import 'dart:io';

class OpencodeConfigBridge {
  OpencodeConfigBridge({String? opencodeHome})
    : opencodeHome =
          opencodeHome ?? '${Platform.environment['HOME'] ?? ''}/.opencode';

  static const String _managedMcpBlockStart =
      '# BEGIN XWORKMATE MANAGED MCP BLOCK';
  static const String _managedMcpBlockEnd = '# END XWORKMATE MANAGED MCP BLOCK';

  final String opencodeHome;

  Future<void> configureManagedMcpServers({
    required List<OpencodeMcpServer> servers,
  }) async {
    final configDir = Directory(opencodeHome);
    if (!await configDir.exists()) {
      await configDir.create(recursive: true);
    }

    final configFile = File('$opencodeHome/config.toml');
    final existingConfig = await configFile.exists()
        ? await configFile.readAsString()
        : '';
    final preserved = _stripManagedMcpBlock(existingConfig).trimRight();
    final managedBlock = _buildManagedMcpBlock(servers);
    final merged = preserved.isEmpty
        ? '$managedBlock\n'
        : '$preserved\n\n$managedBlock\n';
    await configFile.writeAsString(merged);
  }

  Future<String> readConfig() async {
    final configFile = File('$opencodeHome/config.toml');
    if (!await configFile.exists()) {
      return '';
    }
    return configFile.readAsString();
  }

  String _stripManagedMcpBlock(String content) {
    if (content.isEmpty) {
      return content;
    }

    var remaining = content;
    while (true) {
      final start = remaining.indexOf(_managedMcpBlockStart);
      if (start < 0) {
        break;
      }
      final end = remaining.indexOf(_managedMcpBlockEnd, start);
      if (end < 0) {
        remaining = remaining.substring(0, start);
        break;
      }
      remaining =
          remaining.substring(0, start) +
          remaining.substring(end + _managedMcpBlockEnd.length);
    }
    return remaining;
  }

  String _buildManagedMcpBlock(List<OpencodeMcpServer> servers) {
    final buffer = StringBuffer()
      ..writeln(_managedMcpBlockStart)
      ..writeln('# Generated by XWorkmate - Managed MCP Server Configuration')
      ..writeln('# Last updated: ${DateTime.now().toIso8601String()}')
      ..writeln();

    for (final server in servers) {
      buffer.writeln('[mcp_servers.${server.name}]');
      if (server.url.trim().isNotEmpty) {
        buffer.writeln('url = "${server.url.trim()}"');
      } else {
        buffer.writeln('type = "stdio"');
        buffer.writeln('command = "${server.command}"');
        if (server.args.isNotEmpty) {
          buffer.writeln('args = ${_formatTomlArray(server.args)}');
        }
      }
      if (server.env.isNotEmpty) {
        final entries = server.env.entries
            .map((entry) => '${entry.key} = "${entry.value}"')
            .join(', ');
        buffer.writeln('env = { $entries }');
      }
      buffer.writeln();
    }

    buffer.writeln(_managedMcpBlockEnd);
    return buffer.toString().trimRight();
  }

  String _formatTomlArray(List<String> items) {
    if (items.isEmpty) {
      return '[]';
    }
    return '[${items.map((item) => '"$item"').join(', ')}]';
  }
}

class OpencodeMcpServer {
  const OpencodeMcpServer({
    required this.name,
    this.command = '',
    this.url = '',
    this.args = const <String>[],
    this.env = const <String, String>{},
  });

  final String name;
  final String command;
  final String url;
  final List<String> args;
  final Map<String, String> env;
}