using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using SVSim.Database;
using SVSim.Database.Enums;
using SVSim.Database.Models;
using SVSim.Database.Services;
using SVSim.EmulatedEntrypoint.Models.Dtos;
using SVSim.EmulatedEntrypoint.Models.Dtos.Requests.LeaderSkin;
using SVSim.EmulatedEntrypoint.Models.Dtos.Responses.LeaderSkin;

namespace SVSim.EmulatedEntrypoint.Controllers;

/// <summary>
/// /leader_skin/* — the leader-skin shop family.
/// <list type="bullet">
///   <item><c>/set</c>: per-class equipped-skin preference (the fallback when a deck has
///   <c>leader_skin_id == 0</c>). Per-deck overrides go through /deck/update_leader_skin.</item>
///   <item><c>/products</c>: shop catalog (dict-keyed by series_id).</item>
///   <item><c>/buy</c>: single-skin purchase. Currency dispatch crystal/rupy/ticket(501).</item>
///   <item><c>/buy_set</c>: whole-series purchase at set discount.</item>
///   <item><c>/buy_set_item</c>: claim series-completion bonus (idempotent via
///   <see cref="ViewerLeaderSkinSetClaim"/>).</item>
///   <item><c>/ids</c>: flat list of owned skin ids for badge refresh.</item>
/// </list>
/// </summary>
[Route("leader_skin")]
public class LeaderSkinController : SVSimController
{
    private readonly SVSimDbContext _db;
    private readonly RewardGrantService _rewards;
    private readonly TimeProvider _time;

    public LeaderSkinController(SVSimDbContext db, RewardGrantService rewards, TimeProvider time)
    {
        _db = db;
        _rewards = rewards;
        _time = time;
    }

    [HttpPost("set")]
    public async Task<ActionResult<LeaderSkinSetResponse>> Set(LeaderSkinSetRequest request)
    {
        if (!TryGetViewerId(out long viewerId)) return Unauthorized();

        if (request.IsRandomLeaderSkin)
        {
            return StatusCode(StatusCodes.Status501NotImplemented,
                new { error = "random_leader_skin_not_implemented" });
        }

        var viewer = await _db.Viewers
            .Include(v => v.Classes).ThenInclude(c => c.Class)
            .Include(v => v.Classes).ThenInclude(c => c.LeaderSkin)
            .Include(v => v.LeaderSkins)
            .FirstOrDefaultAsync(v => v.Id == viewerId);
        if (viewer is null) return Unauthorized();

        var classData = viewer.Classes.FirstOrDefault(c => c.Class.Id == request.ClassId);
        if (classData is null) return BadRequest(new { error = "unknown_class" });

        var skin = await _db.LeaderSkins.FindAsync(request.LeaderSkinId);
        if (skin is null) return BadRequest(new { error = "unknown_skin" });
        if (skin.ClassId != request.ClassId) return BadRequest(new { error = "skin_class_mismatch" });
        if (viewer.LeaderSkins.All(s => s.Id != skin.Id))
            return BadRequest(new { error = "skin_not_owned" });

        classData.LeaderSkin = skin;
        await _db.SaveChangesAsync();

        return new LeaderSkinSetResponse
        {
            IsRandomLeaderSkin = false,
            LeaderSkinId = skin.Id,
            LeaderSkinIdList = new(),
        };
    }

    [HttpPost("ids")]
    public async Task<ActionResult<LeaderSkinIdsResponse>> Ids()
    {
        if (!TryGetViewerId(out long viewerId)) return Unauthorized();

        var ids = await _db.Viewers
            .Where(v => v.Id == viewerId)
            .SelectMany(v => v.LeaderSkins.Select(s => s.Id))
            .OrderBy(id => id)
            .ToListAsync();

        return new LeaderSkinIdsResponse { UserLeaderSkinIds = ids };
    }

    [HttpPost("products")]
    public async Task<ActionResult<Dictionary<string, SkinSeriesDto>>> Products()
    {
        if (!TryGetViewerId(out long viewerId)) return Unauthorized();

        var ownedSkinIds = (await _db.Viewers
            .Where(v => v.Id == viewerId)
            .SelectMany(v => v.LeaderSkins.Select(s => s.Id))
            .ToListAsync()).ToHashSet();

        var claimedSeries = (await _db.ViewerLeaderSkinSetClaims
            .Where(c => c.ViewerId == viewerId)
            .Select(c => c.SeriesId)
            .ToListAsync()).ToHashSet();

