import * as Clipboard from 'expo-clipboard';
import * as DocumentPicker from 'expo-document-picker';
import { File, Paths } from 'expo-file-system';
import * as Haptics from 'expo-haptics';
import * as ImagePicker from 'expo-image-picker';
import * as Linking from 'expo-linking';
import * as Notifications from 'expo-notifications';
import * as Sharing from 'expo-sharing';
import {
  Appearance,
  Platform,
  PushNotificationIOS,
  Share,
} from 'react-native';

import {
  type ClipboardReadTextResult,
  type ClipboardWriteTextPayload,
  type FileExportImagePayload,
  type FileExportImageResult,
  type FileExportTextPayload,
  type FileExportTextResult,
  type FileImportImageResult,
  type FileImportTextResult,
  type HapticsImpactPayload,
  HOST_BRIDGE_PROTOCOL,
  HOST_BRIDGE_VERSION,
  type HostBridgeCapability,
  type HostBridgeError,
  type HostBridgeImageMimeType,
  type HostBridgeMethod,
  type HostBridgeRequest,
  type HostBridgeResponse,
  type HostBridgeTextMimeType,
  type NavigateNativePagePayload,
  normalizeHostBridgeBadgeCount,
  normalizeHostBridgeClipboardText,
  normalizeHostBridgeColorScheme,
  normalizeHostBridgeExportFileName,
  normalizeHostBridgeExternalUrl,
  normalizeHostBridgeLocalNotification,
  type OpenExternalUrlPayload,
  type SetBadgeCountPayload,
  type ShareOpenPayload,
} from '../../../packages/shared/src/contracts/hostBridge';
import { resolveMobileShellWebViewUrl } from './mobileShellNavigation';
import { getMobileNetworkStatus } from './mobileShellNetwork';

const WEB_APP_ORIGIN = 'https://app.genarrative.world';
const EXPORT_TEXT_MAX_BYTES = 5 * 1024 * 1024;
const EXPORT_IMAGE_MAX_BYTES = 5 * 1024 * 1024;
const IMPORT_TEXT_MAX_BYTES = 5 * 1024 * 1024;
const IMPORT_IMAGE_MAX_BYTES = 10 * 1024 * 1024;
const LOCAL_NOTIFICATION_CHANNEL_ID = 'genarrative-local';
const HOST_BRIDGE_TEXT_MIME_TYPES = new Set<HostBridgeTextMimeType>([
  'text/plain',
  'text/markdown',
  'text/csv',
  'application/json',
]);
const HOST_BRIDGE_IMAGE_MIME_TYPES = new Set<HostBridgeImageMimeType>([
  'image/png',
  'image/jpeg',
  'image/webp',
]);

Notifications.setNotificationHandler({
  handleNotification: async () => ({
    shouldShowBanner: true,
    shouldShowList: true,
    shouldPlaySound: false,
    shouldSetBadge: false,
  }),
});

export const MOBILE_HOST_CAPABILITIES: HostBridgeCapability[] = [
  'host.getRuntime',
  'appearance.getColorScheme',
  'host.events',
  'app.lifecycle',
  'share.open',
  'share.setTarget',
  'navigation.openNativePage',
  'navigation.canGoBack',
  'app.reloadWebView',
  'app.openExternalUrl',
  'network.status',
  'network.statusChanged',
  'clipboard.writeText',
  'clipboard.readText',
  'file.exportText',
  'file.importText',
  'file.exportImage',
  'file.importImage',
  'haptics.impact',
  'notification.showLocal',
];

export const IOS_MOBILE_HOST_CAPABILITIES: HostBridgeCapability[] = [
  ...MOBILE_HOST_CAPABILITIES,
  'app.setBadgeCount',
];

export function resolveMobileHostCapabilities(platform = Platform.OS) {
  return platform === 'ios'
    ? IOS_MOBILE_HOST_CAPABILITIES
    : MOBILE_HOST_CAPABILITIES;
}

