1 files changed, 166 insertions, 0 deletions
diff --git a/tools/vscode/packages/server/src/plugins/PluginHost.ts b/tools/vscode/packages/server/src/plugins/PluginHost.ts
new file mode 100644
index 000000000..72f098ca1
--- /dev/null
+++ b/tools/vscode/packages/server/src/plugins/PluginHost.ts
@@ -0,0 +1,166 @@
+
+import {
+    CompletionContext,
+    CompletionItem,
+    CompletionList,
+    Position,
+    TextDocumentIdentifier,
+} from 'vscode-languageserver';
+import type { DocumentManager } from '../core/documents';
+import type * as d from './interfaces';
+import { flatten } from '../utils';
+import { FoldingRange } from 'vscode-languageserver-types';
+
+// eslint-disable-next-line no-shadow
+enum ExecuteMode {
+    None,
+    FirstNonNull,
+    Collect
+}
+
+export class PluginHost {
+    private plugins: d.Plugin[] = [];
+
+    constructor(private documentsManager: DocumentManager) {}
+
+    register(plugin: d.Plugin) {
+        this.plugins.push(plugin);
+    }
+
+    async getCompletions(
+        textDocument: TextDocumentIdentifier,
+        position: Position,
+        completionContext?: CompletionContext
+    ): Promise<CompletionList> {
+        const document = this.getDocument(textDocument.uri);
+        if (!document) {
+            throw new Error('Cannot call methods on an unopened document');
+        }
+
+        const completions = (
+            await this.execute<CompletionList>(
+                'getCompletions',
+                [document, position, completionContext],
+                ExecuteMode.Collect
+            )
+        ).filter((completion) => completion != null);
+
+        let flattenedCompletions = flatten(completions.map((completion) => completion.items));
+        const isIncomplete = completions.reduce(
+            (incomplete, completion) => incomplete || completion.isIncomplete,
+            false as boolean
+        );
+
+        return CompletionList.create(flattenedCompletions, isIncomplete);
+    }
+
+    async resolveCompletion(
+        textDocument: TextDocumentIdentifier,
+        completionItem: d.AppCompletionItem
+    ): Promise<CompletionItem> {
+        const document = this.getDocument(textDocument.uri);
+
+        if (!document) {
+            throw new Error('Cannot call methods on an unopened document');
+        }
+
+        const result = await this.execute<CompletionItem>(
+            'resolveCompletion',
+            [document, completionItem],
+            ExecuteMode.FirstNonNull
+        );
+
+        return result ?? completionItem;
+    }
+
+    async doTagComplete(
+        textDocument: TextDocumentIdentifier,
+        position: Position
+    ): Promise<string | null> {
+        const document = this.getDocument(textDocument.uri);
+        if (!document) {
+            throw new Error('Cannot call methods on an unopened document');
+        }
+
+        return this.execute<string | null>(
+            'doTagComplete',
+            [document, position],
+            ExecuteMode.FirstNonNull
+        );
+    }
+
+    async getFoldingRanges(
+        textDocument: TextDocumentIdentifier
+    ): Promise<FoldingRange[]|null> {
+        const document = this.getDocument(textDocument.uri);
+        if (!document) {
+            throw new Error('Cannot call methods on an unopened document');
+        }
+
+        const foldingRanges = flatten(await this.execute<FoldingRange[]>(
+            'getFoldingRanges',
+            [document],
+            ExecuteMode.Collect
+        )).filter((completion) => completion != null)
+
+        return foldingRanges;
+    }
+
+    onWatchFileChanges(onWatchFileChangesParams: any[]): void {
+        for (const support of this.plugins) {
+            support.onWatchFileChanges?.(onWatchFileChangesParams);
+        }
+    }
+
+    private getDocument(uri: string) {
+        return this.documentsManager.get(uri);
+    }
+
+    private execute<T>(
+        name: keyof d.LSProvider,
+        args: any[],
+        mode: ExecuteMode.FirstNonNull
+    ): Promise<T | null>;
+    private execute<T>(
+        name: keyof d.LSProvider,
+        args: any[],
+        mode: ExecuteMode.Collect
+    ): Promise<T[]>;
+    private execute(name: keyof d.LSProvider, args: any[], mode: ExecuteMode.None): Promise<void>;
+    private async execute<T>(
+        name: keyof d.LSProvider,
+        args: any[],
+        mode: ExecuteMode
+    ): Promise<(T | null) | T[] | void> {
+        const plugins = this.plugins.filter((plugin) => typeof plugin[name] === 'function');
+
+        switch (mode) {
+            case ExecuteMode.FirstNonNull:
+                for (const plugin of plugins) {
+                    const res = await this.tryExecutePlugin(plugin, name, args, null);
+                    if (res != null) {
+                        return res;
+                    }
+                }
+                return null;
+            case ExecuteMode.Collect:
+                return Promise.all(
+                    plugins.map((plugin) => this.tryExecutePlugin(plugin, name, args, []))
+                );
+            case ExecuteMode.None:
+                await Promise.all(
+                    plugins.map((plugin) => this.tryExecutePlugin(plugin, name, args, null))
+                );
+                return;
+        }
+    }
+
+    private async tryExecutePlugin(plugin: any, fnName: string, args: any[], failValue: any) {
+        try {
+            return await plugin[fnName](...args);
+        } catch (e) {
+            console.error(e);
+            return failValue;
+        }
+    }
+}