import 'package:collection/collection.dart';
import 'package:fluffychat/pangea/controllers/message_analytics_controller.dart';
import 'package:fluffychat/pangea/matrix_event_wrappers/pangea_message_event.dart';
import 'package:fluffychat/pangea/models/pangea_token_model.dart';
import 'package:fluffychat/widgets/matrix.dart';
import 'package:flutter/gestures.dart';
import 'package:flutter/material.dart';

/// Question - does this need to be stateful or does this work?
/// Need to test.
class MessageTokenText extends StatelessWidget {
  final PangeaMessageEvent _pangeaMessageEvent;

  final List<PangeaToken>? _tokens;

  final TextStyle _style;

  final bool Function(PangeaToken)? _isSelected;
  final void Function(PangeaToken)? _onClick;

  const MessageTokenText({
    super.key,
    required PangeaMessageEvent pangeaMessageEvent,
    required List<PangeaToken>? tokens,
    required TextStyle style,
    required void Function(PangeaToken)? onClick,
    bool Function(PangeaToken)? isSelected,
  })  : _onClick = onClick,
        _isSelected = isSelected,
        _style = style,
        _tokens = tokens,
        _pangeaMessageEvent = pangeaMessageEvent;

  MessageAnalyticsEntry? get messageAnalyticsEntry => _tokens != null
      ? MatrixState.pangeaController.getAnalytics.perMessage.get(
          _tokens!,
          _pangeaMessageEvent,
        )
      : null;

  @override
  Widget build(BuildContext context) {
    if (_tokens == null) {
      return Text(
        _pangeaMessageEvent.messageDisplayText,
        style: _style,
      );
    }

    // Convert the entire message into a list of characters
    final Characters messageCharacters =
        _pangeaMessageEvent.messageDisplayText.characters;

    // When building token positions, use grapheme cluster indices
    final List<TokenPosition> tokenPositions = [];
    int globalIndex = 0;

    for (final token
        in _pangeaMessageEvent.messageDisplayRepresentation!.tokens!) {
      final start = token.start;
      final end = token.end;

      // Calculate the number of grapheme clusters up to the start and end positions
      final int startIndex = messageCharacters.take(start).length;
      final int endIndex = messageCharacters.take(end).length;

      final hideContent =
          messageAnalyticsEntry?.isTokenInHiddenWordActivity(token) ?? false;

      if (globalIndex < startIndex) {
        tokenPositions.add(
          TokenPosition(
            start: globalIndex,
            end: startIndex,
            hideContent: false,
            highlight: _isSelected?.call(token) ?? false,
          ),
        );
      }

      tokenPositions.add(
        TokenPosition(
          start: startIndex,
          end: endIndex,
          token: token,
          hideContent: hideContent,
          highlight: (_isSelected?.call(token) ?? false) && !hideContent,
        ),
      );
      globalIndex = endIndex;
    }

    return RichText(
      text: TextSpan(
        children:
            tokenPositions.mapIndexed((int i, TokenPosition tokenPosition) {
          final substring = messageCharacters
              .skip(tokenPosition.start)
              .take(tokenPosition.end - tokenPosition.start)
              .toString();

          if (tokenPosition.token != null) {
            if (tokenPosition.hideContent) {
              final TextPainter textPainter = TextPainter(
                text: TextSpan(text: substring, style: _style),
                textDirection: TextDirection.ltr,
              )..layout();

              final textWidth = textPainter.size.width;

              return WidgetSpan(
                child: GestureDetector(
                  onTap: () => _onClick != null && tokenPosition.token != null
                      ? _onClick!(tokenPosition.token!)
                      : null,
                  child: Container(
                    width: textWidth,
                    height: 1,
                    color: _style.color,
                    margin: const EdgeInsets.only(bottom: 2),
                  ),
                ),
              );
            }
            return TextSpan(
              recognizer: TapGestureRecognizer()
                ..onTap = () => _onClick != null && tokenPosition.token != null
                    ? _onClick!(tokenPosition.token!)
                    : null,
              text: substring,
              style: _style.merge(
                TextStyle(
                  backgroundColor: tokenPosition.highlight
                      ? Theme.of(context).brightness == Brightness.light
                          ? Colors.black.withOpacity(0.4)
                          : Colors.white.withOpacity(0.4)
                      : Colors.transparent,
                ),
              ),
            );
          } else {
            if ((i > 0 || i < tokenPositions.length - 1) &&
                tokenPositions[i + 1].hideContent &&
                tokenPositions[i - 1].hideContent) {
              final TextPainter textPainter = TextPainter(
                text: TextSpan(text: substring, style: _style),
                textDirection: TextDirection.ltr,
              )..layout();

              final textWidth = textPainter.size.width;

              return WidgetSpan(
                child: GestureDetector(
                  onTap: () => _onClick != null && tokenPosition.token != null
                      ? _onClick!(tokenPosition.token!)
                      : null,
                  child: Container(
                    width: textWidth,
                    height: 1,
                    color: _style.color,
                    margin: const EdgeInsets.only(bottom: 2),
                  ),
                ),
              );
            }
            return TextSpan(
              text: substring,
              style: _style,
            );
          }
        }).toList(),
      ),
    );
  }
}

class TokenPosition {
  final int start;
  final int end;
  final bool highlight;
  final bool hideContent;
  final PangeaToken? token;

  const TokenPosition({
    required this.start,
    required this.end,
    required this.hideContent,
    required this.highlight,
    this.token,
  });
}