'use strict';
/**
 * config.js — Nomad scripts/ shared config resolution layer.
 *
 * Everything in scripts/ resolves paths through this file — never a literal
 * absolute path baked into a script (Nomad `team-skeleton.md` §5, hardcoding
 * points #1/#2/#7). Two things are located purely by directory *structure*,
 * never by a specific directory *name*, so this works regardless of whether
 * a deployment names its folders in English, Chinese, or anything else
 * (`team-skeleton.md` hardcoding point #5):
 *
 *   - team root  = nearest ancestor directory (starting from cwd) containing
 *                   `team-config.json`.
 *   - agent home = nearest ancestor directory (starting from cwd) containing
 *                   `AGENTS.md`.
 *
 * This deliberately does NOT replicate the production hooks-core approach of
 * regex-matching a hardcoded parent-folder name (e.g. `<agent-parent-dir>\(name)`)
 * to infer the agent home. That approach only works because the production
 * deployment's folder name is a known constant; a portable template cannot
 * assume any particular folder name exists at all — see design note in
 * scripts/README.md.
 *
 * Resolution order for every tunable value: environment variable >
 * `team-config.json` > safe built-in fallback (§3 rule, hardcoding point #2).
 */
const fs = require('fs');
const path = require('path');

const CONFIG_FILENAME = 'team-config.json';
const AGENT_MARKER_FILENAME = 'AGENTS.md';

/** Strip a leading UTF-8 BOM if present (team-skeleton.md §3 rule — Windows editors routinely add one). */
function stripBOM(s) {
  if (typeof s === 'string' && s.charCodeAt(0) === 0xfeff) return s.slice(1);
  return s;
}

function readTextFileStripBOM(filePath) {
  return stripBOM(fs.readFileSync(filePath, 'utf8'));
}

function readJsonFile(filePath) {
  return JSON.parse(readTextFileStripBOM(filePath));
}

/**
 * Walk upward from startDir (inclusive) until predicate(dir) is true.
 * Returns the matching absolute directory path, or null if it reaches the
 * filesystem root without a match. Never throws on a missing directory.
 */
function findUp(startDir, predicate) {
  let dir = path.resolve(startDir);
  // eslint-disable-next-line no-constant-condition
  while (true) {
    try {
      if (predicate(dir)) return dir;
    } catch (e) {
      /* a broken predicate should not crash resolution — treat as no-match and keep climbing */
    }
    const parent = path.dirname(dir);
    if (parent === dir) return null; // reached filesystem root
    dir = parent;
  }
}

function hasFile(dir, fileName) {
  try {
    return fs.existsSync(path.join(dir, fileName));
  } catch (e) {
    return false;
  }
}

/**
 * Team root resolution: env `NOMAD_TEAM_ROOT` (validated — must actually contain
 * team-config.json, otherwise ignored, not blindly trusted) > walk up from cwd
 * looking for team-config.json > null.
 */
function resolveTeamRoot(cwd) {
  const envRoot = process.env.NOMAD_TEAM_ROOT;
  if (envRoot && hasFile(envRoot, CONFIG_FILENAME)) {
    return path.resolve(envRoot);
  }
  return findUp(cwd || process.cwd(), (d) => hasFile(d, CONFIG_FILENAME));
}

/**
 * Agent home resolution: nearest ancestor of cwd containing AGENTS.md.
 * No env override — an agent's home is a structural fact about where the
 * script is actually running, not a value worth overriding for a single run
 * (unlike team root, which selftest.js legitimately wants to redirect).
 */
function resolveAgentHome(cwd) {
  return findUp(cwd || process.cwd(), (d) => hasFile(d, AGENT_MARKER_FILENAME));
}

/** Load team-config.json from a resolved team root. Returns null (not throw) on any failure. */
function loadTeamConfig(teamRoot) {
  if (!teamRoot) return null;
  const p = path.join(teamRoot, CONFIG_FILENAME);
  if (!fs.existsSync(p)) return null;
  try {
    return readJsonFile(p);
  } catch (e) {
    return null;
  }
}

/**
 * Language resolution: env `NOMAD_LANG` (must be 'en' or 'zh-CN') >
 * config.principal.language (any 'zh*' value normalizes to 'zh-CN', else 'en') >
 * 'en' fallback. English-default-with-config-override, per this batch's brief —
 * a portable template should not assume Chinese as the silent default.
 */
function resolveLanguage(config) {
  const envLang = process.env.NOMAD_LANG;
  if (envLang === 'en' || envLang === 'zh-CN') return envLang;
  const raw = config && config.principal && config.principal.language;
  if (typeof raw === 'string' && raw.trim()) {
    return raw.trim().toLowerCase().startsWith('zh') ? 'zh-CN' : 'en';
  }
  return 'en';
}

/** Resolve one of config.shared_paths[key] (a team-root-relative path) to an absolute path. Null if unresolvable. */
function resolveSharedPath(teamRoot, config, key) {
  if (!teamRoot || !config || !config.shared_paths) return null;
  const rel = config.shared_paths[key];
  if (!rel || typeof rel !== 'string') return null;
  // shared_paths values are documented as forward-slash-or-native relative paths in team-config.json;
  // split on both separators and rejoin with path.join so this works regardless of which the installer typed.
  const parts = rel.split(/[\\/]+/).filter(Boolean);
  return path.join(teamRoot, ...parts);
}

/**
 * Return the first candidate (joined onto baseDir) that exists on disk, or null.
 * Used for structural-but-name-agnostic lookups this package intentionally does
 * NOT add new team-config.json fields for (e.g. the memory/ dir might be named
 * `记忆` or `memory` — see scripts/README.md "naming agnosticism" note).
 */
function firstExisting(baseDir, candidates) {
  if (!baseDir) return null;
  for (const c of candidates) {
    const p = path.join(baseDir, c);
    if (fs.existsSync(p)) return p;
  }
  return null;
}

module.exports = {
  CONFIG_FILENAME,
  AGENT_MARKER_FILENAME,
  stripBOM,
  readTextFileStripBOM,
  readJsonFile,
  findUp,
  resolveTeamRoot,
  resolveAgentHome,
  loadTeamConfig,
  resolveLanguage,
  resolveSharedPath,
  firstExisting,
};