using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web.Http;
using PagedList;
using Newtonsoft.Json;
using System.Collections;
using System.Data.Entity;

// api/pivot
[ezAuthorize]
public class pivotController : ApiController
{
    private Model.ezEntities _db = new Model.ezEntities();

    #region 報表查詢 API

    /// <summary>
    /// 報名明細查詢 - 對應 Excel 中的視圖結構
    /// GET api/pivot/registration_details
    /// </summary>
    /// <param name="startDate">開始日期</param>
    /// <param name="endDate">結束日期</param>
    /// <param name="activityNum">法會編號</param>
    /// <param name="followerNum">信眾編號</param>
    /// <param name="page">頁碼</param>
    /// <param name="pageSize">每頁筆數</param>
    /// <returns></returns>
    [HttpGet]
    [Route("api/pivot/registration_details")]
    public IHttpActionResult GetRegistrationDetails(string startDate = null, string endDate = null, 
        int? activityNum = null, int? followerNum = null, int page = 1, int pageSize = 1000)
    {
        try
        {
            // 對應 README.md 中的視圖查詢結構，按顏色分類欄位
            var query = from pod in _db.pro_order_detail
                       join po in _db.pro_order on pod.order_no equals po.order_no
                       join ai in _db.actItems on pod.actItem_num equals ai.num
                       join act in _db.activities on po.activity_num equals act.num
                       join f in _db.followers on po.f_num equals f.num
                       join aik in _db.actItem_kind on ai.kind equals aik.num
                       select new
                       {
                           // 🟠 橘色欄位 - 法會基礎資料 (法會相關的直接來源)
                           法會ID = act.num,
                           法會名稱 = act.subject,
                           開始日期 = act.startDate_solar,
                           結束日期 = act.endDate_solar,
                           
                           // 🔵 藍色欄位 - 信眾基礎資料 (信眾相關的直接來源)
                           信眾編號 = f.f_number,
                           信眾姓名 = f.u_name,
                           報名編號 = po.order_no,
                           報名日期 = po.up_time,
                           
                           // 🟢綠色欄位 - 功德資訊欄位 (功德相關資訊)
                           功德主 = pod.parent_num != null ? "是" : "否",
                           功德類型 = aik.kind,
                           功德名稱 = ai.subject,
                           
                           // 🟣 紫色欄位 - 計算欄位 (需要計算)
                           數量 = pod.qty,
                           金額 = pod.price,
                           已收 = 0, // 業務邏輯：固定為 0
                           未收 = pod.price * pod.qty - 0, // 計算未收金額
                           
                           // 額外提供原始資料供進階計算
                           _metadata = new
                           {
                               parent_num = pod.parent_num,
                               unit_price = pod.price,
                               quantity = pod.qty,
                               total_amount = pod.price * pod.qty,
                               kind_num = aik.num,
                               item_num = ai.num,
                               activity_num = act.num,
                               follower_num = f.num
                           }
                       };

            // 日期篩選
            if (!string.IsNullOrEmpty(startDate) && DateTime.TryParse(startDate, out DateTime start))
            {
                query = query.Where(x => x.開始日期 >= start);
            }
            if (!string.IsNullOrEmpty(endDate) && DateTime.TryParse(endDate, out DateTime end))
            {
                query = query.Where(x => x.結束日期 <= end);
            }

            // 法會篩選
            if (activityNum.HasValue)
            {
                query = query.Where(x => x.法會ID == activityNum.Value);
            }

            // 信眾篩選
            if (followerNum.HasValue)
            {
                query = query.Where(x => x.信眾編號 == followerNum.ToString());
            }

            // 分頁處理
            var totalCount = query.Count();
            var pagedQuery = query.OrderByDescending(x => x.報名日期)
                                  .ThenByDescending(x => x.法會ID)
                                  .Skip((page - 1) * pageSize)
                                  .Take(pageSize)
                                  .ToList();

            var result = new
            {
                success = true,
                data = new
                {
                    list = pagedQuery,
                    total = totalCount,
                    page = page,
                    pageSize = pageSize,
                    totalPages = (int)Math.Ceiling((double)totalCount / pageSize)
                },
                message = "查詢成功"
            };

            return Ok(result);
        }
        catch (Exception ex)
        {
            return BadRequest($"查詢失敗：{ex.Message}");
        }
    }

