using System;
using System.Collections.Generic;
using System.Data;
using System.Globalization;
using System.Linq;
using Manager;
using MoreChartFormats.Simai.Errors;
using MoreChartFormats.Simai.LexicalAnalysis;
using MoreChartFormats.Simai.Structures;
using MoreChartFormats.Simai.SyntacticAnalysis.States;

namespace MoreChartFormats.Simai.SyntacticAnalysis;

internal class Deserializer(IEnumerable<Token> sequence) : IDisposable
{
    internal readonly IEnumerator<Token> TokenEnumerator = sequence.GetEnumerator();

    internal BPMChangeData CurrentBpmChange;
    internal NotesTime CurrentTime = new(0);
    
    // References all notes between two TimeSteps
    internal LinkedList<List<NoteData>> CurrentNoteDataCollections;
    
    // References the current note between EACH dividers
    internal List<NoteData> CurrentNoteData;
    
    internal float Subdivision = 4f;
    internal bool IsEndOfFile;
    
    public void Dispose()
    {
        TokenEnumerator.Dispose();
    }

    public void GetChart(NotesReferences refs)
    {
        var manuallyMoved = false;
        var deltaGrids = 0f;
        var index = 1;
        var noteIndex = 0;
        var slideIndex = 0;
        var currentBpmChangeIndex = 0;
        var firstBpmChangeEventIgnored = false;
        var fakeEach = false;

        CurrentBpmChange = refs.Composition._bpmList[currentBpmChangeIndex];
        
        while (!IsEndOfFile && (manuallyMoved || MoveNext()))
        {
            var token = TokenEnumerator.Current;
            manuallyMoved = false;

            switch (token.type)
            {
                case TokenType.Subdivision:
                {
                    if (token.lexeme[0] == '#')
                    {
                        if (!float.TryParse(token.lexeme.Substring(1), NumberStyles.Any, CultureInfo.InvariantCulture, out var absoluteSubdivision))
                        {
                            throw new UnexpectedCharacterException(token.line, token.character, "0-9 or \".\"");
                        }

                        Subdivision = CurrentBpmChange.SecondsPerBar() / absoluteSubdivision;
                    } 
                    else if (!float.TryParse(token.lexeme, NumberStyles.Any, CultureInfo.InvariantCulture, out Subdivision))
                    {
                        throw new UnexpectedCharacterException(token.line, token.character, "0-9 or \".\"");
                    }

                    break;
                }
                case TokenType.Location:
                {
                    // We have to stack up all deltas before adding them because adding it every time 
                    // we reach a TimeStep would cause precision loss due to casting floating points
                    // back to integers.
                    var delta = ParserUtilities.NotesTimeFromGrids(refs, (int)deltaGrids);

                    CurrentTime += delta;
                    deltaGrids -= delta.grid;
                    
                    CurrentNoteDataCollections ??= [];
                    CurrentNoteData = [];
                    CurrentNoteDataCollections.AddLast(CurrentNoteData);

                    // ForceEach not supported
                    if (token.lexeme[0] == '0')
                    {
                        throw new UnsupportedSyntaxException(token.line, token.character);
                    }

                    NoteReader.Process(this, in token, refs, ref index, ref noteIndex, ref slideIndex);
                    manuallyMoved = true;
                    break;
                }
                case TokenType.TimeStep:
                {
                    if (CurrentNoteDataCollections != null)
                    {
                        if (fakeEach)
                        {
                            ProcessFakeEach(refs);
                            fakeEach = false;
                        }
                        refs.Notes._noteData.AddRange(CurrentNoteDataCollections.SelectMany(c => c));
                        CurrentNoteDataCollections = null;
                        CurrentNoteData = null;
                    }

                    deltaGrids += refs.Header._resolutionTime / Subdivision;
                    break;
                }
                case TokenType.EachDivider:
                    fakeEach = fakeEach || token.lexeme[0] == '`';
                    break;
                case TokenType.Decorator:
                    throw new ScopeMismatchException(token.line, token.character,
                        ScopeMismatchException.ScopeType.Note);
                case TokenType.Slide:
                    throw new ScopeMismatchException(token.line, token.character,
                        ScopeMismatchException.ScopeType.Note);
                case TokenType.Duration:
                    throw new ScopeMismatchException(token.line, token.character,
                        ScopeMismatchException.ScopeType.Note |
                        ScopeMismatchException.ScopeType.Slide);
                case TokenType.SlideJoiner:
                    throw new ScopeMismatchException(token.line, token.character,
                        ScopeMismatchException.ScopeType.Slide);
                case TokenType.EndOfFile:
                    // There isn't a way to signal to the game engine that the chart
                    // is ending prematurely, as it expects that every note in the
                    // chart is actually in the chart.
                    IsEndOfFile = true;
                    break;
                case TokenType.Tempo:
                    if (!firstBpmChangeEventIgnored)
                    {
                        firstBpmChangeEventIgnored = true;
                    }
                    else
                    {
                        CurrentBpmChange = refs.Composition._bpmList[++currentBpmChangeIndex];
                    }
                    break;
                case TokenType.None:
                    break;
                default:
                    throw new UnsupportedSyntaxException(token.line, token.character);
            }

            index++;
        }

        if (CurrentNoteDataCollections == null)
        {
            return;
        }

        if (fakeEach)
        {
            ProcessFakeEach(refs);
        }
        refs.Notes._noteData.AddRange(CurrentNoteDataCollections.SelectMany(c => c));
        CurrentNoteDataCollections = null;
        CurrentNoteData = null;
    }

    private void ProcessFakeEach(NotesReferences refs)
    {
        var node = CurrentNoteDataCollections.First.Next;
        var singleTick = new NotesTime(refs.Header._resolutionTime / 384);
        var delta = singleTick;

        while (node != null)
        {
            foreach (var note in node.Value)
            {
                note.time += delta;
                note.end += delta;
                note.beatType = ParserUtilities.GetBeatType(note.time.grid);

                if (note.type.isSlide())
                {
                    note.slideData.shoot.time += delta;
                    note.slideData.arrive.time += delta;
                }

                delta += singleTick;
            }
            
            node = node.Next;
        }
    }

    internal static bool TryReadLocation(in Token token, out int position, out TouchSensorType touchGroup)
    {
        var isSensor = token.lexeme[0] is >= 'A' and <= 'E';
        var index = isSensor ? token.lexeme.Substring(1) : token.lexeme;

        touchGroup = TouchSensorType.Invalid;

        if (isSensor)
        {
            touchGroup = token.lexeme[0] switch
            {
                'A' => TouchSensorType.A,
                'B' => TouchSensorType.B,
                'C' => TouchSensorType.C,
                'D' => TouchSensorType.D,
                'E' => TouchSensorType.E,
                _ => TouchSensorType.Invalid,
            };

            switch (touchGroup)
            {
                case TouchSensorType.Invalid:
                    position = -1;
                    return false;
                case TouchSensorType.C:
                    position = 0;
                    return true;
            }
        }

        if (!int.TryParse(index, out position))
        {
            position = -1;
            return false;
        }

        // Convert to 0-indexed position
        position -= 1;
        return true;
    }

    internal bool MoveNext()
    {
        IsEndOfFile = !TokenEnumerator.MoveNext();
        return !IsEndOfFile;
    }
}