import { NextRequest, NextResponse } from 'next/server';
import { configManager } from '@/lib/admin/config-manager';
import { requireAdminAuth, getClientIP } from '@/lib/admin/session';
import { auditLog } from '@/lib/admin/audit';
import { logger } from '@/lib/logger';
import { POLICY_DOMAINS_HEADER, POLICY_SCOPE_HEADER, type SettingsPolicy } from '@/lib/admin/types';
import { canSeeInstanceDetails, signedInIdentity } from '@/lib/auth/instance-details';
import { scopesVisibleTo } from '@/lib/admin/policy-scopes';
import { configReadOnlyResponse } from '@/lib/admin/config-read-only-response';

/**
 * GET /api/admin/policy - Get settings policy (NOT admin-protected - users read this;
 * visitors who are not signed in get the subset the login page needs)
 */
export async function GET(request: NextRequest) {
  try {
    await configManager.ensureLoaded();
    const policy = configManager.getPolicy();
    if (!(await canSeeInstanceDetails(request))) {
      // The login page needs the theme policy and gates; the plugin lists,
      // push relays and sidebar app URLs map the deployment and are only
      // used after signing in, when the client fetches the policy again.
      return NextResponse.json(
        {
          ...policy,
          forceEnabledPlugins: [],
          approvedPlugins: [],
          pushRelays: [],
          pushRelayUrl: '',
          pushRelayUrlLocked: false,
          defaultSidebarApps: [],
          // Signatures, domain lists and scopes describe the organisation
          // and only apply once someone is signed in.
          organisation: undefined,
          scopes: [],
        },
        { headers: { 'Cache-Control': 'no-store', [POLICY_SCOPE_HEADER]: 'public' } },
      );
    }
    // Users get only the scopes for their own domains, so on an instance
    // shared by several organisations one doesn't see another's settings.
    // Without a session secret the server can't tell who is asking and
    // answers with all of them (documented).
    const identity = await signedInIdentity();
    const filtered = identity !== null && !identity.admin;
    const scopes = filtered
      ? scopesVisibleTo(policy.scopes ?? [], identity.addresses)
      : policy.scopes ?? [];
    // Which domains the scopes were picked for, so a browser that signs in
    // to an account of another domain knows to fetch again.
    const domains = filtered
      ? [...new Set(identity.addresses.map((a) => a.slice(a.lastIndexOf('@') + 1)).filter(Boolean))].join(',')
      : null;
    return NextResponse.json({ ...policy, scopes }, {
      headers: { 'Cache-Control': 'no-store', ...(domains !== null ? { [POLICY_DOMAINS_HEADER]: domains } : {}) },
    });
  } catch (error) {
    logger.error('Policy read error', { error: error instanceof Error ? error.message : 'Unknown error' });
    return NextResponse.json({ error: 'Internal server error' }, { status: 500 });
  }
}

/**
 * PUT /api/admin/policy - Update settings policy (admin-protected)
 */
export async function PUT(request: NextRequest) {
  try {
    const result = await requireAdminAuth(request);
    if ('error' in result) return result.error;

    const ip = getClientIP(request);
    const policy = await request.json() as SettingsPolicy;

    if (!policy || typeof policy !== 'object') {
      return NextResponse.json({ error: 'Invalid policy object' }, { status: 400 });
    }

    // Basic validation
    if (policy.restrictions && typeof policy.restrictions !== 'object') {
      return NextResponse.json({ error: 'restrictions must be an object' }, { status: 400 });
    }
    if (policy.features && typeof policy.features !== 'object') {
      return NextResponse.json({ error: 'features must be an object' }, { status: 400 });
    }
    if (policy.defaults !== undefined && (typeof policy.defaults !== 'object' || policy.defaults === null || Array.isArray(policy.defaults))) {
      return NextResponse.json({ error: 'defaults must be an object' }, { status: 400 });
    }
    if (policy.themePolicy && typeof policy.themePolicy !== 'object') {
      return NextResponse.json({ error: 'themePolicy must be an object' }, { status: 400 });
    }
    if (policy.defaultSidebarApps !== undefined && !Array.isArray(policy.defaultSidebarApps)) {
      return NextResponse.json({ error: 'defaultSidebarApps must be an array' }, { status: 400 });
    }
    if (policy.scopes !== undefined && !Array.isArray(policy.scopes)) {
      return NextResponse.json({ error: 'scopes must be an array' }, { status: 400 });
    }
    if (policy.organisation !== undefined && (typeof policy.organisation !== 'object' || policy.organisation === null || Array.isArray(policy.organisation))) {
      return NextResponse.json({ error: 'organisation must be an object' }, { status: 400 });
    }

    await configManager.setPolicy(policy);
    await auditLog('policy.update', {
      restrictionCount: Object.keys(policy.restrictions || {}).length,
      // Entries the sanitizer dropped never reach users, so log what stuck.
      defaultSidebarAppCount: configManager.getPolicy().defaultSidebarApps?.length ?? 0,
    }, ip);

    return NextResponse.json({ ok: true });
  } catch (error) {
    const readOnly = configReadOnlyResponse(error);
    if (readOnly) return readOnly;
    logger.error('Policy update error', { error: error instanceof Error ? error.message : 'Unknown error' });
    return NextResponse.json({ error: 'Internal server error' }, { status: 500 });
  }
}