From f73cd057be7ddc75705d2f27d7aa8e323e817373 Mon Sep 17 00:00:00 2001
From: Andras Schmelczer <andras@schmelczer.dev>
Date: Thu, 10 Jul 2025 22:14:15 +0100
Subject: [PATCH] Add cursors to example

---
 examples/website/{ => src}/index.html |   8 +-
 examples/website/{ => src}/index.ts   | 100 +++++++++++++++-
 examples/website/{ => src}/style.scss | 164 ++++++++++++++++++++++----
 examples/website/tsconfig.json        |   8 +-
 examples/website/webpack.config.js    |   4 +-
 5 files changed, 243 insertions(+), 41 deletions(-)
 rename examples/website/{ => src}/index.html (96%)
 rename examples/website/{ => src}/index.ts (50%)
 rename examples/website/{ => src}/style.scss (63%)

diff --git a/examples/website/index.html b/examples/website/src/index.html
similarity index 96%
rename from examples/website/index.html
rename to examples/website/src/index.html
index c570dfd..5136fc7 100644
--- a/examples/website/index.html
+++ b/examples/website/src/index.html
@@ -28,7 +28,7 @@
     <div class="scroll-container">
       <div class="page-wrapper">
         <header>
-          <h1>Reconcile: conflict-free 3-way text merging</h1>
+          <h1>Reconcile-text: conflict-free 3-way text merging</h1>
           <p>
             Think
             <a
@@ -96,9 +96,7 @@
                 <span class="radio-custom" aria-hidden="true"></span>
                 <div class="radio-content">
                   <span class="radio-label">Character</span>
-                  <span class="radio-description"
-                    >Fine-grained character-level merging</span
-                  >
+                  <span class="radio-description">Fine-grained merging</span>
                 </div>
               </label>
               <label class="radio-option">
@@ -121,7 +119,7 @@
                 <div class="radio-content">
                   <span class="radio-label">Line</span>
                   <span class="radio-description"
-                    >Line-by-line like <code>git merge</code></span
+                    >Line-by-line, like <code>git merge</code></span
                   >
                 </div>
               </label>
diff --git a/examples/website/index.ts b/examples/website/src/index.ts
similarity index 50%
rename from examples/website/index.ts
rename to examples/website/src/index.ts
index f056621..bab0523 100644
--- a/examples/website/index.ts
+++ b/examples/website/src/index.ts
@@ -16,6 +16,12 @@ async function main(): Promise<void> {
   originalTextArea.addEventListener('input', updateMergedText);
   leftTextArea.addEventListener('input', updateMergedText);
   rightTextArea.addEventListener('input', updateMergedText);
+
+  leftTextArea.addEventListener('selectionchange', updateMergedText);
+  rightTextArea.addEventListener('selectionchange', updateMergedText);
+  leftTextArea.addEventListener('select', updateMergedText);
+  rightTextArea.addEventListener('select', updateMergedText);
+
   window.addEventListener('resize', resizeTextAreas);
 
   tokenizerRadios.forEach((radio) => {
@@ -27,6 +33,7 @@ async function main(): Promise<void> {
   focusTextArea(leftTextArea);
 }
 
+// Edit the instructions to generate example edits
 function loadSample(): void {
   originalTextArea.value = sampleText;
   leftTextArea.value =
@@ -46,16 +53,97 @@ function updateMergedText(): void {
 
   const selectedTokenizer = getSelectedTokenizer();
 
-  const results = reconcileWithHistory(original, left, right, selectedTokenizer);
+  const { leftCursors, rightCursors } = getCursorsFromActiveTextArea();
 
+  const results = reconcileWithHistory(
+    original,
+    {
+      text: left,
+      cursors: leftCursors,
+    },
+    {
+      text: right,
+      cursors: rightCursors,
+    },
+    selectedTokenizer
+  );
+
+  let selectionStart: number = Number.NEGATIVE_INFINITY;
+  let selectionEnd: number = Number.NEGATIVE_INFINITY;
+  if (results.cursors?.length ?? 0 > 0) {
+    selectionStart = results.cursors![0].position;
+    selectionEnd = results.cursors![1].position;
+  }
+
+  const selectionSide = leftCursors ? 'left' : 'right';
   mergedTextArea.innerHTML = '';
 
