feat: Implement methods to get static and template, tempate image

- Add methods in WebAdapter

packages/botfuel-dialog/src/adapters/web-adapter.js

@@ -18,10 +18,21 @@ const express = require('express');
 const exphbs = require('express-handlebars');
 const rp = require('request-promise-native');
 const bodyParser = require('body-parser');
+const url = require('url');
+const querystring = require('querystring');
 const logger = require('logtown')('WebAdapter');
 const MissingImplementationError = require('../errors/missing-implementation-error');
 const Adapter = require('./adapter');
 
+// absolute urls to static and template folders
+const PORT = process.env.PORT || process.env.BOTFUEL_ADAPTER_PORT || 5000;
+const BOT_URL = process.env.BOT_URL || `http://localhost:${PORT}`;
+const STATIC_BASE_URL = url.resolve(BOT_URL, 'static/');
+const TEAMPLATE_BASE_URL = url.resolve(BOT_URL, 'templates/');
+
+// screenshot service url
+const SCREENSHOT_SERVICE_URL = 'https://botfuel-screenshot-service.herokuapp.com/';
+
 /**
  * Generic web adapter (to be subclassed), it serves:
  * - /webhook : requests to the bot
@@ -41,8 +52,7 @@ class WebAdapter extends Adapter {
     app.set('view engine', 'handlebars');
     app.set('views', 'src/templates');
     this.createRoutes(app);
-    const port = process.env.PORT || process.env.BOTFUEL_ADAPTER_PORT || 5000;
-    app.listen(port, () => logger.info('run: listening on port', port));
+    app.listen(PORT, () => logger.info('run: listening on port', PORT));
   }
 
   /**
@@ -137,6 +147,52 @@ class WebAdapter extends Adapter {
   getBody() {
     throw new MissingImplementationError();
   }
+
+  /**
+   * Get absolute url for resource inside static folder
+   * @async
+   * @param {String} resourcePath - resource path relative to static, ex: images/logo.png
+   * @returns {null}
+   */
+  static getStaticUrl(resourcePath) {
+    logger.debug('getStaticUrl', resourcePath);
+    return url.resolve(STATIC_BASE_URL, resourcePath);
+  }
+
+  /**
+   * Get absolute path for template
+   * @async
+   * @param {String} templateName - handlebars template name
+   * @param {Object} params - parameters to be passed to the template
+   * @returns {null}
+   */
+  static getTemplateUrl(templateName, params) {
+    logger.debug('getTemplateUrl', templateName, params);
+    const templateUrl = url.resolve(TEAMPLATE_BASE_URL, templateName);
+    return `${templateUrl}?${querystring.stringify(params)}`;
+  }
+
+  /**
+   * Get absolute path for the screenshot template image
+   * @async
+   * @param {String} templateName - handlebars template name
+   * @param {Object} params - parameters to be passed to the template
+   * @param {Number} width - image width
+   * @param {Number} height - image height
+   * @param {Number} quality - image quality
+   * @returns {null}
+   */
+  static getTemplateImageUrl(templateName, params, width = 800, height = 600, quality = 100) {
+    const templateUrl = getTemplateUrl(templateName, params);
+    const screenshotParams = {
+      url: templateUrl,
+      quality,
+      width,
+      height,
+    };
+
+    return `${SCREENSHOT_SERVICE_URL}?${querystring.stringify(screenshotParams)}`;
+  }
 }
 
 module.exports = WebAdapter;