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//
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// content are licensed under the terms of the Creative Commons Attribution-ShareAlike 4.0
// International. See the License terms at http://creativecommons.org/licenses/by-sa/4.0/legalcode

namespace Textile;

/// <summary>
/// Base class for formatter states.
/// </summary>
/// A formatter state describes the current situation
/// of the text being currently processed. A state can
/// write HTML code when entered, exited, and can modify
/// each line of text it receives.
public abstract class FormatterState
{
    /// <summary>
    /// The formatter this state belongs to.
    /// </summary>
    public TextileFormatter Formatter { get; }

    /// <summary>
    /// Public constructor.
    /// </summary>
    /// <param name="f">The parent formatter.</param>
    protected FormatterState(TextileFormatter formatter)
    {
        Formatter = formatter;
    }

    /// <summary>
    /// 
    /// </summary>
    /// <param name="input"></param>
    /// <param name="m"></param>
    /// <returns></returns>
    public abstract string Consume(string input, Match m);

    /// <summary>
    /// Method called when the state is entered.
    /// </summary>
    public abstract void Enter();
    /// <summary>
    /// Method called when the state is exited.
    /// </summary>
    public abstract void Exit();
    /// <summary>
    /// Method called when a line of text should be written
    /// to the web form.
    /// </summary>
    /// <param name="input">The line of text.</param>
    public abstract void FormatLine(string input);

    /// <summary>
    /// Returns whether this state can last for more than one line.
    /// </summary>
    /// <returns>A boolean value stating whether this state is only for one line.</returns>
    /// This method should return true only if this state is genuinely
    /// multi-line. For example, a header text is only one line long. You can
    /// have several consecutive lines of header texts, but they are not the same
    /// header - just several headers one after the other.
    /// Bulleted and numbered lists are good examples of multi-line states.
    //abstract public bool IsOneLineOnly();

    /// <summary>
    /// 
    /// </summary>
    /// <param name="input"></param>
    /// <returns></returns>
    public abstract bool ShouldExit(string input);

    /// <summary>
    /// 
    /// </summary>
    /// <param name="actualTag"></param>
    /// <param name="alignNfo"></param>
    /// <param name="attNfo"></param>
    /// <returns></returns>
    public virtual bool ShouldNestState(FormatterState other)
    {
        return false;
    }

    /// <summary>
    /// Returns whether block formatting (quick phrase modifiers, etc.) should be
    /// applied to this line.
    /// </summary>
    /// <param name="input">The line of text</param>
    /// <returns>Whether the line should be formatted for blocks</returns>
    public virtual bool ShouldFormatBlocks(string input)
    {
        return true;
    }

    /// <summary>
    /// Returns whether the current state accepts being superceded by another one
    /// we would possibly find by parsing the input line of text.
    /// </summary>
    /// <param name="input"></param>
    /// <returns></returns>
    public virtual bool ShouldParseForNewFormatterState(string input)
    {
        return true;
    }

    /// <summary>
    /// Gets the formatting state we should fallback to if we don't find anything
    /// relevant in a line of text.
    /// </summary>
    public virtual Type FallbackFormattingState
    {
        get
        {
            return typeof(ParagraphFormatterState);
        }
    }

    protected FormatterState CurrentFormatterState
    {
        get { return this.Formatter.CurrentState; }
    }

    protected void ChangeFormatterState(FormatterState formatterState)
    {
        this.Formatter.ChangeState(formatterState);
    }
}