/**
 * DashCaddy License Manager
 *
 * Runtime license validation, activation, and feature gating.
 * Uses credential-manager for secure storage of activation tokens.
 *
 * Hybrid model:
 * - Server-managed installs validate and renew online with a stable key.
 * - Legacy installs without LICENSE_SERVER_URL retain offline HMAC validation.
 * - A cached online entitlement survives a temporary outage only until its cached expiry.
 */

const crypto = require('crypto');
const os = require('os');
const fs = require('fs');
const path = require('path');
const { verifyCode, parseCode, VALID_DURATIONS } = require('../../license-keygen');
const { errorResponse } = require('../utils/responses');

const LICENSE_CRED_KEY = 'license.activation';
const LICENSE_SERVER_URL = process.env.LICENSE_SERVER_URL || null; // Set when license server exists

// Features gated behind premium
const PREMIUM_FEATURES = {
  sso: { name: 'Auto-Login SSO', description: 'Automatic single sign-on for deployed apps' },
  recipes: { name: 'Recipes', description: 'Multi-container stack deployment' },
  swarm: { name: 'Docker Swarm', description: 'Multi-node cluster orchestration' },
  // DC-165: site has always sold Fleet as Premium (pricing page + comparison
  // table); the gate was missing. hasFeature() falls back to
  // Object.keys(PREMIUM_FEATURES) for activations that stored no explicit
  // features list, so existing premium licenses (incl. offline activations
  // like the creator lifetime key) gain fleet automatically on next load.
  // 'fleet' is now part of the shipped entitlement contract — a new
  // PREMIUM_FEATURES key must ALWAYS be accompanied by the license-server
  // grant list (plans.js) or online activations will 403 it.
  fleet: { name: 'Multi-Host Fleet Management', description: 'Register remote DashCaddy instances, health probes, and multi-host deploys' },
  // DC-165: these two have ALWAYS been requirePremium-gated (routes/
  // workflows.js line 32, routes/backups.js schedule routes) but were
  // never listed here — offline activations could therefore never gain
  // them, and the marketing site didn't advertise them either. The site
  // now advertises both (Sami's decision 2026-10-09: "advertise as
  // Premium"); listing them here closes the offline path and makes
  // PREMIUM_FEATURES the single source of truth for gated features.
  workflows: { name: 'Workflow Automation', description: 'Bundled one-click maintenance workflows — update checks, disk cleanup, cert expiry checks — enable, run, and review history' },
  'auto-backup': { name: 'Scheduled Backups', description: 'Automated per-app backup schedules (manual one-click backup stays free)' }
};

class LicenseManager {
  constructor(credentialManager, configFile, log) {
    this.credentialManager = credentialManager;
    this.configFile = configFile;
    this.log = log || console;
    this.activation = null; // Cached activation state
    this.masterSecretHash = null; // Loaded from shipped secret hash (not the secret itself)
    this._loaded = false;
    this._activationGeneration = 0;
    this._activationMutationQueue = Promise.resolve();
  }

  /**
   * Load license state from storage on startup.
   * Primary: encrypted credential store. Fallback: config.json backup.
   * If the credential store fails (e.g. encryption key changed after rebuild),
   * restores from the config.json backup automatically.
   */
  async load() {
    try {
      const stored = await this.credentialManager.retrieve(LICENSE_CRED_KEY);
      if (stored) {
        this.activation = JSON.parse(stored);
        if (!this._isStructurallyValidLoadedActivation()) {
          this.activation = null;
          try { await this.credentialManager.delete(LICENSE_CRED_KEY); } catch (_) { /* fail closed in memory */ }
          try { await this._updateConfig(true); } catch (_) { /* fail closed in memory */ }
          this._loaded = true;
          return;
        }
        if (await this._isRevocationTombstoned(this.activation.code)) {
          this.activation = null;
          try { await this.credentialManager.delete(LICENSE_CRED_KEY); } catch (_) { /* tombstone remains authoritative */ }
          try { await this._updateConfig(true); } catch (error) {
            this.log.warn?.('license', 'Could not persist inactive state after tombstone', { error: error.message });
          }
          this._loaded = true;
          return;
        }
        if (!await this._validateLoadedActivationForServerMode()) {
          this._loaded = true;
          return;
        }
        if (this.isExpired()) {
          this.log.info?.('license', 'License has expired', {
            code: this._maskCode(this.activation.code),
            expiredAt: this.activation.expiresAt
          });
        } else {
          // DC-165 rev2 (judge P0): offline feature-snapshot repair, in a
          // helper to keep load() complexity/nesting inside house lint.
          await this._migrateOfflineFeatureSnapshot();
          this.log.info?.('license', 'License loaded', {
            code: this._maskCode(this.activation.code),
            expiresAt: this.activation.expiresAt,
            daysRemaining: this.daysRemaining()
          });
        }
        this._loaded = true;
        this._startOnlineRefresh();
        return;
      }
    } catch (error) {
      this.log.warn?.('license', 'Failed to load from credential store, trying config backup', { error: error.message });
    }