    /// <summary>
    /// 報名明細查詢 - Excel 匯出格式
    /// GET api/pivot/registration_details_export
    /// </summary>
    /// <param name="startDate">開始日期</param>
    /// <param name="endDate">結束日期</param>
    /// <param name="activityNum">法會編號</param>
    /// <param name="followerNum">信眾編號</param>
    /// <returns></returns>
    [HttpGet]
    [Route("api/pivot/registration_details_export")]
    public IHttpActionResult GetRegistrationDetailsForExport(string startDate = null, string endDate = null, 
        int? activityNum = null, int? followerNum = null)
    {
        try
        {
            // 完全對應 Excel 中的欄位結構
            var query = from pod in _db.pro_order_detail
                       join po in _db.pro_order on pod.order_no equals po.order_no
                       join ai in _db.actItems on pod.actItem_num equals ai.num
                       join act in _db.activities on po.activity_num equals act.num
                       join f in _db.followers on po.f_num equals f.num
                       join aik in _db.actItem_kind on ai.kind equals aik.num
                       select new
                       {
                           // 完全對應 Excel 欄位名稱
                           法會ID = act.num,
                           法會名稱 = act.subject,
                           開始日期 = act.startDate_solar,
                           結束日期 = act.endDate_solar,
                           信眾編號 = f.f_number,
                           信眾姓名 = f.u_name,
                           報名編號 = po.order_no,
                           報名日期 = po.up_time,
                           功德主 = pod.parent_num != null ? "是" : "否",
                           功德類型 = aik.kind,
                           功德名稱 = ai.subject,
                           數量 = pod.qty,
                           金額 = pod.price,
                           已收 = 0,
                           未收 = pod.price * pod.qty
                       };

            // 套用篩選條件
            if (!string.IsNullOrEmpty(startDate) && DateTime.TryParse(startDate, out DateTime start))
            {
                query = query.Where(x => x.開始日期 >= start);
            }
            if (!string.IsNullOrEmpty(endDate) && DateTime.TryParse(endDate, out DateTime end))
            {
                query = query.Where(x => x.結束日期 <= end);
            }
            if (activityNum.HasValue)
            {
                query = query.Where(x => x.法會ID == activityNum.Value);
            }
            if (followerNum.HasValue)
            {
                query = query.Where(x => x.信眾編號 == followerNum.ToString());
            }

            var exportData = query.OrderByDescending(x => x.報名日期)
                                  .ThenByDescending(x => x.法會ID)
                                  .ToList()
                                  .Select(x => new
                                  {
                                      x.法會ID,
                                      x.法會名稱,
                                      開始日期 = x.開始日期.HasValue ? x.開始日期.Value.ToString("yyyy/MM/dd") : "",
                                      結束日期 = x.結束日期.HasValue ? x.結束日期.Value.ToString("yyyy/MM/dd") : "",
                                      x.信眾編號,
                                      x.信眾姓名,
                                      x.報名編號,
                                      報名日期 = x.報名日期.HasValue ? x.報名日期.Value.ToString("yyyy/MM/dd HH:mm") : "",
                                      x.功德主,
                                      x.功德類型,
                                      x.功德名稱,
                                      x.數量,
                                      x.金額,
                                      x.已收,
                                      x.未收
                                  })
                                  .ToList();

            // 統計資訊
            var summary = new
            {
                總筆數 = exportData.Count,
                總金額 = exportData.Sum(x => x.金額 * x.數量),
                參與法會數 = exportData.Select(x => x.法會ID).Distinct().Count(),
                參與信眾數 = exportData.Select(x => x.信眾編號).Distinct().Count(),
                功德主數量 = exportData.Count(x => x.功德主 == "是")
            };

            var result = new
            {
                success = true,
                data = new
                {
                    details = exportData,
                    summary = summary,
                    export_time = DateTime.Now.ToString("yyyy/MM/dd HH:mm:ss"),
                    filters = new
                    {
                        startDate,
                        endDate,
                        activityNum,
                        followerNum
                    }
                },
                message = "匯出資料準備完成"
            };

            return Ok(result);
        }
        catch (Exception ex)
        {
            return BadRequest($"匯出失敗：{ex.Message}");
        }
    }

    /// <summary>
    /// 取得法會報名統計
    /// GET api/pivot/activity_stats
    /// </summary>
    /// <param name="startDate">開始日期</param>
    /// <param name="endDate">結束日期</param>
    /// <param name="activityNum">法會編號</param>
    /// <returns></returns>
    [HttpGet]
    [Route("api/pivot/activity_stats")]
    public IHttpActionResult GetActivityStats(string startDate = null, string endDate = null, int? activityNum = null)
    {
        try
        {
            var query = from pod in _db.pro_order_detail
                       join po in _db.pro_order on pod.order_no equals po.order_no
                       join act in _db.activities on po.activity_num equals act.num
                       join ai in _db.actItems on pod.actItem_num equals ai.num
                       join aik in _db.actItem_kind on ai.kind equals aik.num
                       join f in _db.followers on po.f_num equals f.num
                       select new
                       {
                           ActivityNum = act.num,
                           ActivityName = act.subject,
                           StartDate = act.startDate_solar,
                           EndDate = act.endDate_solar,
                           FollowerNum = f.num,
                           FollowerName = f.u_name,
                           OrderNo = po.order_no,
                           OrderDate = po.up_time,
                           KindName = aik.kind,
                           ItemName = ai.subject,
                           Qty = pod.qty,
                           Price = pod.price,
                           Amount = pod.qty * pod.price
                       };

