adds new WebhookClient and allows you to fetch channel webhooks and such without being "over the top" (#768)

* start blocking out client

* proto webhookclient

* wee working webhooks

* it's all working

* run docs

* fix jsdoc issues

* add example for webhookClient

* add example in the examples place

* fix docs

src/structures/Webhook.js

@@ -0,0 +1,184 @@
+const path = require('path');
+
+/**
+ * Represents a Webhook
+ */
+class Webhook {
+  constructor(client, dataOrID, token) {
+    if (client) {
+      /**
+       * The client that instantiated the Channel
+       * @type {Client}
+       */
+      this.client = client;
+      Object.defineProperty(this, 'client', { enumerable: false, configurable: false });
+      if (dataOrID) this.setup(dataOrID);
+    } else {
+      this.id = dataOrID;
+      this.token = token;
+      this.client = this;
+    }
+  }
+
+  setup(data) {
+    /**
+     * The name of the Webhook
+     * @type {string}
+     */
+    this.name = data.name;
+
+    /**
+     * The token for the Webhook
+     * @type {string}
+     */
+    this.token = data.token;
+
+    /**
+     * The avatar for the Webhook
+     * @type {string}
+     */
+    this.avatar = data.avatar;
+
+    /**
+     * The ID of the Webhook
+     * @type {string}
+     */
+    this.id = data.id;
+
+    /**
+     * The guild the Webhook belongs to
+     * @type {string}
+     */
+    this.guild_id = data.guild_id;
+
+    /**
+     * The channel the Webhook belongs to
+     * @type {string}
+     */
+    this.channel_id = data.channel_id;
+
+    /**
+     * The owner of the Webhook
+     * @type {User}
+     */
+    if (data.user) this.owner = data.user;
+  }
+
+  /**
+   * Options that can be passed into sendMessage, sendTTSMessage, sendFile, sendCode
+   * @typedef {Object} MessageOptions
+   * @property {boolean} [tts=false] Whether or not the message should be spoken aloud
+   * @property {boolean} [disableEveryone=this.options.disableEveryone] Whether or not @everyone and @here
+   * should be replaced with plain-text
+   */
+
+  /**
+   * Send a message with this webhook
+   * @param {StringResolvable} content The content to send
+   * @param {MessageOptions} [options={}] The options to provide
+   * @returns {Promise<Message|Message[]>}
+   * @example
+   * // send a message
+   * webook.sendMessage('hello!')
+   *  .then(message => console.log(`Sent message: ${message.content}`))
+   *  .catch(console.error);
+   */
+  sendMessage(content, options = {}) {
+    return this.client.rest.methods.sendWebhookMessage(this, content, options);
+  }
+
+  /**
+   * Send a text-to-speech message with this webhook
+   * @param {StringResolvable} content The content to send
+   * @param {MessageOptions} [options={}] The options to provide
+   * @returns {Promise<Message|Message[]>}
+   * @example
+   * // send a TTS message
+   * webhook.sendTTSMessage('hello!')
+   *  .then(message => console.log(`Sent tts message: ${message.content}`))
+   *  .catch(console.error);
+   */
+  sendTTSMessage(content, options = {}) {
+    Object.assign(options, { tts: true });
+    return this.client.rest.methods.sendWebhookMessage(this, content, options);
+  }
+
+  /**
+   * Send a file with this webhook
+   * @param {FileResolvable} attachment The file to send
+   * @param {string} [fileName="file.jpg"] The name and extension of the file
+   * @param {StringResolvable} [content] Text message to send with the attachment
+   * @param {MessageOptions} [options] The options to provide
+   * @returns {Promise<Message>}
+   */
+  sendFile(attachment, fileName, content, options = {}) {
+    if (!fileName) {
+      if (typeof attachment === 'string') {
+        fileName = path.basename(attachment);
+      } else if (attachment && attachment.path) {
+        fileName = path.basename(attachment.path);
+      } else {
+        fileName = 'file.jpg';
+      }
+    }
+    return new Promise((resolve, reject) => {
+      this.client.resolver.resolveFile(attachment).then(file => {
+        this.client.rest.methods.sendWebhookMessage(this, content, options, {
+          file,
+          name: fileName,
+        }).then(resolve).catch(reject);
+      }).catch(reject);
+    });
+  }
+
+  /**
+   * Send a code block with this webhook
+   * @param {string} lang Language for the code block
+   * @param {StringResolvable} content Content of the code block
+   * @param {MessageOptions} options The options to provide
+   * @returns {Promise<Message|Message[]>}
+   */
+  sendCode(lang, content, options = {}) {
+    if (options.split) {
+      if (typeof options.split !== 'object') options.split = {};
+      if (!options.split.prepend) options.split.prepend = `\`\`\`${lang ? lang : ''}\n`;
+      if (!options.split.append) options.split.append = '\n```';
+    }
+    content = this.client.resolver.resolveString(content).replace(/```/g, '`\u200b``');
+    return this.sendMessage(`\`\`\`${lang ? lang : ''}\n${content}\n\`\`\``, options);
+  }
+
+  /**
+   * Delete the Webhook
+   * @returns {Promise}
+   */
+  delete() {
+    return this.client.rest.methods.deleteChannelWebhook(this);
+  }
+
+  /**
+   * Edit the Webhook.
+   * @param {string} name The new name for the Webhook
+   * @param {FileResolvable} avatar The new avatar for the Webhook.
+   * @returns {Promise<Webhook>}
+   */
+  edit(name, avatar) {
+    return new Promise((resolve, reject) => {
+      if (avatar) {
+        this.client.resolver.resolveFile(avatar).then(file => {
+          let base64 = new Buffer(file, 'binary').toString('base64');
+          let dataURI = `data:;base64,${base64}`;
+          this.client.rest.methods.editChannelWebhook(this, name, dataURI)
+          .then(resolve).catch(reject);
+        }).catch(reject);
+      } else {
+        this.client.rest.methods.editChannelWebhook(this, name)
+        .then(data => {
+          this.setup(data);
+        }).catch(reject);
+      }
+    });
+  }
+}
+
+module.exports = Webhook;