using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Web.Http;
using System.Configuration;

/// <summary>
/// pivot01Controller - 法會報名統計分析 API
/// 設計理念：直接查詢 SQL VIEW，保持彈性與簡潔
/// </summary>
[ezAuthorize]
public class pivot01Controller : ApiController
{
    // 連線字串
    private readonly string _connectionString;

    public pivot01Controller()
    {
        // 優先使用 shopConn 連線字串（純 SQL Server 連線字串）
        var shopConnectionString = ConfigurationManager.ConnectionStrings["shopConn"]?.ConnectionString;
        if (!string.IsNullOrEmpty(shopConnectionString))
        {
            // 移除不相容的 Provider 參數
            _connectionString = shopConnectionString.Replace("Provider=SQLOLEDB;", "");
        }
        else
        {
            // 備用方案：從 Entity Framework 連線字串中提取 SQL Server 連線字串
            var efConnectionString = ConfigurationManager.ConnectionStrings["ezEntities"]?.ConnectionString;
            if (!string.IsNullOrEmpty(efConnectionString))
            {
                // 解析 EF 連線字串，提取 provider connection string 部分
                var startIndex = efConnectionString.IndexOf("provider connection string=&quot;") + "provider connection string=&quot;".Length;
                var endIndex = efConnectionString.LastIndexOf("&quot;");
                if (startIndex > 0 && endIndex > startIndex)
                {
                    _connectionString = efConnectionString.Substring(startIndex, endIndex - startIndex);
                }
                else
                {
                    throw new InvalidOperationException("無法解析 Entity Framework 連線字串");
                }
            }
            else
            {
                throw new InvalidOperationException("找不到可用的資料庫連線字串");
            }
        }
    }

    #region 通用 VIEW 查詢方法

    /// <summary>
    /// 執行 SQL 查詢並回傳 DataTable
    /// </summary>
    /// <param name="sql">SQL 查詢語句</param>
    /// <param name="parameters">參數陣列</param>
    /// <returns>查詢結果 DataTable</returns>
    private DataTable ExecuteSqlQuery(string sql, SqlParameter[] parameters = null)
    {
        var dataTable = new DataTable();
        
        try
        {
            using (var connection = new SqlConnection(_connectionString))
            using (var command = new SqlCommand(sql, connection))
            {
                // 設定逾時時間為 60 秒
                command.CommandTimeout = 60;
                
                // 加入參數
                if (parameters != null && parameters.Length > 0)
                {
                    command.Parameters.AddRange(parameters);
                }

                // 開啟連線並執行查詢
                connection.Open();
                using (var adapter = new SqlDataAdapter(command))
                {
                    adapter.Fill(dataTable);
                }
            }
        }
        catch (SqlException ex)
        {
            throw new Exception($"SQL 查詢錯誤: {ex.Message}", ex);
        }
        catch (Exception ex)
        {
            throw new Exception($"執行查詢時發生錯誤: {ex.Message}", ex);
        }

        return dataTable;
    }

    /// <summary>
    /// DataTable 轉換為動態物件列表（保留中文欄位名）
    /// </summary>
    /// <param name="dt">DataTable</param>
    /// <returns>Dictionary 列表</returns>
    private List<Dictionary<string, object>> DataTableToDictionary(DataTable dt)
    {
        var list = new List<Dictionary<string, object>>();

        foreach (DataRow row in dt.Rows)
        {
            var dict = new Dictionary<string, object>();
            foreach (DataColumn col in dt.Columns)
            {
                // 保留原始欄位名稱（包含中文）
                dict[col.ColumnName] = row[col] == DBNull.Value ? null : row[col];
            }
            list.Add(dict);
        }

        return list;
    }

    #endregion

    #region API 端點

    /// <summary>
    /// GET /api/pivot01/activity_stats
    /// 查詢法會統計（對應「法會統計」VIEW）
    /// </summary>
    /// <param name="year">查詢年份</param>
    /// <returns>法會統計資料</returns>
    [HttpGet]
    [Route("api/pivot01/activity_stats")]
    public IHttpActionResult GetActivityStats(int year)
    {
        try
        {
            // 驗證年份參數
            if (year < 1900 || year > 2100)
            {
                return BadRequest("年份參數不正確，請輸入 1900 ~ 2100 之間的年份");
            }

            // 建立 SQL 查詢（包含當年度及無日期的法會）
            string sql = @"
                SELECT * FROM [法會統計]
                WHERE (YEAR(開始日期) = @year OR 開始日期 IS NULL)
                ORDER BY 
                    CASE WHEN 開始日期 IS NULL THEN 1 ELSE 0 END,
                    開始日期 DESC, 
                    結束日期 DESC
            ";

            // 建立參數
            var parameters = new[]
            {
                new SqlParameter("@year", SqlDbType.Int) { Value = year }
            };

            // 執行查詢
            var dataTable = ExecuteSqlQuery(sql, parameters);
            var data = DataTableToDictionary(dataTable);

            // 回應結果
            var result = new
            {
                success = true,
                data = data,
                message = "查詢成功",
                rowCount = data.Count
            };

            return Ok(result);
        }
        catch (Exception ex)
        {
            var errorResponse = new
            {
                success = false,
                message = $"查詢失敗：{ex.Message}",
                error = ex.ToString()
            };
            return Content(System.Net.HttpStatusCode.BadRequest, errorResponse);
        }
    }

    /// <summary>
    /// GET /api/pivot01/registration_details
    /// 查詢報名明細（對應「報名明細查詢」VIEW）
    /// </summary>
    /// <param name="activityNum">法會編號（必填）</param>
    /// <returns>報名明細資料</returns>
    [HttpGet]
    [Route("api/pivot01/registration_details")]
    public IHttpActionResult GetRegistrationDetails(int? activityNum = null)
    {
        try
        {
            // 驗證參數
            if (!activityNum.HasValue || activityNum.Value <= 0)
            {
                return BadRequest("請提供有效的法會編號（activityNum）");
            }

            // 建立查詢 SQL
            string sql = @"
                SELECT * FROM [報名明細查詢]
                WHERE 法會ID = @activityNum
                ORDER BY 報名日期 DESC, 報名編號 DESC
            ";

            // 建立參數
            var parameters = new[]
            {
                new SqlParameter("@activityNum", SqlDbType.Int) { Value = activityNum.Value }
            };

            // 執行查詢
            var dataTable = ExecuteSqlQuery(sql, parameters);
            var data = DataTableToDictionary(dataTable);

            // 回應結果
            var result = new
            {
                success = true,
                data = data,
                message = "查詢成功",
                rowCount = data.Count
            };

            return Ok(result);
        }
        catch (Exception ex)
        {
            var errorResponse = new
            {
                success = false,
                message = $"查詢失敗：{ex.Message}",
                error = ex.ToString()
            };
            return Content(System.Net.HttpStatusCode.BadRequest, errorResponse);
        }
    }

    #endregion
}