Refactor task handling (introducing abstraction TaskHandler)

penpot-plugin/src/TaskHandler.ts

@@ -0,0 +1,55 @@
+
+/**
+ * Abstract base class for task handlers in the Penpot MCP plugin.
+ *
+ * @template TParams - The type of parameters this handler expects
+ */
+export abstract class TaskHandler<TParams = any> {
+    /** The task identifier this handler is responsible for */
+    abstract readonly task: string;
+
+    /**
+     * Checks if this handler can process the given task.
+     *
+     * @param task - The task identifier to check
+     * @returns True if this handler applies to the given task
+     */
+    applies(task: string): boolean {
+        return this.task === task;
+    }
+
+    /**
+     * Sends a task response back to the MCP server.
+     */
+    public static sendTaskResponse(taskId: string, success: boolean, data: any = undefined, error: any = undefined): void {
+        const response = {
+            type: "task-response",
+            response: {
+                id: taskId,
+                success: success,
+                data: data,
+                error: error,
+            },
+        };
+
+        // Send to main.ts which will forward to MCP server via WebSocket
+        penpot.ui.sendMessage(response);
+        console.log("Sent task response:", response);
+    }
+
+    public static sendTaskSuccess(taskId: string, data: any = undefined): void {
+        this.sendTaskResponse(taskId, true, data);
+    }
+
+    public static sendTaskError(taskId: string, error: string): void {
+        this.sendTaskResponse(taskId, false, undefined, error);
+    }
+
+    /**
+     * Handles the task with the provided parameters.
+     *
+     * @param taskId - The unique ID of the task request
+     * @param params - The parameters for the task
+     */
+    abstract handle(taskId: string, params: TParams): void;
+}

penpot-plugin/src/plugin.ts

@@ -1,3 +1,13 @@
+import {PrintTextTaskHandler} from "./task-handlers/PrintTextTaskHandler";
+import {TaskHandler} from "./TaskHandler";
+
+/**
+ * Registry of all available task handlers.
+ */
+const taskHandlers: TaskHandler[] = [
+    new PrintTextTaskHandler(),
+];
+
 penpot.ui.open("Penpot MCP Plugin", `?theme=${penpot.theme}`);
 
 // Handle both legacy string messages and new request-based messages
@@ -31,80 +41,24 @@ penpot.ui.onMessage<string | { id: string; task: string; params: any }>((message
 function handlePluginTaskRequest(request: { id: string; task: string; params: any }): void {
     console.log("Executing plugin task:", request.task, request.params);
 
-    switch (request.task) {
-        case "printText":
-            handlePrintTextTask(request.id, request.params);
-            break;
+    // Find the appropriate handler
+    const handler = taskHandlers.find(h => h.applies(request.task));
 
-        default:
-            console.warn("Unknown plugin task:", request.task);
-            sendTaskError(request.id, `Unknown task type: ${request.task}`);
-    }
-}
-
-/**
- * Handles the printText task by creating text in Penpot.
- *
- * @param taskId - The unique ID of the task request
- * @param params - The parameters containing the text to create
- */
-function handlePrintTextTask(taskId: string, params: { text: string }): void {
-    if (!params.text) {
-        console.error("printText task requires 'text' parameter");
-        sendTaskError(taskId, "printText task requires 'text' parameter");
-        return;
-    }
-
-    try {
-        const text = penpot.createText(params.text);
-
-        if (text) {
-            // Center the text in the viewport
-            text.x = penpot.viewport.center.x;
-            text.y = penpot.viewport.center.y;
-
-            // Select the newly created text
-            penpot.selection = [text];
-
-            console.log("Successfully created text:", params.text);
-            sendTaskSuccess(taskId, { textId: text.id });
-        } else {
-            console.error("Failed to create text element");
-            sendTaskError(taskId, "Failed to create text element");
+    if (handler) {
+        try {
+            // Cast the params to the expected type and handle the task
+            handler.handle(request.id, request.params);
+        } catch (error) {
+            console.error(`Error handling task '${request.task}':`, error);
+            const errorMessage = error instanceof Error ? error.message : "Unknown error";
+            TaskHandler.sendTaskError(request.id, `Error handling task: ${errorMessage}`);
         }
-    } catch (error) {
-        console.error("Error creating text:", error);
-        const errorMessage = error instanceof Error ? error.message : "Unknown error";
-        sendTaskError(taskId, `Error creating text: ${errorMessage}`);
+    } else {
+        console.warn("Unknown plugin task:", request.task);
+        TaskHandler.sendTaskError(request.id, `Unknown task type: ${request.task}`);
     }
 }
 
-/**
- * Sends a task response back to the MCP server.
- */
-function sendTaskResponse(taskId: string, success: boolean, data: any = undefined, error: any = undefined): void {
-    const response = {
-        type: "task-response",
-        response: {
-            id: taskId,
-            success: success,
-            data: data,
-            error: error,
-        },
-    };
-
-    // Send to main.ts which will forward to MCP server via WebSocket
-    penpot.ui.sendMessage(response);
-    console.log("Sent task response:", response);
-}
-
-function sendTaskSuccess(taskId: string, data: any = undefined): void {
-    sendTaskResponse(taskId, true, data);
-}
-
-function sendTaskError(taskId: string, error: string): void {
-    sendTaskResponse(taskId, false, undefined, error);
-}
 
 // Update the theme in the iframe
 penpot.on("themechange", (theme) => {

penpot-plugin/src/task-handlers/PrintTextTaskHandler.ts

@@ -0,0 +1,46 @@
+import {TaskHandler} from "../TaskHandler";
+import {PrintTextTaskParams} from "../../../common/src";
+
+/**
+ * Task handler for printing text to Penpot.
+ */
+export class PrintTextTaskHandler extends TaskHandler<PrintTextTaskParams> {
+    readonly task = "printText";
+
+    /**
+     * Handles the printText task by creating text in Penpot.
+     *
+     * @param taskId - The unique ID of the task request
+     * @param params - The parameters containing the text to create
+     */
+    handle(taskId: string, params: PrintTextTaskParams): void {
+        if (!params.text) {
+            console.error("printText task requires 'text' parameter");
+            TaskHandler.sendTaskError(taskId, "printText task requires 'text' parameter");
+            return;
+        }
+
+        try {
+            const text = penpot.createText(params.text);
+
+            if (text) {
+                // Center the text in the viewport
+                text.x = penpot.viewport.center.x;
+                text.y = penpot.viewport.center.y;
+
+                // Select the newly created text
+                penpot.selection = [text];
+
+                console.log("Successfully created text:", params.text);
+                TaskHandler.sendTaskSuccess(taskId, { textId: text.id });
+            } else {
+                console.error("Failed to create text element");
+                TaskHandler.sendTaskError(taskId, "Failed to create text element");
+            }
+        } catch (error) {
+            console.error("Error creating text:", error);
+            const errorMessage = error instanceof Error ? error.message : "Unknown error";
+            TaskHandler.sendTaskError(taskId, `Error creating text: ${errorMessage}`);
+        }
+    }
+}