            // 日期篩選
            if (!string.IsNullOrEmpty(startDate) && DateTime.TryParse(startDate, out DateTime start))
            {
                query = query.Where(x => x.StartDate >= start);
            }
            if (!string.IsNullOrEmpty(endDate) && DateTime.TryParse(endDate, out DateTime end))
            {
                query = query.Where(x => x.EndDate <= end);
            }

            // 法會篩選
            if (activityNum.HasValue)
            {
                query = query.Where(x => x.ActivityNum == activityNum.Value);
            }

            // 統計資料
            var stats = query.GroupBy(x => new { x.ActivityNum, x.ActivityName, x.StartDate, x.EndDate })
                            .Select(g => new
                            {
                                activity_num = g.Key.ActivityNum,
                                activity_name = g.Key.ActivityName,
                                start_date = g.Key.StartDate,
                                end_date = g.Key.EndDate,
                                total_orders = g.Select(x => x.OrderNo).Distinct().Count(),
                                total_followers = g.Select(x => x.FollowerNum).Distinct().Count(),
                                total_amount = g.Sum(x => x.Amount),
                                total_qty = g.Sum(x => x.Qty),
                                avg_amount_per_follower = g.GroupBy(x => x.FollowerNum).Average(fg => fg.Sum(x => x.Amount))
                            })
                            .OrderByDescending(x => x.start_date)
                            .ToList();

            var result = new
            {
                success = true,
                data = stats,
                message = "查詢成功"
            };

            return Ok(result);
        }
        catch (Exception ex)
        {
            return BadRequest($"查詢失敗：{ex.Message}");
        }
    }

    /// <summary>
    /// 取得信眾參與分析
    /// GET api/pivot/follower_analysis
    /// </summary>
    /// <param name="startDate">開始日期</param>
    /// <param name="endDate">結束日期</param>
    /// <param name="followerNum">信眾編號</param>
    /// <returns></returns>
    [HttpGet]
    [Route("api/pivot/follower_analysis")]
    public IHttpActionResult GetFollowerAnalysis(string startDate = null, string endDate = null, int? followerNum = null)
    {
        try
        {
            var query = from pod in _db.pro_order_detail
                       join po in _db.pro_order on pod.order_no equals po.order_no
                       join act in _db.activities on po.activity_num equals act.num
                       join ai in _db.actItems on pod.actItem_num equals ai.num
                       join aik in _db.actItem_kind on ai.kind equals aik.num
                       join f in _db.followers on po.f_num equals f.num
                       select new
                       {
                           FollowerNum = f.num,
                           FollowerName = f.u_name,
                           FollowerCode = f.f_number,
                           ActivityNum = act.num,
                           ActivityName = act.subject,
                           StartDate = act.startDate_solar,
                           EndDate = act.endDate_solar,
                           OrderDate = po.up_time,
                           KindName = aik.kind,
                           ItemName = ai.subject,
                           Amount = pod.qty * pod.price,
                           HasParent = pod.parent_num != null
                       };

            // 日期篩選
            if (!string.IsNullOrEmpty(startDate) && DateTime.TryParse(startDate, out DateTime start))
            {
                query = query.Where(x => x.StartDate >= start);
            }
            if (!string.IsNullOrEmpty(endDate) && DateTime.TryParse(endDate, out DateTime end))
            {
                query = query.Where(x => x.EndDate <= end);
            }

            // 信眾篩選
            if (followerNum.HasValue)
            {
                query = query.Where(x => x.FollowerNum == followerNum.Value);
            }

            // 信眾統計分析
            var followerStats = query.GroupBy(x => new { x.FollowerNum, x.FollowerName, x.FollowerCode })
                                    .Select(g => new
                                    {
                                        follower_num = g.Key.FollowerNum,
                                        follower_name = g.Key.FollowerName,
                                        follower_code = g.Key.FollowerCode,
                                        total_activities = g.Select(x => x.ActivityNum).Distinct().Count(),
                                        total_amount = g.Sum(x => x.Amount),
                                        total_orders = g.Select(x => x.OrderDate).Count(),
                                        avg_amount_per_activity = g.GroupBy(x => x.ActivityNum).Average(ag => ag.Sum(x => x.Amount)),
                                        is_patron_count = g.Count(x => x.HasParent),
                                        participation_rate = Math.Round((double)g.Select(x => x.ActivityNum).Distinct().Count() / _db.activities.Count() * 100, 2),
                                        favorite_kinds = g.GroupBy(x => x.KindName)
                                                        .OrderByDescending(kg => kg.Sum(x => x.Amount))
                                                        .Take(3)
                                                        .Select(kg => new { kind = kg.Key, amount = kg.Sum(x => x.Amount) })
                                                        .ToList(),
                                        recent_activities = g.OrderByDescending(x => x.OrderDate)
                                                          .Take(5)
                                                          .Select(x => new { 
                                                              activity_name = x.ActivityName, 
                                                              order_date = x.OrderDate,
                                                              amount = x.Amount 
                                                          })
                                                          .ToList()
                                    })
                                    .OrderByDescending(x => x.total_amount)
                                    .ToList();

