Add shared utilities for generating text with WebLLM

public/scripts/extensions/shared.js

@@ -176,3 +176,86 @@ function throwIfInvalidModel(useReverseProxy) {
         throw new Error('Custom API URL is not set.');
     }
 }
+
+/**
+ * Check if the WebLLM extension is installed and supported.
+ * @returns {boolean} Whether the extension is installed and supported
+ */
+export function isWebLlmSupported() {
+    if (!('gpu' in navigator)) {
+        toastr.error('Your browser does not support the WebGPU API. Please use a different browser.', 'WebLLM', {
+            preventDuplicates: true,
+            timeOut: 0,
+            extendedTimeOut: 0,
+        });
+        return false;
+    }
+
+    if (!('llm' in SillyTavern)) {
+        toastr.error('WebLLM extension is not installed. Click here to install it.', 'WebLLM', {
+            timeOut: 0,
+            extendedTimeOut: 0,
+            preventDuplicates: true,
+            onclick: () => {
+                const button = document.getElementById('third_party_extension_button');
+                if (button) {
+                    button.click();
+                }
+
+                const input = document.querySelector('dialog textarea');
+
+                if (input instanceof HTMLTextAreaElement) {
+                    input.value = 'https://github.com/SillyTavern/Extension-WebLLM';
+                }
+            },
+        });
+        return false;
+    }
+
+    return true;
+}
+
+/**
+ * Generates text in response to a chat prompt using WebLLM.
+ * @param {any[]} messages Messages to use for generating
+ * @returns {Promise<string>} Generated response
+ */
+export async function generateWebLlmChatPrompt(messages) {
+    if (!isWebLlmSupported()) {
+        throw new Error('WebLLM extension is not installed.');
+    }
+
+    const engine = SillyTavern.llm;
+    const response = await engine.generateChatPrompt(messages);
+    return response;
+}
+
+/**
+ * Counts the number of tokens in the provided text using WebLLM's default model.
+ * @param {string} text Text to count tokens in
+ * @returns {Promise<number>} Number of tokens in the text
+ */
+export async function countWebLlmTokens(text) {
+    if (!isWebLlmSupported()) {
+        throw new Error('WebLLM extension is not installed.');
+    }
+
+    const engine = SillyTavern.llm;
+    const response = await engine.countTokens(text);
+    return response;
+}
+
+/**
+ * Gets the size of the context in the WebLLM's default model.
+ * @returns {Promise<number>} Size of the context in the WebLLM model
+ */
+export async function getWebLlmContextSize() {
+    if (!isWebLlmSupported()) {
+        throw new Error('WebLLM extension is not installed.');
+    }
+
+    const engine = SillyTavern.llm;
+    await engine.loadModel();
+    const model = await engine.getCurrentModelInfo();
+    return model?.context_size;
+}