using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Tango.Scripting.Editors.Document;

namespace Tango.Scripting.Editors.Folding
{
    /// <summary>
    /// Allows producing foldings from a document based on braces.
    /// </summary>
    public class BraceFoldingStrategy
    {
        private class FoldingDefinition
        {
            public String Open { get; set; }
            public String Close { get; set; }

            public FoldingDefinition(String open, String close)
            {
                Open = open;
                Close = close;
            }
        }

        private class FoldingOffset
        {
            public FoldingDefinition Definition { get; set; }
            public int Offset { get; set; }
        }

        private List<FoldingDefinition> foldings = new List<FoldingDefinition>()
        {
             new FoldingDefinition("namespace","}"),
             new FoldingDefinition("public","}"),
             new FoldingDefinition("private","}"),
             new FoldingDefinition("internal","}"),
             new FoldingDefinition("if","}"),
             new FoldingDefinition("class","}"),
             new FoldingDefinition("while","}"),
             new FoldingDefinition("static void","}"),
             new FoldingDefinition("/// <summary>","/// </summary>"),
        };

        /// <summary>
        /// Gets/Sets the opening brace. The default value is '{'.
        /// </summary>
        public char OpeningBrace { get; set; }

        /// <summary>
        /// Gets/Sets the closing brace. The default value is '}'.
        /// </summary>
        public char ClosingBrace { get; set; }

        /// <summary>
        /// Creates a new BraceFoldingStrategy.
        /// </summary>
        public BraceFoldingStrategy()
        {
            this.OpeningBrace = '{';
            this.ClosingBrace = '}';
        }

        public void UpdateFoldings(FoldingManager manager, TextDocument document)
        {
            int firstErrorOffset;
            IEnumerable<NewFolding> newFoldings = CreateNewFoldings(document, out firstErrorOffset);
            manager.UpdateFoldings(newFoldings, firstErrorOffset);
        }

        /// <summary>
        /// Create <see cref="NewFolding"/>s for the specified document.
        /// </summary>
        public IEnumerable<NewFolding> CreateNewFoldings(TextDocument document, out int firstErrorOffset)
        {
            firstErrorOffset = -1;
            return CreateNewFoldings(document);
        }

        /// <summary>
        /// Create <see cref="NewFolding"/>s for the specified document.
        /// </summary>
        public IEnumerable<NewFolding> CreateNewFoldings(ITextSource document)
        {
            List<NewFolding> newFoldings = new List<NewFolding>();

            Stack<FoldingOffset> startOffsets = new Stack<FoldingOffset>();
            int lastNewLineOffset = 0;
            char openingBrace = this.OpeningBrace;
            char closingBrace = this.ClosingBrace;

            var doc = document as TextDocument;

            String current_line = String.Empty;

            foreach (var line in doc.Lines)
            {
                String lineTextFull = doc.GetText(line);
                String lineText = lineTextFull.TrimStart('\t', ' ').TrimEnd('\t', ' ');

                var open_definition = foldings.SingleOrDefault(x => lineText.StartsWith(x.Open + " ") || lineText == x.Open);

                if (open_definition != null)
                {
                    current_line = lineTextFull;
                    startOffsets.Push(new FoldingOffset()
                    {
                        Definition = open_definition,
                        Offset = line.EndOffset
                    });
                }
                else if (foldings.Any(x => lineText.EndsWith(x.Close)))
                {
                    if (startOffsets.Count > 0)
                    {
                        var startOffset = startOffsets.Pop();
                        //if (startOffset < lastNewLineOffset)
                        //{
                        newFoldings.Add(new NewFolding(startOffset.Offset, Math.Min(line.EndOffset, doc.TextLength))
                        {
                            //Name = current_line,
                        });
                    }
                    //}
                }
                else if (lineText.EndsWith("\n") || lineText.EndsWith("\r"))
                {
                    lastNewLineOffset = line.Offset + 1;
                }
            }

            //for (int i = 0; i < document.TextLength; i++)
            //{
            //    char c = document.GetCharAt(i);
            //    if (c == openingBrace)
            //    {
            //        startOffsets.Push(i);
            //    }
            //    else if (c == closingBrace && startOffsets.Count > 0)
            //    {
            //        int startOffset = startOffsets.Pop();
            //        // don't fold if opening and closing brace are on the same line
            //        if (startOffset < lastNewLineOffset)
            //        {
            //            newFoldings.Add(new NewFolding(startOffset, i + 1));
            //        }
            //    }
            //    else if (c == '\n' || c == '\r')
            //    {
            //        lastNewLineOffset = i + 1;
            //    }
            //}

            newFoldings.Sort((a, b) => a.StartOffset.CompareTo(b.StartOffset));
            return newFoldings;
        }
    }
}