            var result = new
            {
                success = true,
                data = followerStats,
                message = "查詢成功"
            };

            return Ok(result);
        }
        catch (Exception ex)
        {
            return BadRequest($"查詢失敗：{ex.Message}");
        }
    }

    /// <summary>
    /// 取得收入統計
    /// GET api/pivot/income_stats
    /// </summary>
    /// <param name="startDate">開始日期</param>
    /// <param name="endDate">結束日期</param>
    /// <param name="groupBy">分組方式 (monthly/yearly/activity)</param>
    /// <returns></returns>
    [HttpGet]
    [Route("api/pivot/income_stats")]
    public IHttpActionResult GetIncomeStats(string startDate = null, string endDate = null, string groupBy = "monthly")
    {
        try
        {
            var query = from pod in _db.pro_order_detail
                       join po in _db.pro_order on pod.order_no equals po.order_no
                       join act in _db.activities on po.activity_num equals act.num
                       join ai in _db.actItems on pod.actItem_num equals ai.num
                       join aik in _db.actItem_kind on ai.kind equals aik.num
                       select new
                       {
                           ActivityNum = act.num,
                           ActivityName = act.subject,
                           StartDate = act.startDate_solar,
                           OrderDate = po.up_time,
                           KindNum = aik.num,
                           KindName = aik.kind,
                           ItemName = ai.subject,
                           Amount = pod.qty * pod.price
                       };

            // 日期篩選
            if (!string.IsNullOrEmpty(startDate) && DateTime.TryParse(startDate, out DateTime start))
            {
                query = query.Where(x => x.StartDate >= start);
            }
            if (!string.IsNullOrEmpty(endDate) && DateTime.TryParse(endDate, out DateTime end))
            {
                query = query.Where(x => x.StartDate <= end);
            }

            object stats = null;

            switch (groupBy?.ToLower())
            {
                case "monthly":
                    stats = query.GroupBy(x => new { 
                                    Year = x.StartDate.Value.Year, 
                                    Month = x.StartDate.Value.Month 
                                })
                                .Select(g => new
                                {
                                    period = $"{g.Key.Year}/{g.Key.Month:00}",
                                    year = g.Key.Year,
                                    month = g.Key.Month,
                                    total_amount = g.Sum(x => x.Amount),
                                    total_activities = g.Select(x => x.ActivityNum).Distinct().Count(),
                                    kind_breakdown = g.GroupBy(x => x.KindName)
                                                   .Select(kg => new { 
                                                       kind = kg.Key, 
                                                       amount = kg.Sum(x => x.Amount) 
                                                   }).ToList()
                                })
                                .OrderBy(x => x.year).ThenBy(x => x.month)
                                .ToList();
                    break;

                case "yearly":
                    stats = query.GroupBy(x => x.StartDate.Value.Year)
                                .Select(g => new
                                {
                                    period = g.Key.ToString(),
                                    year = g.Key,
                                    total_amount = g.Sum(x => x.Amount),
                                    total_activities = g.Select(x => x.ActivityNum).Distinct().Count(),
                                    kind_breakdown = g.GroupBy(x => x.KindName)
                                                   .Select(kg => new { 
                                                       kind = kg.Key, 
                                                       amount = kg.Sum(x => x.Amount) 
                                                   }).ToList(),
                                    monthly_trend = g.GroupBy(x => x.StartDate.Value.Month)
                                                  .Select(mg => new { 
                                                      month = mg.Key, 
                                                      amount = mg.Sum(x => x.Amount) 
                                                  }).OrderBy(x => x.month).ToList()
                                })
                                .OrderBy(x => x.year)
                                .ToList();
                    break;

