using System;
using System.Collections.Generic;

namespace Topten.RichTextKit
{
    partial class TextBlock
    {
        /// <summary>
        /// Determines whether to add ellipsis symbol automatically to a truncated text.
        /// </summary>
        public bool AllowEllipsis { get; set; } = true;

        /// <summary>
        /// Corresponds to LineLimit flag of gdi+ StringFormat. Allows to draw a partially visible text line if set to false.
        /// </summary>
        public bool LineLimit { get; set; } = true;

        /// <summary>
        /// Gets or sets the tab stop list.
        /// </summary>
        public float[] TabStops { get; set; }

        /// <summary>
        /// Gets or sets the default tab width, in pixels.
        /// </summary>
        public float FirstTabOffset { get; set; }

        private float GetTabStopPositionOffset(float pos)
        {
            float result = FirstTabOffset;
            
            if (TabStops != null && TabStops.Length > 0)
            {
                float tabWidth = 0;
                for (int i = 0; i < TabStops.Length; i++)
                {
                    tabWidth = TabStops[i];
                    result += tabWidth;
                    if (result > pos)
                        return result - pos;

                    if (i == 0 && tabWidth > 0)
                        result -= result % tabWidth;
                }

                if (tabWidth <= 0)
                    return 0;

                while (result < pos)
                {
                    result += tabWidth;
                }

                return result - pos;
            }

            if (result > pos)
                return result - pos;
            return 0;
        }

        /// <summary>
        /// Adds a text that may contain tabs.
        /// </summary>
        /// <param name="text">The text to add.</param>
        /// <param name="style">The style.</param>
        public void AddTextWithTabs(string text, Style style)
        {
            // each tab is added as a separate symbol
            if (text.Contains("\t"))
            {
                while (text != "")
                {
                    int tabPos = text.IndexOf("\t");
                    if (tabPos == -1)
                        break;
                    if (tabPos != 0)
                        AddText(text.Substring(0, tabPos), style);
                    AddText("\t", style);
                    text = text.Substring(tabPos + 1);
                }
            }
            
            AddText(text, style);
        }
    }
}