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platform_web/utils/diff.ts

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+import type { ConfigDiffView, DiffLine } from "../contracts/workspace";
+
+export function computeLineDiff(previous: string, next: string): DiffLine[] {
+  const previousLines = previous.split("\n");
+  const nextLines = next.split("\n");
+  const m = previousLines.length;
+  const n = nextLines.length;
+  // classic LCS table; config files are small enough for O(m*n)
+  const lcs: number[][] = Array.from({ length: m + 1 }, () => new Array<number>(n + 1).fill(0));
+  for (let i = m - 1; i >= 0; i -= 1) {
+    for (let j = n - 1; j >= 0; j -= 1) {
+      lcs[i][j] = previousLines[i] === nextLines[j] ? lcs[i + 1][j + 1] + 1 : Math.max(lcs[i + 1][j], lcs[i][j + 1]);
+    }
+  }
+  const lines: DiffLine[] = [];
+  let i = 0;
+  let j = 0;
+  while (i < m && j < n) {
+    if (previousLines[i] === nextLines[j]) {
+      lines.push({ kind: "same", text: previousLines[i] });
+      i += 1;
+      j += 1;
+    } else if (lcs[i + 1][j] >= lcs[i][j + 1]) {
+      lines.push({ kind: "removed", text: previousLines[i] });
+      i += 1;
+    } else {
+      lines.push({ kind: "added", text: nextLines[j] });
+      j += 1;
+    }
+  }
+  while (i < m) {
+    lines.push({ kind: "removed", text: previousLines[i] });
+    i += 1;
+  }
+  while (j < n) {
+    lines.push({ kind: "added", text: nextLines[j] });
+    j += 1;
+  }
+  return lines;
+}
+
+export function buildConfigDiff(serverInstanceId: string, previous: string, next: string): ConfigDiffView {
+  const lines = computeLineDiff(previous, next);
+  const added = lines.filter((line) => line.kind === "added").length;
+  const removed = lines.filter((line) => line.kind === "removed").length;
+  return {
+    serverInstanceId,
+    summary: `+${added} / -${removed} 行变更`,
+    lines,
+    nextContent: next
+  };
+}
+
+export function diffHasChanges(diff: ConfigDiffView): boolean {
+  return diff.lines.some((line) => line.kind !== "same");
+}