpc2.Assigner, error) {
 
 			return handle(ctx, req, lh.TextDocumentHover)
 		},
+		"textDocument/codeAction": func(ctx context.Context, req *jrpc2.Request) (interface{}, error) {
+			err := session.CheckInitializationIsConfirmed()
+			if err != nil {
+				return nil, err
+			}
+
+			ctx = lsctx.WithClientCapabilities(ctx, cc)
+			ctx = lsctx.WithDocumentStorage(ctx, svc.fs)
+			ctx = exec.WithExecutorOpts(ctx, svc.tfExecOpts)
+			ctx = exec.WithExecutorFactory(ctx, svc.tfExecFactory)
+
+			return handle(ctx, req, lh.TextDocumentCodeAction)
+		},
 		"textDocument/codeLens": func(ctx context.Context, req *jrpc2.Request) (interface{}, error) {
 			err := session.CheckInitializationIsConfirmed()
 			if err != nil {