refactor and simplify things

src/renderer.ts

@@ -0,0 +1,84 @@
+import type { Message, MessageOptions, TextBasedChannels } from "discord.js"
+import type { MessageNode } from "./node-tree.js"
+import { getMessageOptions } from "./node-tree.js"
+
+type Action =
+  | { type: "updateMessage"; options: MessageOptions }
+  | { type: "deleteMessage" }
+
+export class MessageRenderer {
+  private channel: TextBasedChannels
+  private message?: Message
+  private actions: Action[] = []
+  private runningPromise?: Promise<void>
+
+  constructor(channel: TextBasedChannels) {
+    this.channel = channel
+  }
+
+  render(node: MessageNode) {
+    this.addAction({
+      type: "updateMessage",
+      options: getMessageOptions(node),
+    })
+  }
+
+  destroy() {
+    this.actions = []
+    this.addAction({ type: "deleteMessage" })
+  }
+
+  completion() {
+    return this.runningPromise ?? Promise.resolve()
+  }
+
+  private addAction(action: Action) {
+    const lastAction = this.actions[this.actions.length - 1]
+    if (lastAction?.type === action.type) {
+      this.actions[this.actions.length - 1] = action
+    } else {
+      this.actions.push(action)
+    }
+    this.runActions()
+  }
+
+  private runActions() {
+    if (this.runningPromise) return
+
+    this.runningPromise = new Promise((resolve) => {
+      // using a microtask to allow multiple actions to be added synchronously
+      queueMicrotask(async () => {
+        let action: Action | undefined
+        while ((action = this.actions.shift())) {
+          try {
+            await this.runAction(action)
+          } catch (error) {
+            console.error(`Failed to run action:`, action)
+            console.error(error)
+          }
+        }
+        resolve()
+        this.runningPromise = undefined
+      })
+    })
+  }
+
+  private async runAction(action: Action) {
+    if (action.type === "updateMessage") {
+      this.message = await (this.message
+        ? this.message.edit({
+            ...action.options,
+
+            // need to ensure that, if there's no text, it's erased
+            // eslint-disable-next-line unicorn/no-null
+            content: action.options.content ?? null,
+          })
+        : this.channel.send(action.options))
+    }
+
+    if (action.type === "deleteMessage") {
+      await this.message?.delete()
+      this.message = undefined
+    }
+  }
+}