using System.IO;
using System.Text;
using Syroot.BinaryData;
using Syroot.Maths;
using Syroot.Worms.Core;

namespace Syroot.Worms.Worms2
{
    /// <summary>
    /// Represents map configuration stored by the land generator in LAND.DAT files.
    /// Used by W2. S. https://worms2d.info/Land_Data_file.
    /// </summary>
    public class LandData : ILoadableFile, ISaveableFile
    {
        // ---- CONSTANTS ----------------------------------------------------------------------------------------------

        private const int _signature = 0x1A444E4C; // "LND", 0x1A

        // ---- CONSTRUCTORS & DESTRUCTOR ------------------------------------------------------------------------------

        /// <summary>
        /// Initializes a new instance of the <see cref="LandData"/> class.
        /// </summary>
        public LandData()
        {
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="LandData"/> class, loading the data from the given
        /// <see cref="Stream"/>.
        /// </summary>
        /// <param name="stream">The <see cref="Stream"/> to load the data from.</param>
        public LandData(Stream stream)
        {
            Load(stream);
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="LandData"/> class, loading the data from the given file.
        /// </summary>
        /// <param name="fileName">The name of the file to load the data from.</param>
        public LandData(string fileName)
        {
            Load(fileName);
        }

        // ---- PROPERTIES ---------------------------------------------------------------------------------------------

        /// <summary>
        /// Gets or sets the size of the landscape in pixels.
        /// </summary>
        public Vector2 Size { get; set; }

        /// <summary>
        /// Gets or sets a value indicating whether an indestructible top border will be enabled.
        /// </summary>
        public bool TopBorder { get; set; }
        
        /// <summary>
        /// Gets or sets an array of coordinates at which objects can be placed.
        /// </summary>
        public Vector2[] ObjectLocations { get; set; }

        /// <summary>
        /// Gets or sets an unknown value, seeming to be 0 most of the time.
        /// </summary>
        public int Unknown { get; set; }

        /// <summary>
        /// Gets or sets the visual foreground image.
        /// </summary>
        public Img Foreground { get; set; }

        /// <summary>
        /// Gets or sets the collision mask of the landscape.
        /// </summary>
        public Img CollisionMask { get; set; }

        /// <summary>
        /// Gets or sets the visual background image.
        /// </summary>
        public Img Background { get; set; }

        /// <summary>
        /// Gets or sets an image of unknown use.
        /// </summary>
        public Img UnknownImage { get; set; }

        /// <summary>
        /// Gets or sets the path to the land image file.
        /// </summary>
        public string LandTexturePath { get; set; }

        /// <summary>
        /// Gets or sets the path to the Water.dir file.
        /// </summary>
        public string WaterDirPath { get; set; }
        
        // ---- METHODS (PUBLIC) ---------------------------------------------------------------------------------------

        /// <summary>
        /// Loads the data from the given <see cref="Stream"/>.
        /// </summary>
        /// <param name="stream">The <see cref="Stream"/> to load the data from.</param>
        public void Load(Stream stream)
        {
            using (BinaryStream reader = new BinaryStream(stream, encoding: Encoding.ASCII, leaveOpen: true))
            {
                // Read the header.
                if (reader.ReadInt32() != _signature)
                {
                    throw new InvalidDataException("Invalid LND file signature.");
                }
                int fileSize = reader.ReadInt32();

                // Read the data.
                Size = reader.ReadStruct<Vector2>();
                TopBorder = reader.ReadBoolean(BooleanCoding.Dword);

                // Read the possible object coordinate array.
                ObjectLocations = reader.ReadStructs<Vector2>(reader.ReadInt32());
                Unknown = reader.ReadInt32();

                // Read the image data.
                Foreground = reader.Load<Img>();
                CollisionMask = reader.Load<Img>();
                Background = reader.Load<Img>();
                UnknownImage = reader.Load<Img>();

                // Read the file paths.
                LandTexturePath = reader.ReadString(StringCoding.ByteCharCount);
                WaterDirPath = reader.ReadString(StringCoding.ByteCharCount);
            }
        }

        /// <summary>
        /// Loads the data from the given file.
        /// </summary>
        /// <param name="fileName">The name of the file to load the data from.</param>
        public void Load(string fileName)
        {
            using (FileStream stream = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.Read))
            {
                Load(stream);
            }
        }

        /// <summary>
        /// Saves the data into the given <paramref name="stream"/>.
        /// </summary>
        /// <param name="stream">The <see cref="Stream"/> to save the data to.</param>
        public void Save(Stream stream)
        {
            using (BinaryStream writer = new BinaryStream(stream, encoding: Encoding.ASCII))
            {
                // Write the header.
                writer.Write(_signature);
                uint fileSizeOffset = writer.ReserveOffset();

                // Write the data.
                writer.Write(Size);
                writer.Write(TopBorder, BooleanCoding.Dword);

                // Write the possible object coordinate array.
                writer.Write(ObjectLocations.Length);
                writer.Write(ObjectLocations);
                writer.Write(Unknown);

                // Write the image data.
                Foreground.Save(writer.BaseStream);
                CollisionMask.Save(writer.BaseStream);
                Background.Save(writer.BaseStream);
                UnknownImage.Save(writer.BaseStream);

                // Write the file paths.
                writer.Write(LandTexturePath, StringCoding.ByteCharCount);
                writer.Write(WaterDirPath, StringCoding.ByteCharCount);

                writer.SatisfyOffset(fileSizeOffset, (int)writer.Position);
            }
        }

        /// <summary>
        /// Saves the data in the given file.
        /// </summary>
        /// <param name="fileName">The name of the file to save the data in.</param>
        public void Save(string fileName)
        {
            using (FileStream stream = new FileStream(fileName, FileMode.Create, FileAccess.Write, FileShare.None))
            {
                Save(stream);
            }
        }
    }
}