export const PORTAL_ACCESS_CLASS = Object.freeze({
  PUBLIC: 'public',
  OPTIONAL_USER: 'optional-user',
  AUTHENTICATED: 'authenticated',
  INTERNAL: 'internal',
  ROUTE_AUTHORIZED: 'route-authorized',
});

export const PORTAL_ACCESS_POLICY_MODE = Object.freeze({
  OFF: 'off',
  SHADOW: 'shadow',
});

export const PORTAL_ACCESS_ENFORCEMENT_GROUPS = Object.freeze([
  'legacy-page-data',
  'page-data-public',
  'plaza-optional-user',
]);

const DEFAULT_SHADOW_LOG_INTERVAL_MS = 60_000;
const MIN_SHADOW_LOG_INTERVAL_MS = 1_000;
const MAX_SHADOW_LOG_INTERVAL_MS = 60 * 60_000;

function freezeRule(rule) {
  return Object.freeze({
    ...rule,
    paths: rule.paths ? Object.freeze([...rule.paths]) : undefined,
    methods: rule.methods ? Object.freeze([...rule.methods]) : undefined,
  });
}

export const PORTAL_STATIC_ACCESS_RULES = Object.freeze([
  freezeRule({
    id: 'runtime-status',
    accessClass: PORTAL_ACCESS_CLASS.PUBLIC,
    legacyDirectBypass: true,
    paths: ['/status', '/runtime/status'],
  }),
  freezeRule({
    id: 'blocked-words',
    accessClass: PORTAL_ACCESS_CLASS.PUBLIC,
    legacyDirectBypass: true,
    paths: ['/config/blocked-words'],
  }),
  freezeRule({
    id: 'internal-agent',
    accessClass: PORTAL_ACCESS_CLASS.INTERNAL,
    legacyDirectBypass: true,
    pathPrefix: '/internal/agent/',
  }),
  freezeRule({
    id: 'internal-deep-search-llm',
    accessClass: PORTAL_ACCESS_CLASS.INTERNAL,
    legacyDirectBypass: true,
    paths: ['/internal/deep-search/llm'],
  }),
  freezeRule({
    id: 'mindspace-agent-callback',
    accessClass: PORTAL_ACCESS_CLASS.INTERNAL,
    legacyDirectBypass: true,
    paths: [
      '/agent/mindspace_page_patch',
      '/agent/mindspace_asset_delete',
      '/agent/mindspace_asset_download',
      '/agent/mindspace_image_generate',
    ],
  }),
  freezeRule({
    id: 'image-make-runtime-config',
    accessClass: PORTAL_ACCESS_CLASS.INTERNAL,
    legacyDirectBypass: true,
    paths: ['/internal/image-make/runtime-config'],
  }),
  freezeRule({
    id: 'mindspace-asset-download',
    accessClass: PORTAL_ACCESS_CLASS.ROUTE_AUTHORIZED,
    legacyDirectBypass: true,
    methods: ['GET'],
    pathPattern: /^\/mindspace\/v1\/assets\/[^/]+\/download$/,
  }),
  freezeRule({
    id: 'plaza-events',
    policyGroup: 'plaza-optional-user',
    accessClass: PORTAL_ACCESS_CLASS.OPTIONAL_USER,
    methods: ['POST'],
    paths: ['/plaza/v1/events'],
  }),
  freezeRule({
    id: 'plaza-discovery',
    policyGroup: 'plaza-optional-user',
    accessClass: PORTAL_ACCESS_CLASS.OPTIONAL_USER,
    methods: ['GET'],
    paths: ['/plaza/v1/feed', '/plaza/v1/categories', '/plaza/v1/seo/sitemap'],
  }),
  freezeRule({
    id: 'plaza-post-detail',
    policyGroup: 'plaza-optional-user',
    accessClass: PORTAL_ACCESS_CLASS.OPTIONAL_USER,
    methods: ['GET'],
    pathPattern: /^\/plaza\/v1\/posts\/[^/]+$/,
  }),
  freezeRule({
    id: 'plaza-post-comments',
    policyGroup: 'plaza-optional-user',
    accessClass: PORTAL_ACCESS_CLASS.OPTIONAL_USER,
    methods: ['GET'],
    pathPattern: /^\/plaza\/v1\/posts\/[^/]+\/comments$/,
  }),
  freezeRule({
    id: 'plaza-user-profile',
    policyGroup: 'plaza-optional-user',
    accessClass: PORTAL_ACCESS_CLASS.OPTIONAL_USER,
    methods: ['GET'],
    pathPattern: /^\/plaza\/v1\/users\/[^/]+$/,
  }),
  freezeRule({
    id: 'plaza-user-posts',
    policyGroup: 'plaza-optional-user',
    accessClass: PORTAL_ACCESS_CLASS.OPTIONAL_USER,
    methods: ['GET'],
    pathPattern: /^\/plaza\/v1\/users\/[^/]+\/posts$/,
  }),
]);

function normalizeRequest({ path, method } = {}) {
  return {
    path: String(path ?? ''),
    method: String(method ?? 'GET').trim().toUpperCase() || 'GET',
  };
}

