Fix resolving schemas on web

- Use URI instead of filepath on web, since the web environment
  sometimes uses URIs with schemes other than `file://` for the
  workspace files

Fixes redhat-developer/vscode-yaml#1194

Signed-off-by: David Thompson <davthomp@redhat.com>

Author: datho7561

src/languageservice/services/schemaRequestHandler.ts

@@ -1,15 +1,21 @@
 import { URI } from 'vscode-uri';
-import { Connection, WorkspaceFolder } from 'vscode-languageserver';
+import { Connection, RequestType, WorkspaceFolder } from 'vscode-languageserver';
 import { xhr, XHRResponse, getErrorStatusDescription } from 'request-light';
 import * as URL from 'url';
 import { CustomSchemaContentRequest, VSCodeContentRequest } from '../../requestTypes';
 import { isRelativePath, relativeToAbsolutePath } from '../utils/paths';
 import { WorkspaceContextService } from '../yamlLanguageService';
+import { dirname, join } from 'path';
 
 export interface FileSystem {
   readFile(fsPath: string, encoding?: string): Promise<string>;
 }
 
+// eslint-disable-next-line @typescript-eslint/no-namespace
+namespace FSReadUri {
+  export const type: RequestType<string, string, unknown> = new RequestType('fs/readUri');
+}
+
 /**
  * Handles schema content requests given the schema URI
  * @param uri can be a local file, vscode request, http(s) request or a custom request
@@ -29,7 +35,18 @@ export const schemaRequestHandler = (
   // If the requested schema URI is a relative file path
   // Convert it into a proper absolute path URI
   if (isRelativePath(uri)) {
-    uri = relativeToAbsolutePath(workspaceFolders, workspaceRoot, uri);
+    if (workspaceFolders.length === 1) {
+      const wsUri = URI.parse(workspaceFolders[0].uri);
+      const wsDirname = dirname(wsUri.path);
+      connection.window.showInformationMessage(`wsDirname: ${wsDirname}`);
+      const modifiedUri = wsUri.with({ path: join(wsDirname, uri) });
+      return connection.sendRequest(FSReadUri.type, modifiedUri.toString()).catch((e) => {
+        connection.window.showErrorMessage(`failed to get content of '${modifiedUri}': ${e}`);
+        throw e;
+      });
+    } else {
+      uri = relativeToAbsolutePath(workspaceFolders, workspaceRoot, uri);
+    }
   }
 
   let scheme = URI.parse(uri).scheme.toLowerCase();