-  for (const { text, history } of results.history) {
-    const span = document.createElement('span');
-    span.className = history;
-    span.textContent = text;
-    mergedTextArea.appendChild(span);
+  let currentPosition = 0;
+  if (selectionEnd === 0) {
+    mergedTextArea.appendChild(createCaret(selectionSide === 'left'));
   }
+
+  for (const { text, history } of results.history) {
+    for (const character of text) {
+      const span = document.createElement('span');
+      span.className = history;
+      span.textContent = character;
+
+      if (selectionStart <= currentPosition && currentPosition < selectionEnd) {
+        span.className += ` selection-${selectionSide}`;
+      }
+
+      mergedTextArea.appendChild(span);
+
+      if (currentPosition == selectionEnd - 1) {
+        mergedTextArea.appendChild(createCaret(selectionSide === 'left'));
+      }
+
+      if (history !== 'RemovedFromLeft' && history !== 'RemovedFromRight') {
+        // Only increment currentPosition for non-removed characters
+        currentPosition++;
+      }
+    }
+  }
+}
+
+function getCursorsFromActiveTextArea() {
+  const activeElement = document.activeElement;
+  let leftCursors = undefined;
+  let rightCursors = undefined;
+
+  if (activeElement === leftTextArea) {
+    leftCursors = [
+      { id: 1, position: leftTextArea.selectionStart },
+      { id: 2, position: leftTextArea.selectionEnd },
+    ];
+  } else if (activeElement === rightTextArea) {
+    rightCursors = [
+      { id: 1, position: rightTextArea.selectionStart },
+      { id: 2, position: rightTextArea.selectionEnd },
+    ];
+  }
+  return { leftCursors, rightCursors };
+}
+
+function createCaret(isLeft: boolean): HTMLSpanElement {
+  const caretSpan = document.createElement('span');
+  caretSpan.className = `selection-caret selection-caret-${isLeft ? 'left' : 'right'}`;
+
+  const stickDiv = document.createElement('div');
+  stickDiv.className = 'stick';
+  caretSpan.appendChild(stickDiv);
+
+  const dotDiv = document.createElement('div');
+  dotDiv.className = 'dot';
+  caretSpan.appendChild(dotDiv);
+
+  const infoDiv = document.createElement('div');
+  infoDiv.className = 'info';
+  infoDiv.textContent = isLeft ? "Left user's cursor" : "Right user's cursor";
+  caretSpan.appendChild(infoDiv);
+
+  return caretSpan;
 }
 
 function getSelectedTokenizer(): Tokenizer {
diff --git a/examples/website/style.scss b/examples/website/src/style.scss
similarity index 63%
rename from examples/website/style.scss
rename to examples/website/src/style.scss
index 8abe682..a60438f 100644
--- a/examples/website/style.scss
+++ b/examples/website/src/style.scss
@@ -1,3 +1,21 @@
+// Colour palette
+$primary-blue: #2451a6;
+$light-blue: #85bff7;
+$green: #12d197;
+$text-primary: #23272f;
+$text-secondary: #5a6272;
+$border-grey: #d1d5db;
+$code-bg: #61769a;
+$code-text: #e2e8f0;
+$white: #fff;
+$light-bg: #f8fafc;
+$gradient-end: #e0e7ef;
+
+// Function to create selection colour with opacity
+@function selection-colour($colour, $opacity: 0.3) {
+  @return rgba($colour, $opacity);
+}
+
 * {
   box-sizing: border-box;
   margin: 0;
@@ -11,7 +29,7 @@ body {
 
 body {
   font-family: 'Segoe UI', Arial, sans-serif;
-  color: #23272f;
+  color: $text-primary;
 }
 
