using System;
using System.Web;
using System.IO;
using Newtonsoft.Json;
using WebLib;

namespace Education.Services
{
    public class TrainFareUploadHandler : IHttpHandler, System.Web.SessionState.IRequiresSessionState
    {
        public bool IsReusable => false;

        public void ProcessRequest(HttpContext context)
        {
            context.Response.ContentType = "application/json; charset=utf-8";

            try
            {
                if (context.Request.Files.Count == 0)
                {
                    WriteResponse(context, false, "沒有檔案被上傳", null);
                    return;
                }

                HttpPostedFile uploadFile = context.Request.Files[0];
                if (uploadFile == null || uploadFile.ContentLength == 0)
                {
                    WriteResponse(context, false, "檔案為空", null);
                    return;
                }

                string uploadDir = Path.Combine(context.Server.MapPath("~/"), "DocUpload");

                if (!Directory.Exists(uploadDir))
                {
                    Directory.CreateDirectory(uploadDir);
                }

                // 使用 TrainFareImport_時間戳.xlsx 格式命名
                string timestamp = PublicVariable.TaiwanNow.ToString("yyyyMMdd_HHmmss_fff");
                string tempFileName = Path.Combine(uploadDir, $"TrainFareImport_{timestamp}.xlsx");

                // 確保檔案是 XLSX 或 XLS 格式
                if (!uploadFile.FileName.EndsWith(".xlsx", StringComparison.OrdinalIgnoreCase) &&
                    !uploadFile.FileName.EndsWith(".xls", StringComparison.OrdinalIgnoreCase))
                {
                    WriteResponse(context, false, "只支援 .xlsx 或 .xls 格式的檔案", null);
                    return;
                }

                uploadFile.SaveAs(tempFileName);

                context.Session["火車票價匯入檔案"] = tempFileName;

                WriteResponse(context, true, "上傳成功", tempFileName);
            }
            catch (Exception ex)
            {
                WriteResponse(context, false, $"上傳失敗：{ex.Message}", null);
            }
        }

        private void WriteResponse(HttpContext context, bool success, string message, string data)
        {
            var response = new
            {
                Success = success,
                Message = message,
                Data = data
            };
            context.Response.Write(JsonConvert.SerializeObject(response));
        }
    }
}