using foodmarket.Application.Common.Tenancy;
using foodmarket.Domain.Catalog;
using foodmarket.Infrastructure.Persistence;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;

namespace foodmarket.Infrastructure.Integrations.MoySklad;

public record MoySkladImportResult(
    int Total,
    int Created,
    int Skipped,
    int GroupsCreated,
    IReadOnlyList<string> Errors);

public class MoySkladImportService
{
    private readonly MoySkladClient _client;
    private readonly AppDbContext _db;
    private readonly ITenantContext _tenant;
    private readonly ILogger<MoySkladImportService> _log;

    public MoySkladImportService(
        MoySkladClient client,
        AppDbContext db,
        ITenantContext tenant,
        ILogger<MoySkladImportService> log)
    {
        _client = client;
        _db = db;
        _tenant = tenant;
        _log = log;
    }

    public Task<MoySkladApiResult<MsOrganization>> TestConnectionAsync(string token, CancellationToken ct)
        => _client.WhoAmIAsync(token, ct);

    public async Task<MoySkladImportResult> ImportProductsAsync(
        string token,
        bool overwriteExisting,
        CancellationToken ct)
    {
        var orgId = _tenant.OrganizationId ?? throw new InvalidOperationException("No tenant organization in context.");

        // Pre-load tenant defaults.
        var defaultVat = await _db.VatRates.FirstOrDefaultAsync(v => v.IsDefault, ct)
                         ?? await _db.VatRates.FirstAsync(ct);
        var vatByPercent = await _db.VatRates.ToDictionaryAsync(v => (int)v.Percent, v => v.Id, ct);
        var baseUnit = await _db.UnitsOfMeasure.FirstOrDefaultAsync(u => u.IsBase, ct)
                       ?? await _db.UnitsOfMeasure.FirstAsync(ct);
        var retailType = await _db.PriceTypes.FirstOrDefaultAsync(p => p.IsRetail, ct)
                         ?? await _db.PriceTypes.FirstAsync(ct);
        var kzt = await _db.Currencies.FirstAsync(c => c.Code == "KZT", ct);

        var countriesByName = await _db.Countries
            .IgnoreQueryFilters()
            .ToDictionaryAsync(c => c.Name, c => c.Id, ct);

        // Import folders first — build flat then link parents.
        var folders = await _client.GetAllFoldersAsync(token, ct);
        var localGroupByMsId = new Dictionary<string, Guid>();
        var groupsCreated = 0;
        foreach (var f in folders.Where(f => !f.Archived).OrderBy(f => f.PathName?.Length ?? 0))
        {
            if (f.Id is null) continue;
            var existing = await _db.ProductGroups.FirstOrDefaultAsync(
                g => g.Name == f.Name && g.Path == (f.PathName ?? f.Name), ct);
            if (existing is not null)
            {
                localGroupByMsId[f.Id] = existing.Id;
                continue;
            }
            var g = new ProductGroup
            {
                OrganizationId = orgId,
                Name = f.Name,
                Path = string.IsNullOrEmpty(f.PathName) ? f.Name : $"{f.PathName}/{f.Name}",
                IsActive = true,
            };
            _db.ProductGroups.Add(g);
            localGroupByMsId[f.Id] = g.Id;
            groupsCreated++;
        }
        if (groupsCreated > 0) await _db.SaveChangesAsync(ct);

        // Import products
        var errors = new List<string>();
        var created = 0;
        var skipped = 0;
        var total = 0;
        var existingArticles = await _db.Products
            .Where(p => p.Article != null)
            .Select(p => p.Article!)
            .ToListAsync(ct);
        var existingArticleSet = new HashSet<string>(existingArticles, StringComparer.OrdinalIgnoreCase);
        var existingBarcodeSet = new HashSet<string>(
            await _db.ProductBarcodes.Select(b => b.Code).ToListAsync(ct));

        await foreach (var p in _client.StreamProductsAsync(token, ct))
        {
            total++;
            if (p.Archived) { skipped++; continue; }

            var article = string.IsNullOrWhiteSpace(p.Article) ? p.Code : p.Article;
            var primaryBarcode = ExtractBarcodes(p).FirstOrDefault();

