using System;
using System.IO;
using System.Linq;
using JD.LogService;
using TeaBox.Macros;

namespace JDSongConverter.Tasks
{
    /// <summary>
    /// Cleans a wave file from Lyn by removing dirty header if necessary
    /// </summary>
    class CleanWaveHeaderTask : Task
    {
        public string InputFile { get; set; }
        public string OutputFile { get; set; }

        private const int DirtyHeaderLength = 20;
        
        public void Init(string inputFile, string outputFile)
        {
            InputFile = inputFile;
            OutputFile = outputFile;
        }
        
        public override string Name
        {
            get { return "Clean wave files with dirty headers"; }
            set { }
        }

        public override string ProgressText
        {
            get { return String.Format("Cleaning wave file '{0}'", InputFile); }
        }

        public override TaskResult Process(IExecutionContext executionContext)
        {
            if (string.IsNullOrEmpty(InputFile) || !File.Exists(InputFile))
                return TaskResult.ParametersError;
            
            try
            {
                byte[] wave;
                
                using (var input = new FileStream(InputFile, FileMode.Open, FileAccess.Read))
                {
                    var riffHeader = new byte[4];
                    input.Read(riffHeader, 0, 4);
                    if (riffHeader.SequenceEqual(new[] { (byte)'R', (byte)'I', (byte)'F', (byte)'F' }))
                    {
                        executionContext.LogMessage("No need to clean wave header.");
                        input.Seek(0, SeekOrigin.Begin);
                        wave = new byte[input.Length];
                    }
                    else
                    {
                        input.Seek(DirtyHeaderLength, SeekOrigin.Begin);
                        wave = new byte[input.Length - DirtyHeaderLength];
                    }
                    input.Read(wave, 0, wave.Length);
                }
                if (File.Exists(OutputFile))
                {
                    File.SetAttributes(OutputFile, FileAttributes.Normal);
                }
                using (FileStream output = System.IO.File.Open(OutputFile, FileMode.Create))
                {
                    output.Write(wave, 0, wave.Length);
                }
            }
            catch (Exception)
            {
                return TaskResult.Error;
            }
            return TaskResult.Ok;
        }
    }
}