// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
using System.Collections.Generic;
using Microsoft.CodeAnalysis.Text;
using Roslyn.Utilities;
 
namespace Microsoft.CodeAnalysis.Formatting
{
    /// <summary>
    /// this provides information about the syntax tree formatting service is formatting.
    /// this provides necessary abstraction between different kinds of syntax trees so that ones that contain
    /// actual text or cache can answer queries more efficiently.
    /// </summary>
    internal abstract partial class TreeData
    {
        public static TreeData Create(SyntaxNode root)
        {
            // either there is no tree or a tree that is not generated from a text.
            if (root.SyntaxTree == null || !root.SyntaxTree.TryGetText(out var text))
            {
                return new Node(root);
            }
 
#if DEBUG
            return new Debug(root, text);
#else
            return new NodeAndText(root, text);
#endif
        }
 
        public static TreeData Create(SyntaxTrivia trivia, int initialColumn)
            => new StructuredTrivia(trivia, initialColumn);
 
        private readonly SyntaxNode _root;
        private readonly SyntaxToken _firstToken;
        private readonly SyntaxToken _lastToken;
 
        public TreeData(SyntaxNode root)
        {
            Contract.ThrowIfNull(root);
            _root = root;
 
            _firstToken = _root.GetFirstToken(includeZeroWidth: true);
            _lastToken = _root.GetLastToken(includeZeroWidth: true);
        }
 
        public abstract string GetTextBetween(SyntaxToken token1, SyntaxToken token2);
        public abstract int GetOriginalColumn(int tabSize, SyntaxToken token);
 
        public SyntaxNode Root => _root;
 
        public bool IsFirstToken(SyntaxToken token)
            => _firstToken == token;
 
        public bool IsLastToken(SyntaxToken token)
            => _lastToken == token;
 
        public int StartPosition
        {
            get { return this.Root.FullSpan.Start; }
        }
 
        public int EndPosition
        {
            get { return this.Root.FullSpan.End; }
        }
 
        public IEnumerable<SyntaxToken> GetApplicableTokens(TextSpan textSpan)
            => this.Root.DescendantTokens(textSpan);
    }
}