From 29ca9f74df42f9bf0a7c2395b2c61789445b5fe6 Mon Sep 17 00:00:00 2001
From: Mykola Morhun <mmorhun@redhat.com>
Date: Fri, 30 Aug 2019 11:55:56 +0000
Subject: [PATCH] Add plugins resources provider contribution point

Signed-off-by: Mykola Morhun <mmorhun@redhat.com>
---
 .../plugin-ext/src/common/plugin-protocol.ts  | 19 +++++++++++++++
 .../src/hosted/node/plugin-reader.ts          | 23 ++++++++++++++++---
 2 files changed, 39 insertions(+), 3 deletions(-)

diff --git a/packages/plugin-ext/src/common/plugin-protocol.ts b/packages/plugin-ext/src/common/plugin-protocol.ts
index bd515f9a112c3..c07647441c7c0 100644
--- a/packages/plugin-ext/src/common/plugin-protocol.ts
+++ b/packages/plugin-ext/src/common/plugin-protocol.ts
@@ -585,6 +585,25 @@ export interface MetadataProcessor {
     process(pluginMetadata: PluginMetadata): void;
 }
 
+/**
+ * Designed to retreive plugins resources from non default or remote location.
+ */
+export const PluginResourcesProvider = Symbol.for('ResourcesProvider');
+export interface PluginResourcesProvider {
+    /**
+     * Checks if this provider has resources for the given plugin.
+     * @param pluginId id of plugin to check presence of resources for
+     */
+    hasResources(pluginId: string): boolean;
+
+    /**
+     * Returns resource by given path or undefined if no resource exists.
+     * @param pluginId id of plugin that requests resource is for.
+     * @param resourcePath path to requested resource. Might be relative to plugin location
+     */
+    getResource(pluginId: string, resourcePath: string): Promise<Buffer | undefined>;
+}
+
 export function getPluginId(plugin: PluginPackage | PluginModel): string {
     return `${plugin.publisher}_${plugin.name}`.replace(/\W/g, '_');
 }
diff --git a/packages/plugin-ext/src/hosted/node/plugin-reader.ts b/packages/plugin-ext/src/hosted/node/plugin-reader.ts
index 8f80c724a6d88..9b979e7d2fbb4 100644
--- a/packages/plugin-ext/src/hosted/node/plugin-reader.ts
+++ b/packages/plugin-ext/src/hosted/node/plugin-reader.ts
@@ -23,7 +23,7 @@ import * as escape_html from 'escape-html';
 import { ILogger } from '@theia/core';
 import { inject, injectable, optional, multiInject } from 'inversify';
 import { BackendApplicationContribution } from '@theia/core/lib/node/backend-application';
-import { PluginMetadata, getPluginId, MetadataProcessor } from '../../common/plugin-protocol';
+import { PluginMetadata, getPluginId, MetadataProcessor, PluginResourcesProvider } from '../../common/plugin-protocol';
 import { MetadataScanner } from './metadata-scanner';
 
 @injectable()
@@ -36,7 +36,12 @@ export class HostedPluginReader implements BackendApplicationContribution {
     private readonly scanner: MetadataScanner;
 
     @optional()
-    @multiInject(MetadataProcessor) private readonly metadataProcessors: MetadataProcessor[];
+    @multiInject(MetadataProcessor)
+    private readonly metadataProcessors: MetadataProcessor[];
+
+    @optional()
+    @multiInject(PluginResourcesProvider)
+    private readonly resourcesProvider: PluginResourcesProvider[];
 
     /**
      * Map between a plugin's id and the local storage
@@ -44,7 +49,7 @@ export class HostedPluginReader implements BackendApplicationContribution {
     private pluginsIdsFiles: Map<string, string> = new Map();
 
     configure(app: express.Application): void {
-        app.get('/hostedPlugin/:pluginId/:path(*)', (req, res) => {
+        app.get('/hostedPlugin/:pluginId/:path(*)', async (req, res) => {
             const pluginId = req.params.pluginId;
             const filePath = req.params.path;
 
@@ -54,6 +59,18 @@ export class HostedPluginReader implements BackendApplicationContribution {
                     res.status(404).send(`No such file for plugin with id '${escape_html(pluginId)}'.`);
                 });
             } else {
+                // Requested resource is not local. Check providers if any.
+                for (const provider of this.resourcesProvider) {
+                    if (provider.hasResources(pluginId)) {
+                        const resource = await provider.getResource(pluginId, filePath);
+                        if (resource) {
+                            res.type(path.extname(filePath));
+                            res.send(resource);
+                            return;
+                        }
+                    }
+                }
+
                 res.status(404).send(`The plugin with id '${escape_html(pluginId)}' does not exist.`);
             }
         });