using System;
using System.Collections.Generic;
using System.Text;
using UnityEngine;

public static class ComPortScanner
{
    // Параметры соединения
    private const int BaudRate = 115200;
    private const int DataBits = 8;
    private const int Parity = 0;          // 0 = None
    private const int StopBits = 1;         // 1 = One
    private const int ReadTimeoutMs = 5;
    private const int WriteTimeoutMs = 10;

    // Команды устройств
    private const string CmdPrize = "97";        // Для витрины и периферийника2
    private const string CmdControllerAuth = "07";
    private const int DeviceResponseTimeoutMs = 1000;

    // Типы устройств
    public enum DeviceType
    {
        None,
        ControllerV1,      // Периферийник1
        ControllerV2,      // Периферийник2
        PrizeShowcase      // Витрина
    }

    // Префиксы ответов
    private const string RolePrefix = "ROLE :";                         // Периферийник2 и витрина на 97
    private const string PrizeRoleValue = "vitrina";                     // Витрина: ROLE : vitrina

    /// <summary>
    /// Сканирует все доступные COM-порты и возвращает словарь {порт = тип устройства}
    /// </summary>
    public static Dictionary<string, DeviceType> ScanPorts()
    {
        var result = new Dictionary<string, DeviceType>();
        string[] ports = ComNativeWrapper.ListPorts();

        foreach (string port in ports)
        {
            if (port == "COM1") continue;


            DeviceType type = CheckPort(port);
            if (type != DeviceType.None)
            {
                result[port] = type;
            }
        }

        return result;
    }

    /// <summary>
    /// Проверяет один порт на наличие известных устройств
    /// </summary>
    private static DeviceType CheckPort(string port)
    {
        Debug.Log($"Проверка порта {port}");
        string response97 = CheckDevice(
            port,
            CmdPrize,
            line => line.StartsWith(RolePrefix, StringComparison.Ordinal));
        if (response97 != null && response97.StartsWith(RolePrefix))
        {
            Debug.Log($"Role: {response97}");
            // Извлекаем значение после "ROLE : "
            string roleValue = response97.Substring(RolePrefix.Length).Trim();

            // Если роль = "vitrina" - это витрина
            if (string.Equals(roleValue, PrizeRoleValue, StringComparison.OrdinalIgnoreCase))
            {
                return DeviceType.PrizeShowcase;
            }
            else
            {
                return DeviceType.ControllerV2;
            }
        }

        string computerChallenge = BoardAuthentication.CreateChallengeHex();
        string authResponse = CheckDevice(
            port,
            CmdControllerAuth + computerChallenge,
            IsAuthenticationResponse);
        if (authResponse != null)
            return DeviceType.ControllerV1;

        return DeviceType.None;
    }

    /// <summary>
    /// Очищает входной буфер порта
    /// </summary>
    private static void ClearPortBuffer(int handle)
    {
        byte[] tempBuffer = new byte[1024];
        const float idleTimeout = 0.5f;
        const int maxreads = 50;

        int reads = 0;
        float startTime = Time.unscaledTime;

        while (reads < maxreads)
        {
            int bytesRead = ComNativeWrapper.Serial_ReadLineUTF8_bytes(handle, tempBuffer, tempBuffer.Length);
            reads++;

            if (bytesRead > 0)
            {
                startTime = Time.unscaledTime;
                continue;
            }
            else if (bytesRead == 0)
            {
                float elapsed = Time.unscaledTime - startTime;
                if (elapsed >= idleTimeout)
                {
                    break;
                }
            }
            else
            {
                break;
            }
        }
    }

    /// <summary>
    /// Проверяет устройство на порту и возвращает ответ
    /// </summary>
    private static string CheckDevice(string port, string command, Func<string, bool> isExpectedResponse)
    {
        int handle = ComNativeWrapper.Serial_Open(port, BaudRate, DataBits, Parity, StopBits, 10, WriteTimeoutMs);
        if (handle <= 0)
        {
            return null;
        }

        try
        {
            ClearPortBuffer(handle);

            int writeResult = ComNativeWrapper.Serial_WriteStringUTF8(handle, command, 1);
            if (writeResult < 0)
            {
                return null;
            }

            byte[] buffer = new byte[1024];
            long deadline = DateTime.UtcNow.Ticks
                            + DeviceResponseTimeoutMs * TimeSpan.TicksPerMillisecond;
            while (DateTime.UtcNow.Ticks < deadline)
            {
                int bytesRead = ComNativeWrapper.Serial_ReadLineUTF8_bytes(handle, buffer, buffer.Length);
                if (bytesRead <= 0)
                    continue;

                string line = Encoding.UTF8.GetString(buffer, 0, bytesRead).Trim();
                if (!string.IsNullOrEmpty(line) && isExpectedResponse(line))
                    return line;
            }

            return null;
        }
        finally
        {
            ComNativeWrapper.Serial_Close(handle);
        }
    }

    private static bool IsAuthenticationResponse(string line)
        => BoardAuthentication.TryExtractHexPayload(line, "CHAL", out _)
           || BoardAuthentication.TryExtractHexPayload(line, "RAES", out _);
}