    // Fallback: restore from config.json backup
    try {
      const fsp = require('fs').promises;
      const data = await fsp.readFile(this.configFile, 'utf8');
      const config = JSON.parse(data);
      if (config.licenseBackup) {
        // Server-managed entitlements are never restored from plaintext config backup.
        // Only the credential store plus online validation/bounded cache is authoritative.
        if (LICENSE_SERVER_URL) {
          this.log.warn?.('license', 'Ignoring config license backup in server-managed mode');
          this._loaded = true;
          return;
        }
        this.activation = config.licenseBackup;
        if (!this._isStructurallyValidLoadedActivation()) {
          this.activation = null;
          this._loaded = true;
          return;
        }
        if (await this._isRevocationTombstoned(this.activation.code)) {
          this.activation = null;
          this._loaded = true;
          return;
        }
        if (!await this._validateLoadedActivationForServerMode()) {
          this._loaded = true;
          return;
        }
        this.log.info?.('license', 'License restored from config backup', {
          code: this._maskCode(this.activation.code),
          lifetime: this.activation.lifetime
        });
        // Re-store in credential manager so future loads succeed
        try {
          await this.credentialManager.store(LICENSE_CRED_KEY, JSON.stringify(this.activation));
          this.log.info?.('license', 'License re-stored in credential manager');
        } catch (storeErr) {
          this.log.warn?.('license', 'Could not re-store license in credential manager', { error: storeErr.message });
        }
        this._loaded = true;
        this._startOnlineRefresh();
        return;
      }
    } catch (_) {
      // Config doesn't exist or no backup — continue
    }

    this.log.info?.('license', 'No active license');
    this.activation = null;
    this._loaded = true;
  }

  /**
   * Load the shipped master secret hash for offline validation.
   * The actual master secret is NEVER shipped — only a hash of it is embedded
   * in the product, and the keygen embeds HMAC signatures in codes using the real secret.
   * For offline validation, we verify the code's internal HMAC consistency.
   *
   * @param {string} secretFile - Path to .license-secret file (dev only) or .license-secret-hash (shipped)
   */
  loadSecret(secretFile) {
    try {
      if (fs.existsSync(secretFile)) {
        const secret = fs.readFileSync(secretFile, 'utf8').trim();
        this.masterSecretHash = secret;
        return true;
      }
    } catch (error) {
      this.log.warn?.('license', 'Could not load license secret', { error: error.message });
    }
    return false;
  }

  /**
   * Generate a machine fingerprint for activation binding
   */
  getMachineFingerprint() {
    const components = [
      os.hostname(),
      os.platform(),
      os.arch(),
      os.cpus()[0]?.model || 'unknown'
    ];
    // Get primary MAC address
    const interfaces = os.networkInterfaces();
    for (const name of Object.keys(interfaces)) {
      for (const iface of interfaces[name]) {
        if (!iface.internal && iface.mac && iface.mac !== '00:00:00:00:00:00') {
          components.push(iface.mac);
          break;
        }
      }
    }
    return crypto.createHash('sha256').update(components.join('|')).digest('hex').substring(0, 16);
  }

  /**
   * Activate a license code
   * @param {string} code - License code (DC-XXXXX-XXXXX-XXXXX-XXXXX-XXXXX)
   * @returns {Object} { success, message, activation? }
   */
  async activate(code) {
    const previousMutation = this._activationMutationQueue;
    let releaseMutation;
    this._activationMutationQueue = new Promise((resolve) => { releaseMutation = resolve; });
    await previousMutation;
    try {
    if (!code || typeof code !== 'string') {
      return { success: false, message: 'License code is required' };
    }

