// Copyright (c) 2023 Timothy Schenk. Subject to the GNU AGPL Version 3 License.

using DotNext.Collections.Generic;
using Microsoft.EntityFrameworkCore;
using NetCoreServer;
using Server.DB;
using Server.DB.Documents;
using Wonderking.Game.Data.Character;
using Wonderking.Packets.Incoming;
using Wonderking.Packets.Outgoing;
using Wonderking.Packets.Outgoing.Data;

namespace Server.PacketHandlers;

public class ChannelSelectionHandler : IPacketHandler<ChannelSelectionPacket>
{
    private readonly WonderkingContext _wonderkingContext;

    public ChannelSelectionHandler(WonderkingContext wonderkingContext)
    {
        _wonderkingContext = wonderkingContext;
    }

    public async Task HandleAsync(ChannelSelectionPacket packet, TcpSession session)
    {
        var authSession = (AuthSession)session;
        ChannelSelectionResponsePacket responsePacket;
        var guildNameResponsePacket = new CharacterSelectionSetGuildNamePacket { GuildNames = Array.Empty<string>() };

        var account = await _wonderkingContext.Accounts
            .FirstOrDefaultAsync(a => a.Id == authSession.AccountId);

        var amountOfCharacter = await _wonderkingContext.Characters
            .Where(c => c.Account.Id == authSession.AccountId)
            .CountAsync();

        if (account != null && amountOfCharacter > 0)
        {
            responsePacket = new ChannelSelectionResponsePacket
            {
                ChannelIsFullFlag = 0,
                Endpoint = "127.0.0.1",
                Port = 2000,
                Characters = await GetCharacterDataAsync(account.Id).ToArrayAsync()
            };

            guildNameResponsePacket.GuildNames = await _wonderkingContext.Characters
                .Where(c => c.Account.Id == authSession.AccountId)
                .Where(c => c.Guild != null)
                .Select(character => character.Guild.Name).ToArrayAsync();
        }
        else
        {
            responsePacket = new ChannelSelectionResponsePacket
            {
                ChannelIsFullFlag = 0,
                Endpoint = "127.0.0.1",
                Port = 2000,
                Characters = Array.Empty<CharacterData>()
            };
        }

        await authSession.SendAsync(responsePacket);
        if (guildNameResponsePacket.GuildNames.Length > 0 &&
            guildNameResponsePacket.GuildNames.Select(n => n != string.Empty).Any())
        {
            await authSession.SendAsync(guildNameResponsePacket);
        }
    }

    private static ushort[] GetItemIDsByInventoryTab(IEnumerable<InventoryItemProjection> items)
    {
        var ids = new ushort[20];
        ids.AsSpan().Clear();

        foreach (var item in items)
        {
            if (item.Slot > 20)
            {
                continue;
            }

            ids[item.Slot] = item.ItemId;
        }

        return ids;
    }

    private async IAsyncEnumerable<CharacterData> GetCharacterDataAsync(Guid accountId)
    {
        await foreach (var c in _getCharacters(_wonderkingContext, accountId))
        {
            yield return new CharacterData
            {
                Name = c.Name,
                Job = c.JobData,
                Gender = c.Gender,
                Level = c.Level,
                // TODO: Calculate instead of clamping based on max experience for level
                Experience = Math.Clamp(c.Experience, 0, 100),
                Stats = c.BaseStats,
                Health = c.Health,
                Mana = c.Mana,
                EquippedItems =
                    GetItemIDsByInventoryTab(c.InventoryItems.Where(i =>
                        i.InventoryTab == InventoryTab.WornEquipment)),
                EquippedCashItems = GetItemIDsByInventoryTab(c.InventoryItems.Where(i =>
                    i.InventoryTab == InventoryTab.WornCashEquipment))
            };
        }
    }

    private static readonly Func<WonderkingContext, Guid, IAsyncEnumerable<CharacterDataProjection>> _getCharacters =
        EF.CompileAsyncQuery((WonderkingContext context, Guid accountId) =>
            context.Characters.AsNoTracking().AsSplitQuery()
                .Where(c => c.Account.Id == accountId)
                .Select(c => new CharacterDataProjection(
                    c.Name,
                    c.JobData,
                    c.Gender,
                    c.Level,
                    c.Experience,
                    c.BaseStats,
                    c.Health,
                    c.Mana,
                    c.InventoryItems.Select(i => new InventoryItemProjection(i.ItemId, i.Slot, i.InventoryTab))
                )).Take(3));

    private sealed record InventoryItemProjection(ushort ItemId, byte Slot, InventoryTab InventoryTab);

    private sealed record CharacterDataProjection(
        string Name,
        JobData JobData,
        Gender Gender,
        ushort Level,
        long Experience,
        BaseStats BaseStats,
        int Health,
        int Mana,
        IEnumerable<InventoryItemProjection> InventoryItems);
}