library mustache.node;

abstract class Node {
  Node(this.start, this.end);
  
  // The offset of the start of the token in the file. Unless this is a section
  // or inverse section, then this stores the start of the content of the
  // section.
  final int start;
  final int end;
  
  void accept(Visitor visitor);
  void visitChildren(Visitor visitor) { }  
}

abstract class Visitor {
  void visitText(TextNode node);
  void visitVariable(VariableNode node);
  void visitSection(SectionNode node);
  void visitPartial(PartialNode node);
}

class TextNode extends Node {
  
  TextNode(this.text, int start, int end) : super(start, end);
    
  final String text;
  
  String toString() => '(TextNode "$_debugText" $start $end)';
  
  String get _debugText {
    var t = text.replaceAll('\n', '\\n');
    return t.length < 50 ? t : t.substring(0, 48) + '...';
  }
  
  void accept(Visitor visitor) => visitor.visitText(this);  
}

class VariableNode extends Node {
  
  VariableNode(this.name, int start, int end, {this.escape: true})
    : super(start, end);
  
  final String name;
  final bool escape;

  void accept(Visitor visitor) => visitor.visitVariable(this);
  
  String toString() => '(VariableNode "$name" escape: $escape $start $end)';  
}


class SectionNode extends Node {
  
  SectionNode(this.name, int start, int end, this.delimiters,
      {this.inverse: false})
    : contentStart = end,
      super(start, end);
  
  final String name;
  final String delimiters;
  final bool inverse;
  final int contentStart;
  int contentEnd; // Set in parser when close tag is parsed.
  final List<Node> children = <Node>[];

  void accept(Visitor visitor) => visitor.visitSection(this);
  
  void visitChildren(Visitor visitor) {
    children.forEach((node) => node.accept(visitor));
  }
  
  toString() => '(SectionNode $name inverse: $inverse $start $end)'; 
}

class PartialNode extends Node {

  PartialNode(this.name, int start, int end, this.indent)
    : super(start, end);
  
  final String name;
  
  // Used to store the preceding whitespace before a partial tag, so that
  // it's content can be correctly indented.
  final String indent;

  void accept(Visitor visitor) => visitor.visitPartial(this);
  
  toString() => '(PartialNode $name $start $end "$indent")';  
}