/**
 * Network invite routes — DC-142 (link-first invites via network provider).
 *
 *   GET    /api/v1/network/invites        → list active invites via provider
 *   POST   /api/v1/network/invites        → create an invite (link-first)
 *   DELETE /api/v1/network/invites/:id    → revoke an invite (204)
 *
 * Link-first contract (DC-085 pattern, specs/PRIVATE-NETWORK-SPEC.md §5):
 *   - The inviteUrl IS the deliverable. Email is an opt-in checkbox
 *     (`sendEmail: true`, strict === true — default NO email).
 *   - POST response ALWAYS includes { inviteUrl, shareText, deliveredVia }:
 *       shareText   — pre-formed human sentence (never a JSON blob), built
 *                     server-side so every client picks up the wording
 *       deliveredVia — 'manual' (no email requested) | 'email' (provider
 *                     confirmed the send) | 'failed' (email was requested but
 *                     the send failed — the link is STILL returned so the
 *                     operator can share it manually)
 *   - NEVER log raw inviteUrl/token values. Every log call goes through
 *     redact() which replaces link-bearing fields with '[REDACTED]'. The DC-048
 *     mistake (echoing invite links to the server console) must not return.
 *
 * Provider resolution goes exclusively through deps.networkRegistry
 * (src/network registry). When no provider is connected the registry throws
 * ProviderNotActiveError; this module maps it (and a missing registry) to a
 * 503 with code 'provider_not_active' — the setup wizard (DC-152) is the fix.
 *
 * Hermetic by construction: the factory takes an injectable registry, logger
 * and asyncHandler; tests pass a mocked provider, no network.
 */

'use strict';

const { ValidationError, NotFoundError } = require('../src/utilities/errors');
const { ok, created, noContent } = require('../src/utils/responses');
const { ProviderError, ProviderNotActiveError } = require('../src/network/errors');

/** Tailscale user-invite roles (provider contract, DC-140). */
const VALID_ROLES = new Set(['member', 'admin']);

const REDACTED = '[REDACTED]';
/** Fields whose values embed the raw invite link — never allowed into logs. */
const REDACT_KEYS = new Set(['inviteUrl', 'acceptUrl', 'url', 'token', 'shareText']);

/**
 * Shallow-copy a log-fields object, replacing link/token-bearing values.
 * The admin already has the link in the API response; the console does not
 * need a copy (DC-085 rule 2).
 */
function redact(fields) {
  const out = {};
  for (const [key, value] of Object.entries(fields || {})) {
    out[key] = REDACT_KEYS.has(key) ? REDACTED : value;
  }
  return out;
}

/** 503 — no network provider connected (mapped from ProviderNotActiveError). */
class ProviderInactiveError extends Error {
  constructor(message) {
    super(message || 'No active network provider configured');
    this.name = 'ProviderInactiveError';
    this.statusCode = 503;
    this.code = 'provider_not_active';
    this.isOperational = true;
  }
}

/** Validate the provider's createInvite result shape. */
function assertInviteResult(invite) {
  if (!invite || typeof invite.inviteUrl !== 'string' || !invite.inviteUrl) {
    throw new Error('provider createInvite() must return { inviteUrl }');
  }
}

/** Pull the still-valid link off a failed email send, or null. */
function linkFromEmailFailure(err) {
  if (!err || err.code !== 'email_send_failed') return null;
  const details = err.details;
  const url = err.inviteUrl || (details && details.inviteUrl);
  return url ? { url, id: (details && details.id) || null } : null;
}

module.exports = function networkInvitesRoutesFactory({
  networkRegistry,
  asyncHandler,
  log = { info() {}, warn() {}, error() {} },
} = {}) {
  const router = require('express').Router();

  const safeAsync = typeof asyncHandler === 'function'
    ? asyncHandler
    : (fn) => (req, res, next) => Promise.resolve(fn(req, res, next)).catch(next);

  /** Resolve the active provider or throw the 503-mapped inactive error. */
  function requireProvider() {
    if (!networkRegistry || typeof networkRegistry.getActiveProvider !== 'function') {
      throw new ProviderInactiveError();
    }
    try {
      return networkRegistry.getActiveProvider();
    } catch (err) {
      if (err instanceof ProviderNotActiveError || (err && err.code === 'provider_not_active')) {
        throw new ProviderInactiveError(err.message);
      }
      throw err;
    }
  }

  /** Map ProviderError codes onto HTTP statuses for the error middleware. */
  function mapProviderError(err) {
    if (err instanceof ProviderInactiveError) return err;
    if (err && (err instanceof ProviderError || typeof err.code === 'string')) {
      if (err.code === 'not_found') return new NotFoundError(err.message || 'invite not found');
      if (err.code === 'bad_input') return new ValidationError(err.message || 'invalid input', 'invite');
      if (err.code === 'provider_not_active') return new ProviderInactiveError(err.message);
      const upstream = new Error(err.message || 'network provider error');
      upstream.statusCode = 502;
      upstream.code = err.code || 'provider_error';
      upstream.isOperational = true;
      return upstream;
    }
    return err;
  }

