Show a progress bar for the probability of completing the proof of work challenge (#87)

Since the challenge is done off of the main thread, there is no simple
way to report the progress done towards completing it. This change
adds a callback parameter, `progressCallback`, which is called with
the most recently attempted nonce every ~1024 iterations (should this
be configurable?). For the single-threaded "slow" algorithm, this is
exactly every 1024 iterations. For the multi-threaded "fast" algorithm,
threads take turns reporting in a round-robin as then notice they
have passed a multiple of 1024. This complexity is to avoid individual
threads falling behind their siblings due to the overhead of messaging
the main thread. To minimize this overhead as much as possible, a
regular number is sent instead of an object.

With the new information provided by the callback, a hash rate display
is added to the challenge page. This display is updated at most once
per second and set with tabular numbers to avoid the constantly changing
value being too visually distracting.

* web: show a progress bar based on completion probability

To provide more feedback to the user, the spinner is replaced with a
progress bar of the probability the challenge is complete. Since it
looks a little weird that a progress bar would fill up a quarter of the
way and then jump to the end (even though the probability would make
that happen 1 in 4 times), the bar is mapped with a quadratic easing
function to move faster at the beginning and then slow down as the
probability of redirection increases. If the probability exceeds 90%,
a message appears letting the user know things are taking longer than
expected and to continue being patient.

Signed-off-by: Xe Iaso <me@xeiaso.net>

1 files changed, 20 insertions, 119 deletions

diff --git a/web/index.templ b/web/index.templ
index 8aa626c..1899ae3 100644
--- a/web/index.templ
+++ b/web/index.templ
@@ -27,120 +27,28 @@ templ base(title string, body templ.Component) {
       text-align: center;
     }
 
-    .lds-roller,
-    .lds-roller div,
-    .lds-roller div:after {
-      box-sizing: border-box;
+    #status {
+      font-variant-numeric: tabular-nums;
     }
 
-    .lds-roller {
-      display: inline-block;
-      position: relative;
-      width: 80px;
-      height: 80px;
+    #progress {
+      display: none;
+      width: min(20rem, 90%);
+      height: 2rem;
+      border-radius: 1rem;
+      overflow: hidden;
+      margin: 1rem 0 2rem;
+      outline-color: #b16286;
+      outline-offset: 2px;
+      outline-style: solid;
+      outline-width: 4px;
     }
 
-    .lds-roller div {
-      animation: lds-roller 1.2s cubic-bezier(0.5, 0, 0.5, 1) infinite;
-      transform-origin: 40px 40px;
-    }
-
-    .lds-roller div:after {
-      content: " ";
-      display: block;
-      position: absolute;
-      width: 7.2px;
-      height: 7.2px;
-      border-radius: 50%;
-      background: currentColor;
-      margin: -3.6px 0 0 -3.6px;
-    }
-
-    .lds-roller div:nth-child(1) {
-      animation-delay: -0.036s;
-    }
-
-    .lds-roller div:nth-child(1):after {
-      top: 62.62742px;
-      left: 62.62742px;
-    }
-
-    .lds-roller div:nth-child(2) {
-      animation-delay: -0.072s;
-    }
-
-    .lds-roller div:nth-child(2):after {
-      top: 67.71281px;
-      left: 56px;
-    }
-
-    .lds-roller div:nth-child(3) {
-      animation-delay: -0.108s;
-    }
-
-    .lds-roller div:nth-child(3):after {
-      top: 70.90963px;
-      left: 48.28221px;
-    }
-
-    .lds-roller div:nth-child(4) {
-      animation-delay: -0.144s;
-    }
-
-    .lds-roller div:nth-child(4):after {
-      top: 72px;
-      left: 40px;
-    }
-
-    .lds-roller div:nth-child(5) {
-      animation-delay: -0.18s;
-    }
-
-    .lds-roller div:nth-child(5):after {
-      top: 70.90963px;
-      left: 31.71779px;
-    }
-
-    .lds-roller div:nth-child(6) {
-      animation-delay: -0.216s;
-    }
-
-    .lds-roller div:nth-child(6):after {
-      top: 67.71281px;
-      left: 24px;
-    }
-
-    .lds-roller div:nth-child(7) {
-      animation-delay: -0.252s;
-    }
-
-    .lds-roller div:nth-child(7):after {
-      top: 62.62742px;
-      left: 17.37258px;
-    }
-
-    .lds-roller div:nth-child(8) {
-      animation-delay: -0.288s;
-    }
-
-    .lds-roller div:nth-child(8):after {
-      top: 56px;
-      left: 12.28719px;
-    }
-
-    .mx-auto {
-      margin-left: auto;
-      margin-right: auto;
-    }
-
-    @keyframes lds-roller {
-      0% {
-        transform: rotate(0deg);
-      }
-
-      100% {
-        transform: rotate(360deg);
-      }
+    .bar-inner {
+      background-color: #b16286;
+      height: 100%;
+      width: 0;
+      transition: width 0.25s ease-in;
     }
       </style>
 			@templ.JSONScript("anubis_version", anubis.Version)
@@ -181,15 +89,8 @@ templ index() {
 		/>
 		<p id="status">Loading...</p>
 		<script async type="module" src={ "/.within.website/x/cmd/anubis/static/js/main.mjs?cacheBuster=" + anubis.Version }></script>
-		<div id="spinner" class="lds-roller mx-auto" style="display:none;">
-			<div></div>
-			<div></div>
-			<div></div>
-			<div></div>
-			<div></div>
-			<div></div>
-			<div></div>
-			<div></div>
+		<div id="progress" role="progressbar" aria-labelledby="status">
+			<div class="bar-inner"></div>
 		</div>
 		<details>
 			<summary>Why am I seeing this?</summary>