 .scroll-container {
@@ -21,7 +39,7 @@ body {
 }
 
 .background {
-  background: linear-gradient(135deg, #f8fafc 0%, #e0e7ef 100%);
+  background: linear-gradient(135deg, $light-bg 0%, $gradient-end 100%);
   position: fixed;
   top: 0;
   left: 0;
@@ -46,7 +64,7 @@ header {
 header > h1 {
   font-size: 2.5rem;
   font-weight: 700;
-  color: #2451a6;
+  color: $primary-blue;
   margin-bottom: 24px;
   text-align: center;
 }
@@ -57,8 +75,8 @@ p * {
 }
 
 code {
-  background: #61769a;
-  color: #e2e8f0;
+  background: $code-bg;
+  color: $code-text;
   padding: 2px 6px;
   border-radius: 4px;
   font-family: 'SF Mono', 'Monaco', 'Inconsolata', 'Roboto Mono', 'Consolas', monospace;
@@ -67,7 +85,7 @@ code {
 }
 
 header > p {
-  color: #5a6272;
+  color: $text-secondary;
   font-size: 1.1rem;
   margin-bottom: 0;
 }
@@ -105,9 +123,9 @@ main {
   align-items: center;
   gap: 12px;
   padding: 16px 20px;
-  background: #fff;
+  background: $white;
   border-radius: 12px;
-  box-shadow: 0 2px 8px rgba(36, 81, 166, 0.08);
+  box-shadow: 0 2px 8px selection-colour($primary-blue, 0.08);
   cursor: pointer;
   transition: all 0.2s ease;
   border: 2px solid transparent;
@@ -116,14 +134,14 @@ main {
 }
 
 .radio-option:hover {
-  box-shadow: 0 4px 16px rgba(36, 81, 166, 0.12);
+  box-shadow: 0 4px 16px selection-colour($primary-blue, 0.12);
   transform: translateY(-2px);
 }
 
 .radio-option:has(input:checked) {
-  background: #f0f7ff;
-  border-color: #2451a6;
-  box-shadow: 0 4px 16px rgba(36, 81, 166, 0.16);
+  background: $gradient-end;
+  border-color: $primary-blue;
+  box-shadow: 0 4px 16px selection-colour($primary-blue, 0.16);
 }
 
 .radio-option input[type='radio'] {
@@ -135,7 +153,7 @@ main {
 .radio-custom {
   width: 20px;
   height: 20px;
-  border: 2px solid #d1d5db;
+  border: 2px solid $border-grey;
   border-radius: 50%;
   position: relative;
   transition: all 0.2s ease;
@@ -143,8 +161,8 @@ main {
 }
 
 .radio-option:has(input:checked) .radio-custom {
-  border-color: #2451a6;
-  background: #2451a6;
+  border-color: $primary-blue;
+  background: $primary-blue;
 }
 
 .radio-custom::after {
@@ -172,13 +190,13 @@ main {
 
 .radio-label {
   font-weight: 600;
-  color: #2451a6;
+  color: $primary-blue;
   font-size: 0.95rem;
 }
 
 .radio-description {
   font-size: 0.8rem;
-  color: #6b7280;
+  color: $text-primary;
   line-height: 1.2;
 }
 
@@ -216,9 +234,9 @@ main {
 .text-area-card {
   width: 100%;
   height: 100%;
-  background: #fff;
+  background: $white;
   border-radius: 10px;
-  box-shadow: 0 2px 12px 0 rgba(36, 81, 166, 0.06);
+  box-shadow: 0 2px 12px 0 selection-colour($primary-blue, 0.06);
   padding: 18px 20px 16px 20px;
   margin-bottom: 0;
 }
@@ -227,7 +245,7 @@ label {
   display: inline-block;
   margin-bottom: 8px;
   font-weight: 600;
-  color: #2451a6;
+  color: $primary-blue;
   cursor: help;
 }
 
@@ -245,7 +263,7 @@ textarea {
   border: none;
   font-size: 1rem;
   font-family: inherit;
-  color: #23272f;
+  color: $text-primary;
   box-sizing: border-box;
   resize: none;
   outline: none;
@@ -256,6 +274,10 @@ textarea {
 #merged {
   width: 100%;
   user-select: text;
+
+  > * {
+    position: relative;
+  }
 }
 
 .Unchanged {
@@ -266,14 +288,32 @@ textarea {
 .AddedFromLeft,
 .RemovedFromLeft {
   user-select: text;
-  background: #12d197;
+  background: $green;
+}
+
+.selection-left::after,
+.selection-right::after {
+  content: '';
+  position: absolute;
+  top: 0;
+  left: 0;
+  width: 100%;
+  height: 100%;
+}
+
+.selection-left::after {
+  background: selection-colour($green);
+}
+
+.selection-right::after {
+  background: selection-colour($light-blue);
 }
 
