From 0e50ee39dfc1056984bdda301270951c235091cc Mon Sep 17 00:00:00 2001
From: Antonin Stefanutti <antonin@stefanutti.fr>
Date: Sat, 19 Aug 2017 00:00:31 +0200
Subject: [PATCH] Migrate the generic plugin to Puppeteer API

---
 plugins/generic.js | 81 +++++++++++++++++++---------------------------
 1 file changed, 34 insertions(+), 47 deletions(-)

diff --git a/plugins/generic.js b/plugins/generic.js
index 49a8af8..3e0a0cb 100644
--- a/plugins/generic.js
+++ b/plugins/generic.js
@@ -1,26 +1,27 @@
-// The generic plugin emulates end-user interaction by pressing keyboard and detects changes to the DOM.
-// The deck is considered over when no change is detected afterward.
+// The generic plugin emulates end-user interaction by pressing keyboard
+// and detects changes to the DOM. The deck is considered over when no change
+// is detected afterward.
 
 exports.options = {
-    keycode: {
-        default: 'Right',
-        metavar: '<code>',
-        help: 'Key code pressed to navigate to next slide'
+    key : {
+        default : 'ArrowRight',
+        metavar : '<key>',
+        help    : 'Key pressed to navigate to next slide'
     },
-    maxSlides: {
-        full: 'max-slides',
-        metavar: '<size>',
-        help: 'Maximum number of slides to export'
+    maxSlides : {
+        full    : 'max-slides',
+        metavar : '<size>',
+        help    : 'Maximum number of slides to export'
     }
 };
 
 exports.help =
-    'Emulates the end-user interaction by pressing the key with the specified --keycode option\n' +
-    'and iterates over the presentation as long as:\n' +
-    '- Any change to the DOM is detected by observing mutation events targeting the body element\n' +
-    '  and its subtree,\n' +
-    '- Nor the number of slides exported has reached the specified --max-slides option.\n' +
-    'The --keycode option must be one of the PhantomJS page event keys and defaults to [Right].';
+`Emulates the end-user interaction by pressing the key with the specified --key option
+and iterates over the presentation as long as:
+- Any change to the DOM is detected by observing mutation events targeting the body element
+  and its subtree,
+- Nor the number of slides exported has reached the specified --max-slides option.
+  The --key option must be one of the 'KeyboardEvent' keys and defaults to [${exports.options.key.default}].`;
 
 exports.create = function (page, options) {
     return new Generic(page, options);
@@ -30,7 +31,7 @@ function Generic(page, options) {
     this.page = page;
     this.options = options;
     this.isNextSlideDetected = false;
-    this.keycode = this.page.event.key[this.options.keycode || exports.options.keycode.default];
+    this.key = this.options.key || exports.options.key.default;
 }
 
 Generic.prototype = {
@@ -43,50 +44,36 @@ Generic.prototype = {
         return true;
     },
 
-    configure: function () {
-        this.page.evaluate(function () {
-            var observer = new window.MutationObserver(function () {
-                window.callPhantom({ isNextSlideDetected: true });
-            });
-            observer.observe(document.querySelector('body'), { attributes: true, childList: true, subtree: true });
-        });
-        var plugin = this;
-        this.page.onCallback = function (mutation) {
-            if (mutation.isNextSlideDetected)
-                plugin.isNextSlideDetected = true;
-        };
+    configure: async function () {
+        await this.page.exposeFunction('onMutation', _ => this.isNextSlideDetected = true);
+        return this.page.evaluate(_ => new MutationObserver(_ => window.onMutation())
+            .observe(document, { attributes: true, childList: true, subtree: true })
+        );
     },
 
     slideCount: function () {
         return undefined;
     },
 
-    // A priori knowledge is impossible to achieve in a generic way. Thus the only way is to actually emulate end-user interaction by pressing the configured key and check whether the DOM has changed a posteriori.
-    hasNextSlide: function () {
+    // A priori knowledge is impossible to achieve in a generic way. Thus the only way is to
+    // actually emulate end-user interaction by pressing the configured key and check whether
+    // the DOM has changed a posteriori.
+    hasNextSlide: async function () {
         if (this.options.maxSlides && this.currentSlide >= this.options.maxSlides)
             return false;
-        // PhantomJS actually sends a 'keydown' DOM event when sending a 'keypress' user event. Hence 'keypress' event is skipped to avoid moving forward two steps instead of one. See https://github.com/ariya/phantomjs/issues/11094 for more details.
-        ['keydown'/*, 'keypress'*/, 'keyup'].forEach(function (event) {
-            this.page.sendEvent(event, this.keycode);
-        }, this);
-        var plugin = this;
-        return new Promise(function (fulfill) {
-            // TODO: use mutation event directly instead of relying on a timeout
-            // TODO: detect cycle to avoid infinite navigation for frameworks that support loopable presentations like impress.js and flowtime.js
-            setTimeout(function () {
-                fulfill(plugin.isNextSlideDetected);
-            }, 1000);
-        });
+        await this.page.press(this.key);
+        // TODO: use mutation event directly instead of relying on a timeout
+        // TODO: detect cycle to avoid infinite navigation for frameworks
+        // that support loopable presentations like impress.js and flowtime.js
+        return new Promise(fulfill => setTimeout(_ => fulfill(this.isNextSlideDetected), 1000));
     },
 
     nextSlide: function () {
         this.isNextSlideDetected = false;
     },
 
-    currentSlideIndex: function () {
-        var fragment = this.page.evaluate(function () {
-            return window.location.hash.replace(/^#\/?/, '');
-        });
+    currentSlideIndex: async function () {
+        const fragment = await this.page.evaluate(_ => window.location.hash.replace(/^#\/?/, ''));
         return fragment.length ? fragment : this.currentSlide;
     }
 };
\ No newline at end of file