                case "activity":
                    stats = query.GroupBy(x => new { x.ActivityNum, x.ActivityName, x.StartDate })
                                .Select(g => new
                                {
                                    activity_num = g.Key.ActivityNum,
                                    activity_name = g.Key.ActivityName,
                                    start_date = g.Key.StartDate,
                                    total_amount = g.Sum(x => x.Amount)
                                })
                                .OrderByDescending(x => x.start_date)
                                .ToList()
                                .Select(g => new
                                {
                                    g.activity_num,
                                    g.activity_name,
                                    g.start_date,
                                    g.total_amount,
                                    kind_breakdown = query.Where(x => x.ActivityNum == g.activity_num)
                                                          .GroupBy(x => x.KindName)
                                                          .Select(kg => new
                                                          {
                                                              kind = kg.Key,
                                                              amount = kg.Sum(x => x.Amount),
                                                              percentage = g.total_amount.HasValue && g.total_amount.Value > 0
                                                                  ? Math.Round((double)(kg.Sum(x => x.Amount) ?? 0) / (double)g.total_amount.Value * 100, 2)
                                                                  : 0
                                                          })
                                                          .OrderByDescending(x => x.amount)
                                                          .ToList()
                                })
                                .ToList();
                    break;

                default:
                    return BadRequest("不支援的分組方式，請使用 monthly, yearly 或 activity");
            }

            var result = new
            {
                success = true,
                data = stats,
                groupBy = groupBy,
                message = "查詢成功"
            };

            return Ok(result);
        }
        catch (Exception ex)
        {
            return BadRequest($"查詢失敗：{ex.Message}");
        }
    }

    #endregion

    #region 數據分析 API

    /// <summary>
    /// 樞紐分析
    /// POST api/pivot/pivot_analysis
    /// </summary>
    /// <param name="request">分析請求參數</param>
    /// <returns></returns>
    [HttpPost]
    [Route("api/pivot/pivot_analysis")]
    public IHttpActionResult PostPivotAnalysis(dynamic request)
    {
        try
        {
            // TODO: 實作樞紐分析邏輯
            var result = new
            {
                success = true,
                data = new
                {
                    rows = new List<object>(),
                    columns = new List<object>(),
                    values = new List<object>()
                },
                message = "分析完成"
            };

            return Ok(result);
        }
        catch (Exception ex)
        {
            return BadRequest($"分析失敗：{ex.Message}");
        }
    }

    /// <summary>
    /// 趨勢分析
    /// GET api/pivot/trend_analysis
    /// </summary>
    /// <param name="metric">指標名稱</param>
    /// <param name="startDate">開始日期</param>
    /// <param name="endDate">結束日期</param>
    /// <param name="interval">時間間隔</param>
    /// <returns></returns>
    [HttpGet]
    [Route("api/pivot/trend_analysis")]
    public IHttpActionResult GetTrendAnalysis(string metric, string startDate = null, string endDate = null, string interval = "monthly")
    {
        try
        {
            if (string.IsNullOrEmpty(metric))
            {
                return BadRequest("請指定分析指標");
            }

            var query = from pod in _db.pro_order_detail
                       join po in _db.pro_order on pod.order_no equals po.order_no
                       join act in _db.activities on po.activity_num equals act.num
                       join f in _db.followers on po.f_num equals f.num
                       select new
                       {
                           ActivityDate = act.startDate_solar,
                           OrderDate = po.up_time,
                           Amount = pod.qty * pod.price,
                           FollowerNum = f.num,
                           ActivityNum = act.num
                       };

            // 日期篩選
            if (!string.IsNullOrEmpty(startDate) && DateTime.TryParse(startDate, out DateTime start))
            {
                query = query.Where(x => x.ActivityDate >= start);
            }
            if (!string.IsNullOrEmpty(endDate) && DateTime.TryParse(endDate, out DateTime end))
            {
                query = query.Where(x => x.ActivityDate <= end);
            }

            object trendData = null;
            string trendDirection = "stable";

            switch (metric?.ToLower())
            {
                case "income": // 收入趨勢
                    if (interval == "monthly")
                    {
                        var monthlyIncome = query.GroupBy(x => new { 
                                                    Year = x.ActivityDate.Value.Year, 
                                                    Month = x.ActivityDate.Value.Month 
                                                })
                                                .Select(g => new
                                                {
                                                    period = $"{g.Key.Year}/{g.Key.Month:00}",
                                                    value = g.Sum(x => x.Amount),
                                                    date = new DateTime(g.Key.Year, g.Key.Month, 1)
                                                })
                                                .OrderBy(x => x.date)
                                                .ToList();

                        // 計算趨勢方向
                        if (monthlyIncome.Count >= 2)
                        {
                            var firstHalf = monthlyIncome.Take(monthlyIncome.Count / 2).Average(x => (double)x.value);
                            var secondHalf = monthlyIncome.Skip(monthlyIncome.Count / 2).Average(x => (double)x.value);
                            trendDirection = secondHalf > firstHalf * 1.05 ? "up" : (secondHalf < firstHalf * 0.95 ? "down" : "stable");
                        }

