From 47a0910344a58c3d1bd17c1ceec73d848ca88a24 Mon Sep 17 00:00:00 2001
From: Adam Bull <adam@speakeasy.com>
Date: Fri, 13 Jun 2025 14:02:21 +0100
Subject: [PATCH] feat: diff summary

---
 src/components/DiffSummary/index.stories.tsx | 60 +++++++++++++++
 src/components/DiffSummary/index.tsx         | 81 ++++++++++++++++++++
 2 files changed, 141 insertions(+)
 create mode 100644 src/components/DiffSummary/index.stories.tsx
 create mode 100644 src/components/DiffSummary/index.tsx

diff --git a/src/components/DiffSummary/index.stories.tsx b/src/components/DiffSummary/index.stories.tsx
new file mode 100644
index 00000000..2111d6eb
--- /dev/null
+++ b/src/components/DiffSummary/index.stories.tsx
@@ -0,0 +1,60 @@
+import { Meta, StoryObj } from '@storybook/react'
+import DiffSummary from '.'
+
+const meta: Meta<typeof DiffSummary> = {
+  component: DiffSummary,
+}
+
+export default meta
+
+type Story = StoryObj<typeof DiffSummary>
+
+export const Default: Story = {
+  args: {
+    addedLines: 10,
+    removedLines: 5,
+    squareCount: 5,
+  },
+}
+
+export const ManyLineChanges: Story = {
+  args: {
+    addedLines: 1500,
+    removedLines: 2050,
+    squareCount: 5,
+  },
+}
+
+export const NoChanges: Story = {
+  args: {
+    addedLines: 0,
+    removedLines: 0,
+    squareCount: 5,
+  },
+}
+
+export const NoLabel: Story = {
+  args: {
+    addedLines: 10,
+    removedLines: 5,
+    squareCount: 5,
+    showLabel: false,
+  },
+}
+
+export const CustomSquareCount: Story = {
+  args: {
+    addedLines: 10,
+    removedLines: 5,
+    squareCount: 10,
+  },
+}
+
+export const CustomSquareClassName: Story = {
+  args: {
+    addedLines: 10,
+    removedLines: 5,
+    squareCount: 5,
+    squareClassName: 'size-4',
+  },
+}
diff --git a/src/components/DiffSummary/index.tsx b/src/components/DiffSummary/index.tsx
new file mode 100644
index 00000000..b693c0ad
--- /dev/null
+++ b/src/components/DiffSummary/index.tsx
@@ -0,0 +1,81 @@
+import { cn } from '@/lib/utils'
+
+interface DiffSummaryProps {
+  addedLines: number
+  removedLines: number
+  squareCount?: number
+  squareClassName?: string
+  showLabel?: boolean
+}
+
+export default function DiffSummary({
+  addedLines,
+  removedLines,
+  squareCount = 5,
+  squareClassName,
+  showLabel = true,
+}: DiffSummaryProps) {
+  const totalLines = addedLines + removedLines
+  const filledAddedSquares =
+    totalLines > 0 ? Math.round((addedLines / totalLines) * squareCount) : 0
+  const filledRemovedSquares =
+    totalLines > 0 ? Math.round((removedLines / totalLines) * squareCount) : 0
+
+  // Ensure the total does not exceed squareCount
+  let greenCount = filledAddedSquares
+  let redCount = filledRemovedSquares
+  if (greenCount + redCount > squareCount) {
+    const overflow = greenCount + redCount - squareCount
+    if (greenCount > redCount) {
+      greenCount -= overflow
+    } else {
+      redCount -= overflow
+    }
+  }
+
+  const baseSquareClasses = cn('w-3.5 h-3.5 rounded-sm', squareClassName)
+
+  const squares = Array.from({ length: squareCount }, (_, index) => {
+    if (index < greenCount) {
+      return (
+        <div
+          key={index}
+          className={cn(
+            baseSquareClasses,
+            'bg-emerald-500 dark:bg-emerald-400'
+          )}
+        />
+      )
+    } else if (index < greenCount + redCount) {
+      return (
+        <div
+          key={index}
+          className={cn(baseSquareClasses, 'bg-rose-500 dark:bg-rose-400')}
+        />
+      )
+    } else {
+      return (
+        <div
+          key={index}
+          className={cn(baseSquareClasses, 'bg-gray-200 dark:bg-gray-200')}
+        />
+      )
+    }
+  })
+
+  return (
+    <div className="flex items-center gap-1.5">
+      {showLabel && (
+        <span className="flex flex-row gap-1.5 text-sm font-semibold">
+          <span className="text-emerald-500 dark:text-emerald-400">
+            +{addedLines}
+          </span>
+          <span className="text-rose-500 dark:text-rose-400">
+            -{removedLines}
+          </span>
+        </span>
+      )}
+      <div className="flex items-center gap-0.5">{squares}</div>
+    </div>
+  )
+}