import 'dart:convert';

/// Parsed representation of one tool call emitted as a `<details type="tool_calls" ...>` block
class ToolCallEntry {
  final String id;
  final String name;
  final bool done;
  final dynamic arguments; // decoded JSON when possible, else String
  final dynamic result; // decoded JSON when possible, else String
  final List<dynamic>? files; // decoded JSON array when present

  const ToolCallEntry({
    required this.id,
    required this.name,
    required this.done,
    this.arguments,
    this.result,
    this.files,
  });
}

/// Container for extracted tool calls and the remaining main content
class ToolCallsContent {
  final List<ToolCallEntry> toolCalls;
  final String mainContent;
  final String originalContent;

  const ToolCallsContent({
    required this.toolCalls,
    required this.mainContent,
    required this.originalContent,
  });
}

/// Utility to parse <details type="tool_calls"> blocks from content
class ToolCallsParser {
  /// Represents a mixed stream of text and tool-call entries in original order
  /// as they appeared in the content.
  static List<ToolCallsSegment>? segments(String content) {
    if (content.isEmpty || !content.contains('<details')) return null;

    final segs = <ToolCallsSegment>[];
    int index = 0;

    while (index < content.length) {
      final start = content.indexOf('<details', index);
      if (start == -1) {
        if (index < content.length) {
          segs.add(ToolCallsSegment.text(content.substring(index)));
        }
        break;
      }

      // Text before the block
      if (start > index) {
        segs.add(ToolCallsSegment.text(content.substring(index, start)));
      }

      // Find end of opening tag
      final openEnd = content.indexOf('>', start);
      if (openEnd == -1) {
        // Malformed; append rest as text
        segs.add(ToolCallsSegment.text(content.substring(start)));
        break;
      }
      final openTag = content.substring(start, openEnd + 1);

      // Find matching closing tag with nesting support
      int depth = 1;
      int i = openEnd + 1;
      while (i < content.length && depth > 0) {
        final nextOpen = content.indexOf('<details', i);
        final nextClose = content.indexOf('</details>', i);
        if (nextClose == -1 && nextOpen == -1) break;
        if (nextOpen != -1 && (nextClose == -1 || nextOpen < nextClose)) {
          depth++;
          i = nextOpen + 8; // '<details'
        } else {
          depth--;
          i = (nextClose != -1) ? nextClose + 10 : content.length; // '</details>'
        }
      }

      if (depth != 0) {
        // Unclosed details; append the rest as text
        segs.add(ToolCallsSegment.text(content.substring(start)));
        break;
      }

      final fullMatch = content.substring(start, i);

      // Parse attributes from opening tag
      final attrs = <String, String>{};
      final attrRegex = RegExp(r'(\w+)="(.*?)"');
      for (final m in attrRegex.allMatches(openTag)) {
        attrs[m.group(1)!] = m.group(2) ?? '';
      }

      if ((attrs['type'] ?? '') == 'tool_calls') {
        dynamic _decode(String? s) {
          if (s == null || s.isEmpty) return null;
          try {
            return json.decode(s);
          } catch (_) {
            return s;
          }
        }

        final id = (attrs['id'] ?? '');
        final name = (attrs['name'] ?? 'tool');
        final done = (attrs['done'] == 'true');
        final args = _decode(attrs['arguments']);
        final result = _decode(attrs['result']);
        final files = _decode(attrs['files']);

        segs.add(
          ToolCallsSegment.entry(
            ToolCallEntry(
              id: id.isNotEmpty ? id : '${name}_$start',
              name: name,
              done: done,
              arguments: args,
              result: result,
              files: (files is List) ? files as List : null,
            ),
          ),
        );
      } else {
        segs.add(ToolCallsSegment.text(fullMatch));
      }

      index = i;
    }

    return segs.isEmpty ? null : segs;
  }

  /// Extracts tool call blocks and returns the remaining content with those blocks removed.
  static ToolCallsContent? parse(String content) {
    if (content.isEmpty || !content.contains('<details')) return null;

    final segs = segments(content);
    if (segs == null) return null;

    final calls = <ToolCallEntry>[];
    final buf = StringBuffer();
    for (final seg in segs) {
      if (seg.isToolCall && seg.entry != null) {
        calls.add(seg.entry!);
      } else if (seg.text != null && seg.text!.isNotEmpty) {
        buf.write(seg.text);
      }
    }

    if (calls.isEmpty) return null;
    return ToolCallsContent(
      toolCalls: calls,
      mainContent: buf.toString().trim(),
      originalContent: content,
    );
  }

  /// Legacy helper that summarizes tool blocks to text (kept for fallback)
  static String summarize(String content) {
    final parsed = parse(content);
    if (parsed == null) return content;
    final buf = StringBuffer();
    for (final c in parsed.toolCalls) {
      buf.writeln(c.done ? 'Tool Executed: ${c.name}' : 'Running tool: ${c.name}…');
      final args = _prettyMaybe(c.arguments, max: 400);
      final res = _prettyMaybe(c.result, max: 800);
      if (args.isNotEmpty) {
        buf.writeln('\nArguments:\n```json');
        buf.writeln(args);
        buf.writeln('```');
      }
      if (res.isNotEmpty) {
        buf.writeln('\nResult:\n```json');
        buf.writeln(res);
        buf.writeln('```');
      }
      buf.writeln();
    }
    buf.writeln(parsed.mainContent);
    return buf.toString().trim();
  }

  static String _prettyMaybe(dynamic value, {int max = 600}) {
    if (value == null) return '';
    try {
      final pretty = const JsonEncoder.withIndent('  ').convert(value);
      return pretty.length > max ? pretty.substring(0, max) + '\n…' : pretty;
    } catch (_) {
      final raw = value.toString();
      return raw.length > max ? raw.substring(0, max) + '…' : raw;
    }
  }
}

/// Ordered piece of content: either plain text or a tool-call entry
class ToolCallsSegment {
  final String? text;
  final ToolCallEntry? entry;

  const ToolCallsSegment._({this.text, this.entry});
  factory ToolCallsSegment.text(String text) => ToolCallsSegment._(text: text);
  factory ToolCallsSegment.entry(ToolCallEntry entry) =>
      ToolCallsSegment._(entry: entry);

  bool get isToolCall => entry != null;
}