using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Zentral.API.Apps.Purchases.Dtos;
using Zentral.API.Services;
using Zentral.Domain.Entities.Purchases;
using Zentral.Infrastructure.Data;
using Microsoft.EntityFrameworkCore;

namespace Zentral.API.Apps.Purchases.Services;

public class SupplierService
{
    private readonly ZentralDbContext _db;
    private readonly AutoCodeService _autoCodeService;

    public SupplierService(ZentralDbContext db, AutoCodeService autoCodeService)
    {
        _db = db;
        _autoCodeService = autoCodeService;
    }

    public async Task<List<SupplierDto>> GetAllAsync()
    {
        return await _db.Suppliers
            .AsNoTracking()
            .OrderBy(s => s.Name)
            .Select(s => new SupplierDto
            {
                Id = s.Id,
                Code = s.Code,
                Name = s.Name,
                VatNumber = s.VatNumber,
                FiscalCode = s.FiscalCode,
                Address = s.Address,
                City = s.City,
                Province = s.Province,
                ZipCode = s.ZipCode,
                Country = s.Country,
                Email = s.Email,
                Pec = s.Pec,
                Phone = s.Phone,
                Website = s.Website,
                PaymentTerms = s.PaymentTerms,
                Notes = s.Notes,
                IsActive = s.IsActive,
                CreatedAt = s.CreatedAt,
                UpdatedAt = s.UpdatedAt
            })
            .ToListAsync();
    }

    public async Task<SupplierDto?> GetByIdAsync(int id)
    {
        var supplier = await _db.Suppliers
            .AsNoTracking()
            .FirstOrDefaultAsync(s => s.Id == id);

        if (supplier == null) return null;

        return new SupplierDto
        {
            Id = supplier.Id,
            Code = supplier.Code,
            Name = supplier.Name,
            VatNumber = supplier.VatNumber,
            FiscalCode = supplier.FiscalCode,
            Address = supplier.Address,
            City = supplier.City,
            Province = supplier.Province,
            ZipCode = supplier.ZipCode,
            Country = supplier.Country,
            Email = supplier.Email,
            Pec = supplier.Pec,
            Phone = supplier.Phone,
            Website = supplier.Website,
            PaymentTerms = supplier.PaymentTerms,
            Notes = supplier.Notes,
            IsActive = supplier.IsActive,
            CreatedAt = supplier.CreatedAt,
            UpdatedAt = supplier.UpdatedAt
        };
    }

    public async Task<SupplierDto> CreateAsync(CreateSupplierDto dto)
    {
        // Genera codice automatico
        var code = await _autoCodeService.GenerateNextCodeAsync("supplier");
        if (string.IsNullOrEmpty(code))
        {
            // Fallback se disabilitato
            code = $"FOR-{DateTime.Now:yyyyMMdd}-{Guid.NewGuid().ToString().Substring(0, 4).ToUpper()}";
        }

        var supplier = new Supplier
        {
            Code = code,
            Name = dto.Name,
            VatNumber = dto.VatNumber,
            FiscalCode = dto.FiscalCode,
            Address = dto.Address,
            City = dto.City,
            Province = dto.Province,
            ZipCode = dto.ZipCode,
            Country = dto.Country,
            Email = dto.Email,
            Pec = dto.Pec,
            Phone = dto.Phone,
            Website = dto.Website,
            PaymentTerms = dto.PaymentTerms,
            Notes = dto.Notes,
            IsActive = true,
            CreatedAt = DateTime.Now
        };

        _db.Suppliers.Add(supplier);
        await _db.SaveChangesAsync();

        return await GetByIdAsync(supplier.Id) ?? throw new InvalidOperationException("Failed to retrieve created supplier");
    }

    public async Task<SupplierDto?> UpdateAsync(int id, UpdateSupplierDto dto)
    {
        var supplier = await _db.Suppliers.FindAsync(id);
        if (supplier == null) return null;

        supplier.Name = dto.Name;
        supplier.VatNumber = dto.VatNumber;
        supplier.FiscalCode = dto.FiscalCode;
        supplier.Address = dto.Address;
        supplier.City = dto.City;
        supplier.Province = dto.Province;
        supplier.ZipCode = dto.ZipCode;
        supplier.Country = dto.Country;
        supplier.Email = dto.Email;
        supplier.Pec = dto.Pec;
        supplier.Phone = dto.Phone;
        supplier.Website = dto.Website;
        supplier.PaymentTerms = dto.PaymentTerms;
        supplier.Notes = dto.Notes;
        supplier.IsActive = dto.IsActive;
        supplier.UpdatedAt = DateTime.Now;

        await _db.SaveChangesAsync();

        return await GetByIdAsync(id);
    }

    public async Task<bool> DeleteAsync(int id)
    {
        var supplier = await _db.Suppliers.FindAsync(id);
        if (supplier == null) return false;

        // Check if used in purchase orders
        var hasOrders = await _db.PurchaseOrders.AnyAsync(o => o.SupplierId == id);
        if (hasOrders)
        {
            throw new InvalidOperationException("Impossibile eliminare il fornitore perché ha ordini associati.");
        }

        _db.Suppliers.Remove(supplier);
        await _db.SaveChangesAsync();
        return true;
    }
}