/// Document model for Mews pages (mews-spec/SPEC.md sections 3 to 6).
/// Pure data: no Flutter imports, so it can be built inside an isolate.
library;

/// The `body` variant class a page carries (spec 5.3), or [plain] when absent.
enum MewsVariant { plain, warm, cool, green, mono }

/// A parsed page. [specVersion] holds the conformance marker's value and is
/// null on a page without the marker, which must be shown plainly (spec 8.1).
class MewsPage {
  const MewsPage({
    required this.url,
    required this.body,
    required this.lang,
    required this.direction,
    required this.variant,
    required this.entries,
    this.specVersion,
    this.title,
    this.description,
    this.author,
    this.atomFeedHref,
  });

  final String url;
  final List<MewsBlock> body;
  final String lang;
  final TextDirection direction;
  final MewsVariant variant;
  final List<MewsEntry> entries;
  final String? specVersion;
  final String? title;
  final String? description;
  final String? author;
  final String? atomFeedHref;

  bool get isMews => specVersion != null;
}

/// TextDirection without importing Flutter: pages with dir="rtl" render
/// right-to-left (spec 3).
enum TextDirection { ltr, rtl }

/// A dated link that starts a list item (spec 6.1).
class MewsEntry {
  const MewsEntry({required this.url, required this.date, required this.title});

  final String url;
  final DateTime date;
  final String title;
}

sealed class MewsBlock {
  const MewsBlock();
}

class HeadingBlock extends MewsBlock {
  const HeadingBlock(this.level, this.inline);

  final int level; // 1 to 6
  final List<MewsInline> inline;
}

class ParagraphBlock extends MewsBlock {
  const ParagraphBlock(this.inline);

  final List<MewsInline> inline;
}

class QuoteBlock extends MewsBlock {
  const QuoteBlock(this.children);

  final List<MewsBlock> children;
}

class PreBlock extends MewsBlock {
  const PreBlock(this.text);

  final String text;
}

class AddressBlock extends MewsBlock {
  const AddressBlock(this.inline);

  final List<MewsInline> inline;
}

class RuleBlock extends MewsBlock {
  const RuleBlock();
}

class ListBlock extends MewsBlock {
  const ListBlock({required this.ordered, required this.start, required this.items});

  final bool ordered;
  final int start;
  final List<MewsListItem> items;
}

class MewsListItem {
  const MewsListItem(this.blocks);

  final List<MewsBlock> blocks;
}

class DefinitionItem {
  const DefinitionItem(this.term, this.definition);

  final List<MewsInline> term;
  final List<MewsInline> definition;
}

class DefinitionListBlock extends MewsBlock {
  const DefinitionListBlock(this.items);

  final List<DefinitionItem> items;
}

class TableBlock extends MewsBlock {
  const TableBlock({required this.rows, this.caption, this.summary});

  final List<MewsTableRow> rows;
  final String? caption;
  final String? summary;
}

class MewsTableRow {
  const MewsTableRow(this.cells);

  final List<MewsTableCell> cells;
}

class MewsTableCell {
  const MewsTableCell({
    required this.header,
    required this.inline,
    this.colspan = 1,
    this.rowspan = 1,
  });

  final bool header;
  final List<MewsInline> inline;
  final int colspan;
  final int rowspan;
}

/// Same-site images load normally; off-site or data: sources are refused by
/// the client without reader action (specs 4.2 and 8.1), and the alt text is
/// shown in their place.
class ImageBlock extends MewsBlock {
  const ImageBlock({required this.src, required this.alt, required this.allowed});

  final String src;
  final String alt;
  final bool allowed;
}

class FormBlock extends MewsBlock {
  const FormBlock({
    required this.action,
    required this.method,
    required this.fields,
    required this.submitLabel,
  });

  final String action;
  final String method;
  final List<MewsFormField> fields;
  final String? submitLabel;
}

sealed class MewsFormField {
  const MewsFormField({required this.name, this.label});

  final String name;
  final String? label;
}

class MewsTextField extends MewsFormField {
  const MewsTextField({
    required super.name,
    required this.password,
    this.value = '',
    this.maxLength,
    this.inputMode,
    super.label,
  });

  final bool password;
  final String value;
  final int? maxLength;
  final String? inputMode;
}

class MewsCheckboxField extends MewsFormField {
  const MewsCheckboxField({
    required super.name,
    required this.checked,
    this.value = 'on',
    super.label,
  });

  final bool checked;
  final String value;
}

class MewsRadioField extends MewsFormField {
  const MewsRadioField({
    required super.name,
    required this.checked,
    required this.value,
    super.label,
  });

  final bool checked;
  final String value;
}

class MewsSelectField extends MewsFormField {
  const MewsSelectField({required super.name, required this.options, super.label});

  final List<MewsSelectOption> options;
}

class MewsSelectOption {
  const MewsSelectOption({required this.value, required this.selected});

  final String value;
  final bool selected;
}

class MewsTextAreaField extends MewsFormField {
  const MewsTextAreaField({
    required super.name,
    required this.value,
    this.rows = 3,
    super.label,
  });

  final String value;
  final int rows;
}

/// A hidden input; kept in the model so it round-trips on submit.
class MewsHiddenField extends MewsFormField {
  const MewsHiddenField({required super.name, required this.value});

  final String value;
}

/// One or more inputs of kind submit/reset collapse into this control.
class MewsSubmitField extends MewsFormField {
  const MewsSubmitField({required this.reset, super.label, super.name = ''});

  final bool reset;
}

sealed class MewsInline {
  const MewsInline();
}

class MewsText extends MewsInline {
  const MewsText(this.text);

  final String text;
}

enum EmphasisStyle { emphasis, strong, code, sample, variable, term, quote }

/// em, i, cite and abbr map to [EmphasisStyle.emphasis]; strong and b to
/// [EmphasisStyle.strong]; kbd and samp to [EmphasisStyle.sample]; var to
/// [EmphasisStyle.variable]; dfn to [EmphasisStyle.term]; q to
/// [EmphasisStyle.quote]. The distinction keeps the renderer honest about what
/// authors meant, per the reader-controls-presentation principle.
class MewsEmphasis extends MewsInline {
  const MewsEmphasis(this.style, this.children);

  final EmphasisStyle style;
  final List<MewsInline> children;
}

class MewsLink extends MewsInline {
  const MewsLink(this.href, this.children);

  final String href;
  final List<MewsInline> children;
}

class MewsLineBreak extends MewsInline {
  const MewsLineBreak();
}