                        trendData = new
                        {
                            labels = monthlyIncome.Select(x => x.period).ToList(),
                            values = monthlyIncome.Select(x => x.value).ToList(),
                            growth_rates = monthlyIncome.Select((x, i) => i == 0 ? 0.0 : 
                                Math.Round((double)(x.value - monthlyIncome[i-1].value) / (double)monthlyIncome[i-1].value * 100, 2))
                                .ToList()
                        };
                    }
                    break;

                case "followers": // 參與信眾數趨勢
                    if (interval == "monthly")
                    {
                        var monthlyFollowers = query.GroupBy(x => new { 
                                                        Year = x.ActivityDate.Value.Year, 
                                                        Month = x.ActivityDate.Value.Month 
                                                    })
                                                    .Select(g => new
                                                    {
                                                        period = $"{g.Key.Year}/{g.Key.Month:00}",
                                                        value = g.Select(x => x.FollowerNum).Distinct().Count(),
                                                        date = new DateTime(g.Key.Year, g.Key.Month, 1)
                                                    })
                                                    .OrderBy(x => x.date)
                                                    .ToList();

                        // 計算趨勢方向
                        if (monthlyFollowers.Count >= 2)
                        {
                            var firstHalf = monthlyFollowers.Take(monthlyFollowers.Count / 2).Average(x => (double)x.value);
                            var secondHalf = monthlyFollowers.Skip(monthlyFollowers.Count / 2).Average(x => (double)x.value);
                            trendDirection = secondHalf > firstHalf * 1.05 ? "up" : (secondHalf < firstHalf * 0.95 ? "down" : "stable");
                        }

                        trendData = new
                        {
                            labels = monthlyFollowers.Select(x => x.period).ToList(),
                            values = monthlyFollowers.Select(x => x.value).ToList(),
                            growth_rates = monthlyFollowers.Select((x, i) => i == 0 ? 0.0 : 
                                Math.Round((double)(x.value - monthlyFollowers[i-1].value) / (double)monthlyFollowers[i-1].value * 100, 2))
                                .ToList()
                        };
                    }
                    break;

                case "activities": // 法會數量趨勢
                    var monthlyActivities = query.GroupBy(x => new { 
                                                    Year = x.ActivityDate.Value.Year, 
                                                    Month = x.ActivityDate.Value.Month 
                                                })
                                                .Select(g => new
                                                {
                                                    period = $"{g.Key.Year}/{g.Key.Month:00}",
                                                    value = g.Select(x => x.ActivityNum).Distinct().Count(),
                                                    date = new DateTime(g.Key.Year, g.Key.Month, 1)
                                                })
                                                .OrderBy(x => x.date)
                                                .ToList();

                    trendData = new
                    {
                        labels = monthlyActivities.Select(x => x.period).ToList(),
                        values = monthlyActivities.Select(x => x.value).ToList()
                    };
                    break;

                default:
                    return BadRequest("不支援的指標，請使用 income, followers 或 activities");
            }

            var result = new
            {
                success = true,
                data = new
                {
                    metric = metric,
                    interval = interval,
                    trend = trendDirection,
                    chart_data = trendData
                },
                message = "分析完成"
            };

            return Ok(result);
        }
        catch (Exception ex)
        {
            return BadRequest($"分析失敗：{ex.Message}");
        }
    }

    /// <summary>
    /// 對比分析
    /// GET api/pivot/comparative_analysis
    /// </summary>
    /// <param name="compareType">對比類型</param>
    /// <param name="period1">期間1</param>
    /// <param name="period2">期間2</param>
    /// <returns></returns>
    [HttpGet]
    [Route("api/pivot/comparative_analysis")]
    public IHttpActionResult GetComparativeAnalysis(string compareType, string period1, string period2)
    {
        try
        {
            // TODO: 實作對比分析邏輯
            var result = new
            {
                success = true,
                data = new
                {
                    period1_data = new List<object>(),
                    period2_data = new List<object>(),
                    comparison = new
                    {
                        growth_rate = 0.0,
                        difference = 0.0
                    }
                },
                message = "對比完成"
            };

            return Ok(result);
        }
        catch (Exception ex)
        {
            return BadRequest($"對比失敗：{ex.Message}");
        }
    }

    #endregion

    #region 報表管理 API

    /// <summary>
    /// 取得自訂報表清單
    /// GET api/pivot/custom_reports
    /// </summary>
    /// <param name="page">頁碼</param>
    /// <param name="pageSize">每頁筆數</param>
    /// <returns></returns>
    [HttpGet]
    [Route("api/pivot/custom_reports")]
    public IHttpActionResult GetCustomReports(int page = 1, int pageSize = 10)
    {
        try
        {
            // TODO: 實作自訂報表查詢邏輯
            var result = new
            {
                success = true,
                data = new
                {
                    list = new List<object>(),
                    total = 0,
                    page = page,
                    pageSize = pageSize
                },
                message = "查詢成功"
            };

            return Ok(result);
        }
        catch (Exception ex)
        {
            return BadRequest($"查詢失敗：{ex.Message}");
        }
    }

