3 files changed, 159 insertions, 0 deletions
diff --git a/extension/react-app/src/util/api.ts b/extension/react-app/src/util/api.ts
new file mode 100644
index 00000000..bdec1d20
--- /dev/null
+++ b/extension/react-app/src/util/api.ts
@@ -0,0 +1,43 @@
+import {
+  Configuration,
+  DebugApi,
+  UnittestApi,
+  ChatApi,
+} from "../../../src/client";
+import { useSelector } from "react-redux";
+import { useEffect, useState } from "react";
+import { RootStore } from "../redux/store";
+
+export function useApi() {
+  const apiUrl = useSelector((state: RootStore) => state.config.apiUrl);
+  const vscMachineId = useSelector(
+    (state: RootStore) => state.config.vscMachineId
+  );
+  const [debugApi, setDebugApi] = useState<DebugApi>();
+  const [unittestApi, setUnittestApi] = useState<UnittestApi>();
+  const [chatApi, setChatApi] = useState<ChatApi>();
+
+  useEffect(() => {
+    if (apiUrl && vscMachineId) {
+      let config = new Configuration({
+        basePath: apiUrl,
+        fetchApi: fetch,
+        middleware: [
+          {
+            pre: async (context) => {
+              context.init.headers = {
+                ...context.init.headers,
+                "x-vsc-machine-id": vscMachineId,
+              };
+            },
+          },
+        ],
+      });
+      setDebugApi(new DebugApi(config));
+      setUnittestApi(new UnittestApi(config));
+      setChatApi(new ChatApi(config));
+    }
+  }, [apiUrl, vscMachineId]);
+
+  return { debugApi, unittestApi, chatApi };
+}
diff --git a/extension/react-app/src/util/editCache.ts b/extension/react-app/src/util/editCache.ts
new file mode 100644
index 00000000..b8071127
--- /dev/null
+++ b/extension/react-app/src/util/editCache.ts
@@ -0,0 +1,89 @@
+import { useApi } from "../util/api";
+import { FileEdit, SerializedDebugContext } from "../../../src/client";
+import { useCallback, useEffect, useState } from "react";
+
+export function useEditCache() {
+  const { debugApi } = useApi();
+
+  const fetchNewEdit = useCallback(
+    async (debugContext: SerializedDebugContext) => {
+      return (
+        await debugApi?.editEndpointDebugEditPost({
+          serializedDebugContext: debugContext,
+        })
+      )?.completion;
+    },
+    [debugApi]
+  );
+
+  const [editCache, setEditCache] = useState(new EditCache(fetchNewEdit));
+
+  useEffect(() => {
+    setEditCache(new EditCache(fetchNewEdit));
+  }, [fetchNewEdit]);
+
+  return editCache;
+}
+
+/**
+ * Stores preloaded edits, invalidating based off of debug context changes
+ */
+class EditCache {
+  private _lastDebugContext: SerializedDebugContext | undefined;
+  private _cachedEdits: FileEdit[] | undefined;
+  private _fetchNewEdit: (
+    debugContext: SerializedDebugContext
+  ) => Promise<FileEdit[] | undefined>;
+  private _debounceTimer: NodeJS.Timeout | undefined;
+
+  private _debugContextChanged(debugContext: SerializedDebugContext): boolean {
+    if (!this._lastDebugContext) {
+      return true;
+    }
+
+    return (
+      JSON.stringify(this._lastDebugContext) !== JSON.stringify(debugContext)
+    );
+  }
+
+  private _debugContextComplete(debugContext: SerializedDebugContext): boolean {
+    return debugContext.rangesInFiles.length > 0;
+  }
+
+  public async preloadEdit(debugContext: SerializedDebugContext) {
+    if (this._debounceTimer) {
+      clearTimeout(this._debounceTimer);
+    }
+    if (
+      this._debugContextComplete(debugContext) &&
+      this._debugContextChanged(debugContext)
+    ) {
+      this._debounceTimer = setTimeout(async () => {
+        console.log("Preloading edits");
+        this._cachedEdits = await this._fetchNewEdit(debugContext);
+        this._lastDebugContext = debugContext;
+      }, 200);
+    }
+  }
+
+  public async getEdit(
+    debugContext: SerializedDebugContext
+  ): Promise<FileEdit[]> {
+    if (this._debugContextChanged(debugContext)) {
+      console.log("Cache miss");
+      this._cachedEdits = await this._fetchNewEdit(debugContext);
+    } else {
+      console.log("Cache hit");
+    }
+
+    return this._cachedEdits!;
+  }
+
+  constructor(
+    fetchNewEdit: (
+      debugContext: SerializedDebugContext
+    ) => Promise<FileEdit[] | undefined>
+  ) {
+    this._fetchNewEdit = fetchNewEdit;
+  }
+}
diff --git a/extension/react-app/src/util/index.ts b/extension/react-app/src/util/index.ts
new file mode 100644
index 00000000..458f9d95
--- /dev/null
+++ b/extension/react-app/src/util/index.ts
@@ -0,0 +1,27 @@
+import { RangeInFile } from "../../../src/client";
+
+export function readRangeInVirtualFileSystem(
+  rangeInFile: RangeInFile,
+  filesystem: { [filepath: string]: string }
+): string | undefined {
+  const range = rangeInFile.range;
+
+  let data = filesystem[rangeInFile.filepath];
+  if (data === undefined) {
+    console.log("File not found");
+    return undefined;
+  } else {
+    let lines = data.toString().split("\n");
+    if (range.start.line === range.end.line) {
+      return lines[rangeInFile.range.start.line].slice(
+        rangeInFile.range.start.character,
+        rangeInFile.range.end.character
+      );
+    } else {
+      let firstLine = lines[range.start.line].slice(range.start.character);
+      let lastLine = lines[range.end.line].slice(0, range.end.character);
+      let middleLines = lines.slice(range.start.line + 1, range.end.line);
+      return [firstLine, ...middleLines, lastLine].join("\n");
+    }
+  }
+}