    // Normalize code format
    code = code.trim().toUpperCase();
    if (!code.startsWith('DC-')) {
      return { success: false, message: 'Invalid code format. Codes start with DC-' };
    }
    if (this._refreshInFlight) await this._refreshInFlight;
    this._activationGeneration++;
    const previousActivation = this.activation;

    // Check if already activated with this code
    if (this.activation && this.activation.code === code && !this.isExpired() && !LICENSE_SERVER_URL) {
      return {
        success: true,
        message: 'This code is already activated',
        activation: this.getStatus()
      };
    }

    // Try online validation first
    let onlineResult = null;
    if (LICENSE_SERVER_URL) {
      onlineResult = await this._validateOnline(code);
      if (onlineResult && !onlineResult.success) {
        // Server explicitly rejected — revoke any matching cached entitlement.
        if (this.activation?.code === code) await this._revokeCachedEntitlement(onlineResult.message);
        return onlineResult;
      }
      if (!onlineResult) {
        if (this.activation && this.activation.code === code && this._isValidBoundedOnlineCache()) {
          return {
            success: true,
            message: 'License server unavailable; using the last online entitlement until its cached expiry',
            activation: this.getStatus()
          };
        }
        return { success: false, message: 'License server is temporarily unavailable. Try again shortly.' };
      }
    }

    // Offline validation (HMAC check)
    if (!onlineResult && !LICENSE_SERVER_URL) {
      const offlineResult = this._validateOffline(code);
      if (!offlineResult.valid) {
        return { success: false, message: offlineResult.reason || 'Invalid license code' };
      }
      if (offlineResult.expired) {
        return { success: false, message: 'License code has expired' };
      }

      // DC-052: LIFETIME keys are creator-only. Reject any lifetime code
      // unless ALLOW_LIFETIME_LICENSE=true is set on this host (Sami's
      // dev machine). Production / paid customers must NEVER be able to
      // activate a LIFETIME code — every other license is time-bound.
      const isLifetime = offlineResult.durationDays === 0;
      if (isLifetime && !this.allowsLifetimeLicense()) {
        this.log.warn?.('license', 'LIFETIME code rejected — not allowed on this host', {
          code: this._maskCode(code),
        });
        return {
          success: false,
          message: 'Lifetime licenses are not available. Please use a time-bounded license key.',
        };
      }

      // Code is cryptographically valid AND lifetime check passed
      const machineId = this.getMachineFingerprint();
      const now = new Date();
      const expiresAt = isLifetime
        ? new Date('2099-12-31T23:59:59.999Z')
        : new Date(offlineResult.expiresAt);

      this.activation = {
        code,
        codeId: offlineResult.codeId,
        durationDays: offlineResult.durationDays,
        lifetime: isLifetime,
        activatedAt: now.toISOString(),
        expiresAt: expiresAt.toISOString(),
        machineId,
        validationMethod: 'offline',
        features: Object.keys(PREMIUM_FEATURES)
      };
    } else {
      // Online validation succeeded — use server response
      this.activation = onlineResult.activation;
      this.activation.validationMethod = 'online';
      this.activation.lastOnlineValidatedAt = new Date().toISOString();
    }

    // Store activation token
    try {
      await this.credentialManager.store(LICENSE_CRED_KEY, JSON.stringify(this.activation), {
        activatedAt: this.activation.activatedAt,
        expiresAt: this.activation.expiresAt
      });
      await this._clearRevocationTombstone();
    } catch (error) {
      this.activation = previousActivation || null;
      this.log.error?.('license', 'Failed to store activation', { error: error.message });
      return { success: false, message: 'License validated but failed to save activation' };
    }

    // Update config.json with license info (non-sensitive)
    await this._updateConfig();
    this._startOnlineRefresh();

    this.log.info?.('license', 'License activated', {
      code: this._maskCode(code),
      durationDays: this.activation.durationDays,
      expiresAt: this.activation.expiresAt,
      method: this.activation.validationMethod
    });

    const durationLabel = this.activation.lifetime ? 'lifetime' : `${this.activation.durationDays} days`;
    return {
      success: true,
      message: `License activated for ${durationLabel}`,
      activation: this.getStatus()
    };
    } finally {
      releaseMutation();
    }
  }