function ruleMatches(rule, request) {
  if (rule.methods && !rule.methods.includes(request.method)) return false;
  if (rule.paths?.includes(request.path)) return true;
  if (rule.pathPrefix && request.path.startsWith(rule.pathPrefix)) return true;
  return Boolean(rule.pathPattern?.test(request.path));
}

export function findPortalStaticAccessRule(requestInput) {
  const request = normalizeRequest(requestInput);
  return PORTAL_STATIC_ACCESS_RULES.find((rule) => ruleMatches(rule, request)) ?? null;
}

export function resolvePortalAccessPolicyMode(env = process.env) {
  const raw = String(env.MEMIND_PORTAL_ACCESS_POLICY_MODE ?? '').trim().toLowerCase();
  return raw === PORTAL_ACCESS_POLICY_MODE.SHADOW
    ? PORTAL_ACCESS_POLICY_MODE.SHADOW
    : PORTAL_ACCESS_POLICY_MODE.OFF;
}

export function resolvePortalAccessShadowLogIntervalMs(env = process.env) {
  const parsed = Number(env.MEMIND_PORTAL_ACCESS_SHADOW_LOG_INTERVAL_MS);
  if (!Number.isFinite(parsed)) return DEFAULT_SHADOW_LOG_INTERVAL_MS;
  return Math.min(
    MAX_SHADOW_LOG_INTERVAL_MS,
    Math.max(MIN_SHADOW_LOG_INTERVAL_MS, Math.trunc(parsed)),
  );
}

function isExplicitlyEnabled(value) {
  return String(value ?? '').trim() === '1';
}

export function resolvePortalAccessEnforcementConfig(env = process.env) {
  const masterEnabled = isExplicitlyEnabled(
    env.MEMIND_PORTAL_ACCESS_POLICY_ENFORCEMENT_ENABLED,
  );
  const killSwitch = isExplicitlyEnabled(
    env.MEMIND_PORTAL_ACCESS_POLICY_KILL_SWITCH,
  );
  const requestedGroups = [
    ...new Set(
      String(env.MEMIND_PORTAL_ACCESS_POLICY_ENFORCE_GROUPS ?? '')
        .split(',')
        .map((group) => group.trim())
        .filter(Boolean),
    ),
  ];
  const unknownGroups = requestedGroups.filter(
    (group) => !PORTAL_ACCESS_ENFORCEMENT_GROUPS.includes(group),
  );

  if (masterEnabled && unknownGroups.length > 0) {
    throw new Error(
      `Unknown Portal access enforcement group(s): ${unknownGroups.join(', ')}`,
    );
  }

  const activeGroups =
    masterEnabled && !killSwitch
      ? requestedGroups.filter((group) =>
          PORTAL_ACCESS_ENFORCEMENT_GROUPS.includes(group))
      : [];

  return Object.freeze({
    masterEnabled,
    killSwitch,
    enabled: activeGroups.length > 0,
    requestedGroups: Object.freeze(requestedGroups),
    activeGroups: Object.freeze(activeGroups),
    unknownGroups: Object.freeze(unknownGroups),
  });
}

export function isPortalLegacyDirectGlobalAuthBypass(path, method) {
  return Boolean(
    findPortalStaticAccessRule({ path, method })?.legacyDirectBypass,
  );
}

export function isPortalPlazaOptionalUserPath(path, method) {
  return (
    findPortalStaticAccessRule({ path, method })?.policyGroup ===
    'plaza-optional-user'
  );
}

export function resolvePortalApiAccess(
  requestInput,
  {
    isPageDataPublicPath = () => false,
    isLegacyPageDataApiPath = () => false,
  } = {},
) {
  const request = normalizeRequest(requestInput);
  const staticRule = findPortalStaticAccessRule(request);
  if (staticRule) {
    return {
      accessClass: staticRule.accessClass,
      ruleId: staticRule.id,
      policyGroup: staticRule.policyGroup ?? staticRule.id,
    };
  }

  if (isPageDataPublicPath(request.path, request.method)) {
    return {
      accessClass: PORTAL_ACCESS_CLASS.ROUTE_AUTHORIZED,
      ruleId: 'page-data-public',
      policyGroup: 'page-data-public',
    };
  }

  if (isLegacyPageDataApiPath(request.path)) {
    return {
      accessClass: PORTAL_ACCESS_CLASS.PUBLIC,
      ruleId: 'legacy-page-data',
      policyGroup: 'legacy-page-data',
    };
  }

  return {
    accessClass: PORTAL_ACCESS_CLASS.AUTHENTICATED,
    ruleId: 'authenticated-default',
    policyGroup: 'authenticated-default',
  };
}

export function classifyPortalApiAccess(requestInput, predicates = {}) {
  return resolvePortalApiAccess(requestInput, predicates).accessClass;
}

export function portalAccessBypassesGlobalAuth(accessClass) {
  return accessClass !== PORTAL_ACCESS_CLASS.AUTHENTICATED;
}