export type MobileHostBridgeNavigation = {
  allowedOrigin: string;
  openWebViewUrl: (url: string) => void;
  reloadWebView: () => void;
};

let currentShareTarget: unknown = null;
let navigation: MobileHostBridgeNavigation | null = null;

export function configureMobileHostBridgeNavigation(
  nextNavigation: MobileHostBridgeNavigation | null,
) {
  navigation = nextNavigation;
}

function unsupported(method: HostBridgeMethod): HostBridgeError {
  return {
    code: 'unsupported_method',
    message: `${method} unsupported in mobile shell`,
  };
}

function invalidRequest(message: string): HostBridgeError {
  return {
    code: 'invalid_request',
    message,
  };
}

function utf8ByteLength(value: string) {
  let bytes = 0;
  for (const character of value) {
    const codePoint = character.codePointAt(0) ?? 0;
    if (codePoint <= 0x7f) {
      bytes += 1;
    } else if (codePoint <= 0x7ff) {
      bytes += 2;
    } else if (codePoint <= 0xffff) {
      bytes += 3;
    } else {
      bytes += 4;
    }
  }
  return bytes;
}

function normalizedBase64Data(value: unknown) {
  if (typeof value !== 'string') {
    return null;
  }

  const normalizedValue = value.trim();
  if (
    !normalizedValue ||
    normalizedValue.length % 4 !== 0 ||
    !/^[A-Za-z0-9+/]+={0,2}$/u.test(normalizedValue)
  ) {
    return null;
  }

  return normalizedValue;
}

function base64DecodedByteLength(value: string) {
  const padding = value.endsWith('==') ? 2 : value.endsWith('=') ? 1 : 0;
  return Math.floor((value.length * 3) / 4) - padding;
}

function isHostBridgeRequest(value: unknown): value is HostBridgeRequest {
  if (!value || typeof value !== 'object') {
    return false;
  }

  const candidate = value as Partial<HostBridgeRequest>;
  return (
    candidate.bridge === HOST_BRIDGE_PROTOCOL &&
    candidate.version === HOST_BRIDGE_VERSION &&
    typeof candidate.id === 'string' &&
    typeof candidate.method === 'string'
  );
}

function parseRequest(raw: string) {
  try {
    return JSON.parse(raw) as unknown;
  } catch {
    return null;
  }
}

function ok<Result>(
  request: HostBridgeRequest,
  result?: Result,
): HostBridgeResponse<Result> {
  return {
    bridge: HOST_BRIDGE_PROTOCOL,
    version: HOST_BRIDGE_VERSION,
    id: request.id,
    ok: true,
    result,
  };
}

function failure(
  request: Pick<HostBridgeRequest, 'id'>,
  error: HostBridgeError,
): HostBridgeResponse {
  return {
    bridge: HOST_BRIDGE_PROTOCOL,
    version: HOST_BRIDGE_VERSION,
    id: request.id,
    ok: false,
    error,
  };
}

async function openExternalUrl(payload: unknown) {
  const url = normalizeHostBridgeExternalUrl(
    (payload as OpenExternalUrlPayload | undefined)?.url,
  );
  if (!url) {
    throw invalidRequest('url must use an allowed external protocol');
  }

  await Linking.openURL(url);
  return true;
}

async function writeClipboard(payload: unknown) {
  const text = (payload as ClipboardWriteTextPayload | undefined)?.text;
  if (typeof text !== 'string') {
    throw invalidRequest('text is required');
  }

  await Clipboard.setStringAsync(text);
  return true;
}

async function readClipboard(): Promise<ClipboardReadTextResult> {
  const result = normalizeHostBridgeClipboardText(
    await Clipboard.getStringAsync(),
  );
  if (!result) {
    throw {
      code: 'host_error',
      message: 'clipboard text unavailable',
    } satisfies HostBridgeError;
  }

