fix(amazonq): fix indentation for edits multi-line suggestion

Author: atonaamz

packages/amazonq/src/app/inline/EditRendering/stringUtils.ts

@@ -0,0 +1,28 @@
+/*!
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * Strips common indentation from each line of code that may contain HTML tags
+ * @param lines Array of code lines (may contain HTML tags)
+ * @returns Array of code lines with common indentation removed
+ */
+export function stripCommonIndentation(lines: string[]): string[] {
+    if (lines.length === 0) {
+        return lines
+    }
+    const removeFirstTag = (line: string) => line.replace(/^<[^>]*>/, '')
+    const getLeadingWhitespace = (text: string) => text.match(/^\s*/)?.[0] || ''
+
+    // Find minimum indentation across all lines
+    const minIndentLength = Math.min(...lines.map((line) => getLeadingWhitespace(removeFirstTag(line)).length))
+
+    // Remove common indentation from each line
+    return lines.map((line) => {
+        const firstTagRemovedLine = removeFirstTag(line)
+        const leadingWhitespace = getLeadingWhitespace(firstTagRemovedLine)
+        const reducedWhitespace = leadingWhitespace.substring(minIndentLength)
+        return line.replace(leadingWhitespace, reducedWhitespace)
+    })
+}

packages/amazonq/src/app/inline/EditRendering/svgGenerator.ts

@@ -7,6 +7,7 @@ import { diffWordsWithSpace, diffLines } from 'diff'
 import * as vscode from 'vscode'
 import { ToolkitError, getLogger } from 'aws-core-vscode/shared'
 import { diffUtilities } from 'aws-core-vscode/shared'
+import { stripCommonIndentation } from './stringUtils'
 type Range = { line: number; start: number; end: number }
 
 const logger = getLogger('nextEditPrediction')
@@ -78,6 +79,7 @@ export class SvgGenerationService {
 
         const highlightRanges = this.generateHighlightRanges(removedLines, addedLines, modifiedLines)
         const diffAddedWithHighlight = this.getHighlightEdit(addedLines, highlightRanges.addedRanges)
+        const normalizedDiffLines = stripCommonIndentation(diffAddedWithHighlight)
 
         // Create SVG window, document, and container
         const window = createSVGWindow()
@@ -90,7 +92,7 @@ export class SvgGenerationService {
 
         // Generate CSS for syntax highlighting HTML content based on theme
         const styles = this.generateStyles(currentTheme)
-        const htmlContent = this.generateHtmlContent(diffAddedWithHighlight, styles, offset)
+        const htmlContent = this.generateHtmlContent(normalizedDiffLines, styles, offset)
 
         // Create foreignObject to embed HTML
         const foreignObject = draw.foreignObject(width + offset, height)
@@ -162,6 +164,9 @@ export class SvgGenerationService {
                 white-space: pre-wrap; /* Preserve whitespace */
                 background-color: ${diffAdded};
             }
+            .diff-unchanged {
+                white-space: pre-wrap; /* Preserve indentation for unchanged lines */
+            }
         `
     }
 
@@ -229,7 +234,7 @@ export class SvgGenerationService {
 
             // If no ranges for this line, leave it as-is with HTML escaping
             if (lineRanges.length === 0) {
-                result.push(this.escapeHtml(line))
+                result.push(`<span class="diff-unchanged">${this.escapeHtml(line)}</span>`)
                 continue
             }
 
@@ -244,7 +249,7 @@ export class SvgGenerationService {
                 // Add text before the current range (with HTML escaping)
                 if (range.start > currentPos) {
                     const beforeText = line.substring(currentPos, range.start)
-                    highlightedLine += this.escapeHtml(beforeText)
+                    highlightedLine += `<span class="diff-unchanged">${this.escapeHtml(beforeText)}</span>`
                 }
 
                 // Add the highlighted part (with HTML escaping)
@@ -258,7 +263,7 @@ export class SvgGenerationService {
             // Add any remaining text after the last range (with HTML escaping)
             if (currentPos < line.length) {
                 const afterText = line.substring(currentPos)
-                highlightedLine += this.escapeHtml(afterText)
+                highlightedLine += `<span class="diff-unchanged">${this.escapeHtml(afterText)}</span>`
             }
 
             result.push(highlightedLine)

packages/amazonq/test/unit/amazonq/apps/inline/EditRendering/stringUtils.test.ts

@@ -0,0 +1,47 @@
+/*!
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+import assert from 'assert'
+import { stripCommonIndentation } from '../../../../../../src/app/inline/EditRendering/stringUtils'
+
+describe('stripCommonIndentation', () => {
+    it('should strip common leading whitespace', () => {
+        const input = ['    line1 ', '    line2 ', '        line3   ']
+        const expected = ['line1 ', 'line2 ', '    line3   ']
+        assert.deepStrictEqual(stripCommonIndentation(input), expected)
+    })
+
+    it('should handle HTML tags', () => {
+        const input = [
+            '<span class="diff-unchanged>       line1 </span>',
+            '<span class="diff-changed>   line2  </span>',
+        ]
+        const expected = ['<span class="diff-unchanged>    line1 </span>', '<span class="diff-changed>line2  </span>']
+        assert.deepStrictEqual(stripCommonIndentation(input), expected)
+    })
+
+    it('should handle mixed indentation', () => {
+        const input = [' line1', '    line2', '  line3']
+        const expected = ['line1', '   line2', ' line3']
+        assert.deepStrictEqual(stripCommonIndentation(input), expected)
+    })
+
+    it('should handle empty lines', () => {
+        const input = ['    line1', '', '    line2']
+        const expected = ['    line1', '', '    line2']
+        assert.deepStrictEqual(stripCommonIndentation(input), expected)
+    })
+
+    it('should handle no indentation', () => {
+        const input = ['line1', 'line2']
+        const expected = ['line1', 'line2']
+        assert.deepStrictEqual(stripCommonIndentation(input), expected)
+    })
+
+    it('should handle single line', () => {
+        const input = ['    single line']
+        const expected = ['single line']
+        assert.deepStrictEqual(stripCommonIndentation(input), expected)
+    })
+})