using FinlyticAssets.Database;
using FinlyticAssets.Entities;
using FinlyticCore.Dtos.TradeRepublic;
using FinlyticCore.Services.TradeRepublic;
using Microsoft.EntityFrameworkCore;

namespace FinlyticAssets.Services;

/// <summary>
/// Defines database operations for managing Trade Republic asset entities.
/// </summary>
public interface IAssetsDbService
{
    public Task<List<AssetEntity>> GetAllValidAssetsAsync();
    public Task<bool> AddOrUpdateAssetAsync(TradeRepublicAsset dtoAsset);
    public Task<int> AddOrUpdateAssetsAsync(IEnumerable<TradeRepublicAsset> dtoAssets);
    public Task<List<AssetEntity>> GetAssetsByIsinAsync(string isin);
    public Task<List<AssetEntity>> GetValidAssetsByIsinAsync(string isin);
    public Task<List<AssetEntity>> FindAffectedActiveAssetsAsync(string searchQuery);
    public Task UpdateAssetImageIdAsync(string isin, string imageId);
    public Task<bool> DeleteAssetAsync(string isin);
    public Task<List<AssetEntity>> GetDiscoveryAssetsAsync(int limit = 15);
    public Task<List<DerivativeEntity>> GetDerivativesByUnderlyingAsync(string underlyingIsin, string optionType = "long", decimal? targetLeverage = null, string? after = null, int? page = null, bool forceRefresh = false, CancellationToken cancellationToken = default);
}

/// <inheritdoc />
public class AssetsDbService : IAssetsDbService
{
    private readonly AssetsDbContext _context;
    private readonly ITradeRepublicService _tradeRepublicService;
    private readonly ILogger<AssetsDbService> _logger;

    public AssetsDbService(AssetsDbContext context, ILogger<AssetsDbService> logger, ITradeRepublicService tradeRepublicService)
    {
        _context = context;
        _logger = logger;
        _tradeRepublicService = tradeRepublicService;
    }

    /// <summary>Inherits documentation from interface.</summary>
    public async Task<List<AssetEntity>> GetDiscoveryAssetsAsync(int limit = 15)
    {
        var cutoff = DateTime.UtcNow.AddDays(-90);

        var validAssets = await _context.TradeRepublicAssets
            .AsNoTracking()
            .Include(a => a.Tags)
            .Where(a => a.LastUpdatedAt >= cutoff && !string.IsNullOrEmpty(a.Name))
            .ToListAsync();

        if (validAssets.Count == 0) return [];

        var scored = validAssets
            .Select(a => new
            {
                Asset = a,
                Score = (a.Tags?.Count ?? 0) * 10
                      + (a.HasCfd ? 5 : 0)
                      + (string.IsNullOrEmpty(a.ImageId) ? 0 : 15)
                      + (a.Name.Length > 3 ? 5 : 0)
            })
            .OrderByDescending(x => x.Score)
            .ThenByDescending(x => x.Asset.LastUpdatedAt)
            .ToList();

        var result = new List<AssetEntity>();
        var grouped = scored.GroupBy(x => x.Asset.Type).ToList();

        int index = 0;
        while (result.Count < limit && grouped.Any(g => g.Any()))
        {
            bool addedAny = false;
            foreach (var group in grouped)
            {
                var item = group.Skip(index).FirstOrDefault();
                if (item != null)
                {
                    result.Add(item.Asset);
                    addedAny = true;
                    if (result.Count >= limit) break;
                }
            }
            index++;
            if (!addedAny) break;
        }

        return result;
    }

    /// <summary>Inherits documentation from interface.</summary>
    public async Task<List<AssetEntity>> GetAllValidAssetsAsync()
    {
        var cutoff = DateTime.UtcNow.AddDays(-90);
        
        return await _context.TradeRepublicAssets
            .AsNoTracking()
            .Include(a => a.Tags)
            .Where(a => a.LastUpdatedAt >= cutoff)
            .ToListAsync();
    }

