/**
 * Network lifecycle orchestration — DC-143 (specs/PRIVATE-NETWORK-SPEC.md §5).
 *
 * Block / unblock / remove person + revoke device, coordinating four systems
 * behind one consistent operation each:
 *
 *   - the network provider (deny at ACL/firewall level, expire device keys)
 *   - the people store (status: active | blocked | removed)
 *   - the access store (person-level grants: purged on block, restored on
 *     unblock, deleted on remove)
 *   - DashCaddy sessions (killed on block/remove)
 *
 * ## Honest unblock (NORMATIVE, spec §5)
 *
 * Blocking a Tailscale person EXPIRES their device keys. Those keys are NOT
 * silently un-expired on unblock — blocked devices must re-authenticate with
 * Tailscale on next connect. unblockPerson() therefore returns
 * `reauthRequired: true` for the tailscale provider plus a human-readable
 * note; WireGuard peers are re-generated server-side from the stored pubkey
 * and reconnect immediately (reauthRequired: false, different note).
 *
 * ## Ordering rules (consistency under provider failure)
 *
 *   block:   guard → snapshot grants → provider.blockPerson → mark blocked
 *            → purge grants → kill sessions → audit.
 *            A provider failure leaves the person ACTIVE with grants intact
 *            (nothing mutated before the provider call succeeds).
 *   unblock: mark active → restore grants → provider.unblockPerson → audit.
 *   remove:  guard → provider.removePerson → delete person + grants +
 *            snapshot → kill sessions → audit.
 *
 * Provider errors are mapped to ProviderError at this boundary and NEVER
 * swallowed — the caller (route) sees them.
 *
 * All dependencies are injectable; nothing here touches the network or the
 * filesystem beyond the (optional, injectable) grant-snapshot sidecar file.
 */

'use strict';

const fs = require('fs');
const path = require('path');
const os = require('os');
const { ProviderError } = require('./errors');

const REAUTH_NOTES = {
  tailscale:
    'Unblocked, but blocked devices were signed out and their network keys expired — they will need to sign in again to reconnect.',
  wireguard:
    'Unblocked — WireGuard peers are restored from their stored keys and reconnect immediately; no re-authentication needed.',
};

const DEFAULT_NOTE =
  'Unblocked — device access has been restored.';

/**
 * Read/write sidecar holding grant snapshots taken at block time so unblock
 * can restore them. Plain JSON, best-effort (a missing/corrupt file means
 * "nothing to restore", never a failed unblock).
 */
function _createSnapshotStore(dataDir) {
  const file = path.join(dataDir, 'network-block-snapshots.json');
  function load() {
    try {
      const data = JSON.parse(fs.readFileSync(file, 'utf8'));
      return data && typeof data === 'object' && data.snapshots
        ? data
        : { snapshots: {} };
    } catch (_err) {
      return { snapshots: {} };
    }
  }
  function save(data) {
    const tmp = `${file}.tmp-${process.pid}-${Date.now()}`;
    fs.writeFileSync(tmp, JSON.stringify(data, null, 2));
    fs.renameSync(tmp, file);
  }
  return {
    get(personId) {
      const snaps = load().snapshots[personId];
      return Array.isArray(snaps) ? snaps : [];
    },
    put(personId, grants) {
      const data = load();
      data.snapshots[personId] = grants;
      save(data);
    },
    clear(personId) {
      const data = load();
      if (!(personId in data.snapshots)) return;
      delete data.snapshots[personId];
      save(data);
    },
  };
}

function createNetworkLifecycle({
  provider,
  peopleStore,
  accessStore,
  sessionKiller,
  auditLog,
  logger = { info() {}, warn() {}, error() {} },
  snapshotDataDir,
} = {}) {
  if (!provider) throw new TypeError('lifecycle requires a provider');
  if (!peopleStore) throw new TypeError('lifecycle requires a peopleStore');
  if (!accessStore) throw new TypeError('lifecycle requires an accessStore');

  const killSessions =
    typeof sessionKiller === 'function'
      ? sessionKiller
      : async (personId) => {
          logger.warn && logger.warn('network-lifecycle',
            'no sessionKiller injected; sessions left standing', { personId });
          return 0;
        };

  const audit =
    auditLog && typeof auditLog.log === 'function'
      ? (entry) => auditLog.log(entry).catch((err) => {
          logger.warn && logger.warn('network-lifecycle',
            'audit write failed (isolated)', { err: err && err.message });
        })
      : (_entry) => Promise.resolve();

  const snapshots = _createSnapshotStore(
    typeof snapshotDataDir === 'string' && snapshotDataDir
      ? snapshotDataDir
      : os.tmpdir()
  );

  /**
   * Wrap a provider call: ProviderError passes through untouched; any other
   * thrown value is mapped to a ProviderError so no provider-specific error
   * type escapes the lifecycle. Never swallows.
   */
  async function _callProvider(method, ...args) {
    try {
      return await provider[method](...args);
    } catch (err) {
      if (err instanceof ProviderError) throw err;
      throw new ProviderError(
        `provider.${method} failed: ${err && err.message ? err.message : String(err)}`,
        { code: (err && err.code) || 'server_error', cause: err }
      );
    }
  }

  /** Person-level grants currently in the access map. */
  async function _personGrants(personId) {
    const map = await accessStore.getAccessMap();
    return (map.grants || [])
      .filter(g => g.principal && g.principal.type === 'person' && g.principal.id === personId)
      .map(g => ({ principal: { type: 'person', id: personId }, resource: g.resource, allowed: g.allowed }));
  }

  async function _requirePerson(personId) {
    const person = await peopleStore.getPerson(personId);
    if (!person) {
      const err = new Error(`person not found: ${personId}`);
      err.name = 'NotFoundError';
      err.statusCode = 404;
      err.code = 'not_found';
      throw err;
    }
    return person;
  }

