using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;

namespace 水電瓦斯抄錶.Models
{
    public class MeterItem
    {
        public string ItemId { get; set; }
        public string Shop { get; set; }
        public string Type { get; set; }
        public string Loc { get; set; }
        public string Meter { get; set; }
        public string Month { get; set; }
        public decimal LastVal { get; set; }
        public decimal? NowVal { get; set; }
        public string Photo { get; set; }
    }

    public class UserModel
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public string Pass { get; set; }
        public string Role { get; set; }
    }

    public class MeterDbHelper
    {
        private static string ConnStr =>
            ConfigurationManager.ConnectionStrings["BitanDb"].ConnectionString;

        private SqlConnection GetConn() => new SqlConnection(ConnStr);

        // ── 使用者 ──────────────────────────────────────────
        public UserModel GetUser(string name)
        {
            using (var conn = GetConn())
            using (var cmd = new SqlCommand(
                "SELECT Id,Name,Pass,Role FROM Users WHERE Name=@n", conn))
            {
                cmd.Parameters.AddWithValue("@n", name);
                conn.Open();
                using (var r = cmd.ExecuteReader())
                {
                    if (!r.Read()) return null;
                    return new UserModel
                    {
                        Id = (int)r["Id"],
                        Name = r["Name"].ToString(),
                        Pass = r["Pass"].ToString(),
                        Role = r["Role"].ToString()
                    };
                }
            }
        }

        public List<UserModel> GetAllUsers()
        {
            var list = new List<UserModel>();
            using (var conn = GetConn())
            using (var cmd = new SqlCommand(
                "SELECT Id,Name,Pass,Role FROM Users ORDER BY CASE Role WHEN 'pending' THEN 0 ELSE 1 END, Id", conn))
            {
                conn.Open();
                using (var r = cmd.ExecuteReader())
                    while (r.Read())
                        list.Add(new UserModel
                        {
                            Id = (int)r["Id"],
                            Name = r["Name"].ToString(),
                            Pass = r["Pass"].ToString(),
                            Role = r["Role"].ToString()
                        });
            }
            return list;
        }

        public bool AddUser(string name, string pass)
        {
            using (var conn = GetConn())
            using (var cmd = new SqlCommand(
                "INSERT INTO Users(Name,Pass,Role) VALUES(@n,@p,'pending')", conn))
            {
                cmd.Parameters.AddWithValue("@n", name);
                cmd.Parameters.AddWithValue("@p", pass);
                conn.Open();
                return cmd.ExecuteNonQuery() > 0;
            }
        }

        public bool UpdateUserRole(int id, string role)
        {
            using (var conn = GetConn())
            using (var cmd = new SqlCommand(
                "UPDATE Users SET Role=@r WHERE Id=@id", conn))
            {
                cmd.Parameters.AddWithValue("@r", role);
                cmd.Parameters.AddWithValue("@id", id);
                conn.Open();
                return cmd.ExecuteNonQuery() > 0;
            }
        }

        public bool DeleteUser(int id)
        {
            using (var conn = GetConn())
            using (var cmd = new SqlCommand("DELETE FROM Users WHERE Id=@id", conn))
            {
                cmd.Parameters.AddWithValue("@id", id);
                conn.Open();
                return cmd.ExecuteNonQuery() > 0;
            }
        }

        // ── 抄表資料 ────────────────────────────────────────
        public List<MeterItem> GetByMonth(string month)
        {
            var list = new List<MeterItem>();
            using (var conn = GetConn())
            using (var cmd = new SqlCommand(
                "SELECT ItemId,Shop,Type,Loc,Meter,Month,LastVal,NowVal,Photo FROM MeterItems WHERE Month=@m ORDER BY Id", conn))
            {
                cmd.Parameters.AddWithValue("@m", month);
                conn.Open();
                using (var r = cmd.ExecuteReader())
                    while (r.Read())
                        list.Add(MapItem(r));
            }
            return list;
        }

        public void SaveItems(string month, List<MeterItem> items)
        {
            using (var conn = GetConn())
            {
                conn.Open();
                using (var tx = conn.BeginTransaction())
                {
                    // 刪除該月舊資料再重新插入
                    var del = new SqlCommand("DELETE FROM MeterItems WHERE Month=@m", conn, tx);
                    del.Parameters.AddWithValue("@m", month);
                    del.ExecuteNonQuery();

