using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace MatrixIO.IO.Bmff.Boxes
{
    /// <summary>
    /// Composition Offset Box ("ctts")
    /// </summary>
    [Box("ctts", "Composition Offset Box")]
    public class CompositionOffsetBox : FullBox, ITableBox<CompositionOffsetBox.CompositionOffsetEntry>
    {
        public CompositionOffsetBox() : base() { }
        public CompositionOffsetBox(Stream stream) : base(stream) { }

        internal override ulong CalculateSize()
        {
            return base.CalculateSize() + 4 + ((ulong)_Entries.Count * (4 + 4));
        }

        protected override void LoadFromStream(Stream stream)
        {
            base.LoadFromStream(stream);

            uint entryCount = stream.ReadBEUInt32();

            for (uint i = 0; i < entryCount; i++)
            {
                _Entries.Add(new CompositionOffsetEntry()
                {
                    SampleCount = stream.ReadBEUInt32(),
                    SampleOffset = stream.ReadBEUInt32(),
                });
            }
        }

        protected override void SaveToStream(Stream stream)
        {
            base.SaveToStream(stream);

            stream.WriteBEUInt32((uint)_Entries.Count);

            foreach (CompositionOffsetEntry CompositionOffsetEntry in _Entries)
            {
                stream.WriteBEUInt32(CompositionOffsetEntry.SampleCount);
                stream.WriteBEUInt32(CompositionOffsetEntry.SampleOffset);
            }
        }

        private IList<CompositionOffsetEntry> _Entries = Portability.CreateList<CompositionOffsetEntry>();
        public IList<CompositionOffsetEntry> Entries
        {
            get
            {
                return _Entries;
            }
        }

        public int EntryCount { get { return _Entries.Count; } }

        public class CompositionOffsetEntry
        {
            public uint SampleCount { get; set; }
            public uint SampleOffset { get; set; }

            public CompositionOffsetEntry() { }
            public CompositionOffsetEntry(uint sampleCount, uint sampleDelta)
            {
                SampleCount = sampleCount;
                SampleOffset = sampleDelta;
            }
        }
    }
}