import { ILogger } from 'js-logger';

import {
  AbstractRemote,
  AbstractRemoteOptions,
  BSONImplementation,
  DEFAULT_REMOTE_LOGGER,
  DataStream,
  FetchImplementation,
  FetchImplementationProvider,
  RemoteConnector,
  SyncStreamOptions
} from '@powersync/common';
import { Platform } from 'react-native';
// Note docs for React Native https://github.com/mongodb/js-bson?tab=readme-ov-file#react-native
import { BSON } from 'bson';
import { TextDecoder } from 'text-encoding';

import { fetch } from 'react-native-fetch-api';

export const STREAMING_POST_TIMEOUT_MS = 30_000;

/**
 * Directly imports fetch implementation from react-native-fetch-api.
 * This removes the requirement for the global `fetch` to be overridden by
 * a polyfill.
 */
class ReactNativeFetchProvider extends FetchImplementationProvider {
  getFetch(): FetchImplementation {
    return fetch.bind(globalThis);
  }
}

export class ReactNativeRemote extends AbstractRemote {
  constructor(
    protected connector: RemoteConnector,
    protected logger: ILogger = DEFAULT_REMOTE_LOGGER,
    options?: Partial<AbstractRemoteOptions>
  ) {
    super(connector, logger, {
      ...(options ?? {}),
      fetchImplementation: options?.fetchImplementation ?? new ReactNativeFetchProvider()
    });
  }

  getUserAgent(): string {
    return [
      super.getUserAgent(),
      `powersync-react-native`,
      `react-native/${Platform.constants.reactNativeVersion.major}.${Platform.constants.reactNativeVersion.minor}`,
      `${Platform.OS}/${Platform.Version}`
    ].join(' ');
  }

  async getBSON(): Promise<BSONImplementation> {
    return BSON;
  }

  protected createTextDecoder(): TextDecoder {
    return new TextDecoder();
  }

  async postStreamRaw<T>(options: SyncStreamOptions, mapLine: (line: string) => T): Promise<DataStream<T>> {
    const timeout =
      Platform.OS == 'android'
        ? setTimeout(() => {
            this.logger.warn(
              `HTTP Streaming POST is taking longer than ${Math.ceil(
                STREAMING_POST_TIMEOUT_MS / 1000
              )} seconds to resolve. If using a debug build, please ensure Flipper Network plugin is disabled.`
            );
          }, STREAMING_POST_TIMEOUT_MS)
        : null;

    try {
      return await super.postStreamRaw(
        {
          ...options,
          fetchOptions: {
            ...options.fetchOptions,
            /**
             * The `react-native-fetch-api` polyfill provides streaming support via
             * this non-standard flag
             * https://github.com/react-native-community/fetch#enable-text-streaming
             */
            // @ts-expect-error https://github.com/react-native-community/fetch#enable-text-streaming
            reactNative: { textStreaming: true }
          }
        },
        mapLine
      );
    } finally {
      if (timeout) {
        clearTimeout(timeout);
      }
    }
  }
}