// DashCaddy Platform Paths
// Provides cross-platform path resolution for Windows and Linux deployments.
// All paths can be overridden via environment variables.

const path = require('path');
const fs = require('fs');
const isWindows = process.platform === 'win32';

// Base directories
const CADDY_BASE = process.env.CADDY_BASE || (isWindows ? 'C:/caddy' : '/etc/dashcaddy');
const DOCKER_DATA = process.env.DOCKER_DATA || (isWindows ? 'E:/dockerdata' : '/opt/dockerdata');
const CADDY_SITES = process.env.CADDY_SITES || path.join(CADDY_BASE, 'sites');

// Runtime state must not default beside source modules: those paths move whenever
// files are reorganized and are not mounted in production containers. Derive a
// stable data directory from the canonical services file instead. This supports
// both current /app/data mounts and legacy /app single-file mounts without
// requiring per-module environment variables.
const SERVICES_FILE = process.env.SERVICES_FILE || path.join(CADDY_BASE, 'services.json');
const DATA_DIR = process.env.DATA_DIR || path.dirname(SERVICES_FILE);
const CONFIG_FILE = process.env.CONFIG_FILE || path.join(DATA_DIR, 'config.json');
const DNS_CREDENTIALS_FILE = process.env.DNS_CREDENTIALS_FILE || path.join(DATA_DIR, 'dns-credentials.json');

// Caddy PKI certificates
const CADDY_PKI = process.env.CADDY_PKI || (isWindows
  ? 'C:/caddy/certs/pki/authorities/local'
  : '/var/lib/caddy/.local/share/caddy/pki/authorities/local');

const paths = {
  // Base directories
  caddyBase: CADDY_BASE,
  caddySites: CADDY_SITES,
  dockerData: DOCKER_DATA,

  // Caddy configuration
  caddyfile: process.env.CADDYFILE_PATH || path.join(CADDY_BASE, 'Caddyfile'),
  caddyAdminUrl: process.env.CADDY_ADMIN_URL || (isWindows ? 'http://host.docker.internal:2019' : 'http://localhost:2019'),

  // Service config files
  servicesFile: SERVICES_FILE,
  configFile: CONFIG_FILE,
  dnsCredentialsFile: DNS_CREDENTIALS_FILE,
  dataDir: DATA_DIR,

  // CA certificate paths
  caCertDir: path.join(CADDY_SITES, 'ca'),
  pkiRootCert: path.join(CADDY_PKI, 'root.crt'),
  pkiIntermediateCert: path.join(CADDY_PKI, 'intermediate.crt'),
  generatedCertsDir: path.join(CADDY_SITES, 'generated-certs'),
  pkiDir: CADDY_PKI,

  // Static site base path
  sitePath: (subdomain) => path.join(CADDY_SITES, subdomain),

  // Docker data path for app volumes
  appData: (appName) => path.join(DOCKER_DATA, appName),

  // In-container paths (used by self-updater and Docker deployments)
  // Override via env vars for custom Docker layouts
  containerUpdatesDir: process.env.DASHCADDY_UPDATES_DIR || '/app/updates',
  containerFrontendDir: process.env.DASHCADDY_FRONTEND_DIR || '/app/dashboard',
  containerAssetsDir: process.env.ASSETS_DIR || '/app/assets',

  // Asset path resolution — supports both Docker (single file mount) and
  // consolidated data directory layouts
  resolveAssetsPath: (envPath) => {
    if (envPath) return envPath;
    // Standard Docker mount: /app/assets (volume-mounted)
    if (fs.existsSync('/app/assets')) return '/app/assets';
    // Consolidated data directory: /app/data/assets
    if (fs.existsSync(path.join(CADDY_BASE, 'assets'))) return path.join(CADDY_BASE, 'assets');
    // Fall back to /app/assets even if it doesn't exist (will create on write)
    return '/app/assets';
  },

  // Log digest directory
  digestDir: process.env.DIGEST_DIR || path.join(CADDY_BASE, 'digests'),

  // Log paths (for allowed log file access)
  allowedLogPaths: isWindows
    ? [
        process.env.LOCALAPPDATA || 'C:\\Users',
        process.env.APPDATA || 'C:\\Users',
        'C:\\ProgramData',
        '/var/log',
        '/opt'
      ]
    : [
        '/var/log',
        '/opt',
        '/home'
      ],

  // Platform detection helpers
  isWindows,
  isLinux: process.platform === 'linux',
};

// Convert host paths to Docker-compatible mount paths
// On Windows Docker Desktop: C:/foo → //mnt/host/c/foo
// On Linux: paths pass through unchanged (native Docker)
paths.toDockerMountPath = function(hostPath) {
  if (!isWindows) return hostPath;
  if (hostPath.startsWith('//mnt/host/') || hostPath.startsWith('/')) return hostPath;
  const match = hostPath.match(/^([A-Za-z]):[/\\](.*)$/);
  if (match) {
    const driveLetter = match[1].toLowerCase();
    const restOfPath = match[2].replace(/\\/g, '/');
    return `//mnt/host/${driveLetter}/${restOfPath}`;
  }
  return hostPath;
};