    /// <summary>Inherits documentation from interface.</summary>
    public async Task<bool> AddOrUpdateAssetAsync(TradeRepublicAsset dtoAsset)
    {
        var existingEntity = await _context.TradeRepublicAssets
            .Include(a => a.Tags)
            .FirstOrDefaultAsync(a => a.Isin == dtoAsset.Isin);

        var now = DateTime.UtcNow;

        var mappedTags = new List<TagEntity>();
        foreach (var tagDto in dtoAsset.Tags ?? Array.Empty<TradeRepublicTag>())
        {
            var existingTag = await _context.TradeRepublicTags.FirstOrDefaultAsync(t => t.Id == tagDto.Id);
            if (existingTag == null)
            {
                _logger.LogTrace("Creating missing asset tag object in storage cache context. ID: {TagId}", tagDto.Id);
                existingTag = new TagEntity { Id = tagDto.Id, Name = tagDto.Name, Type = tagDto.Type };
                await _context.TradeRepublicTags.AddAsync(existingTag);
            }

            mappedTags.Add(existingTag);
        }

        if (existingEntity == null)
        {
            _logger.LogDebug("Asset with ISIN {Isin} not found. Mapping and creating a new entity.", dtoAsset.Isin);

            var newEntity = MapDtoToEntity(dtoAsset);
            newEntity.LastUpdatedAt = now;
            newEntity.Tags = mappedTags;

            await _context.TradeRepublicAssets.AddAsync(newEntity);
            await _context.SaveChangesAsync();
            return true;
        }

        _logger.LogDebug("Asset with ISIN {Isin} exists. Merging properties and updating database record.", dtoAsset.Isin);

        existingEntity.Name = dtoAsset.Name;
        existingEntity.Type = dtoAsset.Type;
        existingEntity.InstrumentCategory = dtoAsset.InstrumentCategory;
        existingEntity.HasCfd = dtoAsset.HasCfd;
        existingEntity.ImageId = dtoAsset.ImageId;
        existingEntity.LastUpdatedAt = now;

        UpdateSubtypeProperties(existingEntity, dtoAsset);
        existingEntity.Tags = mappedTags;

        _context.TradeRepublicAssets.Update(existingEntity);
        await _context.SaveChangesAsync();
        return true;
    }

    /// <summary>Inherits documentation from interface.</summary>
    public async Task<int> AddOrUpdateAssetsAsync(IEnumerable<TradeRepublicAsset> dtoAssets)
    {
        var assetsList = dtoAssets.ToList();
        if (assetsList.Count == 0) return 0;

        var now = DateTime.UtcNow;
        int changedCount = 0;

        var isins = assetsList.Select(a => a.Isin).Distinct().ToList();
        var existingAssets = await _context.TradeRepublicAssets
            .Include(a => a.Tags)
            .Where(a => isins.Contains(a.Isin))
            .ToDictionaryAsync(a => a.Isin);

        var tagIds = assetsList
            .SelectMany(a => a.Tags ?? Array.Empty<TradeRepublicTag>())
            .Select(t => t.Id)
            .Distinct()
            .ToList();

        var tagCache = await _context.TradeRepublicTags
            .Where(t => tagIds.Contains(t.Id))
            .ToDictionaryAsync(t => t.Id);

        foreach (var dto in assetsList)
        {
            var isChanged = false;
            var existingEntity = existingAssets.GetValueOrDefault(dto.Isin);

            var mappedTags = new List<TagEntity>();
            foreach (var tagDto in dto.Tags ?? Array.Empty<TradeRepublicTag>())
            {
                if (!tagCache.TryGetValue(tagDto.Id, out var tagEntity))
                {
                    _logger.LogTrace("Creating missing asset tag object in storage cache context. ID: {TagId}", tagDto.Id);
                    tagEntity = new TagEntity { Id = tagDto.Id, Name = tagDto.Name, Type = tagDto.Type };
                    await _context.TradeRepublicTags.AddAsync(tagEntity);
                    tagCache.Add(tagDto.Id, tagEntity);
                }
                mappedTags.Add(tagEntity);
            }

