import { normalizeRouteRules } from '../routingRules.js';

const MODES = new Set(['client', 'gateway']);
const CONNECTION_STATES = new Set(['running', 'stopped']);
const OPERATION_STATES = new Set(['idle', 'running', 'failed']);

const text = (value) => String(value || '').trim();
const nullableText = (value) => value == null ? null : String(value);
const dateOrNull = (value) => (
  typeof value === 'string' && Number.isFinite(Date.parse(value)) ? value : null
);

export function normalizeStoredState(value) {
  const state = value && typeof value === 'object' && !Array.isArray(value) ? value : {};
  const selectedTag = text(state.selectedTag);
  return {
    ...state,
    revision: Number.isSafeInteger(state.revision) && state.revision >= 0 ? state.revision : 0,
    selectedTag,
    appliedTag: Object.hasOwn(state, 'appliedTag') ? text(state.appliedTag) : selectedTag,
    servers: Array.isArray(state.servers) ? state.servers : [],
    routeRules: normalizeRouteRules(state.routeRules),
    appliedRouteRules: normalizeRouteRules(state.appliedRouteRules),
    routeRulesRevision: Number.isSafeInteger(state.routeRulesRevision) && state.routeRulesRevision >= 0
      ? state.routeRulesRevision
      : 0,
  };
}

export function createStateSnapshot({
  storedState,
  runtime,
  gatewayAuto,
  appMode,
  configExists,
  subscriptionHost,
  operation = { kind: null, status: 'idle', startedAt: null, error: null },
  now = new Date(),
}) {
  const stored = normalizeStoredState(storedState);
  const mode = MODES.has(appMode) ? appMode : 'gateway';
  const hasSubscription = Boolean(stored.subscriptionUrl);
  const desired = CONNECTION_STATES.has(stored.connectionDesired)
    ? stored.connectionDesired
    : configExists ? 'running' : 'stopped';
  const servers = stored.servers.map((server) => {
    const tag = text(server.tag);
    return {
      ...server,
      id: tag,
      label: tag,
      host: text(server.server),
      port: Number(server.server_port) || 0,
      protocol: text(server.type),
      // v0 compatibility: the current UI and integrations still read these aliases.
      tag,
      server: text(server.server),
      server_port: Number(server.server_port) || 0,
      type: text(server.type),
    };
  });
  const routeMode = mode === 'client' ? gatewayAuto?.mode || 'local-vpn' : 'gateway-transparent';
  const activeLocalRules = runtime?.running ? stored.appliedRouteRules : [];

  return assertStateSnapshot({
    apiVersion: 1,
    revision: stored.revision,
    generatedAt: now.toISOString(),
    mode,
    subscription: {
      status: hasSubscription ? 'ready' : 'missing',
      host: hasSubscription ? subscriptionHost : '',
      fetchedAt: dateOrNull(stored.fetchedAt),
      userInfo: stored.userInfo && typeof stored.userInfo === 'object' ? stored.userInfo : {},
    },
    selection: {
      desiredServerId: stored.selectedTag,
      appliedServerId: stored.appliedTag,
    },
    connection: {
      desired,
      process: runtime?.running ? 'running' : 'stopped',
      startedAt: dateOrNull(runtime?.startedAt),
      lastError: null,
    },
    route: {
      mode: routeMode,
      gatewayAddress: mode === 'client' ? gatewayAuto?.gateway?.gateway || null : null,
      lastVerifiedAt: null,
      reason: mode === 'client' && stored.gatewayAutoEnabled !== false ? 'auto' : 'manual',
      localRules: stored.routeRules,
      activeLocalRules,
      localRulesRevision: stored.routeRulesRevision,
      localRulesPendingRestart: !isSameRules(stored.routeRules, activeLocalRules),
    },
    operation: {
      kind: nullableText(operation.kind),
      status: operation.status,
      startedAt: nullableText(operation.startedAt),
      error: nullableText(operation.error),
    },
    servers,
  });
}

