From 060097c118129cf64b8c874e0ca8c032598bce91 Mon Sep 17 00:00:00 2001
From: Richard Lewis <richrd.lewis@gmail.com>
Date: Tue, 10 Jul 2018 23:29:53 +0300
Subject: [PATCH] Implement keyboard navigation in user list.

---
 client/components/ChatUserList.vue     | 86 +++++++++++++++++++++++++-
 client/components/Username.vue         |  3 +-
 client/components/UsernameFiltered.vue |  3 +-
 client/js/vue.js                       |  5 ++
 4 files changed, 94 insertions(+), 3 deletions(-)

diff --git a/client/components/ChatUserList.vue b/client/components/ChatUserList.vue
index 90406384..464129dd 100644
--- a/client/components/ChatUserList.vue
+++ b/client/components/ChatUserList.vue
@@ -1,13 +1,22 @@
 <template>
-	<aside class="userlist">
+	<aside
+		ref="userlist"
+		class="userlist"
+	>
 		<div class="count">
 			<input
+				ref="input"
 				:placeholder="channel.users.length + ' user' + (channel.users.length === 1 ? '' : 's')"
 				v-model="userSearchInput"
 				type="search"
 				class="search"
 				aria-label="Search among the user list"
 				tabindex="-1"
+				@keydown.up="navigateUserList(-1)"
+				@keydown.down="navigateUserList(1)"
+				@keydown.page-up="navigateUserList(-10)"
+				@keydown.page-down="navigateUserList(10)"
+				@keydown.enter="selectUser"
 			>
 		</div>
 		<div class="names">
@@ -20,12 +29,14 @@
 					<UsernameFiltered
 						v-for="user in users"
 						:key="user.original.nick"
+						:active="user.original === activeUser"
 						:user="user"/>
 				</template>
 				<template v-else>
 					<Username
 						v-for="user in users"
 						:key="user.nick"
+						:active="user === activeUser"
 						:user="user"/>
 				</template>
 			</div>
@@ -60,6 +71,7 @@ export default {
 	data() {
 		return {
 			userSearchInput: "",
+			activeUser: null,
 		};
 	},
 	computed: {
@@ -101,6 +113,78 @@ export default {
 		getModeClass(mode) {
 			return modes[mode];
 		},
+		selectUser() {
+			// Simulate a click on the active user to open the context menu.
+			// Coordinates are provided to position the menu correctly.
+			if (!this.activeUser) {
+				return;
+			}
+
+			const el = this.$refs.userlist.querySelector(".active");
+			const rect = el.getBoundingClientRect();
+			const ev = new MouseEvent("click", {
+				view: window,
+				bubbles: true,
+				cancelable: true,
+				clientX: rect.x,
+				clientY: rect.y + rect.height,
+			});
+			el.dispatchEvent(ev);
+		},
+		navigateUserList(direction) {
+			let users = this.channel.users;
+
+			// If a search is active, get the matching user objects
+			// TODO: this could probably be cached via `computed`
+			//		 to avoid refiltering on each keypress
+			if (this.userSearchInput) {
+				const results = fuzzy.filter(
+					this.userSearchInput,
+					this.channel.users,
+					{
+						extract: (u) => u.nick,
+					}
+				);
+				users = results.map((result) => result.original);
+			}
+
+			// Bail out if there's no users to select
+			if (!users.length) {
+				this.activeUser = null;
+				return;
+			}
+
+			let currentIndex = users.indexOf(this.activeUser);
+
+			// If there's no active user select the first or last one depending on direction
+			if (!this.activeUser || currentIndex === -1) {
+				this.activeUser = direction ? users[0] : users[users.length - 1];
+				this.scrollToActiveUser();
+				return;
+			}
+
+			currentIndex += direction;
+
+			// Wrap around the list if necessary. Normaly each loop iterates once at most,
+			// but might iterate more often if pgup or pgdown are used in a very short user list
+			while (currentIndex < 0) {
+				currentIndex += users.length;
+			}
+
+			while (currentIndex > users.length - 1) {
+				currentIndex -= users.length;
+			}
+
+			this.activeUser = users[currentIndex];
+			this.scrollToActiveUser();
+		},
+		scrollToActiveUser() {
+			// Scroll the list if needed after the active class is applied
+			this.$nextTick(() => {
+				const el = this.$refs.userlist.querySelector(".active");
+				el.scrollIntoView({block: "nearest", inline: "nearest"});
+			});
+		},
 	},
 };
 </script>
diff --git a/client/components/Username.vue b/client/components/Username.vue
index b3ebeff0..6da1cf97 100644
--- a/client/components/Username.vue
+++ b/client/components/Username.vue
@@ -1,6 +1,6 @@
 <template>
 	<span
-		:class="['user', $options.filters.colorClass(user.nick)]"
+		:class="['user', $options.filters.colorClass(user.nick), active ? 'active' : '']"
 		:data-name="user.nick"
 		role="button">{{ user.mode }}{{ user.nick }}</span>
 </template>
@@ -10,6 +10,7 @@ export default {
 	name: "Username",
 	props: {
 		user: Object,
+		active: Boolean,
 	},
 };
 </script>
diff --git a/client/components/UsernameFiltered.vue b/client/components/UsernameFiltered.vue
index 27567332..f8b10764 100644
--- a/client/components/UsernameFiltered.vue
+++ b/client/components/UsernameFiltered.vue
@@ -1,6 +1,6 @@
 <template>
 	<span
-		:class="['user', $options.filters.colorClass(user.original.nick)]"
+		:class="['user', $options.filters.colorClass(user.original.nick), active ? 'active' : '']"
 		:data-name="user.original.nick"
 		role="button"
 		v-html="user.original.mode + user.string"/>
@@ -11,6 +11,7 @@ export default {
 	name: "UsernameFiltered",
 	props: {
 		user: Object,
+		active: Boolean,
 	},
 };
 </script>
diff --git a/client/js/vue.js b/client/js/vue.js
index 4da110c7..d95bac57 100644
--- a/client/js/vue.js
+++ b/client/js/vue.js
@@ -20,6 +20,11 @@ Vue.filter("friendlysize", friendlysize);
 Vue.filter("colorClass", colorClass);
 Vue.filter("roundBadgeNumber", roundBadgeNumber);
 
+Vue.config.keyCodes = {
+	"page-up": 33,
+	"page-down": 34,
+};
+
 const vueApp = new Vue({
 	el: "#viewport",
 	data: {