            if (existingEntity == null)
            {
                _logger.LogDebug("Asset with ISIN {Isin} not found. Mapping and creating a new entity.", dto.Isin);

                var newEntity = MapDtoToEntity(dto);
                newEntity.LastUpdatedAt = now;
                newEntity.Tags = mappedTags;

                await _context.TradeRepublicAssets.AddAsync(newEntity);
                isChanged = true;
            }
            else
            {
                _logger.LogDebug("Asset with ISIN {Isin} exists. Merging properties and updating database record.", dto.Isin);

                if (existingEntity.Name != dto.Name ||
                    existingEntity.Type != dto.Type ||
                    existingEntity.InstrumentCategory != dto.InstrumentCategory ||
                    existingEntity.HasCfd != dto.HasCfd ||
                    existingEntity.ImageId != dto.ImageId ||
                    !existingEntity.Tags.SequenceEqual(mappedTags))
                {
                    existingEntity.Name = dto.Name;
                    existingEntity.Type = dto.Type;
                    existingEntity.InstrumentCategory = dto.InstrumentCategory;
                    existingEntity.HasCfd = dto.HasCfd;
                    existingEntity.ImageId = dto.ImageId;
                    existingEntity.LastUpdatedAt = now;

                    UpdateSubtypeProperties(existingEntity, dto);
                    existingEntity.Tags = mappedTags;

                    _context.TradeRepublicAssets.Update(existingEntity);
                    isChanged = true;
                }
            }

            if (isChanged)
            {
                changedCount++;
            }
        }

        if (changedCount > 0)
        {
            await _context.SaveChangesAsync();
        }

        return changedCount;
    }

    /// <summary>Inherits documentation from interface.</summary>
    public async Task<List<AssetEntity>> GetAssetsByIsinAsync(string isin)
    {
        var localAssets = await _context.TradeRepublicAssets
            .Include(a => a.Tags)
            .Where(a => a.Isin == isin)
            .ToListAsync();

        if (localAssets.Count > 0)
        {
            return localAssets;
        }

        // JIT-Fetch via API
        var trAssetDto = await _tradeRepublicService.GetAsset(isin);
        if (trAssetDto?.Results != null && trAssetDto.Results.Count > 0)
        {
            foreach (var asset in trAssetDto.Results)
            {
                await AddOrUpdateAssetAsync(asset);
            }

            return await _context.TradeRepublicAssets
                .Include(a => a.Tags)
                .Where(a => a.Isin == isin)
                .ToListAsync();
        }

        return [];
    }

    /// <summary>Inherits documentation from interface.</summary>
    public async Task<List<AssetEntity>> GetValidAssetsByIsinAsync(string isin)
    {
        var cutoff = DateTime.UtcNow.AddDays(-14);

        return await _context.TradeRepublicAssets
            .AsNoTracking()
            .Include(a => a.Tags)
            .Where(a => a.Isin == isin && a.LastUpdatedAt >= cutoff)
            .ToListAsync();
    }

    /// <summary>Inherits documentation from interface.</summary>
    public async Task<List<AssetEntity>> FindAffectedActiveAssetsAsync(string searchQuery)
    {
        if (string.IsNullOrWhiteSpace(searchQuery)) return [];

        var cutoff = DateTime.UtcNow.AddDays(-14);

        var searchTerms = searchQuery
            .Split(',')
            .Select(t => t.Trim())
            .Where(t => !string.IsNullOrEmpty(t))
            .Distinct()
            .ToList();

        if (searchTerms.Count == 0) return [];

        var query = _context.TradeRepublicAssets
            .AsNoTracking()
            .Where(a => a.LastUpdatedAt >= cutoff)
            .Include(a => a.Tags)
            .AsQueryable();

        foreach (var term in searchTerms)
        {
            var lowerTerm = term.ToLower();
            query = query.Where(a =>
                a.Isin.ToLower().Contains(lowerTerm) ||
                a.Name.ToLower().Contains(lowerTerm) ||
                a.Tags.Any(tag => tag.Name.ToLower().Contains(lowerTerm)));
        }

