import 'dart:async';
import 'dart:io';
import 'dart:isolate';
import 'dart:ui';

import 'package:drift/drift.dart';
import 'package:drift/isolate.dart';
import 'package:drift/native.dart';
import 'package:drift_flutter/drift_flutter.dart';
import 'package:meta/meta.dart';
import 'package:path_provider/path_provider.dart';
import 'package:path/path.dart' as p;
import 'package:sqlite3/sqlite3.dart';
import 'package:sqlite3_flutter_libs/sqlite3_flutter_libs.dart';

@internal
bool hasConfiguredSqlite = false;

String portName(String databaseName) {
  return 'drift-db/$databaseName';
}

String isolateControlPortName(String databaseName) {
  return 'drift-db/$databaseName/control';
}

QueryExecutor driftDatabaseTest({required String name, DriftWebOptions? web, DriftNativeOptions? native}) {
  Future<File> databaseFile() async {
    if (native?.databasePath case final lookupPath?) {
      return File(await lookupPath());
    } else {
      final resolvedDirectory = await (native?.databaseDirectory ?? getApplicationDocumentsDirectory)();

      return File(
        p.join(switch (resolvedDirectory) {
          Directory(:final path) => path,
          final String path => path,
          final other => throw ArgumentError.value(
            other,
            'other',
            'databaseDirectory on DriftNativeOptions must resolve to a '
                'directory or a path as string.',
          ),
        }, '$name.sqlite'),
      );
    }
  }

  return DatabaseConnection.delayed(
    Future(() async {
      if (!hasConfiguredSqlite) {
        // Also work around limitations on old Android versions
        if (Platform.isAndroid) {
          await applyWorkaroundToOpenSqlite3OnOldAndroidVersions();
        }

        // Make sqlite3 pick a more suitable location for temporary files - the
        // one from the system may be inaccessible due to sandboxing.
        final cachebase = await (native?.tempDirectoryPath?.call() ?? getTemporaryDirectory().then((d) => d.path));

        if (cachebase != null) {
          // We can't access /tmp on Android, which sqlite3 would try by default.
          // Explicitly tell it about the correct temporary directory.
          sqlite3.tempDirectory = cachebase;
        }

        hasConfiguredSqlite = true;
      }

      if (native != null && native.shareAcrossIsolates) {
        const connectTimeout = Duration(seconds: 1);

        while (true) {
          if (IsolateNameServer.lookupPortByName(portName(name)) case final port?) {
            final isolate = DriftIsolate.fromConnectPort(port);
            try {
              return await isolate.connect(connectTimeout: connectTimeout, isolateDebugLog: true);
            } on TimeoutException {
              // Isolate has stopped shortly after the register call. It should
              // also remove the port mapping, so we can just try again in another
              // iteration.
              // However, it's possible for the isolate to become unreachable
              // without unregistering itself (either due to a fatal error or when
              // doing a hot restart). Check if the isolate is still reachable,
              // and remove the mapping if it's not.
              final controlPort = IsolateNameServer.lookupPortByName(isolateControlPortName(name));
              if (controlPort == null) {
                continue;
              }
              final supposedIsolate = Isolate(controlPort);
              if (!await supposedIsolate.pingWithTimeout()) {
                // Yup, gone!
                IsolateNameServer.removePortNameMapping(portName(name));
              }
              // Otherwise, the isolate is probably paused. Keep trying...
            }
          } else {
            // No port has been registered yet! Spawn an isolate that will try to
            // register itself as the database server.
            final receiveFromPending = ReceivePort();
            final firstMessage = receiveFromPending.first;
            await Isolate.spawn(_isolateEntrypoint, (
              name: name,
              options: native,
              sendResponses: receiveFromPending.sendPort,
              path: (await databaseFile()).path,
            ), onExit: receiveFromPending.sendPort);

            // The isolate will either succeed in registering its connect port to
            // the name server (in which case it sends us the port), or it fails
            // due to a race condition (in which case it exits).
            final first = await firstMessage;
            if (first case SendPort port) {
              return await DriftIsolate.fromConnectPort(port).connect(isolateDebugLog: true);
            }
          }
        }
      }

      return NativeDatabase.createBackgroundConnection(await databaseFile());
    }),
  );
}

typedef _EntrypointMessage = ({String name, String path, DriftNativeOptions options, SendPort sendResponses});

void _isolateEntrypoint(_EntrypointMessage message) {
  final connections = ReceivePort();
  if (IsolateNameServer.registerPortWithName(connections.sendPort, portName(message.name))) {
    final controlPortName = isolateControlPortName(message.name);
    final server = DriftIsolate.inCurrent(
      () => NativeDatabase(File(message.path)),
      port: connections,
      beforeShutdown: () {
        IsolateNameServer.removePortNameMapping(portName(message.name));
        IsolateNameServer.removePortNameMapping(controlPortName);
      },
      killIsolateWhenDone: true,
      shutdownAfterLastDisconnect: true,
    );

    message.sendResponses.send(server.connectPort);

    IsolateNameServer.removePortNameMapping(controlPortName);
    IsolateNameServer.registerPortWithName(Isolate.current.controlPort, controlPortName);
  } else {
    // Another isolate is responsible for hosting this database, abort.
    connections.close();
    return;
  }
}