 .Right,
 .AddedFromRight,
 .RemovedFromRight {
   user-select: text;
-  background: #85bff7;
+  background: $light-blue;
 }
 
 .RemovedFromLeft,
@@ -282,6 +322,80 @@ textarea {
   text-decoration: line-through;
 }
 
+// Selection caret styles
+$CARET_WIDTH: 2;
+$DOT_RADIUS: 4;
+
+.selection-caret {
+  position: relative;
+
+  &.selection-caret-left {
+    background: $green;
+  }
+
+  &.selection-caret-right {
+    background: $light-blue;
+  }
+
+  > * {
+    position: absolute;
+    background-color: inherit;
+  }
+
+  > .stick {
+    left: 0;
+    top: 0;
+    transform: translateX(-50%);
+    width: #{$CARET_WIDTH}px;
+    height: 100%;
+    display: block;
+    border-radius: calc(#{$CARET_WIDTH} / 2 * 1px);
+    animation: blink-stick 1s steps(1) infinite;
+  }
+
+  > .dot {
+    border-radius: 50%;
+    width: #{$DOT_RADIUS * 2}px;
+    height: #{$DOT_RADIUS * 2}px;
+    top: -#{$DOT_RADIUS}px;
+    left: -#{$DOT_RADIUS}px;
+    transition: transform 0.3s ease-in-out;
+    transform-origin: bottom center;
+    box-sizing: border-box;
+  }
+
+  &:hover > .dot {
+    transform: scale(0);
+  }
+
+  > .info {
+    top: -1.3em;
+    left: calc(-#{$CARET_WIDTH} / 2 * 1px);
+    font-size: 0.9em;
+    user-select: none;
+    color: white;
+    padding: 0 2px;
+    transition: opacity 0.3s ease-in-out;
+    opacity: 0;
+    white-space: nowrap;
+    border-radius: 3px 3px 3px 0;
+  }
+
+  &:hover > .info {
+    opacity: 1;
+  }
+}
+
+@keyframes blink-stick {
+  0%,
+  100% {
+    opacity: 1;
+  }
+  50% {
+    opacity: 0;
+  }
+}
+
 @media (max-width: 900px) {
   header {
     padding: 32px 18px 0 18px;
@@ -349,12 +463,12 @@ footer {
   display: flex;
   justify-content: center;
   align-items: center;
-  color: #5a6272;
+  color: $text-secondary;
 }
 
 .github-link > svg {
   position: absolute;
-  color: #5a6272;
+  color: $text-secondary;
   top: 50%;
   right: 36px;
   transform: translateY(-50%);
diff --git a/examples/website/tsconfig.json b/examples/website/tsconfig.json
index 5c7b64f..6cf10b0 100644
--- a/examples/website/tsconfig.json
+++ b/examples/website/tsconfig.json
@@ -7,9 +7,11 @@
     "esModuleInterop": true,
     "moduleResolution": "bundler",
     "outDir": "./dist",
-    "rootDir": ".",
+    "rootDir": "./src",
     "skipLibCheck": true,
     "inlineSourceMap": true
   },
-  "exclude": ["./dist"]
-}
+  "exclude": [
+    "./dist"
+  ]
+}
\ No newline at end of file
diff --git a/examples/website/webpack.config.js b/examples/website/webpack.config.js
index 3ed06e7..df1d3e0 100644
--- a/examples/website/webpack.config.js
+++ b/examples/website/webpack.config.js
@@ -7,7 +7,7 @@ const MiniCssExtractPlugin = require('mini-css-extract-plugin');
 module.exports = (_env, argv) => ({
   devtool: argv.mode === 'development' ? 'inline-source-map' : false,
   entry: {
-    index: './index.ts',
+    index: './src/index.ts',
   },
   devServer: {
     allowedHosts: 'all',
@@ -31,7 +31,7 @@ module.exports = (_env, argv) => ({
   },
   plugins: [
     new HtmlWebpackPlugin({
-      template: './index.html',
+      template: './src/index.html',
     }),
     new MiniCssExtractPlugin(),
     argv.mode === 'production'