using System.Collections.Concurrent;
using System.Text.Json;
using Hokm.Server.Data;
using Hokm.Server.Game;
using Hokm.Server.Hubs;
using Hokm.Server.Profiles;
using Microsoft.AspNetCore.SignalR;
using Microsoft.EntityFrameworkCore;

namespace Hokm.Server.Social;

public class SocialService
{
    private readonly AppDbContext _db;
    private readonly GameManager _mgr;
    private readonly IHubContext<GameHub> _hub;

    /// <summary>Max outgoing friend requests allowed per user within a rolling hour.</summary>
    public const int FriendReqLimit = 10;
    private static readonly TimeSpan FriendReqWindow = TimeSpan.FromHours(1);
    // Process-wide log of each user's recent outgoing-request timestamps (resets on restart).
    private static readonly ConcurrentDictionary<string, List<DateTime>> _reqLog = new();

    public SocialService(AppDbContext db, GameManager mgr, IHubContext<GameHub> hub)
    {
        _db = db;
        _mgr = mgr;
        _hub = hub;
    }

    /// <summary>
    /// Records an outgoing friend-request attempt against the rolling-hour cap.
    /// Returns false (with the minutes until a slot frees) when over the limit.
    /// </summary>
    private static bool TryRecordRequest(string uid, out int retryMins)
    {
        retryMins = 0;
        var now = DateTime.UtcNow;
        var list = _reqLog.GetOrAdd(uid, _ => new List<DateTime>());
        lock (list)
        {
            list.RemoveAll(t => now - t >= FriendReqWindow);
            if (list.Count >= FriendReqLimit)
            {
                retryMins = Math.Max(1, (int)Math.Ceiling((FriendReqWindow - (now - list[0])).TotalMinutes));
                return false;
            }
            list.Add(now);
            return true;
        }
    }

    private async Task<FriendDto> FriendDtoFor(string userId)
    {
        var row = await _db.Profiles.FindAsync(userId);
        var p = row != null ? JsonSerializer.Deserialize<ProfileDto>(row.Json, JsonOpts.Default) : null;
        return new FriendDto
        {
            Id = userId,
            Username = p?.Username ?? userId,
            DisplayName = p?.DisplayName ?? userId,
            Avatar = p?.Avatar ?? "a-fox",
            Level = p?.Level ?? 1,
            Rating = p?.Rating ?? 1000,
            Status = _mgr.IsOnline(userId) ? "online" : "offline",
        };
    }

    /* ----------------------------- friends ----------------------------- */

    public async Task<List<FriendDto>> ListFriends(string uid)
    {
        var ids = await _db.Friends.Where(f => f.UserId == uid).Select(f => f.FriendId).ToListAsync();
        var list = new List<FriendDto>();
        foreach (var id in ids) list.Add(await FriendDtoFor(id));
        return list;
    }

    public async Task<List<FriendRequestDto>> ListRequests(string uid)
    {
        var reqs = await _db.FriendRequests.Where(r => r.ToUserId == uid).ToListAsync();
        var list = new List<FriendRequestDto>();
        foreach (var r in reqs)
            list.Add(new FriendRequestDto { Id = r.Id.ToString(), From = await FriendDtoFor(r.FromUserId), CreatedAt = new DateTimeOffset(r.CreatedAt).ToUnixTimeMilliseconds() });
        return list;
    }

    public async Task<(bool ok, string messageFa, string messageEn)> AddFriend(string uid, string query)
    {
        var digits = new string(query.Where(char.IsDigit).ToArray());
        var targetId = query.Contains(':') ? query.Trim() : (digits.Length >= 4 ? "phone:" + digits : query.Trim());
        return await AddFriendById(uid, targetId);
    }