  /**
   * Deactivate the current license
   * @returns {Object} { success, message }
   */
  async deactivate() {
    const previousMutation = this._activationMutationQueue;
    let releaseMutation;
    this._activationMutationQueue = new Promise((resolve) => { releaseMutation = resolve; });
    await previousMutation;
    try {
    if (!this.activation) {
      return { success: false, message: 'No active license to deactivate' };
    }
    if (this._refreshInFlight) await this._refreshInFlight;
    if (!this.activation) {
      return { success: false, message: 'License was already revoked during online refresh' };
    }
    this._activationGeneration++;

    const code = this._maskCode(this.activation.code);

    // If online server exists, notify it of deactivation
    if (LICENSE_SERVER_URL) {
      try {
        await this._notifyDeactivation();
      } catch (error) {
        this.log.warn?.('license', 'Could not notify license server of deactivation', { error: error.message });
      }
    }

    // Clear local activation
    await this.credentialManager.delete(LICENSE_CRED_KEY);
    this.activation = null;
    if (this._onlineRefreshTimer) {
      clearInterval(this._onlineRefreshTimer);
      this._onlineRefreshTimer = null;
    }
    await this._updateConfig();

    this.log.info?.('license', 'License deactivated', { code });

    return { success: true, message: 'License deactivated. You can reuse this code on another machine.' };
    } finally {
      releaseMutation();
    }
  }

  /**
   * Get current license status
   * @returns {Object} Status object
   */
  getStatus() {
    if (!this.activation) {
      return {
        active: false,
        tier: 'free',
        features: [],
        premiumFeatures: PREMIUM_FEATURES
      };
    }

    const expired = this.isExpired();
    const isLifetime = !!(this.activation.lifetime || this.activation.durationDays === 0);
    const daysRemaining = isLifetime ? null : this.daysRemaining();

    return {
      active: !expired,
      tier: expired ? 'free' : 'premium',
      lifetime: isLifetime,
      code: this._maskCode(this.activation.code),
      durationDays: this.activation.durationDays,
      activatedAt: this.activation.activatedAt,
      expiresAt: isLifetime ? null : this.activation.expiresAt,
      daysRemaining: isLifetime ? null : Math.max(0, daysRemaining),
      expired,
      features: expired ? [] : (this.activation.features || Object.keys(PREMIUM_FEATURES)),
      premiumFeatures: PREMIUM_FEATURES,
      validationMethod: this.activation.validationMethod
    };
  }

  /** Refresh a server-managed entitlement without changing its stable key. */
  async refreshOnline(force = false) {
    await this._activationMutationQueue;
    if (!LICENSE_SERVER_URL || !this.activation?.code) return false;
    const last = new Date(this.activation.lastOnlineValidatedAt || 0).getTime();
    if (!force && Date.now() - last < 60 * 60 * 1000) return true;
    if (this._refreshInFlight) return this._refreshInFlight;
    this._refreshInFlight = (async () => {
      const generation = this._activationGeneration;
      const refreshingCode = this.activation.code;
      const originalActivatedAt = this.activation.activatedAt;
      const result = await this._validateOnline(refreshingCode);
      if (generation !== this._activationGeneration || this.activation?.code !== refreshingCode) return false;
      if (result === null) return false;
      if (!result.success) {
        this.log.warn?.('license', 'License server explicitly rejected cached entitlement', { message: result.message });
        await this._revokeCachedEntitlement(result.message);
        return false;
      }
      this.activation = {
        ...this.activation,
        ...result.activation,
        activatedAt: originalActivatedAt || result.activation.activatedAt,
        validationMethod: 'online',
        lastOnlineValidatedAt: new Date().toISOString()
      };
      await this.credentialManager.store(LICENSE_CRED_KEY, JSON.stringify(this.activation), {
        activatedAt: this.activation.activatedAt,
        expiresAt: this.activation.expiresAt
      });
      await this._clearRevocationTombstone();
      await this._updateConfig();
      return true;
    })();
    try {
      return await this._refreshInFlight;
    } finally {
      this._refreshInFlight = null;
    }
  }

  _startOnlineRefresh() {
    if (!LICENSE_SERVER_URL || this._onlineRefreshTimer) return;
    this._onlineRefreshTimer = setInterval(() => {
      this.refreshOnline(true).catch((error) => {
        this.log.warn?.('license', 'Periodic online entitlement refresh failed', { error: error.message });
      });
    }, 15 * 60 * 1000);
    this._onlineRefreshTimer.unref?.();
  }

