// ClassicalSharp copyright 2014-2016 UnknownShadow200 | Licensed under MIT
using System;
using System.IO;
using System.IO.Compression;

namespace ClassicalSharp.Map {

	public sealed class MapSchematicExporter : IMapFormatExporter {
		
		public void Save( Stream stream, Game game ) {
			using( GZipStream wrapper = new GZipStream( stream, CompressionMode.Compress ) ) {
				BinaryWriter writer = new BinaryWriter( wrapper );
				NbtFile nbt = new NbtFile( writer );
				World map = game.World;
				
				nbt.Write( NbtTagType.Compound ); nbt.Write( "Schematic" );
				
				nbt.Write( NbtTagType.String );
				nbt.Write( "Materials" ); nbt.Write( "Classic" );
				
				nbt.Write( NbtTagType.Int16 );
				nbt.Write( "Width" ); nbt.WriteInt16( (short)map.Width );
				
				nbt.Write( NbtTagType.Int16 );
				nbt.Write( "Height" ); nbt.WriteInt16( (short)map.Height );
				
				nbt.Write( NbtTagType.Int16 );
				nbt.Write( "Length" ); nbt.WriteInt16( (short)map.Length );
				
				WriteBlocks( nbt, map.blocks );
				
				WriteBlockData( nbt, map.blocks );
				
				nbt.Write( NbtTagType.List );
				nbt.Write( "Entities" );
				nbt.Write( NbtTagType.Compound ); nbt.WriteInt32( 0 );
				
				nbt.Write( NbtTagType.List );
				nbt.Write( "TileEntities" );
				nbt.Write( NbtTagType.Compound ); nbt.WriteInt32( 0 );
				
				nbt.Write( NbtTagType.End );
			}
		}
		
		
		void WriteBlocks( NbtFile nbt, byte[] blocks ) {
			const int chunkSize = 64 * 1024 * 32;
			nbt.Write( NbtTagType.Int8Array );
			nbt.Write( "Blocks" );
			nbt.WriteInt32( blocks.Length );
			
			for( int i = 0; i < blocks.Length; i += chunkSize ) {
				int count = Math.Min( chunkSize, blocks.Length - i );
				nbt.WriteBytes( blocks, i, count );
			}
		}
		
		void WriteBlockData( NbtFile nbt, byte[] blocks ) {
			const int chunkSize = 64 * 1024;
			byte[] chunk = new byte[chunkSize];
			nbt.Write( NbtTagType.Int8Array );
			nbt.Write( "Data" );
			nbt.WriteInt32( blocks.Length );
			
			for( int i = 0; i < blocks.Length; i += chunkSize ) {
				// All 0 so we can skip this.
				int count = Math.Min( chunkSize, blocks.Length - i );
				nbt.WriteBytes( chunk, 0, count );
			}
		}
	}
}