        var series = await _db.LeaderSkinShopSeries
            .Where(s => s.IsEnabled)
            .Include(s => s.SetCompletionRewards)
            .Include(s => s.Products.Where(p => p.IsEnabled)).ThenInclude(p => p.Rewards)
            .OrderBy(s => s.Id)
            .ToListAsync();

        var result = new Dictionary<string, SkinSeriesDto>();
        foreach (var s in series)
        {
            var products = s.Products.OrderBy(p => p.Id).Select(p => ToProductDto(p, ownedSkinIds)).ToList();
            bool seriesCompleted = products.Count > 0 && products.All(p => p.IsPurchased);
            int rewardStatus = ComputeRewardStatus(s, seriesCompleted, claimedSeries.Contains(s.Id));

            result[s.Id.ToString()] = new SkinSeriesDto
            {
                SeriesId = s.Id,
                IsCompleted = seriesCompleted,
                IsNew = s.IsNew,
                SetSalesStatus = s.SetSalesStatus,
                Rewards = new SkinSeriesRewardsDto
                {
                    Status = rewardStatus,
                    Items = s.SetCompletionRewards.OrderBy(r => r.OrderIndex).Select(r => new SkinSeriesRewardItemDto
                    {
                        RewardType = r.RewardType,
                        RewardDetailId = r.RewardDetailId,
                        RewardNumber = r.RewardNumber,
                    }).ToList(),
                },
                SetPrices = new SkinSeriesSetPricesDto
                {
                    SetPriceCrystal = s.SetPriceCrystal,
                    SetPriceRupy = s.SetPriceRupy,
                    SetPriceTicket = s.SetPriceTicket,
                    TicketId = s.SetPriceTicketId,
                },
                Products = products,
            };
        }

        return result;
    }

    [HttpPost("buy")]
    public async Task<ActionResult<LeaderSkinBuyResponse>> Buy(LeaderSkinBuyRequest request)
    {
        if (!TryGetViewerId(out long viewerId)) return Unauthorized();

        if (request.SalesType is 3)
            return StatusCode(StatusCodes.Status501NotImplemented,
                new { error = "ticket_currency_path_not_implemented" });
        if (request.SalesType is < 0 or > 3)
            return BadRequest(new { error = "invalid_sales_type" });

        var product = await _db.LeaderSkinShopProducts
            .Include(p => p.Rewards)
            .Include(p => p.Series)
            .FirstOrDefaultAsync(p => p.Id == request.ProductId);
        if (product is null) return NotFound(new { error = "unknown_product" });
        if (!product.IsEnabled || product.Series is not { IsEnabled: true })
            return BadRequest(new { error = "product_not_available" });

        var viewer = await LoadViewerGraphAsync(viewerId);

        // Already-purchased = viewer owns the leader_skin this product grants.
        if (viewer.LeaderSkins.Any(s => s.Id == product.LeaderSkinId))
            return BadRequest(new { error = "already_purchased" });

        var rewardList = new List<RewardListEntry>();
        var debit = DebitProductPrice(viewer, product, request.SalesType);
        if (debit.Error is not null) return BadRequest(new { error = debit.Error });
        if (debit.PostState is not null) rewardList.Add(debit.PostState);

        await ApplyRewardsAsync(viewer, product.Rewards, rewardList);

        await _db.SaveChangesAsync();
        return new LeaderSkinBuyResponse { RewardList = rewardList };
    }

    [HttpPost("buy_set")]
    public async Task<ActionResult<LeaderSkinBuyResponse>> BuySet(LeaderSkinBuySetRequest request)
    {
        if (!TryGetViewerId(out long viewerId)) return Unauthorized();

        if (request.SalesType is 3)
            return StatusCode(StatusCodes.Status501NotImplemented,
                new { error = "ticket_currency_path_not_implemented" });
        if (request.SalesType is < 0 or > 3)
            return BadRequest(new { error = "invalid_sales_type" });

        var series = await _db.LeaderSkinShopSeries
            .Include(s => s.Products.Where(p => p.IsEnabled)).ThenInclude(p => p.Rewards)
            .FirstOrDefaultAsync(s => s.Id == request.SeriesId);
        if (series is null) return NotFound(new { error = "unknown_series" });
        if (!series.IsEnabled || series.SetSalesStatus == 0)
            return BadRequest(new { error = "set_sale_not_active" });

        var viewer = await LoadViewerGraphAsync(viewerId);

        var rewardList = new List<RewardListEntry>();
        var debit = DebitSetPrice(viewer, series, request.SalesType);
        if (debit.Error is not null) return BadRequest(new { error = debit.Error });
        if (debit.PostState is not null) rewardList.Add(debit.PostState);