  return result;
}

async function exportTextFile(payload: unknown): Promise<FileExportTextResult> {
  const exportPayload = payload as FileExportTextPayload | undefined;
  const content = exportPayload?.content;
  if (typeof content !== 'string') {
    throw invalidRequest('content is required');
  }

  const bytes = utf8ByteLength(content);
  if (bytes > EXPORT_TEXT_MAX_BYTES) {
    throw invalidRequest('content exceeds file export size limit');
  }

  const isSharingAvailable = await Sharing.isAvailableAsync();
  if (!isSharingAvailable) {
    throw {
      code: 'unsupported_capability',
      message: 'file sharing is unavailable in mobile shell',
    } satisfies HostBridgeError;
  }

  const fileName = normalizeHostBridgeExportFileName(exportPayload?.fileName);
  const mimeType = exportPayload?.mimeType || 'text/plain';
  const file = new File(Paths.cache, fileName);
  file.write(content);
  await Sharing.shareAsync(file.uri, {
    mimeType,
    UTI: 'public.plain-text',
    dialogTitle: fileName,
  });

  return {
    action: 'saved',
    fileName,
    bytes,
  };
}

function normalizeImportedTextMimeType(
  value: unknown,
  fileName: string,
): HostBridgeTextMimeType | null {
  if (typeof value === 'string') {
    const mimeType = value.toLowerCase();
    if (HOST_BRIDGE_TEXT_MIME_TYPES.has(mimeType as HostBridgeTextMimeType)) {
      return mimeType as HostBridgeTextMimeType;
    }
  }

  const normalizedName = fileName.toLowerCase();
  if (normalizedName.endsWith('.json')) {
    return 'application/json';
  }
  if (normalizedName.endsWith('.md') || normalizedName.endsWith('.markdown')) {
    return 'text/markdown';
  }
  if (normalizedName.endsWith('.csv')) {
    return 'text/csv';
  }
  if (normalizedName.endsWith('.txt')) {
    return 'text/plain';
  }

  return null;
}

async function importTextFile(): Promise<FileImportTextResult> {
  const result = await DocumentPicker.getDocumentAsync({
    copyToCacheDirectory: true,
    multiple: false,
    type: ['text/*', 'application/json'],
  });
  if (result.canceled) {
    throw {
      code: 'cancelled',
      message: 'file import cancelled',
    } satisfies HostBridgeError;
  }

  const asset = result.assets[0];
  if (!asset?.uri) {
    throw invalidRequest('text file is required');
  }

  const fileName = normalizeHostBridgeExportFileName(
    asset.name || 'genarrative-import.txt',
  );
  const mimeType = normalizeImportedTextMimeType(asset.mimeType, fileName);
  if (!mimeType) {
    throw invalidRequest('mimeType must be an allowed text type');
  }
  if (
    typeof asset.size === 'number' &&
    (asset.size <= 0 || asset.size > IMPORT_TEXT_MAX_BYTES)
  ) {
    throw invalidRequest('text exceeds file import size limit');
  }

  const file = new File(asset.uri);
  const content = await file.text();
  const bytes = utf8ByteLength(content);
  if (bytes <= 0 || bytes > IMPORT_TEXT_MAX_BYTES) {
    throw invalidRequest('text exceeds file import size limit');
  }

  return {
    action: 'selected',
    fileName,
    content,
    mimeType,
    bytes,
  };
}

async function exportImageFile(payload: unknown): Promise<FileExportImageResult> {
  const exportPayload = payload as FileExportImagePayload | undefined;
  const mimeType = exportPayload?.mimeType;
  if (
    typeof mimeType !== 'string' ||
    !HOST_BRIDGE_IMAGE_MIME_TYPES.has(mimeType as HostBridgeImageMimeType)
  ) {
    throw invalidRequest('mimeType must be an allowed image type');
  }

  const base64Data = normalizedBase64Data(exportPayload?.base64Data);
  if (!base64Data) {
    throw invalidRequest('base64Data is required');
  }
  const bytes = base64DecodedByteLength(base64Data);
  if (bytes > EXPORT_IMAGE_MAX_BYTES) {
    throw invalidRequest('image exceeds file export size limit');
  }

