//-----------------------------------------------------------------------
//-----------------------------------------------------------------------
//     file="ScriptSourceTransmitter.cs"
//     Project: StgSharp
//     AuthorGroup: Nitload Space
//     Copyright (c) Nitload Space. All rights reserved.
//     
//     Permission is hereby granted, free of charge, to any person 
//     obtaining a copy of this software and associated documentation 
//     files (the “Software”), to deal in the Software without restriction, 
//     including without limitation the rights to use, copy, modify, merge,
//     publish, distribute, sublicense, and/or sell copies of the Software, 
//     and to permit persons to whom the Software is furnished to do so, 
//     subject to the following conditions:
//     
//     The above copyright notice and 
//     this permission notice shall be included in all copies 
//     or substantial portions of the Software.
//     
//     THE SOFTWARE IS PROVIDED “AS IS”, 
//     WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, 
//     INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
//     FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. 
//     IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, 
//     DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, 
//     ARISING FROM, OUT OF OR IN CONNECTION WITH 
//     THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//     
//-----------------------------------------------------------------------
//-----------------------------------------------------------------------
using System;
using System.Collections;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Text;
using System.Text.RegularExpressions;

namespace StgSharp.Script
{
    /// <summary>
    /// Transmit a continuous part of script code to interpreter or compiler.
    /// This transmitter is designed for single-thread-write and single-thread
    /// read. Any multi thread operation will cause undefined behaviour.
    /// </summary>
    public class ScriptSourceTransmitter : IScriptSourceProvider
    {
        private bool _isWriting = true;
        private List<string> _cache;
        private string[] _buffer;
        private int _begin, _index;
        private readonly string _completeMark;

        public ScriptSourceTransmitter( string endMark, int start )
        {
            _cache = new List<string>();
            _completeMark = endMark;
            _begin = start;
            _index = 0;
        }

        public ScriptSourceTransmitter(string endMark, int start, int capacity)
        {
            _cache = new List<string>(capacity);
            _completeMark = endMark;
            _begin = start;
            _index = 0;
        }

        internal ScriptSourceTransmitter(string[] buffer, int start)
        {
            _buffer = buffer;
            _begin = start;
            _isWriting = false;
        }

        public bool IsEmpty => _isWriting ? 
            (_cache.Count == 0) :
            (_buffer.Length == 0) || (_index >= _buffer.Length - 1);

        public int Location => _begin + _index;

        public bool IsFrozen => !_isWriting;

        public string ReadLine()
        {
            if (_isWriting) 
            {
                throw new InvalidOperationException("Cannot read before all writing operation.");
            }
            var str = _buffer[_index];
            _index++;
            return str;
        }

        public string ReadLine(out int position)
        {
            if (_isWriting)
            {
                throw new InvalidOperationException("Cannot read before all writing operation.");
            }
            position = _begin + _index;
            var str = _buffer[_index];
            _index++;
            return str;
        }

        public void WriteLine( string line )
        {
            if( !_isWriting ) {
                return;
            }
            if( string.Equals( _completeMark, line ) ) {
                EndWriting();
                return;
            }
            _cache.Add( line );
        }

        public void EndWriting()
        {
            if (!_isWriting) 
            {
                return;
            }
            _isWriting = false;
            _buffer = _cache.ToArray();
            _cache = null!;
        }

        public IScriptSourceProvider Slice(int location, int count)
        {
            ArgumentOutOfRangeException.ThrowIfLessThan(location, _begin);
            ArgumentOutOfRangeException.ThrowIfGreaterThan(
                location + count,_begin + _buffer.Length);
            return new ScriptSourceTransmitter( 
                _buffer.AsSpan().Slice( location, count ).ToArray(),
                location);
        }
    }
}