    /// <summary>
    /// 建立自訂報表
    /// POST api/pivot/custom_reports
    /// </summary>
    /// <param name="request">報表設定</param>
    /// <returns></returns>
    [HttpPost]
    [Route("api/pivot/custom_reports")]
    public IHttpActionResult PostCustomReport(dynamic request)
    {
        try
        {
            // TODO: 實作自訂報表建立邏輯
            var result = new
            {
                success = true,
                data = new { id = 1 },
                message = "報表建立成功"
            };

            return Ok(result);
        }
        catch (Exception ex)
        {
            return BadRequest($"建立失敗：{ex.Message}");
        }
    }

    /// <summary>
    /// 匯出報表
    /// GET api/pivot/export/{reportId}
    /// </summary>
    /// <param name="reportId">報表編號</param>
    /// <param name="format">匯出格式 (excel/pdf/csv)</param>
    /// <returns></returns>
    [HttpGet]
    [Route("api/pivot/export/{reportId}")]
    public IHttpActionResult GetReportExport(int reportId, string format = "excel")
    {
        try
        {
            // TODO: 實作報表匯出邏輯
            var result = new
            {
                success = true,
                data = new
                {
                    download_url = $"/admin/pivot/downloads/report_{reportId}.{format}",
                    file_name = $"report_{reportId}_{DateTime.Now:yyyyMMdd}.{format}"
                },
                message = "匯出成功"
            };

            return Ok(result);
        }
        catch (Exception ex)
        {
            return BadRequest($"匯出失敗：{ex.Message}");
        }
    }

    #endregion

    #region Excel 數據連接 API

    /// <summary>
    /// Excel 數據連接專用 - 簡化格式
    /// GET api/pivot/excel_data
    /// </summary>
    /// <param name="format">回傳格式 (json/csv)</param>
    /// <param name="limit">限制筆數</param>
    /// <returns></returns>
    [HttpGet]
    [Route("api/pivot/excel_data")]
    [AllowAnonymous] // 允許 Excel 直接呼叫
    public IHttpActionResult GetExcelData(string format = "json", int limit = 5000)
    {
        try
        {
            // 直接查詢，對應視圖結構
            var query = from pod in _db.pro_order_detail
                       join po in _db.pro_order on pod.order_no equals po.order_no
                       join ai in _db.actItems on pod.actItem_num equals ai.num
                       join act in _db.activities on po.activity_num equals act.num
                       join f in _db.followers on po.f_num equals f.num
                       join aik in _db.actItem_kind on ai.kind equals aik.num
                       orderby po.up_time descending, act.num descending
                       select new
                       {
                           ActivityId = act.num,
                           ActivityName = act.subject,
                           StartDate = act.startDate_solar,
                           EndDate = act.endDate_solar,
                           FollowerCode = f.f_number,
                           FollowerName = f.u_name,
                           OrderNo = po.order_no,
                           OrderDate = po.up_time,
                           IsPatron = pod.parent_num != null ? "是" : "否",
                           KindName = aik.kind,
                           ItemName = ai.subject,
                           Quantity = pod.qty,
                           Price = pod.price,
                           Received = 0,
                           Outstanding = pod.price * pod.qty
                       };

            var data = query.Take(limit).ToList();

            if (format?.ToLower() == "csv")
            {
                // CSV 格式回傳
                var csv = "法會ID,法會名稱,開始日期,結束日期,信眾編號,信眾姓名,報名編號,報名日期,功德主,功德類型,功德名稱,數量,金額,已收,未收\n";
                foreach (var item in data)
                {
                    csv += $"{item.ActivityId},{item.ActivityName},{item.StartDate:yyyy/MM/dd},{item.EndDate:yyyy/MM/dd}," +
                           $"{item.FollowerCode},{item.FollowerName},{item.OrderNo},{item.OrderDate:yyyy/MM/dd HH:mm}," +
                           $"{item.IsPatron},{item.KindName},{item.ItemName},{item.Quantity},{item.Price},{item.Received},{item.Outstanding}\n";
                }
                
                return Ok(csv);
            }

            // JSON 格式回傳 (預設)
            var result = new
            {
                success = true,
                data = data,
                count = data.Count,
                generated_at = DateTime.Now,
                message = "資料查詢成功"
            };

            return Ok(result);
        }
        catch (Exception ex)
        {
            return BadRequest($"資料查詢失敗：{ex.Message}");
        }
    }