            var alreadyByArticle = !string.IsNullOrWhiteSpace(article) && existingArticleSet.Contains(article);
            var alreadyByBarcode = primaryBarcode is not null && existingBarcodeSet.Contains(primaryBarcode.Code);

            if ((alreadyByArticle || alreadyByBarcode) && !overwriteExisting)
            {
                skipped++;
                continue;
            }

            try
            {
                var vatId = p.Vat is int vp && vatByPercent.TryGetValue(vp, out var id) ? id : defaultVat.Id;
                Guid? groupId = p.ProductFolder?.Meta?.Href is { } href && TryExtractId(href) is { } msGroupId
                                && localGroupByMsId.TryGetValue(msGroupId, out var gId) ? gId : null;
                Guid? countryId = p.Country?.Name is { } cn && countriesByName.TryGetValue(cn, out var cId) ? cId : null;

                var retailPrice = p.SalePrices?.FirstOrDefault(sp => sp.PriceType?.Name?.Contains("Розничная", StringComparison.OrdinalIgnoreCase) == true)
                                  ?? p.SalePrices?.FirstOrDefault();

                var product = new Product
                {
                    OrganizationId = orgId,
                    Name = Trim(p.Name, 500),
                    Article = Trim(article, 500),
                    Description = p.Description,
                    UnitOfMeasureId = baseUnit.Id,
                    VatRateId = vatId,
                    ProductGroupId = groupId,
                    CountryOfOriginId = countryId,
                    IsWeighed = p.Weighed,
                    IsAlcohol = p.Alcoholic is not null,
                    IsMarked = !string.IsNullOrEmpty(p.TrackingType) && p.TrackingType != "NOT_TRACKED",
                    IsActive = !p.Archived,
                    PurchasePrice = p.BuyPrice is null ? null : p.BuyPrice.Value / 100m,
                    PurchaseCurrencyId = kzt.Id,
                };

                if (retailPrice is not null)
                {
                    product.Prices.Add(new ProductPrice
                    {
                        OrganizationId = orgId,
                        PriceTypeId = retailType.Id,
                        Amount = retailPrice.Value / 100m,
                        CurrencyId = kzt.Id,
                    });
                }

                foreach (var b in ExtractBarcodes(p))
                {
                    if (existingBarcodeSet.Contains(b.Code)) continue;
                    product.Barcodes.Add(b);
                    existingBarcodeSet.Add(b.Code);
                }

                _db.Products.Add(product);
                if (!string.IsNullOrWhiteSpace(article)) existingArticleSet.Add(article);
                created++;

                // Flush every 500 products to keep change tracker light.
                if (created % 500 == 0) await _db.SaveChangesAsync(ct);
            }
            catch (Exception ex)
            {
                _log.LogWarning(ex, "Failed to import MoySklad product {Name}", p.Name);
                errors.Add($"{p.Name}: {ex.Message}");
            }
        }

        await _db.SaveChangesAsync(ct);
        return new MoySkladImportResult(total, created, skipped, groupsCreated, errors);
    }

    private static List<ProductBarcode> ExtractBarcodes(MsProduct p)
    {
        if (p.Barcodes is null) return [];
        var list = new List<ProductBarcode>();
        var primarySet = false;
        foreach (var entry in p.Barcodes)
        {
            foreach (var (kind, code) in entry)
            {
                if (string.IsNullOrWhiteSpace(code)) continue;
                var type = kind switch
                {
                    "ean13" => BarcodeType.Ean13,
                    "ean8" => BarcodeType.Ean8,
                    "code128" => BarcodeType.Code128,
                    "gtin" => BarcodeType.Ean13,
                    "upca" => BarcodeType.Upca,
                    "upce" => BarcodeType.Upce,
                    _ => BarcodeType.Other,
                };
                list.Add(new ProductBarcode { Code = code.Length > 500 ? code[..500] : code, Type = type, IsPrimary = !primarySet });
                primarySet = true;
            }
        }
        return list;
    }

    private static string? Trim(string? s, int max)
        => string.IsNullOrEmpty(s) ? s : (s.Length <= max ? s : s[..max]);

    private static string? TryExtractId(string href)
    {
        // href like "https://api.moysklad.ru/api/remap/1.2/entity/productfolder/<guid>"
        var lastSlash = href.LastIndexOf('/');
        return lastSlash >= 0 ? href[(lastSlash + 1)..] : null;
    }
}