import { promises as fs } from "fs";
import { atomicWrite, fsError, looksBinary, MAX_FILE_BYTES } from "../fsutil";
import { resolveInScope } from "../paths";

export async function runEdit(
  root: string,
  args: { path: string; old_string: string; new_string: string; replace_all?: boolean },
): Promise<string> {
  if (args.old_string === "") return "Error: old_string must not be empty";
  if (args.old_string === args.new_string) return "Error: old_string and new_string are identical";

  const r = await resolveInScope(root, args.path);
  if (!r.ok) return r.error;

  let text: string;
  try {
    const st = await fs.stat(r.abs);
    if (st.isDirectory()) return `Error: is a directory, not a file: ${args.path}`;
    if (!st.isFile()) return `Error: not a regular file: ${args.path}`;
    if (st.size > MAX_FILE_BYTES) {
      return `Error: file is too large to edit (${st.size} bytes, limit ${MAX_FILE_BYTES})`;
    }
    const buf = await fs.readFile(r.abs);
    if (looksBinary(buf.subarray(0, 8192))) return `Error: binary file, cannot edit as text: ${args.path}`;
    text = buf.toString("utf8");
    if (!Buffer.from(text, "utf8").equals(buf)) return `Error: file is not valid UTF-8, cannot edit: ${args.path}`;
  } catch (e) {
    return fsError(e, args.path);
  }

  // Files that are purely CRLF: models send "\n", so translate both strings to match.
  const pureCrlf = text.includes("\r\n") && !/(^|[^\r])\n/.test(text);
  const toFile = (s: string) => (pureCrlf ? s.replace(/\r?\n/g, "\r\n") : s);
  const oldS = toFile(args.old_string);
  const newS = toFile(args.new_string);

  let count = 0;
  for (let i = text.indexOf(oldS); i !== -1; i = text.indexOf(oldS, i + oldS.length)) count++;

  if (count === 0) return `Error: old_string not found in ${args.path}`;
  if (count > 1 && !args.replace_all) {
    return (
      `Error: old_string matches ${count} places in ${args.path}; ` +
      `add surrounding context to make it unique, or set replace_all=true`
    );
  }

  let updated: string;
  try {
    updated = args.replace_all
      ? text.split(oldS).join(newS)
      : text.slice(0, text.indexOf(oldS)) + newS + text.slice(text.indexOf(oldS) + oldS.length);
  } catch {
    return `Error: edit result too large or invalid for ${args.path}`;
  }
  const replacements = args.replace_all ? count : 1;

  try {
    await atomicWrite(r.abs, updated);
  } catch (e) {
    return fsError(e, args.path);
  }
  return `edited ${args.path}: ${replacements} replacement(s)`;
}

import { promises as fs } from "fs";
import { atomicWrite, fsError, looksBinary, MAX_FILE_BYTES } from "../fsutil";
import { resolveInScope } from "../paths";

export async function runEdit(
  root: string,
  args: { path: string; old_string: string; new_string: string; replace_all?: boolean },
): Promise<string> {
  if (args.old_string === "") return "Error: old_string must not be empty";
  if (args.old_string === args.new_string) return "Error: old_string and new_string are identical";

  const r = await resolveInScope(root, args.path);
  if (!r.ok) return r.error;

  let text: string;
  try {
    const st = await fs.stat(r.abs);
    if (st.isDirectory()) return `Error: is a directory, not a file: ${args.path}`;
    if (!st.isFile()) return `Error: not a regular file: ${args.path}`;
    if (st.size > MAX_FILE_BYTES) {
      return `Error: file is too large to edit (${st.size} bytes, limit ${MAX_FILE_BYTES})`;
    }
    const buf = await fs.readFile(r.abs);
    if (looksBinary(buf.subarray(0, 8192))) return `Error: binary file, cannot edit as text: ${args.path}`;
    text = buf.toString("utf8");
    if (!Buffer.from(text, "utf8").equals(buf)) return `Error: file is not valid UTF-8, cannot edit: ${args.path}`;
  } catch (e) {
    return fsError(e, args.path);
  }

  // Files that are purely CRLF: models send "\n", so translate both strings to match.
  const pureCrlf = text.includes("\r\n") && !/(^|[^\r])\n/.test(text);
  const toFile = (s: string) => (pureCrlf ? s.replace(/\r?\n/g, "\r\n") : s);
  const oldS = toFile(args.old_string);
  const newS = toFile(args.new_string);

  let count = 0;
  for (let i = text.indexOf(oldS); i !== -1; i = text.indexOf(oldS, i + oldS.length)) count++;

  if (count === 0) return `Error: old_string not found in ${args.path}`;
  if (count > 1 && !args.replace_all) {
    return (
      `Error: old_string matches ${count} places in ${args.path}; ` +
      `add surrounding context to make it unique, or set replace_all=true`
    );
  }

  let updated: string;
  try {
    updated = args.replace_all
      ? text.split(oldS).join(newS)
      : text.slice(0, text.indexOf(oldS)) + newS + text.slice(text.indexOf(oldS) + oldS.length);
  } catch {
    return `Error: edit result too large or invalid for ${args.path}`;
  }
  const replacements = args.replace_all ? count : 1;

  try {
    await atomicWrite(r.abs, updated);
  } catch (e) {
    return fsError(e, args.path);
  }
  return `edited ${args.path}: ${replacements} replacement(s)`;
}