    /// <summary>Send a friend request to a concrete user id (rate-limited to 10/hour).</summary>
    public async Task<(bool ok, string messageFa, string messageEn)> AddFriendById(string uid, string targetId)
    {
        targetId = targetId.Trim();
        var target = await _db.Profiles.FindAsync(targetId);
        if (target == null || targetId == uid)
            return (false, "کاربر پیدا نشد", "User not found");
        if (await _db.Friends.AnyAsync(f => f.UserId == uid && f.FriendId == targetId))
            return (false, "از قبل دوست هستید", "Already friends");
        // Already pending → idempotent success, doesn't consume the hourly quota.
        if (await _db.FriendRequests.AnyAsync(r => r.FromUserId == uid && r.ToUserId == targetId))
            return (true, "درخواست دوستی ارسال شد", "Friend request sent");
        if (!TryRecordRequest(uid, out var mins))
            return (false,
                $"در هر ساعت حداکثر {FriendReqLimit} درخواست دوستی می‌توانید بفرستید. {mins} دقیقه دیگر تلاش کنید.",
                $"You can send at most {FriendReqLimit} friend requests per hour. Try again in {mins} min.");
        _db.FriendRequests.Add(new FriendRequestRow { FromUserId = uid, ToUserId = targetId, CreatedAt = DateTime.UtcNow });
        await _db.SaveChangesAsync();
        await _hub.Clients.User(targetId).SendAsync("friendRequest", await FriendDtoFor(uid));
        return (true, "درخواست دوستی ارسال شد", "Friend request sent");
    }

    /* --------------------------- discovery ----------------------------- */

    private PlayerSummaryDto ToSummary(ProfileDto p, HashSet<string> friendIds, HashSet<string> sentIds) => new()
    {
        Id = p.Id,
        DisplayName = p.DisplayName,
        Avatar = p.Avatar,
        AvatarImage = p.AvatarImage,
        Level = p.Level,
        Rating = p.Rating,
        Status = _mgr.IsOnline(p.Id) ? "online" : "offline",
        Gender = p.Gender ?? "",
        Title = p.Title,
        IsFriend = friendIds.Contains(p.Id),
        RequestSent = sentIds.Contains(p.Id),
    };

    /// <summary>Search players by display name (case-insensitive contains).</summary>
    public async Task<List<PlayerSummaryDto>> SearchPlayers(string uid, string query)
    {
        query = (query ?? "").Trim();
        if (query.Length == 0) return new();
        var friendIds = (await _db.Friends.Where(f => f.UserId == uid).Select(f => f.FriendId).ToListAsync()).ToHashSet();
        var sentIds = (await _db.FriendRequests.Where(r => r.FromUserId == uid).Select(r => r.ToUserId).ToListAsync()).ToHashSet();
        var rows = await _db.Profiles.Where(p => p.Id != uid).ToListAsync();
        var list = new List<PlayerSummaryDto>();
        foreach (var row in rows)
        {
            var p = JsonSerializer.Deserialize<ProfileDto>(row.Json, JsonOpts.Default);
            if (p?.DisplayName == null) continue;
            if (!p.DisplayName.Contains(query, StringComparison.OrdinalIgnoreCase)) continue;
            list.Add(ToSummary(p, friendIds, sentIds));
            if (list.Count >= 20) break;
        }
        return list;
    }

    /// <summary>Suggested players to befriend (online-first, excludes existing friends).</summary>
    public async Task<List<PlayerSummaryDto>> Suggested(string uid)
    {
        var friendIds = (await _db.Friends.Where(f => f.UserId == uid).Select(f => f.FriendId).ToListAsync()).ToHashSet();
        var sentIds = (await _db.FriendRequests.Where(r => r.FromUserId == uid).Select(r => r.ToUserId).ToListAsync()).ToHashSet();
        var rows = await _db.Profiles.Where(p => p.Id != uid).Take(80).ToListAsync();
        var list = new List<PlayerSummaryDto>();
        foreach (var row in rows)
        {
            var p = JsonSerializer.Deserialize<ProfileDto>(row.Json, JsonOpts.Default);
            if (p == null || friendIds.Contains(p.Id)) continue;
            list.Add(ToSummary(p, friendIds, sentIds));
        }
        // Online players first, then by rating.
        return list
            .OrderByDescending(x => x.Status == "online")
            .ThenByDescending(x => x.Rating)
            .Take(12)
            .ToList();
    }

    /// <summary>Another player's public profile + achievement board (no private fields).</summary>
    public async Task<PublicProfileDto?> GetPublicProfile(string uid, string targetId)
    {
        targetId = targetId.Trim();
        var row = await _db.Profiles.FindAsync(targetId);
        if (row == null) return null;
        var p = JsonSerializer.Deserialize<ProfileDto>(row.Json, JsonOpts.Default);
        if (p == null) return null;

        var isFriend = await _db.Friends.AnyAsync(f => f.UserId == uid && f.FriendId == targetId);
        var requestSent = await _db.FriendRequests.AnyAsync(r => r.FromUserId == uid && r.ToUserId == targetId);
        var isYou = targetId == uid;

