//
// Copyright (c) Microsoft. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.
//

using Microsoft.SqlServer.Management.SqlParser.Parser;
using Microsoft.SqlTools.ServiceLayer.Utility;
using Microsoft.SqlTools.ServiceLayer.Workspace.Contracts;

namespace Microsoft.SqlTools.ServiceLayer.LanguageServices.Completion
{
    /// <summary>
    /// A class to calculate the numbers used by SQL parser using the text positions and content
    /// </summary>
    internal class ScriptDocumentInfo
    {
        /// <summary>
        /// Create new instance
        /// </summary>
        public ScriptDocumentInfo(TextDocumentPosition textDocumentPosition, ScriptFile scriptFile, ScriptParseInfo scriptParseInfo)
        {
            StartLine = textDocumentPosition.Position.Line;
            ParserLine = textDocumentPosition.Position.Line + 1;
            StartColumn = TextUtilities.PositionOfPrevDelimeter(
                                scriptFile.Contents,
                                textDocumentPosition.Position.Line,
                                textDocumentPosition.Position.Character);
            EndColumn = TextUtilities.PositionOfNextDelimeter(
                                scriptFile.Contents,
                                textDocumentPosition.Position.Line,
                                textDocumentPosition.Position.Character);
            ParserColumn = textDocumentPosition.Position.Character + 1;
            ScriptParseInfo = scriptParseInfo;
            Contents = scriptFile.Contents;

            // need to adjust line & column for base-1 parser indices
            Token = GetToken(scriptParseInfo, ParserLine, ParserColumn);
        }

        /// <summary>
        /// Gets a string containing the full contents of the file.
        /// </summary>
        public string Contents { get; private set; }

        /// <summary>
        /// Script Parse Info Instance
        /// </summary>
        public ScriptParseInfo ScriptParseInfo { get; private set; }

        /// <summary>
        /// Start Line
        /// </summary>
        public int StartLine { get; private set; }

        /// <summary>
        /// Parser Line
        /// </summary>
        public int ParserLine { get; private set; }

        /// <summary>
        /// Start Column
        /// </summary>
        public int StartColumn { get; private set; }

        /// <summary>
        /// end Column
        /// </summary>
        public int EndColumn { get; private set; }

        /// <summary>
        /// Parser Column
        /// </summary>
        public int ParserColumn { get; private set; }

        /// <summary>
        /// The token text in the file content used for completion list
        /// </summary>
        public string TokenText
        {
            get
            {
                return Token != null ? Token.Text : null;
            }
        }

        /// <summary>
        /// The token in the file content used for completion list
        /// </summary>
        public Token Token { get; private set; }

        /// <summary>
        /// Returns the token that will be used by SQL parser for creating the completion list
        /// </summary>
        internal static Token GetToken(ScriptParseInfo scriptParseInfo, int startLine, int startColumn)
        {
            if (scriptParseInfo != null && scriptParseInfo.ParseResult != null && scriptParseInfo.ParseResult.Script != null && scriptParseInfo.ParseResult.Script.Tokens != null)
            {
                var tokenIndex = scriptParseInfo.ParseResult.Script.TokenManager.FindToken(startLine, startColumn);
                if (tokenIndex >= 0)
                {
                    // return the current token
                    int currentIndex = 0;
                    foreach (var token in scriptParseInfo.ParseResult.Script.Tokens)
                    {
                        if (currentIndex == tokenIndex)
                        {
                            return token;
                        }
                        ++currentIndex;
                    }
                }
            }
            return null;
        }
    }
}