using System.Data;
using InServiceQue.Core.Models;
using InServiceQue.Core.Repositories;

namespace InServiceQue.InMemory;

public class TaskRepositoryInMemory: ITaskRepository
{
    private static object _lockObject = new();
    private static int _currentShard;
    private static Dictionary<string, Queue<QueueTask>> _quesByType = new();
    public void Dispose()
    {
        // TODO release managed resources here
    }

    public void Insert(QueueTask task)
    {
        lock (_lockObject)
        {
            if (_quesByType.ContainsKey(task.TaskType))
            {
                _quesByType[task.TaskType].Enqueue(task);
            }
            else
            {
                _quesByType.Add(task.TaskType, new Queue<QueueTask>(new []{task}));
            }
            
        }
    }

    public async Task InsertAsync(QueueTask task)
    {
        Insert(task);
        await Task.CompletedTask;
    }

    public IDbTransaction StartTransaction()
    {
        return null;
    }

    public async Task<IDbTransaction> StartTransactionAsync()
    {
        return await Task.FromResult<IDbTransaction>(null);
    }

    public void CommitTransaction(IDbTransaction tx)
    {
       
    }

    public async Task CommitTransactionAsync(IDbTransaction tx)
    {
        await Task.CompletedTask;
    }

    public void RollbackTransaction(IDbTransaction tx)
    {
        
    }

    public async Task RollbackTransactionAsync(IDbTransaction tx)
    {
        await Task.CompletedTask;
    }

    public QueueTask? GetNextTask(IDbTransaction tx, string? taskType = null)
    {
        if (taskType == null)
            return GetNextTaskRolling();
        
        QueueTask? task = null;
        if (_quesByType.TryGetValue(taskType, out var que))
        {
            que.TryDequeue(out task);
        }

        return task;
    }

    public QueueTask? GetNextTaskRolling()
    {
        QueueTask? task = null;
        lock (_lockObject)
        {
            var topicsCount = _quesByType.Count;
            for (int i = 0; i < topicsCount; i++)
            {
                if (i == _currentShard)
                {
                    var keyValuePair = _quesByType.ToArray()[i];
                    var que = keyValuePair.Value;
                    task = que.Dequeue();

                    if (!que.Any())
                    {
                        _quesByType.Remove(keyValuePair.Key);
                    }
                    break;
                }
            }
            
            _currentShard = _currentShard == topicsCount - 1 ? 0 : _currentShard + 1;
        }
        
        return task;
    }
    
    

    public async Task<QueueTask?> GetNextTaskAsync(IDbTransaction tx, string? taskType = null)
    {
        if (taskType == null)
            return await Task.FromResult(GetNextTaskRolling());
        
        QueueTask? task = null;
        lock (_lockObject)
        {
            if (_quesByType.TryGetValue(taskType, out var que))
            {
                que.TryDequeue(out task);
            }
        }
        
        
        return await Task.FromResult(task);
    }

    public void SaveTask(QueueTask task, IDbTransaction tx)
    {
        
    }

    public async Task SaveTaskAsync(QueueTask task, IDbTransaction tx)
    {
        await Task.CompletedTask;
    }
}