using System;
using System.Collections.Generic;
using System.ComponentModel.Composition;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Pithos.Interfaces;
using System.IO;
using System.Diagnostics;

namespace Pithos.Core
{
    [Export(typeof(IPithosWorkflow))]
    public class PithosWorkflow:IPithosWorkflow
    {
        [Import]
        public IPithosSettings Settings { get; set; }

        [Import]
        public IStatusKeeper StatusKeeper { get; set; }

        public FileStatus SetFileStatus(string path, FileStatus status)
        {
            Debug.Assert(!path.Contains("fragments"));
            Debug.Assert(!path.EndsWith(".ignore",StringComparison.InvariantCultureIgnoreCase));

            if (String.IsNullOrWhiteSpace(path))
                throw new ArgumentNullException("path", "The path parameter must not be emtpy");

            var oldStatus=StatusKeeper.GetFileStatus(path);

            if (oldStatus == status)
                return oldStatus;

            switch(oldStatus)
            {
                case FileStatus.Unchanged :
                    break;
                case FileStatus.Created:
                    if (status == FileStatus.Modified)
                        return oldStatus;
                    break;
                case FileStatus.Modified:
                case FileStatus.Renamed:
                    if (status == FileStatus.Created)
                        return oldStatus;
                    break;
                case FileStatus.Deleted:
                    return oldStatus;                    
            }
            StatusKeeper.SetFileStatus(path, status);
            return status;
        }

        public void ClearFileStatus(string path)
        {
            if (String.IsNullOrWhiteSpace(path))
                throw new ArgumentNullException("path", "The path parameter must not be emtpy");

            StatusKeeper.ClearFileStatus(path.ToLower());
        }
       

        public Task<FileStream> OpenStreamWithWaiting(string path)
        {
            if (String.IsNullOrWhiteSpace(path))
                throw new ArgumentNullException("path","The path parameter must not be emtpy");

            if (!File.Exists(path))
                throw new FileNotFoundException("The specified file or path does not exist", path);

            return new Task<FileStream>(() =>
                    {
                        int counter = 0;
                        while (true)
                        {
                            try
                            {
                                var stream=File.OpenRead(path);
                                return stream;                                
                            }
                            catch 
                            {
                                Thread.Sleep(500);
                                if (++counter > 10)
                                    throw;
                            }
                        }
                    });
        }
    }
}