                    foreach (var item in items)
                    {
                        var ins = new SqlCommand(@"
                            INSERT INTO MeterItems(ItemId,Shop,Type,Loc,Meter,Month,LastVal,NowVal,Photo,UpdatedAt)
                            VALUES(@id,@shop,@type,@loc,@meter,@month,@last,@now,@photo,GETDATE())", conn, tx);
                        ins.Parameters.AddWithValue("@id", item.ItemId ?? "");
                        ins.Parameters.AddWithValue("@shop", item.Shop ?? "");
                        ins.Parameters.AddWithValue("@type", item.Type ?? "");
                        ins.Parameters.AddWithValue("@loc", (object)item.Loc ?? DBNull.Value);
                        ins.Parameters.AddWithValue("@meter", (object)item.Meter ?? DBNull.Value);
                        ins.Parameters.AddWithValue("@month", month);
                        ins.Parameters.AddWithValue("@last", item.LastVal);
                        ins.Parameters.AddWithValue("@now", (object)item.NowVal ?? DBNull.Value);
                        ins.Parameters.AddWithValue("@photo", (object)item.Photo ?? DBNull.Value);
                        ins.ExecuteNonQuery();
                    }
                    tx.Commit();
                }
            }
        }

        public void DeleteItemAllMonths(string itemId, string type)
        {
            using (var conn = GetConn())
            using (var cmd = new SqlCommand(
                "DELETE FROM MeterItems WHERE ItemId=@id AND Type=@t", conn))
            {
                cmd.Parameters.AddWithValue("@id", itemId);
                cmd.Parameters.AddWithValue("@t", type);
                conn.Open();
                cmd.ExecuteNonQuery();
            }
        }

        public void DeleteMonth(string month)
        {
            using (var conn = GetConn())
            using (var cmd = new SqlCommand("DELETE FROM MeterItems WHERE Month=@m", conn))
            {
                cmd.Parameters.AddWithValue("@m", month);
                conn.Open();
                cmd.ExecuteNonQuery();
            }
        }

        // ── 抄錄日期 ────────────────────────────────────────
        public string GetRecordDate(string month)
        {
            using (var conn = GetConn())
            using (var cmd = new SqlCommand(
                "SELECT RecordDate FROM DateLog WHERE Month=@m", conn))
            {
                cmd.Parameters.AddWithValue("@m", month);
                conn.Open();
                var val = cmd.ExecuteScalar();
                return val == null ? "" : Convert.ToDateTime(val).ToString("yyyy-MM-dd");
            }
        }

        public void SaveRecordDate(string month, string date)
        {
            using (var conn = GetConn())
            using (var cmd = new SqlCommand(@"
                MERGE DateLog AS t
                USING (SELECT @m AS Month, @d AS RecordDate) AS s
                ON t.Month = s.Month
                WHEN MATCHED THEN UPDATE SET RecordDate=s.RecordDate
                WHEN NOT MATCHED THEN INSERT(Month,RecordDate) VALUES(s.Month,s.RecordDate);", conn))
            {
                cmd.Parameters.AddWithValue("@m", month);
                cmd.Parameters.AddWithValue("@d", date);
                conn.Open();
                cmd.ExecuteNonQuery();
            }
        }

        private MeterItem MapItem(IDataReader r) => new MeterItem
        {
            ItemId = r["ItemId"].ToString(),
            Shop = r["Shop"].ToString(),
            Type = r["Type"].ToString(),
            Loc = r["Loc"] == DBNull.Value ? "" : r["Loc"].ToString(),
            Meter = r["Meter"] == DBNull.Value ? "" : r["Meter"].ToString(),
            Month = r["Month"].ToString().Trim(),
            LastVal = Convert.ToDecimal(r["LastVal"]),
            NowVal = r["NowVal"] == DBNull.Value ? (decimal?)null : Convert.ToDecimal(r["NowVal"]),
            Photo = r["Photo"] == DBNull.Value ? "" : r["Photo"].ToString()
        };
    }
}