  _startStartupRecovery() {
    if (this._startupRecoveryTimer || !this._pendingStartupCode) return;
    this._startupRecoveryTimer = setInterval(() => {
      this._retryStartupValidation().catch((error) => {
        this.log.warn?.('license', 'Startup license recovery retry failed', { error: error.message });
      });
    }, 60 * 1000);
    this._startupRecoveryTimer.unref?.();
  }

  async _retryStartupValidation() {
    if (!this._pendingStartupCode || this.activation) return false;
    const code = this._pendingStartupCode;
    const result = await this._validateOnline(code);
    if (result === null) return false;
    if (!result.success) {
      const stored = await this.credentialManager.retrieve(LICENSE_CRED_KEY);
      try { this.activation = stored ? JSON.parse(stored) : { code }; } catch (_) { this.activation = { code }; }
      await this._revokeCachedEntitlement(result.message || 'Server rejected entitlement');
      this._pendingStartupCode = null;
      clearInterval(this._startupRecoveryTimer);
      this._startupRecoveryTimer = null;
      return false;
    }
    const nextActivation = {
      ...result.activation,
      validationMethod: 'online',
      lastOnlineValidatedAt: new Date().toISOString()
    };
    const previousStored = await this.credentialManager.retrieve(LICENSE_CRED_KEY);
    try {
      await this.credentialManager.store(LICENSE_CRED_KEY, JSON.stringify(nextActivation));
      this.activation = nextActivation;
      await this._updateConfig(true);
    } catch (error) {
      this.activation = null;
      try {
        if (previousStored) await this.credentialManager.store(LICENSE_CRED_KEY, previousStored);
        else await this.credentialManager.delete(LICENSE_CRED_KEY);
      } catch (rollbackError) {
        this.log.error?.('license', 'Recovery credential rollback failed; startup validation will still fail closed', { error: rollbackError.message });
      }
      this.log.warn?.('license', 'Recovered entitlement could not be committed; remaining fail-closed', { error: error.message });
      return false;
    }
    this._pendingStartupCode = null;
    clearInterval(this._startupRecoveryTimer);
    this._startupRecoveryTimer = null;
    this._startOnlineRefresh();
    return true;
  }

  /**
   * DC-165 rev2 (judge P0): repair an OFFLINE activation's feature snapshot
   * when it was stored by an older build whose PREMIUM_FEATURES lacked a
   * key this build gates (fleet, workflows, auto-backup). Without this the
   * offline snapshot would deny the feature forever despite an active
   * premium license. Refresh is an APPEND-ONLY union: current premium keys
   * first, then any unknown legacy entries preserved verbatim — a
   * missing-key repair never implies removal. Result is identical to what
   * re-activating the same code today would store (activate() writes
   * Object.keys(PREMIUM_FEATURES)). ONLINE activations are NOT touched:
   * their authoritative feature list comes from the license server on
   * validation; this only reconciles a local build's own derived snapshot
   * with its own constant. Store failure warns — in-memory state stays
   * correct for this process.
   */
  async _migrateOfflineFeatureSnapshot() {
    if (!this.activation || this.activation.validationMethod !== 'offline') return;
    if (!Array.isArray(this.activation.features)) return;
    const current = Object.keys(PREMIUM_FEATURES);
    const stored = new Set(this.activation.features);
    const missing = current.filter((f) => !stored.has(f));
    if (!missing.length) return;
    const extras = this.activation.features.filter((f) => !current.includes(f));
    this.activation.features = current.concat(extras);
    try {
      await this.credentialManager.store(LICENSE_CRED_KEY, JSON.stringify(this.activation), {
        activatedAt: this.activation.activatedAt,
        expiresAt: this.activation.expiresAt
      });
    } catch (error) {
      this.log.warn?.('license', 'Could not persist premium-feature migration (in-memory state still correct)', { error: error.message });
    }
    this.log.info?.('license', 'Migrated offline activation to current premium feature set', { added: missing });
  }

