Allow configuring environmental variables in panel (#626)

- [ ] Add test cases

src/ipc/handlers/app_env_vars_handlers.ts

@@ -0,0 +1,81 @@
+/**
+ * DO NOT USE LOGGER HERE.
+ * Environment variables are sensitive and should not be logged.
+ */
+import { ipcMain } from "electron";
+import * as fs from "fs";
+import * as path from "path";
+import { db } from "../../db";
+import { apps } from "../../db/schema";
+import { eq } from "drizzle-orm";
+import { getDyadAppPath } from "../../paths/paths";
+import { GetAppEnvVarsParams, SetAppEnvVarsParams } from "../ipc_types";
+import { parseEnvFile, serializeEnvFile } from "../utils/app_env_var_utils";
+
+export function registerAppEnvVarsHandlers() {
+  // Handler to get app environment variables
+  ipcMain.handle(
+    "get-app-env-vars",
+    async (event, { appId }: GetAppEnvVarsParams) => {
+      try {
+        const app = await db.query.apps.findFirst({
+          where: eq(apps.id, appId),
+        });
+
+        if (!app) {
+          throw new Error("App not found");
+        }
+
+        const appPath = getDyadAppPath(app.path);
+        const envFilePath = path.join(appPath, ".env.local");
+
+        // If .env.local doesn't exist, return empty array
+        try {
+          await fs.promises.access(envFilePath);
+        } catch {
+          return [];
+        }
+
+        const content = await fs.promises.readFile(envFilePath, "utf8");
+        const envVars = parseEnvFile(content);
+
+        return envVars;
+      } catch (error) {
+        console.error("Error getting app environment variables:", error);
+        throw new Error(
+          `Failed to get environment variables: ${error instanceof Error ? error.message : "Unknown error"}`,
+        );
+      }
+    },
+  );
+
+  // Handler to set app environment variables
+  ipcMain.handle(
+    "set-app-env-vars",
+    async (event, { appId, envVars }: SetAppEnvVarsParams) => {
+      try {
+        const app = await db.query.apps.findFirst({
+          where: eq(apps.id, appId),
+        });
+
+        if (!app) {
+          throw new Error("App not found");
+        }
+
+        const appPath = getDyadAppPath(app.path);
+        const envFilePath = path.join(appPath, ".env.local");
+
+        // Serialize environment variables to .env.local format
+        const content = serializeEnvFile(envVars);
+
+        // Write to .env.local file
+        await fs.promises.writeFile(envFilePath, content, "utf8");
+      } catch (error) {
+        console.error("Error setting app environment variables:", error);
+        throw new Error(
+          `Failed to set environment variables: ${error instanceof Error ? error.message : "Unknown error"}`,
+        );
+      }
+    },
+  );
+}