using Microsoft.Extensions.Logging;
using Opc.Ua;
using S7UaLib.Events;
using S7UaLib.Services;
using System.Collections;

// --- Configuration ---
const string serverUrl = "opc.tcp://192.168.0.1:4840";
const string configFile = "my_plc_structure.json";
const string myIntVarPath = "DataBlocksGlobal.Datablock.TestInt";
const string myStringVarPath = "DataBlocksGlobal.Datablock.TestString";

// 1. Configure the OPC UA Application
var appConfig = new ApplicationConfiguration
{
    ApplicationName = "S7UaLib QuickStart",
    ApplicationType = ApplicationType.Client,
    SecurityConfiguration = new SecurityConfiguration { AutoAcceptUntrustedCertificates = true },
    ClientConfiguration = new ClientConfiguration(),
    TransportQuotas = new TransportQuotas { OperationTimeout = 15000 }
};

// 2. Initialize the S7Service
// The second parameter is the standard OPC UA response validation action.
var service = new S7Service(appConfig, ClientBase.ValidateResponse);

// Optional: Subscribe to value changes
service.VariableValueChanged += OnVariableValueChanged;

try
{
    // 3. Connect to the PLC
    Console.WriteLine($"Connecting to {serverUrl}...");
    await service.ConnectAsync(serverUrl, useSecurity: false);
    Console.WriteLine("Connected!");

    // 4. Load structure from file or discover it
    if (File.Exists(configFile))
    {
        Console.WriteLine("Loading structure from file...");
        await service.LoadStructureAsync(configFile);
    }
    else
    {
        Console.WriteLine("Discovering PLC structure...");
        await service.DiscoverStructureAsync();
        Console.WriteLine("Saving structure for next time...");
        await service.SaveStructureAsync(configFile);
    }
    
    // After discovery/loading, it's often necessary to set the specific S7 data types
    // for variables, as this info isn't always exposed by the server.
    // This is typically done once and saved in the config file.
    await service.UpdateVariableTypeAsync(myIntVarPath, S7DataType.INT);
    await service.UpdateVariableTypeAsync(myStringVarPath, S7DataType.STRING);

    // 5. Read all variables to get the initial state
    Console.WriteLine("\nReading all variable values...");
    await service.ReadAllVariablesAsync();

    // 6. Subscribe to real-time changes for a specific variable
    Console.WriteLine($"Subscribing to changes for '{myIntVarPath}'...");
    await service.SubscribeToVariableAsync(myIntVarPath);
    
    Console.WriteLine("\nLibrary is now listening for changes. Try changing the value in the PLC.");
    Console.WriteLine("Or press Enter to write a value from here and trigger a change...");
    Console.ReadLine();

    // 7. Write a new value to a different variable
    string newValue = $"Hello from S7UaLib at {DateTime.Now:T}";
    Console.WriteLine($"Writing '{newValue}' to '{myStringVarPath}'...");
    bool success = await service.WriteVariableAsync(myStringVarPath, newValue);
    
    if (success)
    {
        Console.WriteLine("Write successful! A new value change event should have been triggered if subscribed.");
    }
    
    Console.WriteLine("\nPress Enter to disconnect.");
    Console.ReadLine();
}
catch (Exception ex)
{
    Console.WriteLine($"An error occurred: {ex.Message}");
}
finally
{
    if (service.IsConnected)
    {
        Console.WriteLine("Disconnecting...");
        await service.DisconnectAsync();
    }
    service.VariableValueChanged -= OnVariableValueChanged;
}

// Event handler for value changes (from polling or subscriptions)
void OnVariableValueChanged(object? sender, VariableValueChangedEventArgs e)
{
    Console.ForegroundColor = ConsoleColor.Cyan;
    Console.WriteLine("\n--- Value Change Detected ---");
    Console.WriteLine($"  Path:      {e.NewVariable.FullPath}");
    Console.WriteLine($"  Old Value: {e.OldVariable.Value ?? "null"}");
    Console.WriteLine($"  New Value: {e.NewVariable.Value ?? "null"}");
    Console.ResetColor();
}