using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using RainOpsMini.Helpers;
using RainOpsMini.Models;
using RainOpsMini.Models;
using SqlSugar;

namespace RainOpsMini.Services
{
    public class CdkService
    {
        public static async Task<List<CdkInfo>> GenerateCdksAsync(string type, int duration, int count, string reason, string creator)
        {
            var list = new List<CdkInfo>();
            using var db = DbHelper.GetInstance();
            string batchId = Guid.NewGuid().ToString("N");

            for (int i = 0; i < count; i++)
            {
                var cdk = new CdkInfo
                {
                    Code = "CDK" + GenerateRandomCode(13), // Total 16 chars
                    Type = type,
                    DurationDays = duration,
                    Reason = reason,
                    Creator = creator,
                    Status = "Unused",
                    CreatedAt = DateTime.UtcNow,
                    BatchId = batchId
                };
                list.Add(cdk);
            }

            await db.Insertable(list).ExecuteCommandAsync();
            return list;
        }

        public static async Task<(bool success, string message)> RedeemCdkAsync(string code, string steamId)
        {
            using var db = DbHelper.GetInstance();
            
            // 1. Find CDK
            var cdk = await db.Queryable<CdkInfo>().FirstAsync(c => c.Code == code);
            if (cdk == null) return (false, "无效的兑换码");
            if (cdk.Status != "Unused") return (false, "该兑换码已被使用");

            // 2. Validate SteamID (Simple check)
            if (string.IsNullOrWhiteSpace(steamId) || steamId.Length < 17) return (false, "无效的 SteamID");

            // 3. Check Batch Limit (One redemption per batch per user)
            if (!string.IsNullOrEmpty(cdk.BatchId))
            {
                var alreadyRedeemed = await db.Queryable<CdkInfo>()
                    .Where(c => c.BatchId == cdk.BatchId && c.RedeemedBy == steamId)
                    .AnyAsync();
                
                if (alreadyRedeemed)
                {
                    return (false, "您已领取过该批次的兑换码，无法重复领取");
                }
            }

            // 4. Update CDK status
            cdk.Status = "Used";
            cdk.RedeemedBy = steamId;
            cdk.RedeemedAt = DateTime.UtcNow;
            await db.Updateable(cdk).ExecuteCommandAsync();

            // 5. Grant VIP/SVIP
            // Map type to internal group name
            bool isRedeemingSvip = cdk.Type == "SVIP";
            
            var existingVip = VipStorage.GetBySteamId(steamId);
            
            // Initializing/Migrating Expiries
            DateTime? currentVipExpiry = null;
            DateTime? currentSvipExpiry = null;
            string finalGroup = "";
            DateTime finalExpiry = DateTime.MinValue;

            if (existingVip != null)
            {
                // Migrate legacy data if needed
                if (existingVip.VipExpiryDate == null && existingVip.SvipExpiryDate == null)
                {
                    if (existingVip.Group == "SVIP_RainOpsMini")
                    {
                        existingVip.SvipExpiryDate = existingVip.ExpiryDate;
                        // SVIP usually implies VIP privileges, but let's keep them somewhat distinct or 
                        // initialize VIP expiry to same as SVIP if we consider SVIP > VIP.
                        // For independent tracking requested by user, if they were SVIP, we only set SVIP expiry.
                        // But if they downgrade, they might have lost VIP. 
                        // Let's assume SVIP covers VIP, so we might set VIP expiry too?
                        // User said: "我是SVIP身份但是我兑换VIP的CDK也会延长SVIP的时长，要分开独立计算"
                        // This implies they want to accumulate VIP time even while SVIP.
                        // So if we are migrating an SVIP user, we probably should set VIP expiry to same date?
                        // Or maybe leave VIP as null (expired/inactive)?
                        // If we leave VIP null, and they redeem VIP, they get VIP time. 
                        // If their SVIP expires, they fall back to VIP.
                        // Let's set SvipExpiryDate = ExpiryDate. VipExpiryDate = null (or maybe ExpiryDate if we want to be generous).
                        // Let's be strict: SVIP implies SVIP expiry.
                    }
                    else if (existingVip.Group == "VIP_RainOpsMini")
                    {
                        existingVip.VipExpiryDate = existingVip.ExpiryDate;
                    }
                }
                currentVipExpiry = existingVip.VipExpiryDate;
                currentSvipExpiry = existingVip.SvipExpiryDate;
            }

