using BlueLaminate.EFCore.Data;
using BlueLaminate.EFCore.Entities;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;

namespace BlueLaminate.Core.CsMoney;

/// <summary>Outcome of ingesting one skin+wear scrape job's results.</summary>
public sealed record CsMoneyIngestResult(
    int Matched, int Inserted, int Updated, int Removed, int Skipped);

/// <summary>
/// Persists the listings the worker scraped for one targeted skin+wear job into the
/// <c>cs_money_listings</c> table. Mirrors the CSFloat <c>ListingSweepService</c>
/// patterns — upsert by natural key, resolve each listing to a market-agnostic
/// <see cref="SkinInstance"/> by fingerprint, soft-track Removed, flag dupes — but
/// scoped to the one skin+condition the job targeted (so it's the per-band unit, and
/// Removed-tracking is exact). cs.money's free-text search is fuzzy, so results are
/// filtered to the intended skin (by name) and wear (by quality) before persisting.
/// </summary>
public sealed class CsMoneyIngestService
{
    public const string Source = "csmoney";

    private readonly SkinTrackerDbContext _db;
    private readonly ILogger<CsMoneyIngestService> _logger;

    public CsMoneyIngestService(SkinTrackerDbContext db, ILogger<CsMoneyIngestService> logger)
    {
        _db = db;
        _logger = logger;
    }

    /// <param name="complete">
    /// True only when the worker walked the whole skin+wear (stoppedReason "completed").
    /// On a partial sweep we upsert what we saw but skip Removed-marking, the price
    /// point, and the swept-checkpoint — unseen listings may just be unfetched, so the
    /// band stays un-stamped and gets re-queued rather than being wrongly pruned.
    /// </param>
    public async Task<CsMoneyIngestResult> IngestAsync(
        int skinId, int? conditionId, IReadOnlyList<CsMoneyItem> items, bool complete, CancellationToken ct = default)
    {
        var now = DateTimeOffset.UtcNow;

        var skin = await _db.Skins
            .Where(s => s.Id == skinId)
            .Select(s => new { s.Id, s.Name, Weapon = s.Weapon.Name })
            .FirstOrDefaultAsync(ct);
        if (skin is null)
        {
            _logger.LogWarning("Ingest skipped: skin {SkinId} not found.", skinId);
            return new CsMoneyIngestResult(0, 0, 0, 0, items.Count);
        }

        string? conditionName = null;
        if (conditionId is { } cid)
        {
            conditionName = await _db.SkinConditions
                .Where(c => c.Id == cid).Select(c => c.Condition).FirstOrDefaultAsync(ct);
        }

        var expectedShort = Normalize($"{skin.Weapon} | {skin.Name}");
        var expectedQuality = Wear.ToCode(conditionName);

        // cs.money search is fuzzy — keep only items that are actually this skin (by
        // name) and, when the job targets a wear band, this wear (by quality).
        var matched = items.Where(it =>
        {
            var a = it.Asset;
            if (a?.Names?.Short is null)
            {
                return false;
            }

            if (Normalize(a.Names.Short) != expectedShort)
            {
                return false;
            }

            return expectedQuality is null
                || string.Equals(a.Quality, expectedQuality, StringComparison.OrdinalIgnoreCase);
        }).ToList();

        var skipped = items.Count - matched.Count;
        if (matched.Count == 0)
        {
            // Nothing for this skin+wear. If the sweep was complete this is genuine
            // (none listed, or a name mismatch) — stamp the checkpoint so it advances.
            // If it was partial (e.g. challenged before any item), leave it un-stamped
            // so the band is retried.
            if (complete)
            {
                await StampCheckpointAsync(conditionId, now, ct);
                await _db.SaveChangesAsync(ct);
            }

            return new CsMoneyIngestResult(0, 0, 0, 0, skipped);
        }

        var sellOrderIds = matched.Select(it => it.Id).ToList();
        var existing = await _db.CsMoneyListings
            .Where(l => sellOrderIds.Contains(l.SellOrderId))
            .ToDictionaryAsync(l => l.SellOrderId, ct);

        var inserted = 0;
        var updated = 0;
        var touched = new HashSet<long>();
        var touchedInstanceIds = new HashSet<int>();