  /**
   * Email leg of the link-first flow (only entered when sendEmail === true).
   * Never a total failure when the link exists: a failed send downgrades to
   * deliveredVia 'failed' with the link still in the response (DC-085 rule 1).
   */
  async function createInviteWithEmail(provider, { role, email }) {
    let invite;
    let deliveredVia;
    try {
      invite = await provider.createInvite({ role, email });
      assertInviteResult(invite);
      // Providers confirm the email leg with emailSent: true on the result.
      deliveredVia = invite.emailSent === true ? 'email' : 'failed';
      if (deliveredVia === 'failed') {
        log.warn && log.warn(
          'network-invites',
          'provider did not confirm email delivery — link returned for manual sharing',
          redact({ inviteId: invite.id || null, email, role })
        );
      }
      return { invite, deliveredVia };
    } catch (err) {
      const salvaged = linkFromEmailFailure(err);
      if (salvaged) {
        log.warn && log.warn(
          'network-invites',
          'provider email send failed — link returned for manual sharing',
          redact({ inviteId: salvaged.id, email, role })
        );
        return { invite: { inviteUrl: salvaged.url, id: salvaged.id }, deliveredVia: 'failed' };
      }
      throw mapProviderError(err);
    }
  }

  // ─── GET / — list active invites ────────────────────────────────────────
  router.get('/', safeAsync(async (_req, res) => {
    const provider = requireProvider();
    // Capability degradation (spec §3): providers without listInvites (the
    // DC-140 tailscale provider does not expose it yet) get an honest empty
    // list instead of a 500.
    if (typeof provider.listInvites !== 'function') {
      log.info && log.info('network-invites', 'provider cannot list invites — returning empty list');
      ok(res, { data: [], count: 0, supported: false });
      return;
    }
    const invites = await provider.listInvites();
    if (!Array.isArray(invites)) {
      throw new ValidationError('provider listInvites() must return an array', 'provider');
    }
    ok(res, { data: invites, count: invites.length, supported: true });
  }));

  // ─── POST / — create an invite (link-first, email opt-in) ───────────────
  router.post('/', safeAsync(async (req, res) => {
    const body = req.body || {};

    const displayName = typeof body.displayName === 'string' ? body.displayName.trim() : '';
    if (!displayName || displayName.length > 80) {
      throw new ValidationError('displayName is required (1-80 characters)', 'displayName');
    }
    const role = body.role;
    if (!VALID_ROLES.has(role)) {
      throw new ValidationError('role must be one of: ' + [...VALID_ROLES].join(', '), 'role');
    }

    // Strict opt-in: only sendEmail === true counts (never 'yes'/1/'on').
    const sendEmail = body.sendEmail === true;

    let email;
    if (body.email !== undefined && body.email !== null && body.email !== '') {
      if (typeof body.email !== 'string' || !/^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(body.email)) {
        throw new ValidationError('email must be a valid address when provided', 'email');
      }
      email = body.email;
    }
    if (sendEmail && !email) {
      throw new ValidationError('sendEmail: true requires an email address', 'sendEmail');
    }

    const provider = requireProvider();

    let invite;
    let deliveredVia;
    if (sendEmail) {
      ({ invite, deliveredVia } = await createInviteWithEmail(provider, { role, email }));
    } else {
      // Default path: no email key at all — the provider mints the link
      // WITHOUT sending anything (Tailscale user-invites: email optional).
      try {
        invite = await provider.createInvite({ role });
      } catch (err) {
        throw mapProviderError(err);
      }
      assertInviteResult(invite);
      deliveredVia = 'manual';
    }

    // Pre-formed human sentence (never a JSON blob). Server-side canonical
    // wording so every client picks it up on refresh (DC-085 rule 3).
    const shareText = displayName
      + ' invited you to join the family network — open this link on your device: '
      + invite.inviteUrl;

    log.info && log.info(
      'network-invites',
      'invite created',
      redact({ inviteId: invite.id || null, role, deliveredVia, email })
    );

    created(res, {
      inviteUrl: invite.inviteUrl,
      shareText,
      deliveredVia,
      id: invite.id || null,
      role,
      displayName,
    });
  }));

  // ─── DELETE /:id — revoke an invite ─────────────────────────────────────
  router.delete('/:id', safeAsync(async (req, res) => {
    const id = req.params && req.params.id;
    if (!id) throw new ValidationError('invite id is required', 'id');
    const provider = requireProvider();
    try {
      await provider.revokeInvite(id);
    } catch (err) {
      throw mapProviderError(err);
    }
    // inviteId is provider metadata, not the token — safe to log.
    log.info && log.info('network-invites', 'invite revoked', { inviteId: id });
    noContent(res);
  }));

  return router;
};