add fetchText, urlencode (#706)

* add fetchText, urlencode

* minor: fix comment

libs/fetch.ts

@@ -1,15 +1,11 @@
-export async function fetchApi(
-    url: string,
-    init?: {
-        headers?: Record<string, string> | Headers;
-        [x: string]:
-            | string
-            | Record<string, string>
-            | undefined
-            | FormData
-            | Headers;
-    }
-) {
+type FetchInit = {
+    headers?: Record<string, string> | Headers;
+    method?: string;
+    body?: FormData | string;
+    [x: string]: string | Record<string, string> | undefined | FormData | Headers;
+};
+
+const makeInit = async (init?: FetchInit) => {
     let defaultHeaders: Record<string, string> = {};
     try {
         const { getHeaders } = await import("../index.js");
@@ -34,42 +30,66 @@ export async function fetchApi(
             headers: defaultHeaders,
         };
     }
+    return init;
+}
+
+/**
+ * Fetch with (Android) User Agent
+ * @param url 
+ * @param init 
+ * @returns response as normal fetch
+ */
+export async function fetchApi(
+    url: string,
+    init?: FetchInit
+) {
+    init = await makeInit(init);
     console.log(url, init);
     return await fetch(url, init);
 }
 
-export const fetchFile = async function (url: string, init?: RequestInit) {
-    if (!init) init = {};
-    let defaultHeaders: Record<string, string> = {};
-    try {
-        const { getHeaders } = await import("../index.js");
-        defaultHeaders = getHeaders();
-    } catch {
-        // nothing to do
-    }
-    if (init?.headers) {
-        if (init.headers instanceof Headers) {
-            for (const [name, value] of Object.entries(defaultHeaders)) {
-                if (!init.headers.get(name)) init.headers.set(name, value);
-            }
-        } else {
-            init.headers = {
-                ...defaultHeaders,
-                ...init.headers,
-            };
-        }
-    } else {
-        init = {
-            ...init,
-            headers: defaultHeaders,
-        };
-    }
+/**
+ *
+ * @param url
+ * @param init
+ * @returns base64 string of file
+ * @example fetchFile('https://avatars.githubusercontent.com/u/81222734?s=48&v=4');
+ */
+export const fetchFile = async function (url: string, init?: FetchInit) {
+    init = await makeInit(init);
+    console.log(url, init);
     try {
         const res = await fetch(url, init);
-        if (!res.ok) return undefined;
+        if (!res.ok) return '';
         const arrayBuffer = await res.arrayBuffer();
         return Buffer.from(arrayBuffer).toString("base64");
     } catch (e) {
-        return undefined;
+        return '';
+    }
+};
+
+/**
+ *
+ * @param url
+ * @param init
+ * @param encoding default: `utf-8`. link: https://developer.mozilla.org/en-US/docs/Web/API/TextDecoder/encoding
+ * @returns plain text
+ * @example fetchText('https://github.com/LNReader/lnreader', {}, 'gbk');
+ */
+export const fetchText = async function (
+    url: string,
+    init?: FetchInit,
+    encoding?: string,
+): Promise<string> {
+    init = await makeInit(init);
+    console.log(url, init);
+    try {
+        const res = await fetch(url, init);
+        if (!res.ok) return '';
+        const arrayBuffer = await res.arrayBuffer();
+        const decoder = new TextDecoder(encoding);
+        return decoder.decode(arrayBuffer);
+    } catch (e) {
+        return '';
     }
 };