  async _validateLoadedActivationForServerMode() {
    if (!LICENSE_SERVER_URL || !this.activation) return true;
    const cachedWasOnline = this.activation.validationMethod === 'online';
    const result = await this._validateOnline(this.activation.code);
    // Startup always requires a live server decision. Bounded cached access is
    // only an in-process outage bridge; it is never trusted across restart.
    if (result === null) {
      // Fail closed now, preserve a validated-online credential, and retry in
      // this process so connectivity recovery does not require a restart.
      const pendingCode = this.activation.code;
      this.activation = null;
      if (!cachedWasOnline) {
        try { await this.credentialManager.delete(LICENSE_CRED_KEY); } catch (_) { /* remains quarantined */ }
      }
      try { await this._updateConfig(true); } catch (error) {
        this.log.warn?.('license', 'Could not persist startup outage state', { error: error.message });
      }
      if (cachedWasOnline) {
        this._pendingStartupCode = pendingCode;
        this._startStartupRecovery();
      }
      return false;
    }
    if (!result?.success) {
      await this._revokeCachedEntitlement(result?.message || 'Server validation required');
      return false;
    }
    this.activation = {
      ...this.activation,
      ...result.activation,
      validationMethod: 'online',
      lastOnlineValidatedAt: new Date().toISOString()
    };
    await this.credentialManager.store(LICENSE_CRED_KEY, JSON.stringify(this.activation));
    await this._clearRevocationTombstone();
    await this._updateConfig();
    return true;
  }

  async _revokeCachedEntitlement(reason) {
    const rejectedCode = this.activation?.code;
    this.activation = null;
    if (rejectedCode) {
      try {
        await this._writeRevocationTombstone(rejectedCode, reason);
      } catch (error) {
        this.log.error?.('license', 'CRITICAL: rejected entitlement could not be tombstoned; remaining fail-closed in memory', { error: error.message });
      }
    }
    try {
      await this.credentialManager.delete(LICENSE_CRED_KEY);
    } catch (error) {
      this.log.warn?.('license', 'Could not delete rejected entitlement from credential store', { error: error.message });
    }
    try {
      await this._updateConfig(true);
    } catch (error) {
      this.log.warn?.('license', 'Could not update config after entitlement rejection', { error: error.message });
    }
    this.log.warn?.('license', 'Cached entitlement revoked', { reason });
  }

  _revocationTombstonePath() {
    return `${this.configFile}.license-revoked`;
  }

  _codeDigest(code) {
    return crypto.createHash('sha256').update(String(code || '')).digest('hex');
  }

  async _writeRevocationTombstone(code, reason) {
    const tombstone = JSON.stringify({
      codeHash: this._codeDigest(code),
      revokedAt: new Date().toISOString(),
      reason
    });
    const target = this._revocationTombstonePath();
    const temp = `${target}.${process.pid}.${Date.now()}.tmp`;
    let handle;
    try {
      handle = await fs.promises.open(temp, 'wx', 0o600);
      await handle.writeFile(tombstone, 'utf8');
      await handle.sync();
      await handle.close();
      handle = null;
      await fs.promises.rename(temp, target);
      const dirHandle = await fs.promises.open(path.dirname(target), 'r');
      try { await dirHandle.sync(); } finally { await dirHandle.close(); }
    } catch (error) {
      if (handle) await handle.close().catch(() => {});
      await fs.promises.unlink(temp).catch(() => {});
      throw error;
    }
  }

  async _isRevocationTombstoned(code) {
    try {
      const data = JSON.parse(await fs.promises.readFile(this._revocationTombstonePath(), 'utf8'));
      return data.codeHash === this._codeDigest(code);
    } catch (error) {
      if (error.code === 'ENOENT') return false;
      // Corrupt/unreadable marker is fail-closed: never resurrect cached premium access.
      return true;
    }
  }

  async _clearRevocationTombstone() {
    try {
      await fs.promises.unlink(this._revocationTombstonePath());
    } catch (error) {
      if (error.code !== 'ENOENT') throw error;
    }
  }

  _isValidBoundedOnlineCache() {
    if (!this.activation || this.activation.validationMethod !== 'online') return false;
    const expiryMs = new Date(this.activation.expiresAt).getTime();
    const validatedAtMs = new Date(this.activation.lastOnlineValidatedAt || this.activation.activatedAt).getTime();
    const durationDays = Number(this.activation.durationDays);
    const validFeatures = Array.isArray(this.activation.features)
      && this.activation.features.every((item) => typeof item === 'string');
    return Number.isFinite(expiryMs)
      && Number.isFinite(validatedAtMs)
      && expiryMs > Date.now()
      && Number.isInteger(durationDays)
      && durationDays > 0
      && durationDays <= 3650
      && expiryMs <= validatedAtMs + (durationDays + 1) * 24 * 60 * 60 * 1000
      && validFeatures;
  }