            // Calculate new expiry
            if (isRedeemingSvip)
            {
                // Update SVIP Expiry
                DateTime baseTime = (currentSvipExpiry.HasValue && currentSvipExpiry.Value > DateTime.Now) ? currentSvipExpiry.Value : DateTime.Now;
                currentSvipExpiry = baseTime.AddDays(cdk.DurationDays);
            }
            else
            {
                // Update VIP Expiry
                DateTime baseTime = (currentVipExpiry.HasValue && currentVipExpiry.Value > DateTime.Now) ? currentVipExpiry.Value : DateTime.Now;
                currentVipExpiry = baseTime.AddDays(cdk.DurationDays);
            }

            // Determine Effective Group
            // Rule: SVIP > VIP > None
            bool hasActiveSvip = currentSvipExpiry.HasValue && currentSvipExpiry.Value > DateTime.Now;
            bool hasActiveVip = currentVipExpiry.HasValue && currentVipExpiry.Value > DateTime.Now;

            if (hasActiveSvip)
            {
                finalGroup = "SVIP_RainOpsMini";
                finalExpiry = currentSvipExpiry.Value;
            }
            else if (hasActiveVip)
            {
                finalGroup = "VIP_RainOpsMini";
                finalExpiry = currentVipExpiry.Value;
            }
            else
            {
                // Both expired? Or just newly added but expired (unlikely with duration > 0)
                // If redeeming valid CDK, at least one should be active.
                // Fallback
                finalGroup = isRedeemingSvip ? "SVIP_RainOpsMini" : "VIP_RainOpsMini";
                finalExpiry = DateTime.Now.AddDays(cdk.DurationDays); // Should not happen
            }

            if (existingVip != null)
            {
                existingVip.Group = finalGroup;
                existingVip.ExpiryDate = finalExpiry;
                existingVip.VipExpiryDate = currentVipExpiry;
                existingVip.SvipExpiryDate = currentSvipExpiry;
                existingVip.Remark = $"CDK: {cdk.Reason}";
                VipStorage.Save();
            }
            else
            {
                // New User
                var newVip = new VipMember
                {
                    SteamId = steamId,
                    Name = "Redeemed User",
                    Group = finalGroup,
                    ExpiryDate = finalExpiry,
                    VipExpiryDate = currentVipExpiry,
                    SvipExpiryDate = currentSvipExpiry,
                    Remark = $"CDK: {cdk.Reason}",
                    CreatedAt = DateTime.Now
                };

                try 
                {
                    var players = Program.RconCache?.Players?.ToList();
                    if (players != null)
                    {
                        var player = players.FirstOrDefault(p => p.SteamId == steamId);
                        if (player != null) newVip.Name = player.Name;
                    }
                }
                catch {}

                VipStorage.Add(newVip);
            }

            // Sync to config
            try 
            {
                string cfgPath = System.IO.Path.Combine(Environment.CurrentDirectory, "SquadGame", "ServerConfig", "Admins.cfg");
                VipStorage.SyncToAdminConfig(cfgPath);
            }
            catch (Exception ex)
            {
                RainOpsLog.Log($"[CDK] Sync Admin Config Failed: {ex.Message}");
            }

            string svipMsg = hasActiveSvip ? $"{currentSvipExpiry:yyyy-MM-dd HH:mm}" : (currentSvipExpiry.HasValue ? "已过期" : "未开通");
            string vipMsg = hasActiveVip ? $"{currentVipExpiry:yyyy-MM-dd HH:mm}" : (currentVipExpiry.HasValue ? "已过期" : "未开通");
            string groupDisplay = finalGroup == "SVIP_RainOpsMini" ? "SVIP" : "VIP";

            return (true, $"兑换成功！\n当前生效：{groupDisplay}\nSVIP到期：{svipMsg}\nVIP 到期：{vipMsg}");
        }

        private static string GenerateRandomCode(int length)
        {
            const string chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
            var random = new Random();
            return new string(Enumerable.Repeat(chars, length)
                .Select(s => s[random.Next(s.Length)]).ToArray());
        }
    }
}