  const isSharingAvailable = await Sharing.isAvailableAsync();
  if (!isSharingAvailable) {
    throw {
      code: 'unsupported_capability',
      message: 'file sharing is unavailable in mobile shell',
    } satisfies HostBridgeError;
  }

  const fileName = normalizeHostBridgeExportFileName(exportPayload?.fileName);
  const file = new File(Paths.cache, fileName);
  file.write(base64Data, { encoding: 'base64' });
  await Sharing.shareAsync(file.uri, {
    mimeType,
    UTI: mimeType === 'image/png' ? 'public.png' : 'public.image',
    dialogTitle: fileName,
  });

  return {
    action: 'saved',
    fileName,
    bytes,
  };
}

function normalizeImportedImageMimeType(
  value: unknown,
): HostBridgeImageMimeType | null {
  if (typeof value !== 'string') {
    return null;
  }

  const mimeType = value.toLowerCase();
  return HOST_BRIDGE_IMAGE_MIME_TYPES.has(mimeType as HostBridgeImageMimeType)
    ? (mimeType as HostBridgeImageMimeType)
    : null;
}

function fallbackImportedImageFileName(mimeType: HostBridgeImageMimeType) {
  if (mimeType === 'image/jpeg') {
    return 'genarrative-import.jpg';
  }
  if (mimeType === 'image/webp') {
    return 'genarrative-import.webp';
  }
  return 'genarrative-import.png';
}

async function importImageFile(): Promise<FileImportImageResult> {
  const permission = await ImagePicker.requestMediaLibraryPermissionsAsync();
  if (permission.status !== ImagePicker.PermissionStatus.GRANTED) {
    throw {
      code: 'host_error',
      message: 'photo library permission denied',
    } satisfies HostBridgeError;
  }

  const result = await ImagePicker.launchImageLibraryAsync({
    allowsEditing: false,
    allowsMultipleSelection: false,
    base64: true,
    exif: false,
    mediaTypes: ['images'],
    quality: 1,
  });
  if (result.canceled) {
    throw {
      code: 'cancelled',
      message: 'file import cancelled',
    } satisfies HostBridgeError;
  }

  const asset = result.assets[0];
  if (!asset || asset.type !== 'image') {
    throw invalidRequest('image asset is required');
  }

  const mimeType = normalizeImportedImageMimeType(asset.mimeType);
  if (!mimeType) {
    throw invalidRequest('mimeType must be an allowed image type');
  }

  const base64Data = normalizedBase64Data(asset.base64);
  if (!base64Data) {
    throw invalidRequest('base64Data is required');
  }

  const bytes = base64DecodedByteLength(base64Data);
  if (bytes <= 0 || bytes > IMPORT_IMAGE_MAX_BYTES) {
    throw invalidRequest('image exceeds file import size limit');
  }
  if (
    typeof asset.fileSize === 'number' &&
    asset.fileSize > IMPORT_IMAGE_MAX_BYTES
  ) {
    throw invalidRequest('image exceeds file import size limit');
  }

  return {
    action: 'selected',
    fileName: normalizeHostBridgeExportFileName(
      asset.fileName || fallbackImportedImageFileName(mimeType),
    ),
    base64Data,
    mimeType,
    bytes,
  };
}

async function runHaptics(payload: unknown) {
  const style = (payload as HapticsImpactPayload | undefined)?.style;
  const impactStyle =
    style === 'heavy'
      ? Haptics.ImpactFeedbackStyle.Heavy
      : style === 'medium'
        ? Haptics.ImpactFeedbackStyle.Medium
        : Haptics.ImpactFeedbackStyle.Light;

  await Haptics.impactAsync(impactStyle);
  return true;
}

function setBadgeCount(payload: unknown) {
  if (Platform.OS !== 'ios') {
    throw {
      code: 'unsupported_capability',
      message: 'app badge count is only supported on iOS mobile shell',
    } satisfies HostBridgeError;
  }

  const count = normalizeHostBridgeBadgeCount(
    (payload as SetBadgeCountPayload | undefined)?.count,
  );
  if (count === null) {
    throw invalidRequest('count must be an integer between 0 and 99999');
  }