    /// <summary>
    /// Excel 數據連接專用 - 按欄位顏色分類格式
    /// GET api/pivot/excel_data_structured
    /// </summary>
    /// <param name="includeMetadata">是否包含元數據</param>
    /// <param name="limit">限制筆數</param>
    /// <returns></returns>
    [HttpGet]
    [Route("api/pivot/excel_data_structured")]
    [AllowAnonymous]
    public IHttpActionResult GetExcelDataStructured(bool includeMetadata = false, int limit = 5000)
    {
        try
        {
            var query = from pod in _db.pro_order_detail
                       join po in _db.pro_order on pod.order_no equals po.order_no
                       join ai in _db.actItems on pod.actItem_num equals ai.num
                       join act in _db.activities on po.activity_num equals act.num
                       join f in _db.followers on po.f_num equals f.num
                       join aik in _db.actItem_kind on ai.kind equals aik.num
                       orderby po.up_time descending, act.num descending
                       select new
                       {
                           // 🟠 橘色欄位 - 法會基礎資料
                           activity_fields = new
                           {
                               法會ID = act.num,
                               法會名稱 = act.subject,
                               開始日期 = act.startDate_solar,
                               結束日期 = act.endDate_solar
                           },
                           
                           // 🔵 藍色欄位 - 信眾基礎資料
                           follower_fields = new
                           {
                               信眾編號 = f.f_number,
                               信眾姓名 = f.u_name,
                               報名編號 = po.order_no,
                               報名日期 = po.up_time
                           },
                           
                           // 🟢 綠色欄位 - 功德資訊欄位
                           merit_info_fields = new
                           {
                               功德主 = pod.parent_num != null ? "是" : "否",
                               功德類型 = aik.kind,
                               功德名稱 = ai.subject
                           },
                           
                           // 🟣 紫色欄位 - 計算欄位
                           calculated_fields = new
                           {
                               數量 = pod.qty,
                               金額 = pod.price,
                               已收 = 0,
                               未收 = pod.price * pod.qty,
                               小計 = pod.price * pod.qty
                           },
                           
                           // 📊 元數據 (可選)
                           metadata = includeMetadata ? new
                           {
                               原始資料 = new
                               {
                                   parent_num = pod.parent_num,
                                   kind_num = aik.num,
                                   item_num = ai.num,
                                   activity_num = act.num,
                                   follower_num = f.num
                               },
                               欄位分類說明 = new
                               {
                                   橘色欄位_法會資料 = "法會相關的基礎資料，用於法會維度分析",
                                   藍色欄位_信眾資料 = "信眾相關的基礎資料，用於信眾維度分析", 
                                   綠色欄位_功德資訊 = "功德相關的資訊欄位，包含功德主、功德類型和名稱",
                                   紫色欄位_計算欄位 = "需要數學計算或統計的欄位"
                               }
                           } : null
                       };

            var data = query.Take(limit).ToList();

            var result = new
            {
                success = true,
                data = new
                {
                    records = data,
                    field_categories = new
                    {
                        橘色_法會基礎資料 = new[] { "法會ID", "法會名稱", "開始日期", "結束日期" },
                        藍色_信眾基礎資料 = new[] { "信眾編號", "信眾姓名", "報名編號", "報名日期" },
                        綠色_功德資訊欄位 = new[] { "功德主", "功德類型", "功德名稱" },
                        紫色_計算欄位 = new[] { "數量", "金額", "已收", "未收" }
                    },
                    usage_notes = new
                    {
                        橘色欄位說明 = "法會相關基礎資料，適合用於法會維度的篩選和分組",
                        藍色欄位說明 = "信眾相關基礎資料，適合用於信眾維度的篩選和分組",
                        綠色欄位說明 = "功德資訊欄位，包含功德主判斷、功德類型和名稱，適合用於功德維度的篩選和分組",
                        紫色欄位說明 = "計算統計欄位，適合用於樞紐分析的值區域進行加總",
                        Excel樞紐分析建議 = new
                        {
                            篩選器 = "橘色(法會名稱) + 藍色(報名日期) + 綠色(功德類型)",
                            列標籤 = "藍色(信眾姓名) + 綠色(功德主)",
                            欄標籤 = "橘色(法會名稱) 或時間維度",
                            值區域 = "紫色(金額加總、數量計數)"
                        }
                    }
                },
                count = data.Count,
                generated_at = DateTime.Now,
                message = "結構化資料查詢成功"
            };

            return Ok(result);
        }
        catch (Exception ex)
        {
            return BadRequest($"查詢失敗：{ex.Message}");
        }
    }

    #endregion

    #region 工具方法

    /// <summary>
    /// 釋放資源
    /// </summary>
    /// <param name="disposing"></param>
    protected override void Dispose(bool disposing)
    {
        if (disposing)
        {
            _db?.Dispose();
        }
        base.Dispose(disposing);
    }

    #endregion
}