        // Social links honor the owner's privacy: public → everyone, friends → only
        // friends (and the owner), hidden → nobody.
        var vis = string.IsNullOrEmpty(p.SocialsVisibility) ? "public" : p.SocialsVisibility;
        var canSeeSocials = isYou || vis == "public" || (vis == "friends" && isFriend);

        return new PublicProfileDto
        {
            Id = p.Id,
            DisplayName = p.DisplayName,
            Avatar = p.Avatar,
            AvatarImage = p.AvatarImage,
            Plan = p.Plan,
            Title = p.Title,
            Level = p.Level,
            Rating = p.Rating,
            Stats = p.Stats,
            Achievements = p.Achievements,
            Unlocked = p.Unlocked,
            CreatedAt = p.CreatedAt,
            Gender = p.Gender ?? "",
            Socials = canSeeSocials ? p.Socials : null,
            IsFriend = isFriend,
            IsYou = isYou,
            RequestSent = requestSent,
        };
    }

    public async Task Accept(string uid, long requestId)
    {
        var req = await _db.FriendRequests.FirstOrDefaultAsync(r => r.Id == requestId && r.ToUserId == uid);
        if (req == null) return;
        _db.Friends.Add(new FriendEdgeRow { UserId = uid, FriendId = req.FromUserId });
        _db.Friends.Add(new FriendEdgeRow { UserId = req.FromUserId, FriendId = uid });
        _db.FriendRequests.Remove(req);
        await _db.SaveChangesAsync();
        await _hub.Clients.User(req.FromUserId).SendAsync("social", "friend-added");
    }

    public async Task Decline(string uid, long requestId)
    {
        var req = await _db.FriendRequests.FirstOrDefaultAsync(r => r.Id == requestId && r.ToUserId == uid);
        if (req != null) { _db.FriendRequests.Remove(req); await _db.SaveChangesAsync(); }
    }

    public async Task Remove(string uid, string friendId)
    {
        var edges = await _db.Friends.Where(f =>
            (f.UserId == uid && f.FriendId == friendId) || (f.UserId == friendId && f.FriendId == uid)).ToListAsync();
        _db.Friends.RemoveRange(edges);
        await _db.SaveChangesAsync();
        await _hub.Clients.User(friendId).SendAsync("social", "friend-removed");
    }

    /* ------------------------------- chat ------------------------------ */

    public async Task<List<ConversationDto>> Conversations(string uid)
    {
        var msgs = await _db.Messages.Where(m => m.UserId == uid || m.PeerId == uid).ToListAsync();
        var byPartner = msgs.GroupBy(m => m.UserId == uid ? m.PeerId : m.UserId);
        var convs = new List<ConversationDto>();
        foreach (var g in byPartner)
        {
            var last = g.OrderByDescending(m => m.CreatedAt).First();
            convs.Add(new ConversationDto
            {
                Friend = await FriendDtoFor(g.Key),
                LastMessage = ToDto(last, uid),
                Unread = g.Count(m => m.PeerId == uid && !m.ReadByPeer),
            });
        }
        return convs.OrderByDescending(c => c.LastMessage?.Ts ?? 0).ToList();
    }

    public async Task<List<ChatMessageDto>> Messages(string uid, string peerId)
    {
        var msgs = await _db.Messages
            .Where(m => (m.UserId == uid && m.PeerId == peerId) || (m.UserId == peerId && m.PeerId == uid))
            .OrderBy(m => m.CreatedAt).ToListAsync();
        var unread = msgs.Where(m => m.UserId == peerId && m.PeerId == uid && !m.ReadByPeer).ToList();
        if (unread.Count > 0) { unread.ForEach(m => m.ReadByPeer = true); await _db.SaveChangesAsync(); }
        return msgs.Select(m => ToDto(m, uid)).ToList();
    }

    public async Task<ChatMessageDto> Send(string uid, string peerId, string text)
    {
        var m = new MessageRow { UserId = uid, PeerId = peerId, Text = text.Trim(), CreatedAt = DateTime.UtcNow };
        _db.Messages.Add(m);
        await _db.SaveChangesAsync();
        await _hub.Clients.User(peerId).SendAsync("chat", new { peerId = uid });
        return ToDto(m, uid);
    }

    private static ChatMessageDto ToDto(MessageRow m, string uid) => new()
    {
        Id = m.Id.ToString(),
        FromMe = m.UserId == uid,
        Text = m.Text,
        Ts = new DateTimeOffset(m.CreatedAt).ToUnixTimeMilliseconds(),
    };
}