export function withStateV0Compatibility(snapshot, {
  storedState,
  gatewayAuto,
  port,
  proxyPort,
  configExists,
}) {
  const stored = normalizeStoredState(storedState);
  return {
    ...snapshot,
    port,
    proxyPort,
    configExists,
    singboxRunning: snapshot.connection.process === 'running',
    singboxStartedAt: snapshot.connection.startedAt,
    subscriptionHost: snapshot.subscription.host,
    hasSubscription: snapshot.subscription.status === 'ready',
    selectedTag: snapshot.selection.desiredServerId,
    userInfo: snapshot.subscription.userInfo,
    fetchedAt: snapshot.subscription.fetchedAt,
    gatewayAuto: snapshot.mode === 'client' ? {
      mode: gatewayAuto?.mode || 'local-vpn',
      enabled: stored.gatewayAutoEnabled !== false,
      available: Boolean(gatewayAuto?.gatewayId),
      address: gatewayAuto?.gateway?.gateway || '',
      interface: gatewayAuto?.gateway?.interface || '',
      failures: Number(gatewayAuto?.failures) || 0,
      lastError: gatewayAuto?.lastError || '',
    } : null,
  };
}

export function assertStateSnapshot(snapshot) {
  const validDate = (value) => typeof value === 'string' && Number.isFinite(Date.parse(value));
  const nullableDate = (value) => value === null || validDate(value);
  const nullableString = (value) => value === null || typeof value === 'string';
  const validServer = (server) => (
    server &&
    typeof server.id === 'string' &&
    typeof server.label === 'string' &&
    typeof server.host === 'string' &&
    Number.isInteger(server.port) &&
    server.port >= 0 &&
    typeof server.protocol === 'string'
  );
  const validRouteRule = (rule) => (
    rule &&
    ['domain', 'domain_suffix', 'domain_keyword'].includes(rule.type) &&
    typeof rule.value === 'string' &&
    Boolean(rule.value) &&
    typeof rule.enabled === 'boolean'
  );

  if (
    !snapshot ||
    snapshot.apiVersion !== 1 ||
    !Number.isSafeInteger(snapshot.revision) ||
    snapshot.revision < 0 ||
    !validDate(snapshot.generatedAt) ||
    !MODES.has(snapshot.mode) ||
    !snapshot.subscription ||
    !['missing', 'ready'].includes(snapshot.subscription.status) ||
    typeof snapshot.subscription.host !== 'string' ||
    Object.hasOwn(snapshot.subscription, 'url') ||
    !nullableDate(snapshot.subscription.fetchedAt) ||
    !snapshot.subscription.userInfo ||
    typeof snapshot.subscription.userInfo !== 'object' ||
    !snapshot.selection ||
    typeof snapshot.selection.desiredServerId !== 'string' ||
    typeof snapshot.selection.appliedServerId !== 'string' ||
    !snapshot.connection ||
    !CONNECTION_STATES.has(snapshot.connection.desired) ||
    !CONNECTION_STATES.has(snapshot.connection.process) ||
    !nullableDate(snapshot.connection.startedAt) ||
    !nullableString(snapshot.connection.lastError) ||
    !snapshot.route ||
    typeof snapshot.route.mode !== 'string' ||
    !nullableString(snapshot.route.gatewayAddress) ||
    !nullableDate(snapshot.route.lastVerifiedAt) ||
    typeof snapshot.route.reason !== 'string' ||
    !Array.isArray(snapshot.route.localRules) ||
    !snapshot.route.localRules.every(validRouteRule) ||
    !Array.isArray(snapshot.route.activeLocalRules) ||
    !snapshot.route.activeLocalRules.every(validRouteRule) ||
    !Number.isSafeInteger(snapshot.route.localRulesRevision) ||
    snapshot.route.localRulesRevision < 0 ||
    typeof snapshot.route.localRulesPendingRestart !== 'boolean' ||
    !snapshot.operation ||
    !nullableString(snapshot.operation.kind) ||
    !OPERATION_STATES.has(snapshot.operation.status) ||
    !nullableDate(snapshot.operation.startedAt) ||
    !nullableString(snapshot.operation.error) ||
    !Array.isArray(snapshot.servers) ||
    !snapshot.servers.every(validServer)
  ) {
    throw new TypeError('Invalid Harbor state snapshot v1');
  }

  return snapshot;
}

function isSameRules(left, right) {
  return JSON.stringify(left) === JSON.stringify(right);
}