using System;
using System.Collections.Generic;
using System.Text;
using FastReport.Utils;

namespace FastReport.Preview
{
    internal class Outline
    {
        private XmlItem rootItem;
        private XmlItem curItem;
        private int firstPassPosition;

        public XmlItem Xml
        {
            get { return rootItem; }
            set
            {
                rootItem = value;
                curItem = rootItem;
                value.Parent = null;
            }
        }

        internal bool IsEmpty
        {
            get { return rootItem.Count == 0; }
        }

        internal XmlItem CurPosition
        {
            get { return curItem.Count == 0 ? null : curItem[curItem.Count - 1]; }
        }

        private void EnumItems(XmlItem item, float shift)
        {
            int pageNo = int.Parse(item.GetProp("Page"));
            float offset = Converter.StringToFloat(item.GetProp("Offset"));
            item.SetProp("Page", Converter.ToString(pageNo + 1));
            item.SetProp("Offset", Converter.ToString(offset + shift));

            for (int i = 0; i < item.Count; i++)
            {
                EnumItems(item[i], shift);
            }
        }

        internal void Shift(XmlItem from, float newY)
        {
            if (from == null || from.Parent == null)
                return;
            int i = from.Parent.IndexOf(from);
            if (i + 1 >= from.Parent.Count)
                return;
            from = from.Parent[i + 1];

            float topY = Converter.StringToFloat(from.GetProp("Offset"));
            EnumItems(from, newY - topY);
        }

        public void Add(string text, int pageNo, float offsetY)
        {
            curItem = curItem.Add();
            curItem.Name = "item";
            curItem.SetProp("Text", text);
            curItem.SetProp("Page", pageNo.ToString());
            curItem.SetProp("Offset", Converter.ToString(offsetY));
        }

        public void LevelRoot()
        {
            curItem = rootItem;
        }

        public void LevelUp()
        {
            if (curItem != rootItem)
                curItem = curItem.Parent;
        }

        public void Clear()
        {
            Clear(-1);
        }

        private void Clear(int position)
        {
            if (position == -1)
                rootItem.Clear();
            else if (position < rootItem.Count)
                rootItem.Items[position].Dispose();

            LevelRoot();
        }

        public void PrepareToFirstPass()
        {
            firstPassPosition = rootItem.Count == 0 ? -1 : rootItem.Count;
            LevelRoot();
        }

        public void ClearFirstPass()
        {
            Clear(firstPassPosition);
        }

        public Outline()
        {
            rootItem = new XmlItem();
            rootItem.Name = "outline";
            LevelRoot();
        }
    }
}