From c854e518faa2d2661b7b7278634b10607ab0a5f5 Mon Sep 17 00:00:00 2001
From: "jeremy@jermolene.com" <jeremy@jermolene.com>
Date: Tue, 24 Nov 2020 19:01:33 +0000
Subject: [PATCH] Add support for $:/info/darkmode (and for dynamic info
 tiddlers)

---
 core/modules/info/platform.js                 |  9 +++-
 core/modules/startup/info.js                  | 44 +++++++++++--------
 .../tiddlers/mechanisms/InfoMechanism.tid     |  3 +-
 3 files changed, 36 insertions(+), 20 deletions(-)

diff --git a/core/modules/info/platform.js b/core/modules/info/platform.js
index 29ebdd594..a73a5e5df 100644
--- a/core/modules/info/platform.js
+++ b/core/modules/info/platform.js
@@ -12,7 +12,7 @@ Initialise basic platform $:/info/ tiddlers
 /*global $tw: false */
 "use strict";
 
-exports.getInfoTiddlerFields = function() {
+exports.getInfoTiddlerFields = function(updateInfoTiddlersCallback) {
 	var mapBoolean = function(value) {return value ? "yes" : "no";},
 		infoTiddlerFields = [];
 	// Basics
@@ -36,6 +36,13 @@ exports.getInfoTiddlerFields = function() {
 		// Screen size
 		infoTiddlerFields.push({title: "$:/info/browser/screen/width", text: window.screen.width.toString()});
 		infoTiddlerFields.push({title: "$:/info/browser/screen/height", text: window.screen.height.toString()});
+ 		// Dark mode through event listener on MediaQueryList
+ 		var mqList = window.matchMedia("(prefers-color-scheme: dark)"),
+ 			getDarkModeTiddler = function() {return {title: "$:/info/darkmode", text: mqList.matches ? "yes" : "no"};};
+ 		infoTiddlerFields.push(getDarkModeTiddler());
+ 		mqList.addEventListener("change", function(event) {
+ 			updateInfoTiddlersCallback([getDarkModeTiddler()]);
+ 		});
 		// Language
 		infoTiddlerFields.push({title: "$:/info/browser/language", text: navigator.language || ""});
 	}
diff --git a/core/modules/startup/info.js b/core/modules/startup/info.js
index 7efaa5b0e..ed2305930 100644
--- a/core/modules/startup/info.js
+++ b/core/modules/startup/info.js
@@ -21,29 +21,37 @@ exports.synchronous = true;
 var TITLE_INFO_PLUGIN = "$:/temp/info-plugin";
 
 exports.startup = function() {
+	// Function to bake the info plugin with new tiddlers
+	var updateInfoPlugin = function(tiddlerFieldsArray) {
+		// Get the existing tiddlers
+		var json = $tw.wiki.getTiddlerData(TITLE_INFO_PLUGIN,{tiddlers: {}});
+		// Add the new ones
+		$tw.utils.each(tiddlerFieldsArray,function(fields) {
+			if(fields && fields.title) {
+				json.tiddlers[fields.title] = fields;
+			}
+		});
+		// Bake the info tiddlers into a plugin. We use the non-standard plugin-type "info" because ordinary plugins are only registered asynchronously after being loaded dynamically
+		var fields = {
+			title: TITLE_INFO_PLUGIN,
+			type: "application/json",
+			"plugin-type": "info",
+			text: JSON.stringify(json,null,$tw.config.preferences.jsonSpaces)
+		};
+		$tw.wiki.addTiddler(new $tw.Tiddler(fields));
+
+	};
 	// Collect up the info tiddlers
-	var infoTiddlerFields = {};
-	// Give each info module a chance to fill in as many info tiddlers as they want
+	var tiddlerFieldsArray = [];
+	// Give each info module a chance to provide as many info tiddlers as they want as an array, and give them a callback for dynamically updating them
 	$tw.modules.forEachModuleOfType("info",function(title,moduleExports) {
 		if(moduleExports && moduleExports.getInfoTiddlerFields) {
-			var tiddlerFieldsArray = moduleExports.getInfoTiddlerFields(infoTiddlerFields);
-			$tw.utils.each(tiddlerFieldsArray,function(fields) {
-				if(fields) {
-					infoTiddlerFields[fields.title] = fields;
-				}
-			});
+			Array.prototype.push.apply(tiddlerFieldsArray,moduleExports.getInfoTiddlerFields(updateInfoPlugin));
 		}
 	});
-	// Bake the info tiddlers into a plugin. We use the non-standard plugin-type "info" because ordinary plugins are only registered asynchronously after being loaded dynamically
-	var fields = {
-		title: TITLE_INFO_PLUGIN,
-		type: "application/json",
-		"plugin-type": "info",
-		text: JSON.stringify({tiddlers: infoTiddlerFields},null,$tw.config.preferences.jsonSpaces)
-	};
-	$tw.wiki.addTiddler(new $tw.Tiddler(fields));
-	$tw.wiki.readPluginInfo([TITLE_INFO_PLUGIN]);
-	$tw.wiki.registerPluginTiddlers("info");
+	updateInfoPlugin(tiddlerFieldsArray);
+	var changes = $tw.wiki.readPluginInfo([TITLE_INFO_PLUGIN]);
+	$tw.wiki.registerPluginTiddlers("info",[TITLE_INFO_PLUGIN]);
 	$tw.wiki.unpackPluginTiddlers();
 };
 
diff --git a/editions/tw5.com/tiddlers/mechanisms/InfoMechanism.tid b/editions/tw5.com/tiddlers/mechanisms/InfoMechanism.tid
index 62d907076..c56bd47eb 100644
--- a/editions/tw5.com/tiddlers/mechanisms/InfoMechanism.tid
+++ b/editions/tw5.com/tiddlers/mechanisms/InfoMechanism.tid
@@ -1,5 +1,5 @@
 created: 20140720164948099
-modified: 20200506110435897
+modified: 20201124185829706
 tags: Mechanisms
 title: InfoMechanism
 type: text/vnd.tiddlywiki
@@ -27,3 +27,4 @@ System tiddlers in the namespace `$:/info/` are used to expose information about
 |[[$:/info/url/port]] |<<.from-version "5.1.14">> Port portion of URL of wiki (eg, ''<<example port>>'') |
 |[[$:/info/url/protocol]] |<<.from-version "5.1.14">> Protocol portion of URL of wiki (eg, ''<<example protocol>>'') |
 |[[$:/info/url/search]] |<<.from-version "5.1.14">> Search portion of URL of wiki (eg, ''<<example search>>'') |
+|[[$:/info/darkmode]] |<<.from-version "5.1.23">> Is dark mode enabled? ("yes" or "no") |