using System.Collections.Generic;
using System.Linq;

namespace AppsheetEpplus;

/// <summary>
/// This class implements a stack on which instances of <see cref="ParsingScope"/>
/// are put. Each ParsingScope represents the parsing of an address in the workbook.
/// </summary>
public class ParsingScopes {
  private readonly IParsingLifetimeEventHandler _lifetimeEventHandler;

  public ParsingScopes(IParsingLifetimeEventHandler lifetimeEventHandler) {
    _lifetimeEventHandler = lifetimeEventHandler;
  }

  private readonly Stack<ParsingScope> _scopes = new();

  /// <summary>
  /// Creates a new <see cref="ParsingScope"/> and puts it on top of the stack.
  /// </summary>
  /// <param name="address"></param>
  /// <returns></returns>
  public virtual ParsingScope NewScope(RangeAddress address) {
    ParsingScope scope;
    if (_scopes.Count() > 0) {
      scope = new(this, _scopes.Peek(), address);
    } else {
      scope = new(this, address);
    }
    _scopes.Push(scope);
    return scope;
  }

  /// <summary>
  /// The current parsing scope.
  /// </summary>
  public virtual ParsingScope Current => _scopes.Count() > 0 ? _scopes.Peek() : null;

  /// <summary>
  /// Removes the current scope, setting the calling scope to current.
  /// </summary>
  /// <param name="parsingScope"></param>
  public virtual void KillScope(ParsingScope parsingScope) {
    _scopes.Pop();
    if (_scopes.Count() == 0) {
      _lifetimeEventHandler.ParsingCompleted();
    }
  }
}