  /**
   * Check if a specific premium feature is available
   * @param {string} feature - Feature key (e.g., 'sso', 'recipes', 'swarm')
   * @returns {boolean}
   */
  hasFeature(feature) {
    if (!this.activation) return false;
    if (this.isExpired()) return false;
    const features = this.activation.features || Object.keys(PREMIUM_FEATURES);
    return features.includes(feature);
  }

  /**
   * DC-052: shorthand for "is this host on a Pro license right now?"
   *
   * Returns true only when there's an active, non-expired license.
   * Lifetime keys also count as Pro (they're just permanent Pro).
   * Free tier = false. Returns false when no activation exists.
   */
  isPro() {
    if (!this.activation) return false;
    if (this.isExpired()) return false;
    // Lifetime keys are active forever; treat as Pro.
    return true;
  }

  /**
   * DC-052: are LIFETIME license codes permitted on this host?
   *
   * Default false. Set ALLOW_LIFETIME_LICENSE=true ONLY on the operator's
   * own dev machine — production hosts and paid customers must never be
   * able to activate a LIFETIME code. Per PRODUCT-SPEC-DECISIONS.md,
   * LIFETIME keys are creator-only; Stripe never issues them.
   */
  allowsLifetimeLicense() {
    return process.env.ALLOW_LIFETIME_LICENSE === 'true';
  }

  /**
   * Check if the license has expired
   */
  isExpired() {
    if (!this.activation) return true;
    if (this.activation.validationMethod === 'online') {
      const expiryMs = new Date(this.activation.expiresAt).getTime();
      return !Number.isFinite(expiryMs) || expiryMs <= Date.now();
    }
    // Lifetime must be explicitly signed/recorded as lifetime, not inferred from a zero.
    if (this.activation.lifetime === true && this.activation.durationDays === 0) return false;
    const expiryMs = new Date(this.activation.expiresAt).getTime();
    if (!Number.isFinite(expiryMs)) return true;
    return Date.now() > expiryMs;
  }

  _isStructurallyValidLoadedActivation() {
    const value = this.activation;
    if (!value || typeof value.code !== 'string' || !value.code.startsWith('DC-')) return false;
    if (!Array.isArray(value.features) || !value.features.every((feature) => typeof feature === 'string')) return false;
    if (value.validationMethod === 'online') return this._isValidBoundedOnlineCache();
    if (value.validationMethod !== 'offline') return false;
    if (value.lifetime === true) return value.durationDays === 0;
    if (!Number.isInteger(value.durationDays) || value.durationDays <= 0) return false;
    const expiryMs = new Date(value.expiresAt).getTime();
    return Number.isFinite(expiryMs) && expiryMs > Date.now();
  }

  /**
   * Get days remaining on the license
   */
  daysRemaining() {
    if (!this.activation) return 0;
    const remaining = new Date(this.activation.expiresAt).getTime() - Date.now();
    return Math.ceil(remaining / 86400000);
  }

  /**
   * Express middleware: gate a route behind a premium feature
   * @param {string} feature - Feature key
   * @returns {Function} Express middleware
   */
  requirePremium(feature) {
    return (req, res, next) => {
      if (this.hasFeature(feature)) {
        return next();
      }

      const featureInfo = PREMIUM_FEATURES[feature] || { name: feature };
      return errorResponse(res, 403, `${featureInfo.name} requires a DashCaddy Premium subscription.`, {
        premiumRequired: true,
        feature,
        featureName: featureInfo.name,
        featureDescription: featureInfo.description,
        currentTier: this.isExpired() ? 'free' : 'expired',
        upgradeUrl: '/settings#license'
      });
    };
  }

  // Private methods

  /**
   * Validate code offline using HMAC
   */
  _validateOffline(code) {
    if (!this.masterSecretHash) {
      // No secret available — try structural validation only
      try {
        const parsed = parseCode(code);
        // Without the secret we can't verify HMAC, but we can check structure
        if (parsed.version !== 1) return { valid: false, reason: 'Unsupported code version' };
        if (parsed.durationDays !== 0 && !VALID_DURATIONS.includes(parsed.durationDays)) return { valid: false, reason: 'Invalid duration' };
        // Can't verify signature without secret — reject
        return { valid: false, reason: 'License validation unavailable. Please try again when connected to the internet.' };
      } catch (e) {
        return { valid: false, reason: e.message };
      }
    }