// ============================================================================
// dataDir safety guard — DC-046 follow-up to DC-039
// ============================================================================
// The DC-039 fix routed every runtime-data default through `platformPaths.dataDir`
// (derived from SERVICES_FILE → path.dirname(SERVICES_FILE)). That worked because
// /opt/dashcaddy/dashcaddy-api/data is bind-mounted at /app/data in production.
//
// The silent failure mode that survived: if SERVICES_FILE isn't set as an env
// var AND no `services.json` exists in the production bind-mount path, the
// resolution falls back to `path.join(CADDY_BASE, 'services.json')` — and on
// Linux that resolves to `/etc/dashcaddy/services.json` → dataDir = `/etc/dashcaddy`
// which is the IMAGE LAYER, not a bind mount. Audit-log / error-log / license
// files would silently land in the image and vanish on the next recreate.
//
// `assertSafe()` is the structural guard. Called once from server.js startup
// in production mode (NODE_ENV=production). Throws → container refuses to boot
// loudly, instead of running with a path that loses data silently.
//
// Forbidden zones (Docker image layer; recovered only by rebuild):
//   /app/src/, /app/routes/, /app/scripts/, /app/*.js (literally /app itself
//   when no subdir — the WORKDIR in Dockerfile is /app and a misdirected write
//   to /app/audit-log.json would be the same problem)
//
// Permitted zones (bind-mounted in production, mount-relative in dev):
//   /app/data, any non-/app or non-/etc path that resolves onto a real fs
//
// On non-Linux platforms, the guard only checks the Linux-style image zones.
// Windows installs use the E:/ + C:/ ETree and never run inside the Docker image.

const FORBIDDEN_DATA_DIRS = (process.platform === 'linux' && !process.env.SKIP_DATA_DIR_GUARD) ? [
  // DC-039-era broken defaults. Hits only when SERVICES_FILE is unset AND no
  // bind mount at /app/data resolves.
  '/app/src',
  '/app/routes',
  '/app/scripts',
  '/app/utils',
  '/app/managers',
  '/app/security',
  // system dirs that should never be a dataDir
  '/etc',
  '/etc/caddy',
  '/etc/dashcaddy',
  '/usr',
  '/usr/local',
  '/var',
  '/var/lib/caddy',
] : [];

paths.isMountedCheck = function(dir) {
  // Heuristic: a "mounted" dir on Linux is reachable AND writable AND not the
  // Docker image layer. Returning `false` lets start.sh skip migration cleanly
  // rather than crashing.
  if (!fs.existsSync(dir)) return false;
  try {
    fs.accessSync(dir, fs.constants.W_OK);
  } catch {
    return false;
  }
  // On Linux Docker, /app is a baked image layer; /app/data is bind-mounted.
  // Detect /app without /app/data being a separate mountpoint.
  if (process.platform === 'linux' && dir === '/app') {
    return fs.existsSync('/app/data')
      && fs.statSync('/app/data').dev !== fs.statSync('/app').dev;
  }
  return true;
};

paths.assertSafe = function({ mode = 'production' } = {}) {
  if (mode !== 'production') return;  // dev / test pass-through

  const dataDirResolved = path.resolve(paths.dataDir);
  const norm = (p) => p.replace(/\\/g, '/').replace(/\/+$/, '');

  // Zone membership is by first segment, not arbitrary substring matches.
  // `/app/data` is allowed because `/app/data` is the bind mount; `/app/src`
  // is forbidden because that's where the source tree lives.
  for (const forbidden of FORBIDDEN_DATA_DIRS) {
    if (norm(dataDirResolved) === norm(forbidden)
        || norm(dataDirResolved).startsWith(norm(forbidden) + '/')) {
      throw new Error(
        `[platform-paths] FATAL: dataDir resolved to forbidden image-layer path ` +
        `"${dataDirResolved}". This is a DC-039-class regression: runtime state would ` +
        `be written into the Docker image and lost on next container recreate. ` +
        `Set SERVICES_FILE=/app/data/services.json (or equivalent bind-mounted path) ` +
        `in your container env. To bypass during local dev, set SKIP_DATA_DIR_GUARD=1.`
      );
    }
  }

  // Second check: dataDir should be on a writable, persistent mount.
  if (!paths.isMountedCheck(dataDirResolved)) {
    // Not fatal — but loud. Some Windows + dev workflows have ambiguous
    // writability. Warn instead of throw so we don't break the install path
    // for fresh users on Windows.
    console.warn(
      `[platform-paths] WARNING: dataDir "${dataDirResolved}" is not writable ` +
      `or doesn't exist. Runtime writes may fail or land in unexpected places.`
    );
  }
};

module.exports = paths;