        // Grant every product's rewards; RewardGrantService is idempotent on already-owned
        // cosmetics, so partial-set buyers don't double-add.
        foreach (var p in series.Products.OrderBy(p => p.Id))
        {
            await ApplyRewardsAsync(viewer, p.Rewards, rewardList);
        }

        await _db.SaveChangesAsync();
        return new LeaderSkinBuyResponse { RewardList = rewardList };
    }

    [HttpPost("buy_set_item")]
    public async Task<ActionResult<LeaderSkinBuyResponse>> BuySetItem(LeaderSkinBuySetItemRequest request)
    {
        if (!TryGetViewerId(out long viewerId)) return Unauthorized();

        var series = await _db.LeaderSkinShopSeries
            .Include(s => s.SetCompletionRewards)
            .Include(s => s.Products.Where(p => p.IsEnabled))
            .FirstOrDefaultAsync(s => s.Id == request.SeriesId);
        if (series is null) return NotFound(new { error = "unknown_series" });

        // Check claim hasn't been made already (idempotent — returns empty reward_list rather
        // than 400 so the client doesn't error if it retries).
        var existingClaim = await _db.ViewerLeaderSkinSetClaims
            .FirstOrDefaultAsync(c => c.ViewerId == viewerId && c.SeriesId == series.Id);
        if (existingClaim is not null)
            return new LeaderSkinBuyResponse { RewardList = new() };

        var viewer = await LoadViewerGraphAsync(viewerId);

        // Must own every skin in the series to claim the bonus.
        var ownedSkinIds = viewer.LeaderSkins.Select(s => s.Id).ToHashSet();
        bool ownsAll = series.Products.Count > 0 && series.Products.All(p => ownedSkinIds.Contains(p.LeaderSkinId));
        if (!ownsAll)
            return BadRequest(new { error = "series_not_completed" });

        var rewardList = new List<RewardListEntry>();
        await ApplyRewardsAsync(viewer, series.SetCompletionRewards, rewardList);

        _db.ViewerLeaderSkinSetClaims.Add(new ViewerLeaderSkinSetClaim
        {
            ViewerId = viewerId,
            SeriesId = series.Id,
            ClaimedAt = _time.GetUtcNow().UtcDateTime,
        });

        await _db.SaveChangesAsync();
        return new LeaderSkinBuyResponse { RewardList = rewardList };
    }

    /// <summary>
    /// Computes the per-viewer <c>rewards.status</c> for a series:
    ///   0=none — set_sales_status==0 (no set sale active)
    ///   1=not_got — series completed by viewer but bonus unclaimed
    ///   2=got — viewer claimed the bonus
    ///   1 (effectively "available later") when set sale active but viewer hasn't completed it.
    /// The 1/2 distinction matches the client enum (RewardStatus.not_got vs .got).
    /// </summary>
    private static int ComputeRewardStatus(LeaderSkinShopSeriesEntry series, bool seriesCompleted, bool claimed)
    {
        if (series.SetSalesStatus == 0) return 0;
        if (claimed) return 2;
        if (seriesCompleted) return 1;
        return 1;
    }

    private static SkinProductDto ToProductDto(LeaderSkinShopProductEntry p, HashSet<int> ownedSkinIds)
    {
        bool isPurchased = ownedSkinIds.Contains(p.LeaderSkinId);
        return new SkinProductDto
        {
            ProductId = p.Id,
            LeaderSkinId = p.LeaderSkinId,
            ProductName = p.ProductNameKey,
            Introduction = p.IntroductionKey,
            CvName = p.CvNameKey,
            IsPurchased = isPurchased,
            Sale = new SkinProductSaleDto
            {
                SinglePriceCrystal = p.SinglePriceCrystal,
                SinglePriceRupy = p.SinglePriceRupy,
                SinglePriceTicket = p.SinglePriceTicket,
                TicketNumber = p.TicketNumber,
                ItemId = p.TicketItemId,
            },
            Rewards = p.Rewards.OrderBy(r => r.OrderIndex).Select(r => new SkinProductRewardDto
            {
                RewardType = r.RewardType,
                RewardDetailId = r.RewardDetailId,
                RewardNumber = r.RewardNumber,
                IsOwned = IsRewardOwned(r, ownedSkinIds),
            }).ToList(),
        };
    }

