export type ParsedDiffLineType = "context" | "add" | "delete" | "meta" | "hunk"; export interface ParsedDiffLine {  readonly id: string;  readonly type: ParsedDiffLineType;  readonly oldLine: number | null;  readonly newLine: number | null;  readonly content: string;} export interface ParsedDiffFile {  readonly id: string;  readonly oldPath: string | null;  readonly newPath: string | null;  readonly lines: ReadonlyArray<ParsedDiffLine>;} function parseHunkStart(  line: string,): { readonly oldLine: number; readonly newLine: number } | null {  const match = line.match(/^@@ -(\d+)(?:,\d+)? \+(\d+)(?:,\d+)? @@/);  if (!match) {    return null;  }   return {    oldLine: Number.parseInt(match[1] ?? "0", 10),    newLine: Number.parseInt(match[2] ?? "0", 10),  };} function parseDiffPath(line: string, prefix: "--- " | "+++ "): string | null {  if (!line.startsWith(prefix)) {    return null;  }  const raw = line.slice(prefix.length).trim();  if (raw === "/dev/null") {    return null;  }  return raw.replace(/^[ab]\//, "");} export function parseUnifiedDiff(diff: string): ReadonlyArray<ParsedDiffFile> {  const files: ParsedDiffFile[] = [];  let current: {    oldPath: string | null;    newPath: string | null;    lines: ParsedDiffLine[];  } | null = null;  let oldLine: number | null = null;  let newLine: number | null = null;   const pushCurrent = () => {    if (!current) {      return;    }    files.push({      id: `${current.oldPath ?? "null"}:${current.newPath ?? "null"}:${files.length}`,      oldPath: current.oldPath,      newPath: current.newPath,      lines: current.lines,    });  };   for (const rawLine of diff.replace(/\r\n/g, "\n").split("\n")) {    if (rawLine.startsWith("diff --git ")) {      pushCurrent();      const match = rawLine.match(/^diff --git a\/(.+) b\/(.+)$/);      current = {        oldPath: match?.[1] ?? null,        newPath: match?.[2] ?? null,        lines: [],      };      oldLine = null;      newLine = null;      continue;    }     if (!current) {      if (rawLine.trim().length === 0) {        continue;      }      current = { oldPath: null, newPath: null, lines: [] };    }     const oldPath = parseDiffPath(rawLine, "--- ");    if (oldPath !== null || rawLine === "--- /dev/null") {      current.oldPath = oldPath;      continue;    }     const newPath = parseDiffPath(rawLine, "+++ ");    if (newPath !== null || rawLine === "+++ /dev/null") {      current.newPath = newPath;      continue;    }     const hunk = parseHunkStart(rawLine);    if (hunk) {      oldLine = hunk.oldLine;      newLine = hunk.newLine;      current.lines.push({        id: `${current.lines.length}:hunk`,        type: "hunk",        oldLine: null,        newLine: null,        content: rawLine,      });      continue;    }     if (oldLine === null || newLine === null) {      current.lines.push({        id: `${current.lines.length}:meta`,        type: "meta",        oldLine: null,        newLine: null,        content: rawLine,      });      continue;    }     const marker = rawLine[0];    const content = rawLine.length > 0 ? rawLine.slice(1) : "";    if (marker === "+") {      current.lines.push({        id: `${current.lines.length}:add:${newLine}`,        type: "add",        oldLine: null,        newLine,        content,      });      newLine += 1;    } else if (marker === "-") {      current.lines.push({        id: `${current.lines.length}:delete:${oldLine}`,        type: "delete",        oldLine,        newLine: null,        content,      });      oldLine += 1;    } else {      current.lines.push({        id: `${current.lines.length}:context:${oldLine}:${newLine}`,        type: "context",        oldLine,        newLine,        content: marker === " " ? content : rawLine,      });      oldLine += 1;      newLine += 1;    }  }   pushCurrent();  return files.filter((file) => file.lines.length > 0 || file.oldPath || file.newPath);}