using Core.Io;
using System;
using System.Collections.Generic;
using System.IO;

namespace Core.Io
{
    public class TzxParser
    {
        public static List<TzxBlock> Parse(byte[] fileBytes)
        {
            List<TzxBlock> blocks = new List<TzxBlock>();

            using (MemoryStream ms = new MemoryStream(fileBytes))
            using (BinaryReader br = new BinaryReader(ms))
            {
                // 1. Verify the 10-Byte Header
                // Signature is "ZXTape!" followed by EOF (0x1A)
                byte[] signature = br.ReadBytes(8);
                string sigString = System.Text.Encoding.ASCII.GetString(signature);

                if (sigString != "ZXTape!\x1A")
                    throw new Exception("Invalid TZX Signature! Is this a real TZX file?");

                byte majorVersion = br.ReadByte();
                byte minorVersion = br.ReadByte();

                // 2. Read the blocks until we hit the end of the file
                while (ms.Position < ms.Length)
                {
                    byte blockId = br.ReadByte();

                    switch (blockId)
                    {
                        case 0x10: // Standard Speed Data
                            var stdBlock = new StandardSpeedBlock
                            {
                                PauseAfterMs = br.ReadUInt16(),
                                DataLength = br.ReadUInt16()
                            };
                            stdBlock.Data = br.ReadBytes(stdBlock.DataLength);
                            blocks.Add(stdBlock);
                            break;

                        // TODO: Add cases for 0x11 (Turbo), 0x12 (Tone), 0x13 (Pulses), etc.

                        default:
                            throw new NotImplementedException($"TZX Block ID 0x{blockId:X2} is not supported yet!");
                    }
                }
            }

            return blocks;
        }
    }
}