/**
 * @file `agenthub statusline install|uninstall`: writes or removes the
 * `statusLine` entry in Claude Code's user settings (`<CLAUDE_HOME>/settings.json`)
 * — only when the user runs the command, never at bootstrap. A statusLine that
 * is not AgentHub's is left alone unless `force` is set, and the file is backed
 * up beside itself (`settings.json.agenthub-backup-<stamp>`) before any write.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

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

const REPO_ROOT = path.join(__dirname, "..");

/** Our own entries: `node ".../statusline/statusline.js"` or `".../agenthub" statusline`. */
const OURS = /(statusline[\\/]statusline\.js"?|agenthub"? statusline)\s*$/;
const isOurs = (entry) => typeof entry?.command === "string" && OURS.test(entry.command);

/**
 * The command to register. A plugin install runs from a cache directory that
 * every update replaces, so it goes through the stable `~/.local/bin/agenthub`
 * launcher the bootstrap keeps pointed at the current build; a checkout runs
 * the script in place.
 */
function statuslineCommand(root = REPO_ROOT, home = os.homedir()) {
  const launcher = path.join(home, ".local", "bin", "agenthub");
  const inCache = root.includes(`${path.sep}plugins${path.sep}cache${path.sep}`);
  if (inCache && fs.existsSync(launcher)) return `"${launcher}" statusline`;
  return `node "${path.join(root, "statusline", "statusline.js")}"`;
}

function readSettings(file) {
  try {
    return JSON.parse(fs.readFileSync(file, "utf8"));
  } catch (err) {
    if (err.code === "ENOENT") return {};
    throw new Error(`cannot read ${file}: ${err.message}`);
  }
}

function writeSettings(file, settings) {
  if (fs.existsSync(file)) {
    const stamp = new Date().toISOString().replace(/[:.]/g, "-");
    fs.copyFileSync(file, `${file}.agenthub-backup-${stamp}`);
  } else {
    fs.mkdirSync(path.dirname(file), { recursive: true });
  }
  fs.writeFileSync(file, JSON.stringify(settings, null, 2) + "\n", "utf8");
}

/** @returns {{status: "installed"|"unchanged"|"foreign", command: string, previous?: object}} */
function install(file, { force = false, command = statuslineCommand() } = {}) {
  const settings = readSettings(file);
  const current = settings.statusLine;
  if (current && !isOurs(current) && !force)
    return { status: "foreign", command, previous: current };
  if (current?.type === "command" && current.command === command)
    return { status: "unchanged", command };
  settings.statusLine = { type: "command", command, padding: 0 };
  writeSettings(file, settings);
  return { status: "installed", command, previous: current };
}

/** @returns {{status: "removed"|"absent"|"foreign", previous?: object}} */
function uninstall(file, { force = false } = {}) {
  const settings = readSettings(file);
  const current = settings.statusLine;
  if (!current) return { status: "absent" };
  if (!isOurs(current) && !force) return { status: "foreign", previous: current };
  delete settings.statusLine;
  writeSettings(file, settings);
  return { status: "removed", previous: current };
}

module.exports = { install, uninstall, isOurs, statuslineCommand };