//-----------------------------------------------------------------------
// -----------------------------------------------------------------------
// file="ScriptSourceTransmitter"
// 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 static ScriptSourceTransmitter _empty = new ScriptSourceTransmitter(
            string.Empty, 0, 0)
        {
            _cache = [],
            _buffer = []
        };

        private string[] _buffer;
        private bool _isWriting = true;
        private int _begin, _index;
        private List<string> _cache;
        private readonly string _completeMark;

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

        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;
        }

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

        public bool IsFrozen => !_isWriting;

        public int Location => _begin + _index;

        public static ScriptSourceTransmitter Empty => _empty;

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

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

        public string ReadLine(out int position)
        {
            if (_isWriting) {
                throw new InvalidOperationException("Cannot read before all writing operation.");
            }
            if (_index >= _buffer.Length)
            {
                position = -1;
                return string.Empty;
            }
            position = _begin + _index;
            string str = _buffer[_index];
            _index++;
            return str;
        }

        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);
        }

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

    }
}