<%@ WebHandler Language="C#" Class="SendOtp" %>

using System;
using System.Web;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
using System.Net;
using Newtonsoft.Json;

public class SendOtp : IHttpHandler {

    private string connectionString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;

    public void ProcessRequest(HttpContext context) {
        // CORS headers so the Flutter app can call this endpoint
        context.Response.Headers.Add("Access-Control-Allow-Origin", "*");
        context.Response.Headers.Add("Access-Control-Allow-Headers", "Content-Type, Accept");
        context.Response.Headers.Add("Access-Control-Allow-Methods", "GET, OPTIONS");
        context.Response.ContentType = "application/json";

        if (context.Request.HttpMethod == "OPTIONS") {
            context.Response.StatusCode = 200;
            context.Response.End();
            return;
        }

        string memberId = context.Request.QueryString["member_id"];
        string mobile   = context.Request.QueryString["mobile"];

        // If mobile not supplied, look it up by member ID
        if (string.IsNullOrEmpty(mobile) && !string.IsNullOrEmpty(memberId)) {
            using (SqlConnection con = new SqlConnection(connectionString)) {
                con.Open();
                string query = "SELECT top 1 Mobile_1 FROM Memberslist WHERE Ndbano = @id";
                SqlCommand cmd = new SqlCommand(query, con);
                cmd.Parameters.AddWithValue("@id", memberId);
                object mobObj = cmd.ExecuteScalar();
                if (mobObj != null && mobObj != DBNull.Value) {
                    mobile = mobObj.ToString();
                }
            }
        }

        if (string.IsNullOrEmpty(mobile) || mobile == "0") {
            context.Response.StatusCode = 400;
            context.Response.Write(JsonConvert.SerializeObject(new {
                success = false,
                error   = "Mobile number not found or invalid."
            }));
            return;
        }

        // Generate 4-digit OTP
        string otp  = new Random().Next(1000, 9999).ToString();
        
        // Exact approved DLT template & gateway settings compiled inside the live Newdelhibarassocia.dll:
        string text = "Dear User, this is your OTP " + otp + ". Do Not share this with anyone. TEAM NDBA";

        string smsResponse = "";
        try {
            using (WebClient client = new WebClient()) {
                string url = "http://hindit.co.in/API/pushsms.aspx?loginID=P1NDBA&password=6522651&mobile=" 
                             + mobile + "&text=" + HttpUtility.UrlEncode(text) 
                             + "&senderid=NDBATM&route_id=2&Unicode=0&IP=122.1.1.1&Template_id=1207173210411979025";
                
                smsResponse = client.DownloadString(url);
            }
        } catch (Exception ex) {
            smsResponse = "SMS error: " + ex.Message;
        }

        context.Response.Write(JsonConvert.SerializeObject(new {
            success     = true,
            mobile      = mobile,
            otp         = otp,
            smsResponse = smsResponse
        }));
    }

    public bool IsReusable { get { return false; } }
}