basant307/AI_Governance_Project

1/**2 * @license3 * Copyright 2025 Google LLC4 * SPDX-License-Identifier: Apache-2.05 */6 7import * as Diff from 'diff';8import type { DiffStat } from './tools.js';9 10export const DEFAULT_DIFF_OPTIONS: Diff.PatchOptions = {11  context: 3,12  ignoreWhitespace: true,13};14 15/**16 * Returns true when the unified diff patch string contains at least one hunk.17 */18export function hasHunks(patch: string): boolean {19  return patch.includes('\n@@ ');20}21 22/**23 * Creates a unified diff patch with smart whitespace handling.24 *25 * Uses ignoreWhitespace:true first to produce clean diffs when content and26 * whitespace change together. Falls back to ignoreWhitespace:false when no27 * hunks are found, so that whitespace-only edits (e.g. re-indentation) still28 * produce a visible diff instead of "No changes detected".29 */30export function createPatchSmart(31  filename: string,32  oldStr: string,33  newStr: string,34  oldHeader?: string,35  newHeader?: string,36): string {37  const cleanPatch = Diff.createPatch(38    filename,39    oldStr,40    newStr,41    oldHeader,42    newHeader,43    DEFAULT_DIFF_OPTIONS,44  );45 46  if (hasHunks(cleanPatch)) {47    return cleanPatch;48  }49 50  return Diff.createPatch(filename, oldStr, newStr, oldHeader, newHeader, {51    ...DEFAULT_DIFF_OPTIONS,52    ignoreWhitespace: false,53  });54}55 56function structuredPatchSmart(57  filename: string,58  oldStr: string,59  newStr: string,60  oldHeader?: string,61  newHeader?: string,62): Diff.ParsedDiff {63  const result = Diff.structuredPatch(64    filename,65    filename,66    oldStr,67    newStr,68    oldHeader,69    newHeader,70    DEFAULT_DIFF_OPTIONS,71  );72 73  if (result.hunks.length > 0) {74    return result;75  }76 77  return Diff.structuredPatch(78    filename,79    filename,80    oldStr,81    newStr,82    oldHeader,83    newHeader,84    {85      ...DEFAULT_DIFF_OPTIONS,86      ignoreWhitespace: false,87    },88  );89}90 91export function getDiffStat(92  fileName: string,93  oldStr: string,94  aiStr: string,95  userStr: string,96): DiffStat {97  const getStats = (patch: Diff.ParsedDiff) => {98    let addedLines = 0;99    let removedLines = 0;100    let addedChars = 0;101    let removedChars = 0;102 103    patch.hunks.forEach((hunk: Diff.Hunk) => {104      hunk.lines.forEach((line: string) => {105        if (line.startsWith('+')) {106          addedLines++;107          addedChars += line.length - 1;108        } else if (line.startsWith('-')) {109          removedLines++;110          removedChars += line.length - 1;111        }112      });113    });114    return { addedLines, removedLines, addedChars, removedChars };115  };116 117  const modelPatch = structuredPatchSmart(118    fileName,119    oldStr,120    aiStr,121    'Current',122    'Proposed',123  );124  const modelStats = getStats(modelPatch);125 126  const userStats =127    aiStr === userStr128      ? {129          addedLines: 0,130          removedLines: 0,131          addedChars: 0,132          removedChars: 0,133        }134      : getStats(135          structuredPatchSmart(fileName, aiStr, userStr, 'Proposed', 'User'),136        );137 138  return {139    model_added_lines: modelStats.addedLines,140    model_removed_lines: modelStats.removedLines,141    model_added_chars: modelStats.addedChars,142    model_removed_chars: modelStats.removedChars,143    user_added_lines: userStats.addedLines,144    user_removed_lines: userStats.removedLines,145    user_added_chars: userStats.addedChars,146    user_removed_chars: userStats.removedChars,147  };148}149