import 'package:flutter/material.dart';

class AnsiTextParser {
  // Matches CSI (Control Sequence Introducer) sequences: ESC [ ... FinalByte
  // And OSC (Operating System Command) sequences: ESC ] ... BEL(\x07) or ST(\x1B\)
  static final RegExp _ansiRegex = RegExp(r'\x1B\[[0-9;?]*[ -/]*[@-~]|\x1B\].*?(\x07|\x1B\\)');

  static String strip(String text) {
    // Remove ANSI codes
    var clean = text.replaceAll(_ansiRegex, '');
    // Remove control chars (same regex as in parse)
    clean = clean.replaceAll(RegExp(r'[\x00-\x08\x0B\x0C\x0E-\x1F]'), '');
    return clean;
  }

  TextSpan parse(String text) {
    final List<TextSpan> spans = [];
    final matches = _ansiRegex.allMatches(text);
    
    int currentIndex = 0;
    TextStyle currentStyle = const TextStyle(color: Colors.white, fontFamily: 'monospace');

    for (final match in matches) {
      if (match.start > currentIndex) {
        final plainText = text.substring(currentIndex, match.start);
        // Clean up common non-printable control chars from the plain text segment
        // \x07 (Bell), \x08 (Backspace - simple strip, handling logic is complex for stream)
        final cleanText = plainText.replaceAll(RegExp(r'[\x00-\x08\x0B\x0C\x0E-\x1F]'), '');
        
        if (cleanText.isNotEmpty) {
          spans.add(TextSpan(
            text: cleanText,
            style: currentStyle,
          ));
        }
      }

      final String sequence = match.group(0)!;
      // We only process SGR (Select Graphic Rendition) which ends in 'm'
      // All other sequences (cursor movement, clear screen, etc.) are stripped.
      if (sequence.endsWith('m')) {
         currentStyle = _parseSgrSequence(sequence, currentStyle);
      }

      currentIndex = match.end;
    }

    if (currentIndex < text.length) {
      final plainText = text.substring(currentIndex);
      final cleanText = plainText.replaceAll(RegExp(r'[\x00-\x08\x0B\x0C\x0E-\x1F]'), '');
      if (cleanText.isNotEmpty) {
        spans.add(TextSpan(
          text: cleanText,
          style: currentStyle,
        ));
      }
    }

    return TextSpan(children: spans);
  }

  TextStyle _parseSgrSequence(String sequence, TextStyle currentStyle) {
    // Remove \x1B[ and m
    final content = sequence.substring(2, sequence.length - 1);
    final parts = content.split(';');
    
    TextStyle newStyle = currentStyle;

    if (parts.isEmpty || (parts.length == 1 && parts.first.isEmpty)) {
      // Empty usually means reset 0
      return const TextStyle(color: Colors.white, fontFamily: 'monospace');
    }

    for (final part in parts) {
      final int? value = int.tryParse(part);
      if (value == null) continue;

      if (value == 0) {
        newStyle = const TextStyle(color: Colors.white, fontFamily: 'monospace');
      } else if (value == 1) {
        newStyle = newStyle.copyWith(fontWeight: FontWeight.bold);
      } else if (value >= 30 && value <= 37) {
        newStyle = newStyle.copyWith(color: _getAnsiColor(value));
      } else if (value >= 90 && value <= 97) {
        newStyle = newStyle.copyWith(color: _getAnsiColor(value));
      }
      // Add background colors or other styles if needed
    }
    return newStyle;
  }

  Color _getAnsiColor(int code) {
    switch (code) {
      case 30: return Colors.black;
      case 31: return Colors.red;
      case 32: return Colors.green;
      case 33: return Colors.yellow;
      case 34: return Colors.blue;
      case 35: return Colors.purple;
      case 36: return Colors.cyan;
      case 37: return Colors.white;
      case 90: return Colors.grey;
      case 91: return Colors.redAccent;
      case 92: return Colors.greenAccent;
      case 93: return Colors.yellowAccent;
      case 94: return Colors.blueAccent;
      case 95: return Colors.purpleAccent;
      case 96: return Colors.cyanAccent;
      case 97: return Colors.white;
      default: return Colors.white;
    }
  }
}