    // Full verification with secret
    return verifyCode(this.masterSecretHash, code);
  }

  /**
   * Validate code against online license server
   */
  async _validateOnline(code) {
    try {
      const machineId = this.getMachineFingerprint();
      const response = await fetch(`${LICENSE_SERVER_URL}/api/license/validate`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ code, machineId }),
        signal: AbortSignal.timeout(10000) // 10s timeout
      });

      if (!response.ok) {
        const data = await response.json().catch(() => ({}));
        const authoritativeStatuses = new Set([400, 401, 403, 404, 409, 410, 422]);
        if (authoritativeStatuses.has(response.status)) {
          return { success: false, message: data.error || `Server returned ${response.status}` };
        }
        this.log.warn?.('license', 'License server returned a retryable status', { status: response.status });
        return null;
      }

      const data = await response.json();
      if (data.success) {
        const expiryMs = typeof data.expiresAt === 'string' ? new Date(data.expiresAt).getTime() : NaN;
        const durationDays = Number(data.durationDays);
        const validFeatures = Array.isArray(data.features) && data.features.every((item) => typeof item === 'string');
        const maxExpiryMs = Date.now() + (durationDays + 1) * 24 * 60 * 60 * 1000;
        if (!Number.isFinite(expiryMs) || expiryMs <= Date.now()
            || expiryMs > maxExpiryMs
            || !Number.isInteger(durationDays) || durationDays <= 0 || durationDays > 3650
            || !validFeatures) {
          this.log.warn?.('license', 'License server returned a malformed success response');
          return null;
        }
        return {
          success: true,
          activation: {
            code,
            codeId: data.codeId,
            durationDays,
            activatedAt: new Date().toISOString(),
            expiresAt: data.expiresAt,
            machineId,
            features: data.features,
            serverToken: data.token || null
          }
        };
      }

      if (data.success === false && (typeof data.error === 'string' || typeof data.message === 'string')) {
        return { success: false, message: data.error || data.message };
      }
      this.log.warn?.('license', 'License server returned an ambiguous HTTP 200 response');
      return null;
    } catch (error) {
      // Server unreachable — keep only a previously online-validated cached
      // entitlement, bounded by its last server-provided expiry.
      this.log.warn?.('license', 'License server unreachable', {
        error: error.message
      });
      return null;
    }
  }

  /**
   * Notify license server of deactivation
   */
  async _notifyDeactivation() {
    if (!LICENSE_SERVER_URL || !this.activation) return;
    await fetch(`${LICENSE_SERVER_URL}/api/license/deactivate`, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({
        code: this.activation.code,
        machineId: this.activation.machineId,
        serverToken: this.activation.serverToken
      }),
      signal: AbortSignal.timeout(10000)
    });
  }

  /**
   * Update config.json with license summary. Legacy offline mode also stores
   * a backup; server-managed mode keeps activation tokens only in credentials.
   */
  async _updateConfig(throwOnError = false) {
    try {
      const fsp = require('fs').promises;
      let config = {};
      try {
        const data = await fsp.readFile(this.configFile, 'utf8');
        config = JSON.parse(data);
      } catch (e) {
        // Config doesn't exist yet
      }

      if (this.activation && !this.isExpired()) {
        config.license = {
          active: true,
          tier: 'premium',
          expiresAt: this.activation.expiresAt,
          daysRemaining: this.daysRemaining(),
          features: this.activation.features || Object.keys(PREMIUM_FEATURES)
        };
        // Full backup of activation data (config.json is volume-mounted and persists)
        if (LICENSE_SERVER_URL) delete config.licenseBackup;
        else config.licenseBackup = this.activation;
      } else {
        config.license = { active: false, tier: 'free' };
        delete config.licenseBackup;
      }

      config.updatedAt = new Date().toISOString();
      await fsp.writeFile(this.configFile, JSON.stringify(config, null, 2), 'utf8');
    } catch (error) {
      this.log.error?.('license', 'Failed to update config with license info', { error: error.message });
      if (throwOnError) throw error;
    }
  }

  /**
   * Mask a license code for display (show first and last groups only)
   */
  _maskCode(code) {
    if (!code) return 'none';
    const parts = code.split('-');
    if (parts.length < 4) return 'DC-*****';
    return `${parts[0]}-${parts[1]}-*****-*****-${parts[parts.length - 1]}`;
  }
}

module.exports = { LicenseManager, PREMIUM_FEATURES };