packages/frontend/lib/features/shared/models/prompt.dart

import '../utils/widget_tree_helper.dart';

/// Holds a MIME type and data URL pair for media prompt parts.
typedef MediaInfo = ({String mimeType, String url});

class Prompt {
  const Prompt(this.parts);

  factory Prompt.fromString(String s) {
    return Prompt([TextPromptPart(s)]);
  }

  final List<PromptPart> parts;

  bool get isEmpty =>
      parts.isEmpty ||
      parts.every(
        (e) => switch (e) {
          TextPromptPart(:final text) => text.isEmpty,
          ImagePromptPart() => false,
          _ => false,
        },
      );

  String toMessage() {
    return parts.map((e) => e.toMessage()).join();
  }
}

sealed class PromptPart {
  const PromptPart();

  String toMessage();

  /// Returns structured media info (MIME type + data URL) if this part
  /// represents inline media. Returns `null` for text-only parts.
  MediaInfo? toMediaInfo();
}

class TextPromptPart extends PromptPart {
  const TextPromptPart(this.text);

  final String text;

  @override
  String toMessage() {
    return text;
  }

  @override
  MediaInfo? toMediaInfo() => null;
}

class FilePromptPart extends PromptPart {
  const FilePromptPart({
    required this.path,
    required this.lineFrom,
    required this.lineTo,
    required this.text,
  });

  final String path;
  final int lineFrom;
  final int lineTo;
  final String text;

  @override
  String toMessage() {
    final line = lineFrom == lineTo ? '$lineFrom' : '$lineFrom-$lineTo';
    return '<file path="$path" line="$line">$text</file>';
  }

  @override
  MediaInfo? toMediaInfo() => null;
}

class WidgetSnapshotPromptPart extends PromptPart {
  const WidgetSnapshotPromptPart({
    required this.widgetName,
    required this.screenshotBase64,
    required this.summaryTree,
    this.properties = const {},
  });

  final String widgetName;
  final String screenshotBase64;
  final Map<String, dynamic> summaryTree;
  final Map<String, String> properties;

  @override
  String toMessage() {
    const helper = WidgetTreeHelper();
    final xmlTree = helper.nodeToXml(summaryTree, '    ');
    final sb = StringBuffer();
    sb.writeln('<$widgetName>');
    if (properties.isNotEmpty) {
      sb.writeln('  <properties>');
      for (final entry in properties.entries) {
        sb.writeln('    ${entry.key}: ${entry.value}');
      }
      sb.writeln('  </properties>');
    }
    sb.writeln('  <summary_tree>');
    sb.write(xmlTree);
    sb.writeln('  </summary_tree>');
    sb.write('</$widgetName>');
    return sb.toString();
  }

  @override
  MediaInfo? toMediaInfo() => (mimeType: 'image/png', url: 'data:image/png;base64,$screenshotBase64');
}

class DiagnosticPromptPart extends PromptPart {
  const DiagnosticPromptPart({
    required this.path,
    required this.line,
    required this.message,
    required this.severity,
  });

  final String path;
  final int line;
  final String message;
  final String severity;

  @override
  String toMessage() {
    return '<diagnostic path="$path" line="$line" severity="$severity">$message</diagnostic>';
  }

  @override
  MediaInfo? toMediaInfo() => null;
}

/// A prompt part representing a user-uploaded image.
class ImagePromptPart extends PromptPart {
  const ImagePromptPart({
    required this.fileName,
    required this.mimeType,
    required this.base64Data,
  });

  /// Display name of the uploaded file.
  final String fileName;

  /// MIME type, e.g. `image/png`, `image/jpeg`.
  final String mimeType;

  /// Base64-encoded image data.
  final String base64Data;

  /// The full data URL for this image (`data:<mimeType>;base64,<data>`).
  String get dataUrl => 'data:$mimeType;base64,$base64Data';

  /// Accepted MIME types for Gemini 2.5 image input.
  static const Set<String> supportedMimeTypes = {
    'image/png',
    'image/jpeg',
    'image/webp',
    'image/heic',
    'image/heif',
  };

  /// File extensions accepted in the file picker.
  static const String acceptAttribute = '.png,.jpg,.jpeg,.webp,.heic,.heif';

  @override
  // Intentionally empty – image data is sent as a MediaPart via
  // toMediaInfo(), not as inline text in the prompt.
  String toMessage() {
    return '';
  }

  @override
  MediaInfo? toMediaInfo() => (mimeType: mimeType, url: dataUrl);
}