        var localAssets = await query.ToListAsync();

        var possibleIsins = searchTerms
            .Where(t => t.Length == 12 && char.IsLetter(t[0]) && char.IsLetter(t[1]))
            .Select(t => t.ToUpper())
            .ToList();

        if (possibleIsins.Count > 0)
        {
            var foundIsins = localAssets.Select(a => a.Isin).ToHashSet();
            var missingIsins = possibleIsins.Where(isin => !foundIsins.Contains(isin)).ToList();

            if (missingIsins.Count > 0)
            {
                var fetchedNewAsset = false;
                foreach (var missingIsin in missingIsins)
                {
                    var trAssetDto = await _tradeRepublicService.GetAsset(missingIsin);
                    if (trAssetDto?.Results != null)
                    {
                        foreach (var asset in trAssetDto.Results)
                        {
                            await AddOrUpdateAssetAsync(asset);
                        }

                        fetchedNewAsset = true;
                    }
                }

                if (fetchedNewAsset)
                {
                    return await query.ToListAsync();
                }
            }
        }

        return localAssets;
    }

    /// <summary>Inherits documentation from interface.</summary>
    public async Task UpdateAssetImageIdAsync(string isin, string imageId)
    {
        var existingAssets = await _context.TradeRepublicAssets
            .Where(a => a.Isin == isin)
            .ToListAsync();

        if (existingAssets.Count > 0)
        {
            foreach (var asset in existingAssets)
            {
                asset.ImageId = imageId;
            }
            await _context.SaveChangesAsync();
            _logger.LogInformation("[{Channel}] Updated ImageId for ISIN {Isin} in database to '{ImageId}'", "AssetsChannel", isin, imageId);
        }
    }

    /// <summary>Inherits documentation from interface.</summary>
    public async Task<bool> DeleteAssetAsync(string isin)
    {
        var asset = await _context.TradeRepublicAssets.FirstOrDefaultAsync(a => a.Isin == isin);
        if (asset == null)
        {
            _logger.LogWarning("[{Channel}] Delete execution cancelled. Asset with ISIN {Isin} does not exist.", "AssetsChannel", isin);
            return false;
        }

        _context.TradeRepublicAssets.Remove(asset);
        await _context.SaveChangesAsync();
        _logger.LogInformation("[{Channel}] Asset with ISIN {Isin} has been successfully deleted.", "AssetsChannel", isin);
        return true;
    }

    /// <summary>Inherits documentation from interface.</summary>
    public async Task<List<DerivativeEntity>> GetDerivativesByUnderlyingAsync(
        string underlyingIsin,
        string optionType = "long",
        decimal? targetLeverage = null,
        string? after = null,
        int? page = null,
        bool forceRefresh = false,
        CancellationToken cancellationToken = default)
    {
        var targetOptionType = optionType.Equals("short", StringComparison.OrdinalIgnoreCase) ? OptionType.Short : OptionType.Long;
        string cleanOptionType = optionType.Equals("short", StringComparison.OrdinalIgnoreCase) ? "short" : "long";
        const int pageSize = 50;
        int pageIndex = Math.Max(0, page ?? 0);

        decimal levQuery = targetLeverage.HasValue && targetLeverage.Value > 0 ? targetLeverage.Value : 0m;

        // Trade Republic uses page index (0, 1, 2, 3...) for the 'after' pagination parameter in derivatives
        string trAfter = !string.IsNullOrEmpty(after) ? after : (pageIndex > 0 ? pageIndex.ToString() : "0");

        _logger.LogInformation("[{Channel}] Fetching derivatives for {Isin} (OptionType: {Option}, Leverage: {Lev}, Page: {Page}, TR-After: {After})",
            "AssetsChannel", underlyingIsin, cleanOptionType, levQuery, pageIndex, trAfter);

        var trReq = new TradeRepublicDerivativesRequest(
            Underlying: underlyingIsin,
            OptionType: cleanOptionType,
            ProductCategory: "knockOutProduct",
            Leverage: levQuery,
            SortBy: "leverage",
            SortDirection: "asc",
            PageSize: pageSize,
            After: trAfter);

        var trResponse = await _tradeRepublicService.GetDerivativesAsync(trReq, cancellationToken);
        var fetchedItems = trResponse?.Results ?? new List<TradeRepublicDerivativeItemDto>();