  PushNotificationIOS.setApplicationIconBadgeNumber(count);
  return true;
}

function hasNotificationPermission(
  permission: Awaited<ReturnType<typeof Notifications.getPermissionsAsync>>,
) {
  return (
    permission.granted ||
    permission.ios?.status === Notifications.IosAuthorizationStatus.PROVISIONAL
  );
}

async function ensureNotificationPermission() {
  const currentPermission = await Notifications.getPermissionsAsync();
  if (hasNotificationPermission(currentPermission)) {
    return;
  }

  const requestedPermission = await Notifications.requestPermissionsAsync({
    ios: {
      allowAlert: true,
      allowBadge: false,
      allowSound: false,
    },
  });
  if (!hasNotificationPermission(requestedPermission)) {
    throw {
      code: 'host_error',
      message: 'notification permission denied',
    } satisfies HostBridgeError;
  }
}

async function showLocalNotification(payload: unknown) {
  const notification = normalizeHostBridgeLocalNotification(payload);
  if (!notification) {
    throw invalidRequest('title is required');
  }

  await ensureNotificationPermission();
  if (Platform.OS === 'android') {
    await Notifications.setNotificationChannelAsync(
      LOCAL_NOTIFICATION_CHANNEL_ID,
      {
        name: 'Genarrative',
        importance: Notifications.AndroidImportance.DEFAULT,
      },
    );
  }

  await Notifications.scheduleNotificationAsync({
    content: notification,
    trigger:
      Platform.OS === 'android'
        ? { channelId: LOCAL_NOTIFICATION_CHANNEL_ID }
        : null,
  });
  return true;
}

function getColorScheme() {
  return {
    colorScheme: normalizeHostBridgeColorScheme(Appearance.getColorScheme()),
  };
}

function stringField(value: unknown, field: string) {
  if (!value || typeof value !== 'object') {
    return undefined;
  }

  const fieldValue = (value as Record<string, unknown>)[field];
  if (typeof fieldValue !== 'string') {
    return undefined;
  }

  const text = fieldValue.trim();
  return text || undefined;
}

function shareTargetPayload(value: unknown) {
  if (!value || typeof value !== 'object') {
    return value;
  }

  const target = value as Record<string, unknown>;
  return target.target ?? value;
}

function workDetailUrl(work: string) {
  return `${WEB_APP_ORIGIN}/works/detail?work=${encodeURIComponent(work)}`;
}

function webAppPathUrl(path: string) {
  return new URL(path, WEB_APP_ORIGIN).toString();
}

function normalizeSharePayload(value: unknown): ShareOpenPayload | null {
  const target = shareTargetPayload(value);
  const payload =
    target && typeof target === 'object'
      ? (target as Record<string, unknown>).payload ?? target
      : target;

  if (!payload || typeof payload !== 'object') {
    return null;
  }

  const title = stringField(payload, 'title');
  const message = stringField(payload, 'message');
  const directUrl = stringField(payload, 'url') ?? stringField(payload, 'href');
  const work = stringField(payload, 'work');
  const path = stringField(payload, 'path') ?? stringField(payload, 'targetPath');
  const url = directUrl ?? (work ? workDetailUrl(work) : undefined) ?? (path ? webAppPathUrl(path) : undefined);

  if (!title && !message && !url) {
    return null;
  }

  return {
    ...(title ? { title } : {}),
    ...(message ? { message } : {}),
    ...(url ? { url } : {}),
  };
}

async function openShare(payload: unknown) {
  const sharePayload =
    normalizeSharePayload(payload) ?? normalizeSharePayload(currentShareTarget);
  if (!sharePayload) {
    throw invalidRequest('share target is required');
  }

