using System.Text.Json;
using Microsoft.EntityFrameworkCore;
using DorkNet.Server.Data;
using DorkNet.Server.Data.Entities;

namespace DorkNet.Server.Services;

/// <summary>
/// Per-quest reward chest contents. The end-of-quest gift box
/// (RRO quest / Stunt Runner) is the existing <c>gifts/generate</c> +
/// <c>gifts/consume</c> flow: the client asks the server to generate a
/// gift, the box spawns showing it, and opening it grants the item.
///
/// The generate request carries no quest id (only GiftContext /
/// IsGameGift / Message), so the quest is identified by the room the
/// player is in — <see cref="PlayerPresenceService.GetRoom"/>. This
/// service maps that room id to the quest's item pool
/// (<c>data/quest_rewards.json</c>) and resolves one to a real store
/// item to award. When a room has no configured pool the caller falls
/// back to the generic random-wardrobe gift.
/// </summary>
public sealed class QuestRewardService(DorkNetDbContext db)
{
    private sealed class QuestRewardFile
    {
        public Dictionary<string, List<string>> rooms { get; set; } = new();
    }

    private static readonly Lazy<Dictionary<long, List<string>>> _map = new(Load);

    /// <summary>Room id → candidate item slugs for that quest's chest.</summary>
    public static IReadOnlyDictionary<long, List<string>> Map => _map.Value;

    public static bool HasRewardsForRoom(long roomId) =>
        Map.TryGetValue(roomId, out var slugs) && slugs.Count > 0;

    /// <summary>Resolve one active store item for the quest chest in
    /// <paramref name="roomId"/>, chosen deterministically from
    /// <paramref name="seed"/> so repeated generate calls in the same
    /// context are stable. Returns null when the room has no configured
    /// pool or none of its slugs resolve to an active item.</summary>
    public async Task<StoreItemEntity?> PickForRoomAsync(long roomId, int seed)
    {
        if (!Map.TryGetValue(roomId, out var slugs) || slugs.Count == 0) return null;

        var items = await db.StoreItems
            .Where(i => i.IsActive && slugs.Contains(i.Slug))
            .ToListAsync();
        if (items.Count == 0) return null;

        // Order deterministically by (id, seed) hash so the same room +
        // seed always yields the same pick without persisting state.
        return items
            .OrderBy(i => HashCode.Combine(i.Id, seed))
            .First();
    }

    private static Dictionary<long, List<string>> Load()
    {
        var candidates = new[]
        {
            Path.Combine(AppContext.BaseDirectory, "data", "quest_rewards.json"),
            Path.Combine(AppContext.BaseDirectory, "Data", "quest_rewards.json"),
            Path.Combine(Directory.GetCurrentDirectory(), "data", "quest_rewards.json"),
            Path.Combine(Directory.GetCurrentDirectory(), "DorkNet.Server", "Data", "quest_rewards.json"),
        };
        var path = candidates.FirstOrDefault(File.Exists);
        if (path is null) return new();

        try
        {
            using var fs = File.OpenRead(path);
            var data = JsonSerializer.Deserialize<QuestRewardFile>(fs,
                new JsonSerializerOptions { PropertyNameCaseInsensitive = true }) ?? new QuestRewardFile();

            var map = new Dictionary<long, List<string>>();
            foreach (var (key, slugs) in data.rooms)
            {
                if (!long.TryParse(key, out var roomId)) continue;
                var clean = (slugs ?? new())
                    .Where(s => !string.IsNullOrWhiteSpace(s))
                    .Select(s => s.Trim())
                    .Distinct(StringComparer.OrdinalIgnoreCase)
                    .ToList();
                if (clean.Count > 0) map[roomId] = clean;
            }
            return map;
        }
        catch
        {
            return new();
        }
    }
}