        _logger.LogInformation("[{Channel}] TR returned {Count} derivatives for {Isin} (Cursors.After: {NextAfter})",
            "AssetsChannel", fetchedItems.Count, underlyingIsin, trResponse?.Cursors?.After ?? "null");

        if (fetchedItems.Count > 0)
        {
            var now = DateTime.UtcNow;
            var isins = fetchedItems.Select(r => r.Isin).ToList();
            var existingDerivatives = await _context.TradeRepublicAssets
                .OfType<DerivativeEntity>()
                .Where(d => isins.Contains(d.Isin))
                .ToDictionaryAsync(d => d.Isin, cancellationToken);

            List<DerivativeEntity> resultEntities = new();

            foreach (var item in fetchedItems)
            {
                if (!existingDerivatives.TryGetValue(item.Isin, out var entity))
                {
                    entity = new DerivativeEntity
                    {
                        Isin = item.Isin,
                        InstrumentCategory = "derivative",
                        Type = "derivative"
                    };
                    await _context.TradeRepublicAssets.AddAsync(entity, cancellationToken);
                }

                bool isShortItem = string.Equals(item.OptionType, "short", StringComparison.OrdinalIgnoreCase) ||
                                   string.Equals(item.OptionType, "put", StringComparison.OrdinalIgnoreCase) ||
                                   item.OptionType.Contains("short", StringComparison.OrdinalIgnoreCase) ||
                                   item.OptionType.Contains("put", StringComparison.OrdinalIgnoreCase) ||
                                   item.OptionType.Contains("bear", StringComparison.OrdinalIgnoreCase);

                entity.UnderlyingIsin = underlyingIsin;
                entity.OptionType = isShortItem ? OptionType.Short : OptionType.Long;
                entity.ProductCategoryName = item.ProductCategoryName;
                entity.NextGenProductCategoryName = item.NextGenProductCategoryName;
                entity.Strike = item.Strike ?? 0m;
                entity.Barrier = item.Barrier ?? 0m;
                entity.Leverage = item.Leverage ?? 0m;
                entity.Size = item.Size;
                entity.Factor = item.Factor;
                entity.Delta = item.Delta;
                entity.Currency = item.Currency ?? "EUR";
                entity.Expiry = DateTime.TryParse(item.Expiry, System.Globalization.CultureInfo.InvariantCulture, System.Globalization.DateTimeStyles.AdjustToUniversal | System.Globalization.DateTimeStyles.AssumeUniversal, out var exp)
                    ? DateTime.SpecifyKind(exp, DateTimeKind.Utc)
                    : (DateTime?)null;
                entity.Issuer = item.Issuer;
                entity.IssuerDisplayName = item.IssuerDisplayName;
                entity.IssuerImageId = item.IssuerImageId;
                entity.ImageId = item.ImageId;
                entity.Name = $"{item.IssuerDisplayName} {item.NextGenProductCategoryName} ({(isShortItem ? "SHORT" : "LONG")})";
                entity.LastUpdatedAt = now;

                resultEntities.Add(entity);
            }

            await _context.SaveChangesAsync(cancellationToken);
            return resultEntities;
        }