  const url = sharePayload?.url;
  const message = [sharePayload?.message, url].filter(Boolean).join('\n');

  await Share.share({
    title: sharePayload?.title,
    message: message || url || sharePayload?.title || '',
    url,
  });
  return true;
}

function openNativePage(payload: unknown) {
  if (!navigation) {
    throw unsupported('navigation.openNativePage');
  }

  const url = (payload as NavigateNativePagePayload | undefined)?.url;
  if (typeof url !== 'string') {
    throw invalidRequest('url is required');
  }

  const webViewUrl = resolveMobileShellWebViewUrl(
    url,
    navigation.allowedOrigin,
  );
  if (!webViewUrl) {
    throw invalidRequest('url must be an allowed same-origin web path');
  }

  navigation.openWebViewUrl(webViewUrl);
  return true;
}

function reloadWebView() {
  if (!navigation) {
    throw unsupported('app.reloadWebView');
  }

  navigation.reloadWebView();
  return true;
}

async function handleRequest(request: HostBridgeRequest) {
  switch (request.method) {
    case 'host.getRuntime':
      return ok(request, {
        shell: 'expo_mobile',
        platform: Platform.OS === 'ios' ? 'ios' : 'android',
        hostVersion: '0.1.0',
        bridgeVersion: HOST_BRIDGE_VERSION,
        capabilities: resolveMobileHostCapabilities(),
      });
    case 'appearance.getColorScheme':
      return ok(request, getColorScheme());
    case 'app.openExternalUrl':
      return ok(request, await openExternalUrl(request.payload));
    case 'app.reloadWebView':
      return ok(request, reloadWebView());
    case 'network.status':
      return ok(request, await getMobileNetworkStatus());
    case 'clipboard.writeText':
      return ok(request, await writeClipboard(request.payload));
    case 'clipboard.readText':
      return ok(request, await readClipboard());
    case 'file.exportText':
      return ok(request, await exportTextFile(request.payload));
    case 'file.importText':
      return ok(request, await importTextFile());
    case 'file.exportImage':
      return ok(request, await exportImageFile(request.payload));
    case 'file.importImage':
      return ok(request, await importImageFile());
    case 'haptics.impact':
      return ok(request, await runHaptics(request.payload));
    case 'notification.showLocal':
      return ok(request, await showLocalNotification(request.payload));
    case 'app.setBadgeCount':
      return ok(request, setBadgeCount(request.payload));
    case 'share.open':
      return ok(request, await openShare(request.payload));
    case 'share.setTarget':
      currentShareTarget =
        request.payload && typeof request.payload === 'object'
          ? (request.payload as { target?: unknown }).target
          : null;
      return ok(request, true);
    case 'navigation.openNativePage':
      return ok(request, openNativePage(request.payload));
    case 'auth.requestLogin':
    case 'payment.request':
      return failure(request, unsupported(request.method));
    default:
      return failure(request, unsupported(request.method));
  }
}

function normalizeError(error: unknown): HostBridgeError {
  if (
    error &&
    typeof error === 'object' &&
    'code' in error &&
    'message' in error
  ) {
    return error as HostBridgeError;
  }

  return {
    code: 'host_error',
    message: error instanceof Error ? error.message : String(error),
  };
}

export async function handleMobileHostBridgeMessage(
  rawMessage: string,
  sendResponse: (response: HostBridgeResponse) => void,
) {
  const parsed = parseRequest(rawMessage);
  if (!isHostBridgeRequest(parsed)) {
    sendResponse(
      failure(
        { id: 'invalid' },
        invalidRequest('invalid host bridge request'),
      ),
    );
    return;
  }

  try {
    sendResponse(await handleRequest(parsed));
  } catch (error) {
    sendResponse(failure(parsed, normalizeError(error)));
  }
}

export function resetMobileHostBridgeForTest() {
  currentShareTarget = null;
  navigation = null;
}