refactor: rewrite message creation (#2774)

* Rework createMessage
- MessageAttachment is now structurally similar to FileOptions
- No longer mutates the object passed as options
- Supports more permutations of arguments

* Ignore complexity warning

* Refactor name finding

* Fix typo

* Update typings

* Default name to null for MessageAttachment

* Make Message#reply use transformOptions

* Move transformOptions

* Fix Message#reply

* Fix mutation

* Update tests

* Fix options passing

* Refactor into APIMessage

* Fix webhook send

* Expose APIMessage

* Add documentation

* Add types

* Fix type doc

* Fix another type doc

* Fix another another type doc (is this one even right!?)

* Remove trailing comma

* Properly clone split options

* Add support for sending file as stream

* Missed a doc

* Resolve files only once when splitting messages

* This looks nicer

* Assign directly

* Don't cache data and files

* Missing return type

* Use object spread instead Object.assign

* Document constructors

* Crawl is a little dot

* comp pls

* tests: sanitize local file path, disable no-await-in-loop

src/structures/Message.js

@@ -10,7 +10,7 @@ const { MessageTypes } = require('../util/Constants');
 const Permissions = require('../util/Permissions');
 const Base = require('./Base');
 const { Error, TypeError } = require('../errors');
-const { createMessage } = require('./shared');
+const APIMessage = require('./APIMessage');
 
 /**
  * Represents a message on Discord.
@@ -359,7 +359,7 @@ class Message extends Base {
 
   /**
    * Edits the content of the message.
-   * @param {StringResolvable} [content] The new content for the message
+   * @param {StringResolvable} [content=''] The new content for the message
    * @param {MessageEditOptions|MessageEmbed} [options] The options to provide
    * @returns {Promise<Message>}
    * @example
@@ -368,17 +368,8 @@ class Message extends Base {
    *   .then(msg => console.log(`Updated the content of a message to ${msg.content}`))
    *   .catch(console.error);
    */
-  async edit(content, options) {
-    if (!options && typeof content === 'object' && !(content instanceof Array)) {
-      options = content;
-      content = null;
-    } else if (!options) {
-      options = {};
-    }
-    if (!options.content) options.content = content;
-
-    const { data } = await createMessage(this, options);
-
+  edit(content, options) {
+    const data = APIMessage.create(this, content, options).resolveData();
     return this.client.api.channels[this.channel.id].messages[this.id]
       .patch({ data })
       .then(d => {
@@ -467,8 +458,8 @@ class Message extends Base {
 
   /**
    * Replies to the message.
-   * @param {StringResolvable} [content] The content for the message
-   * @param {MessageOptions} [options] The options to provide
+   * @param {StringResolvable} [content=''] The content for the message
+   * @param {MessageOptions|MessageAdditions} [options={}] The options to provide
    * @returns {Promise<Message|Message[]>}
    * @example
    * // Reply to a message
@@ -477,13 +468,7 @@ class Message extends Base {
    *   .catch(console.error);
    */
   reply(content, options) {
-    if (!options && typeof content === 'object' && !(content instanceof Array)) {
-      options = content;
-      content = '';
-    } else if (!options) {
-      options = {};
-    }
-    return this.channel.send(content, Object.assign(options, { reply: this.member || this.author }));
+    return this.channel.send(APIMessage.transformOptions(content, options, { reply: this.member || this.author }));
   }
 
   /**