export function resolvePortalAccessEnforcementDecision(
  requestInput,
  predicates,
  config,
) {
  const proposed = resolvePortalApiAccess(requestInput, predicates);
  const activeGroups = config?.activeGroups ?? [];
  const selected =
    Boolean(config?.enabled) &&
    activeGroups.includes(proposed.policyGroup);
  let reason = 'group-disabled';
  if (config?.killSwitch) reason = 'kill-switch';
  else if (!config?.masterEnabled) reason = 'master-disabled';
  else if (selected) reason = 'group-enabled';

  return {
    selected,
    bypassGlobalAuth:
      selected && portalAccessBypassesGlobalAuth(proposed.accessClass),
    reason,
    proposedAccessClass: proposed.accessClass,
    proposedRuleId: proposed.ruleId,
    policyGroup: proposed.policyGroup,
  };
}

export function shouldOverridePortalLegacyGlobalAuth(
  decision,
  currentGlobalAuthBypass,
) {
  return (
    Boolean(decision?.selected) &&
    Boolean(decision?.bypassGlobalAuth) &&
    !Boolean(currentGlobalAuthBypass)
  );
}

export function comparePortalAccessPolicyShadow(
  requestInput,
  {
    multiUserEnabled = false,
    isPageDataPublicPath = () => false,
    isLegacyPageDataApiPath = () => false,
  } = {},
) {
  const request = normalizeRequest(requestInput);
  const plazaOptionalUser = isPortalPlazaOptionalUserPath(request.path, request.method);
  const pageDataRouteAuthorized = isPageDataPublicPath(request.path, request.method);
  const legacyPageDataPublic = isLegacyPageDataApiPath(request.path);
  const currentGlobalAuthBypass =
    isPortalLegacyDirectGlobalAuthBypass(request.path, request.method) ||
    (
      Boolean(multiUserEnabled) &&
      (plazaOptionalUser || pageDataRouteAuthorized || legacyPageDataPublic)
    );
  const proposed = resolvePortalApiAccess(request, {
    isPageDataPublicPath,
    isLegacyPageDataApiPath,
  });
  const proposedGlobalAuthBypass = portalAccessBypassesGlobalAuth(proposed.accessClass);

  return {
    path: request.path,
    method: request.method,
    proposedAccessClass: proposed.accessClass,
    proposedRuleId: proposed.ruleId,
    policyGroup: proposed.policyGroup,
    currentGlobalAuthBypass,
    proposedGlobalAuthBypass,
    mismatch: currentGlobalAuthBypass !== proposedGlobalAuthBypass,
  };
}

export function assessPortalAccessMigrationReadiness(
  requests,
  {
    knownMismatchPolicyGroups = [],
    ...comparisonOptions
  } = {},
) {
  const knownGroups = new Set(knownMismatchPolicyGroups);
  const comparisons = requests.map((request) =>
    comparePortalAccessPolicyShadow(request, comparisonOptions));
  const mismatches = comparisons.filter((comparison) => comparison.mismatch);
  const knownMismatches = mismatches.filter((comparison) =>
    knownGroups.has(comparison.policyGroup));
  const unexpectedMismatches = mismatches.filter((comparison) =>
    !knownGroups.has(comparison.policyGroup));

  return {
    contractReady: unexpectedMismatches.length === 0,
    safeForBehaviorSwitch: mismatches.length === 0,
    total: comparisons.length,
    aligned: comparisons.length - mismatches.length,
    knownMismatches,
    unexpectedMismatches,
  };
}

export function createPortalAccessShadowReporter({
  intervalMs = DEFAULT_SHADOW_LOG_INTERVAL_MS,
  now = Date.now,
  emit = () => {},
} = {}) {
  const effectiveIntervalMs = Math.min(
    MAX_SHADOW_LOG_INTERVAL_MS,
    Math.max(MIN_SHADOW_LOG_INTERVAL_MS, Math.trunc(Number(intervalMs) || 0)),
  );
  const counters = new Map();

  function record(event) {
    if (!event?.mismatch) return null;
    const key = [
      event.authMode ?? 'unknown',
      event.method ?? 'GET',
      event.policyGroup ?? event.proposedRuleId ?? 'unknown',
    ].join(':');
    const timestamp = Number(now());
    const counter = counters.get(key) ?? {
      key,
      totalOccurrences: 0,
      suppressedSinceLast: 0,
      lastEmittedAt: null,
    };
    counter.totalOccurrences += 1;

    const shouldEmit =
      counter.lastEmittedAt === null ||
      timestamp - counter.lastEmittedAt >= effectiveIntervalMs;
    if (!shouldEmit) {
      counter.suppressedSinceLast += 1;
      counters.set(key, counter);
      return null;
    }

    const payload = {
      ...event,
      occurrences: counter.totalOccurrences,
      suppressedSinceLast: counter.suppressedSinceLast,
      shadowLogIntervalMs: effectiveIntervalMs,
    };
    counter.lastEmittedAt = timestamp;
    counter.suppressedSinceLast = 0;
    counters.set(key, counter);
    emit(payload);
    return payload;
  }

  function snapshot() {
    return [...counters.values()].map((counter) => ({ ...counter }));
  }

  return Object.freeze({ record, snapshot });
}