        // Fallback: Query from DB if Trade Republic returned 0 or was unreachable
        var dbQuery = _context.TradeRepublicAssets
            .OfType<DerivativeEntity>()
            .AsNoTracking()
            .Include(a => a.Tags)
            .Where(d => d.UnderlyingIsin == underlyingIsin && d.OptionType == targetOptionType);

        if (levQuery > 0)
        {
            dbQuery = dbQuery.Where(d => d.Leverage >= (levQuery - 0.2m));
        }

        var results = await dbQuery
            .OrderBy(d => d.Leverage)
            .Skip(pageIndex * pageSize)
            .Take(pageSize)
            .ToListAsync(cancellationToken);

        return results;
    }

    #region Helper & Mapping Methods

    private AssetEntity MapDtoToEntity(TradeRepublicAsset dto)
    {
        AssetEntity entity = dto switch
        {
            TradeRepublicStock stock => new StockEntity
                { Isin = stock.Isin, DerivativeProductCategories = stock.DerivativeProductCategories.ToList() },
            TradeRepublicCrypto crypto => new CryptoEntity
                { Isin = crypto.Isin, Subtitle = crypto.Subtitle, SearchSubtitle = crypto.SearchSubtitle },
            TradeRepublicEtf etf => new EtfEntity
            {
                Isin = etf.Isin, EtfDescription = etf.EtfDescription, MappedEtfIndexName = etf.MappedEtfIndexName,
                Subtitle = etf.Subtitle, SearchSubtitle = etf.SearchSubtitle,
                DerivativeProductCategories = etf.DerivativeProductCategories.ToList()
            },
            TradeRepublicSynthetic synth => new SyntheticEntity
                { Isin = synth.Isin, DerivativeProductCategories = synth.DerivativeProductCategories.ToList() },
            TradeRepublicBond bond => new BondEntity
                { Isin = bond.Isin, BondIssuerName = bond.BondIssuerName, SearchSubtitle = bond.SearchSubtitle },
            TradeRepublicDerivative deriv => new DerivativeEntity
            {
                Isin = deriv.Isin, UnderlyingIsin = deriv.UnderlyingIsin,
                DerivativeProductCategories = deriv.DerivativeProductCategories.ToList()
            },
            _ => throw new NotSupportedException($"Type {dto.GetType().Name} is not supported.")
        };

        return PopulateBaseProperties(entity, dto);
    }

    private AssetEntity PopulateBaseProperties(AssetEntity entity, TradeRepublicAsset dto)
    {
        entity.Name = dto.Name;
        entity.Type = dto.Type;
        entity.InstrumentCategory = dto.InstrumentCategory;
        entity.HasCfd = dto.HasCfd;
        entity.ImageId = dto.ImageId;
        return entity;
    }

    private void UpdateSubtypeProperties(AssetEntity entity, TradeRepublicAsset dto)
    {
        switch (entity)
        {
            case StockEntity stockEntity when dto is TradeRepublicStock stockDto:
                stockEntity.DerivativeProductCategories = stockDto.DerivativeProductCategories.ToList();
                break;
            case CryptoEntity cryptoEntity when dto is TradeRepublicCrypto cryptoDto:
                cryptoEntity.Subtitle = cryptoDto.Subtitle;
                cryptoEntity.SearchSubtitle = cryptoDto.SearchSubtitle;
                break;
            case EtfEntity etfEntity when dto is TradeRepublicEtf etfDto:
                etfEntity.DerivativeProductCategories = etfDto.DerivativeProductCategories.ToList();
                etfEntity.EtfDescription = etfDto.EtfDescription;
                etfEntity.MappedEtfIndexName = etfDto.MappedEtfIndexName;
                etfEntity.Subtitle = etfDto.Subtitle;
                etfEntity.SearchSubtitle = etfDto.SearchSubtitle;
                break;
            case SyntheticEntity synthEntity when dto is TradeRepublicSynthetic synthDto:
                synthEntity.DerivativeProductCategories = synthDto.DerivativeProductCategories.ToList();
                break;
            case BondEntity bondEntity when dto is TradeRepublicBond bondDto:
                bondEntity.BondIssuerName = bondDto.BondIssuerName;
                bondEntity.SearchSubtitle = bondDto.SearchSubtitle;
                break;
            case DerivativeEntity derivEntity when dto is TradeRepublicDerivative derivDto:
                derivEntity.DerivativeProductCategories = derivDto.DerivativeProductCategories.ToList();
                derivEntity.UnderlyingIsin = derivDto.UnderlyingIsin;
                break;
        }
    }

    #endregion
}