  /**
   * BLOCK a person (spec §5): network deny + expire device keys + kill
   * DashCaddy sessions + mark blocked. Person-level grants are snapshotted
   * (for unblock restore) and purged. Returns { blocked, grantSnapshot }.
   */
  async function blockPerson(personId) {
    await _requirePerson(personId);
    // Guard BEFORE any provider or local mutation.
    await peopleStore.assertNotLastAdmin(personId);

    // Snapshot BEFORE any mutation (restored by unblockPerson).
    const grants = await _personGrants(personId);
    snapshots.put(personId, grants);

    // Provider first: a failure here leaves the person active + grants
    // intact (consistent, honest) and the error surfaces to the caller.
    await _callProvider('blockPerson', personId);

    // Mark blocked BEFORE purging grants — a blocked person must never be
    // observable as active-without-grants in the other direction either.
    await peopleStore.updatePerson(personId, { status: 'blocked' });

    for (const g of grants) {
      await accessStore.removeGrant(g.principal, g.resource);
    }

    let sessionsKilled = 0;
    try {
      sessionsKilled = await killSessions(personId) || 0;
    } catch (err) {
      logger.error && logger.error('network-lifecycle',
        'session kill failed after block (person already blocked)', {
          personId, err: err && err.message,
        });
    }

    await audit({
      action: 'network.person.block',
      resource: `network/people/${personId}`,
      details: { personId, grantSnapshot: grants.length, sessionsKilled },
      outcome: 'success',
    });

    logger.info && logger.info('network-lifecycle', 'person blocked', {
      personId, grantSnapshot: grants.length,
    });

    return { blocked: true, grantSnapshot: grants.length, sessionsKilled };
  }

  /**
   * UNBLOCK a person (spec §5, honest-unblock): reverse status, restore
   * grants, reverse the network deny. Tailscale device keys that were
   * expired at block time are NOT un-expired — those devices must sign in
   * again, which the returned note states plainly. WireGuard peers are
   * regenerated from stored pubkeys and reconnect immediately.
   */
  async function unblockPerson(personId) {
    await _requirePerson(personId);

    await peopleStore.updatePerson(personId, { status: 'active' });

    const grants = snapshots.get(personId);
    for (const g of grants) {
      await accessStore.setGrant(g.principal, g.resource, g.allowed);
    }
    snapshots.clear(personId);

    await _callProvider('unblockPerson', personId);

    const providerId = typeof provider.id === 'function' ? provider.id() : 'unknown';
    const reauthRequired = providerId === 'tailscale';
    const note = REAUTH_NOTES[providerId] || DEFAULT_NOTE;

    await audit({
      action: 'network.person.unblock',
      resource: `network/people/${personId}`,
      details: { personId, restoredGrants: grants.length, reauthRequired, providerId },
      outcome: 'success',
    });

    logger.info && logger.info('network-lifecycle', 'person unblocked', {
      personId, restoredGrants: grants.length, reauthRequired,
    });

    return {
      unblocked: true,
      restoredGrants: grants.length,
      reauthRequired,
      note,
      providerId,
    };
  }

  /**
   * REMOVE a person: block semantics + provider device deletion + delete
   * the person record + purge grants + kill sessions. Not reversible.
   */
  async function removePerson(personId) {
    await _requirePerson(personId);
    await peopleStore.assertNotLastAdmin(personId);

    await _callProvider('removePerson', personId);

    await peopleStore.deletePerson(personId);

    const grants = await _personGrants(personId);
    for (const g of grants) {
      await accessStore.removeGrant(g.principal, g.resource);
    }
    snapshots.clear(personId);

    let sessionsKilled = 0;
    try {
      sessionsKilled = await killSessions(personId) || 0;
    } catch (err) {
      logger.error && logger.error('network-lifecycle',
        'session kill failed after remove (person already deleted)', {
          personId, err: err && err.message,
        });
    }

    await audit({
      action: 'network.person.remove',
      resource: `network/people/${personId}`,
      details: { personId, purgedGrants: grants.length, sessionsKilled },
      outcome: 'success',
    });

    logger.info && logger.info('network-lifecycle', 'person removed', { personId });

    return { removed: true, purgedGrants: grants.length, sessionsKilled };
  }

  /**
   * REVOKE one device: expire its access at the provider and drop it from
   * person.devices. `personId` must own the device.
   */
  async function revokeDevice(personId, deviceId) {
    if (!deviceId || typeof deviceId !== 'string') {
      const err = new Error('deviceId is required');
      err.name = 'ValidationError';
      err.statusCode = 400;
      err.code = 'bad_input';
      throw err;
    }
    const person = await _requirePerson(personId);
    if (!person.devices.some(d => (d && d.id) === deviceId || d === deviceId)) {
      const err = new Error(`device ${deviceId} does not belong to person ${personId}`);
      err.name = 'NotFoundError';
      err.statusCode = 404;
      err.code = 'not_found';
      throw err;
    }

    await _callProvider('revokeDevice', deviceId);

    await peopleStore.updatePerson(personId, {
      devices: person.devices.filter(d => (d && d.id) !== deviceId && d !== deviceId),
    });

    await audit({
      action: 'network.device.revoke',
      resource: `network/devices/${deviceId}`,
      details: { personId, deviceId },
      outcome: 'success',
    });

    logger.info && logger.info('network-lifecycle', 'device revoked', {
      personId, deviceId,
    });

    return { revoked: true, personId, deviceId };
  }

  return { blockPerson, unblockPerson, removePerson, revokeDevice };
}

module.exports = { createNetworkLifecycle, REAUTH_NOTES };