/**
 * @file Cleans up what older builds wrote into a lane: `removeStageDoc` takes
 * AgentHub's stage block back out of a codex lane's AGENTS.md. Plain file I/O,
 * so never in an S3 member's folder.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

const fs = require("node:fs");
const path = require("node:path");

// The block older builds wrote into a codex lane's AGENTS.md. Codex lanes no
// longer carry a pipeline, so `removeStageDoc` takes it back out.
const STAGE_BLOCK_START = "<!-- agenthub:stage:start -->";
const STAGE_BLOCK_END = "<!-- agenthub:stage:end -->";

/**
 * Remove AgentHub's stage block from `<cwd>/AGENTS.md`, leaving every other
 * line as it was. A file left with nothing else in it was AgentHub's own
 * creation, so it is deleted. Never throws.
 *
 * @returns {boolean} whether the file changed
 */
function removeStageDoc(cwd) {
  const file = path.join(cwd, "AGENTS.md");
  try {
    // S3: never in a member's folder — the host would read, rewrite or delete
    // through any link the member planted there (with CAP_DAC_READ_SEARCH).
    // Builds that wrote the block predate S3; a member removes it themselves.
    if (require("./run-as").ownerForRead(cwd)) return false;
    const doc = fs.readFileSync(file, "utf8");
    const start = doc.indexOf(STAGE_BLOCK_START);
    const end = doc.indexOf(STAGE_BLOCK_END, start);
    if (start === -1 || end === -1) return false;
    const rest = (
      doc.slice(0, start).trimEnd() +
      "\n\n" +
      doc.slice(end + STAGE_BLOCK_END.length).trimStart()
    ).trim();
    if (rest) fs.writeFileSync(file, `${rest}\n`);
    else fs.rmSync(file);
    return true;
  } catch {
    return false; // no file, or unreadable — nothing of ours to take out
  }
}

module.exports = { removeStageDoc };