    /// <summary>
    /// A bundled reward shows as "owned" when the viewer already has the cosmetic. For now we
    /// only flag the Skin reward (type==10) against the viewer's skin collection — the cascaded
    /// emblem/sleeve typically come with the skin, so the heuristic is "skin owned → all three
    /// bundle items are de-facto owned." Refine later if a capture shows independent state.
    /// </summary>
    private static bool IsRewardOwned(LeaderSkinShopProductRewardEntry r, HashSet<int> ownedSkinIds)
    {
        // Skin reward: direct check.
        if (r.RewardType == (int)UserGoodsType.Skin)
            return ownedSkinIds.Contains((int)r.RewardDetailId);
        // Other types: we don't have the full cosmetic-owned graph in scope here. The product's
        // sibling Skin reward tells us whether the bundle was purchased; piggy-back on that by
        // letting the caller pre-compute IsPurchased. Conservative default: not owned.
        return false;
    }

    private (RewardListEntry? PostState, string? Error) DebitProductPrice(
        Viewer viewer, LeaderSkinShopProductEntry product, int salesType)
    {
        return salesType switch
        {
            0 when product.SinglePriceCrystal == 0 && product.SinglePriceRupy == 0 => (null, null),
            0 => (null, "price_not_available_for_currency"),
            1 => product.SinglePriceCrystal is null
                ? (null, "price_not_available_for_currency")
                : DebitCrystal(viewer, product.SinglePriceCrystal.Value),
            2 => product.SinglePriceRupy is null
                ? (null, "price_not_available_for_currency")
                : DebitRupy(viewer, product.SinglePriceRupy.Value),
            _ => (null, "invalid_sales_type"),
        };
    }

    private (RewardListEntry? PostState, string? Error) DebitSetPrice(
        Viewer viewer, LeaderSkinShopSeriesEntry series, int salesType)
    {
        return salesType switch
        {
            0 when series.SetPriceCrystal == 0 && series.SetPriceRupy == 0 => (null, null),
            0 => (null, "price_not_available_for_currency"),
            1 => series.SetPriceCrystal is null
                ? (null, "price_not_available_for_currency")
                : DebitCrystal(viewer, series.SetPriceCrystal.Value),
            2 => series.SetPriceRupy is null
                ? (null, "price_not_available_for_currency")
                : DebitRupy(viewer, series.SetPriceRupy.Value),
            _ => (null, "invalid_sales_type"),
        };
    }

    private static (RewardListEntry?, string?) DebitCrystal(Viewer viewer, int amount)
    {
        if (viewer.Currency.Crystals < (ulong)amount) return (null, "insufficient_crystals");
        viewer.Currency.Crystals -= (ulong)amount;
        return (new RewardListEntry { RewardType = 2, RewardId = 0, RewardNum = (int)viewer.Currency.Crystals }, null);
    }

    private static (RewardListEntry?, string?) DebitRupy(Viewer viewer, int amount)
    {
        if (viewer.Currency.Rupees < (ulong)amount) return (null, "insufficient_rupees");
        viewer.Currency.Rupees -= (ulong)amount;
        return (new RewardListEntry { RewardType = 9, RewardId = 0, RewardNum = (int)viewer.Currency.Rupees }, null);
    }

    private async Task ApplyRewardsAsync<T>(
        Viewer viewer, IEnumerable<T> rewards, List<RewardListEntry> rewardList) where T : notnull
    {
        foreach (var r in rewards)
        {
            var (type, detailId, number) = ExtractTuple(r);
            var granted = await _rewards.ApplyAsync(viewer, (UserGoodsType)type, detailId, number);
            foreach (var g in granted)
            {
                rewardList.Add(new RewardListEntry
                {
                    RewardType = g.RewardType,
                    RewardId = g.RewardId,
                    RewardNum = g.RewardNum,
                });
            }
        }
    }

    private static (int Type, long Id, int Num) ExtractTuple(object reward) => reward switch
    {
        LeaderSkinShopProductRewardEntry p => (p.RewardType, p.RewardDetailId, p.RewardNumber),
        LeaderSkinShopSeriesRewardEntry s => (s.RewardType, s.RewardDetailId, s.RewardNumber),
        _ => throw new InvalidOperationException($"unexpected reward type {reward.GetType().Name}"),
    };

    private Task<Viewer> LoadViewerGraphAsync(long viewerId) => _db.Viewers
        .Include(v => v.LeaderSkins)
        .Include(v => v.Sleeves)
        .Include(v => v.Emblems)
        .Include(v => v.Degrees)
        .Include(v => v.MyPageBackgrounds)
        .Include(v => v.Items).ThenInclude(i => i.Item)
        .Include(v => v.Cards).ThenInclude(c => c.Card)
        .AsSplitQuery()
        .FirstAsync(v => v.Id == viewerId);
}