import 'package:xterm/core/input/keys.dart';
import 'package:xterm/core/input/keytab/keytab.dart';
import 'package:xterm/utils/platform.dart';
import 'package:xterm/core/state.dart';

class TerminalInputEvent {
  final TerminalKey key;

  final bool shift;

  final bool ctrl;

  final bool alt;

  final TerminalState state;

  final bool altBuffer;

  final TerminalTargetPlatform platform;

  TerminalInputEvent({
    required this.key,
    required this.shift,
    required this.ctrl,
    required this.alt,
    required this.state,
    required this.altBuffer,
    required this.platform,
  });
}

abstract class TerminalInputHandler {
  String? call(TerminalInputEvent event);
}

class CascadeInputHandler implements TerminalInputHandler {
  final List<TerminalInputHandler> _handlers;

  const CascadeInputHandler(this._handlers);

  @override
  String? call(TerminalInputEvent event) {
    for (var handler in _handlers) {
      final result = handler(event);
      if (result != null) {
        return result;
      }
    }
    return null;
  }
}

const defaultInputHandler = CascadeInputHandler([
  KeytabInputHandler(),
  CtrlInputHandler(),
  AltInputHandler(),
]);

final _keytab = Keytab.defaultKeytab();

class KeytabInputHandler implements TerminalInputHandler {
  const KeytabInputHandler();

  @override
  String? call(TerminalInputEvent event) {
    final action = _keytab.find(
      event.key,
      ctrl: event.ctrl,
      alt: event.alt,
      shift: event.shift,
      newLineMode: event.state.lineFeedMode,
      appCursorKeys: event.state.appKeypadMode,
      appKeyPad: event.state.appKeypadMode,
      appScreen: event.altBuffer,
      macos: event.platform == TerminalTargetPlatform.macos,
    );

    if (action == null) {
      return null;
    }

    return action.action.unescapedValue();
  }
}

class CtrlInputHandler implements TerminalInputHandler {
  const CtrlInputHandler();

  @override
  String? call(TerminalInputEvent event) {
    if (!event.ctrl) {
      return null;
    }

    final key = event.key;

    if (key.index >= TerminalKey.keyA.index &&
        key.index <= TerminalKey.keyZ.index) {
      final input = key.index - TerminalKey.keyA.index + 1;
      return String.fromCharCode(input);
    }

    return null;
  }
}

class AltInputHandler implements TerminalInputHandler {
  const AltInputHandler();

  @override
  String? call(TerminalInputEvent event) {
    if (!event.alt) {
      return null;
    }

    if (event.platform == TerminalTargetPlatform.macos) {
      return null;
    }

    final key = event.key;

    if (key.index >= TerminalKey.keyA.index &&
        key.index <= TerminalKey.keyZ.index) {
      final charCode = key.index - TerminalKey.keyA.index + 65;
      final input = [0x1b, charCode];
      return String.fromCharCodes(input);
    }

    return null;
  }
}