using System.Net.Sockets;
using System.Runtime.CompilerServices;
using System.Text.Json;
using DX86;
using Library;

namespace Server;

public class CommandLibrary
{
    [Command("example")]
    public static string ExampleCommand(string[] args, TcpClient? client, TcpServer? socket) =>
        $"Example command executed with arguments: {string.Join(", ", args)}";
    
    #region Basic Commands

        [Command("help")]
        public static string HelpCommand() =>
        "Available commands:\n" +
        "1. help - Show this help message\n" +
        "2. exit - Exit the server\n" +
        "3. user - User management\n" +
        "4. settings - Server settings\n" +
        "5. start - Start the server\n" +
        "6. stop - Stop the server\n";

    #endregion

    #region Client Commands

        [Command("login")]
        public static string LoginCommand(string[] args, TcpClient? client, TcpServer? socket)
        {
            // 1) Argument check
            if (args.Length < 2)
                throw new CommandException("Missing arguments: usage is login <employeeCode> <4-digit PIN>");

            string employeeCode = args[0];
            string pinCode      = args[1];

            // 2) Prevent double‐login
            if (client != null && socket?.LoggedInClients.ContainsKey(client) == true)
                throw new CommandException("User already logged in.");

            // 3) Look up the employee by Code
            var empParams       = new Dictionary<string, object> { { "Code", employeeCode } };
            string empResultJson = Program.mySql.Get("employees", empParams);

            using var empDoc = JsonDocument.Parse(empResultJson);
            bool empError = empDoc.RootElement.GetProperty("error").GetBoolean();
            if (empError)
            {
                string dbMsg = empDoc.RootElement.GetProperty("data").GetString() ?? "Unknown DB error";
                Program.messageSender.Error($"[LoginCommand] DB error when looking up employee: {dbMsg}");
                throw new CommandException("Internal error while checking credentials.");
            }

            var empArray = empDoc.RootElement.GetProperty("data");
            if (empArray.GetArrayLength() == 0)
            {
                // No employee with that Code
                throw new CommandException("Invalid employee code or PIN.");
            }

            // 4) Extract Id from the first row
            var empRow      = empArray[0];
            int employeeId  = empRow.GetProperty("Id").GetInt32();

            // 5) Check PIN for that employeeId
            var pinParams       = new Dictionary<string, object>
            {
                { "EmployeeId", employeeId },
                { "PinCode",    pinCode }
            };
            string pinResultJson = Program.mySql.Get("employee_pins", pinParams);

            using var pinDoc = JsonDocument.Parse(pinResultJson);
            bool pinError = pinDoc.RootElement.GetProperty("error").GetBoolean();
            if (pinError)
            {
                string dbMsg = pinDoc.RootElement.GetProperty("data").GetString() ?? "Unknown DB error";
                Program.messageSender.Error($"[LoginCommand] DB error when checking PIN: {dbMsg}");
                throw new CommandException("Internal error while checking credentials.");
            }

            var pinArray = pinDoc.RootElement.GetProperty("data");
            if (pinArray.GetArrayLength() == 0)
            {
                // No matching PIN entry
                throw new CommandException("Invalid employee code or PIN.");
            }

            // 6) Successful login → add client to LoggedInClients
            if (client == null)
                throw new CommandException("No client connection detected.");

            socket!.LoggedInClients.Add(client, employeeCode);

            // 7) Return “success” (instead of full Employee JSON)
            return "success";
        }
    
        [Command("logout")]
        public static string LogoutCommand(TcpClient? client, TcpServer? socket)
        {
            if (client != null && socket?.LoggedInClients.ContainsKey(client) == true)
            {
                socket.LoggedInClients.Remove(client);
                return "success";
            }
            throw new CommandException("No client provided or not logged in");
        }
        
        [Command("getSelfUser")]
        public static string GetSelfUserCommand(TcpClient? client, TcpServer? socket)
        {
            // 1) Check for a valid client/socket
            if (client == null || socket == null)
                throw new CommandException("No client connection detected.");

            // 2) See if this client is logged in
            if (!socket.LoggedInClients.TryGetValue(client, out var employeeCode))
                throw new CommandException("User not logged in.");

            // 3) Query the database for that employeeCode
            var empParams = new Dictionary<string, object>
            {
                { "Code", employeeCode }
            };
            string empResultJson = Program.mySql.Get("employees", empParams);

            using var empDoc = JsonDocument.Parse(empResultJson);
            bool empError = empDoc.RootElement.GetProperty("error").GetBoolean();
            if (empError)
            {
                // Extract the “data” field as the DB‐side error message, if any
                string dbMsg = empDoc.RootElement.GetProperty("data").GetString() 
                               ?? "Unknown DB error";
                Program.messageSender.Error($"[GetSelfUser] DB error when looking up employee: {dbMsg}");
                throw new CommandException("Internal error while fetching user data.");
            }

            var dataArray = empDoc.RootElement.GetProperty("data");
            if (dataArray.GetArrayLength() == 0)
            {
                // No employee row found for this code
                throw new CommandException("Logged‐in user not found in database.");
            }

            // 4) We expect exactly one row. Take the first element:
            var firstRow = dataArray[0];

            // 5) Deserialize it into an Employee object.
            //    This requires that Employee.Id is an int (matching the DB schema),
            //    or you map fields manually if Id remains a string.
            Employee self;
            try
            {
                string employeeJson = firstRow.GetRawText();
                self = JsonSerializer.Deserialize<Employee>(employeeJson)
                       ?? throw new InvalidOperationException("Deserialized Employee was null.");
            }
            catch (Exception ex)
            {
                Program.messageSender.Error($"[GetSelfUser] Failed to deserialize Employee: {ex.Message}");
                throw new CommandException("Internal error while parsing user data.");
            }

            // 6) Return the Employee’s JSON via the ToJson() helper you already wrote:
            return self.ToJson();
        }

    #endregion

    #region Administration Commands
    
        [Command("get")]
        public static string GetCommand(string[] args, TcpClient? client, TcpServer? socket) =>
        $"not implemented yet, args: {string.Join(", ", args)}";
        
    
    #endregion

    #region DEV-TEST

    private static Employee GenerateTestEmployee()
    {
        return new Employee(
            code: "TEST",
            surname: "Musermann",
            forename: "Max",
            email: "max.mustermann@company.de"
            );
    }

    #endregion
}