        foreach (var it in matched)
        {
            touched.Add(it.Id);
            var instance = await ResolveInstanceAsync(skinId, conditionId, it, now, ct);
            if (instance is not null)
            {
                touchedInstanceIds.Add(instance.Id);
            }

            if (existing.TryGetValue(it.Id, out var row))
            {
                row.Price = it.Pricing?.Default ?? row.Price;
                row.PriceBeforeDiscount = it.Pricing?.PriceBeforeDiscount;
                row.ComputedPrice = it.Pricing?.Computed;
                row.AssetId = it.Asset?.Id?.ToString();
                row.LastSeenAt = now;
                row.Status = ListingStatus.Active;
                row.RemovedAt = null;
                row.ConditionId = conditionId;
                row.SkinInstance = instance;
                updated++;
            }
            else
            {
                var entity = Map(it, skinId, conditionId, now);
                entity.SkinInstance = instance;
                _db.CsMoneyListings.Add(entity);
                inserted++;
            }
        }

        // Persist inserts/updates before the set-based Removed/dupe queries run.
        await _db.SaveChangesAsync(ct);

        await FlagDupesAsync(touchedInstanceIds, now, ct);

        // The following only hold if we saw the FULL skin+wear set. On a partial sweep,
        // listings we didn't fetch are not gone (so don't mark them Removed), the
        // cheapest item may be among the unfetched (so don't record a price point), and
        // the band isn't fully swept (so don't stamp the checkpoint — let it re-queue).
        var removed = 0;
        if (complete)
        {
            removed = await MarkRemovedAsync(skinId, conditionId, touched, now, ct);

            // Record a price point (the cheapest live listing) for this skin+wear.
            if (conditionId is { } condId)
            {
                var minPrice = matched.Where(m => m.Pricing is not null).Select(m => m.Pricing!.Default).Min();
                await _db.PriceHistories.AddAsync(new PriceHistory
                {
                    SkinId = skinId,
                    ConditionId = condId,
                    Price = minPrice,
                    Currency = "USD",
                    RecordedAt = now,
                    Source = Source,
                }, ct);
            }

            await StampCheckpointAsync(conditionId, now, ct);
        }

        await _db.SaveChangesAsync(ct);

        _logger.LogInformation(
            "cs.money ingest {Weapon} | {Skin} ({Wear}): {Matched} matched ({Ins} new, {Upd} upd, "
            + "{Rem} removed), {Skipped} skipped by filter{Partial}.",
            skin.Weapon, skin.Name, conditionName ?? "all", matched.Count, inserted, updated, removed, skipped,
            complete ? "" : " [PARTIAL — not pruned/checkpointed]");

        return new CsMoneyIngestResult(matched.Count, inserted, updated, removed, skipped);
    }

    // Find the physical item matching this listing's fingerprint, or create one.
    // Shared with CSFloat listings, so a copy seen on both markets is one instance.
    // Skipped for non-skin items (no float/pattern) — the fingerprint is meaningless.
    private async Task<SkinInstance?> ResolveInstanceAsync(
        int skinId, int? conditionId, CsMoneyItem it, DateTimeOffset now, CancellationToken ct)
    {
        if (it.Asset?.Float is not { } floatValue || it.Asset.Pattern is not { } pattern)
        {
            return null;
        }

        var seed = pattern.ToString();
        var st = it.Asset.IsStatTrak;
        var sv = it.Asset.IsSouvenir;

        var tracked = _db.ChangeTracker.Entries<SkinInstance>()
            .Select(e => e.Entity)
            .FirstOrDefault(i => i.SkinId == skinId && i.FloatValue == floatValue
                && i.PaintSeed == seed && i.StatTrak == st && i.Souvenir == sv);
        if (tracked is not null)
        {
            tracked.LastSeenAt = now;
            return tracked;
        }

        var instance = await _db.SkinInstances.FirstOrDefaultAsync(
            i => i.SkinId == skinId && i.FloatValue == floatValue
                && i.PaintSeed == seed && i.StatTrak == st && i.Souvenir == sv, ct);
        if (instance is not null)
        {
            instance.LastSeenAt = now;
            return instance;
        }

        instance = new SkinInstance
        {
            SkinId = skinId,
            ConditionId = conditionId,
            FloatValue = floatValue,
            PaintSeed = seed,
            StatTrak = st,
            Souvenir = sv,
            FirstSeenAt = now,
            LastSeenAt = now,
        };
        _db.SkinInstances.Add(instance);
        return instance;
    }

    // Flag this skin+wear's once-Active listings we didn't see this run as Removed.
    private async Task<int> MarkRemovedAsync(
        int skinId, int? conditionId, HashSet<long> touched, DateTimeOffset now, CancellationToken ct)
    {
        return await _db.CsMoneyListings
            .Where(l => l.SkinId == skinId
                && l.ConditionId == conditionId
                && l.Status == ListingStatus.Active
                && !touched.Contains(l.SellOrderId))
            .ExecuteUpdateAsync(setters => setters
                .SetProperty(l => l.Status, ListingStatus.Removed)
                .SetProperty(l => l.RemovedAt, now), ct);
    }

    // Same dupe signal as CSFloat: a fingerprint live under 2+ distinct asset ids at
    // once. Considers cs.money listings only (cross-market dupe analysis is later).
    private async Task FlagDupesAsync(HashSet<int> instanceIds, DateTimeOffset now, CancellationToken ct)
    {
        if (instanceIds.Count == 0)
        {
            return;
        }

        var dupeInstanceIds = await _db.CsMoneyListings
            .Where(l => l.SkinInstanceId != null
                && instanceIds.Contains(l.SkinInstanceId!.Value)
                && l.Status == ListingStatus.Active
                && l.AssetId != null)
            .GroupBy(l => l.SkinInstanceId!.Value)
            .Where(g => g.Select(l => l.AssetId).Distinct().Count() >= 2)
            .Select(g => g.Key)
            .ToListAsync(ct);

        if (dupeInstanceIds.Count == 0)
        {
            return;
        }

        var newlyFlagged = await _db.SkinInstances
            .Where(i => dupeInstanceIds.Contains(i.Id) && !i.SuspectedDupe)
            .ExecuteUpdateAsync(setters => setters
                .SetProperty(i => i.SuspectedDupe, true)
                .SetProperty(i => i.DupeFirstSeenAt, now), ct);

        if (newlyFlagged > 0)
        {
            _logger.LogWarning("cs.money dupe detection: {Count} instance(s) newly flagged.", newlyFlagged);
        }
    }

    private async Task StampCheckpointAsync(int? conditionId, DateTimeOffset now, CancellationToken ct)
    {
        if (conditionId is { } cid)
        {
            await _db.SkinConditions
                .Where(c => c.Id == cid)
                .ExecuteUpdateAsync(s => s.SetProperty(c => c.ListingsSweptAt, now), ct);
        }
    }

    private static CsMoneyListing Map(CsMoneyItem it, int skinId, int? conditionId, DateTimeOffset now) => new()
    {
        SellOrderId = it.Id,
        AssetId = it.Asset?.Id?.ToString(),
        SkinId = skinId,
        ConditionId = conditionId,
        MarketHashName = it.Asset?.Names?.Full ?? it.Asset?.Names?.Short ?? "",
        Quality = it.Asset?.Quality,
        FloatValue = it.Asset?.Float,
        PaintSeed = it.Asset?.Pattern,
        Phase = it.Asset?.Phase,
        IsStatTrak = it.Asset?.IsStatTrak ?? false,
        IsSouvenir = it.Asset?.IsSouvenir ?? false,
        StickerCount = it.Stickers?.Count(s => s is not null) ?? 0,
        Price = it.Pricing?.Default ?? 0m,
        PriceBeforeDiscount = it.Pricing?.PriceBeforeDiscount,
        ComputedPrice = it.Pricing?.Computed,
        Currency = "USD",
        InspectLink = it.Links?.InspectLink,
        FirstSeenAt = now,
        LastSeenAt = now,
        Status = ListingStatus.Active,
    };

    // Normalize a market name for matching: drop the StatTrak/Souvenir/★ adornments,
    // collapse whitespace, lowercase. So "StatTrak™ M4A4 | Cyber Security" and the
    // catalogue's "M4A4 | Cyber Security" compare equal.
    private static string Normalize(string name)
    {
        var s = name
            .Replace("★", " ", StringComparison.Ordinal)
            .Replace("StatTrak™", " ", StringComparison.OrdinalIgnoreCase)
            .Replace("Souvenir", " ", StringComparison.OrdinalIgnoreCase);
        return string.Join(' ', s.Split(' ', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries))
            .ToLowerInvariant();
    }
}