using System.Diagnostics;
using Microsoft.EntityFrameworkCore;

namespace Api;

public static class Seeder
{
    public const int Customers = 1_000;
    public const int Products = 500;
    public const int Orders = 20_000;
    public const int LinesPerOrder = 5;
    public const int Days = 30;
    public static readonly DateTime FirstDay = new(2026, 9, 27, 0, 0, 0, DateTimeKind.Utc);

    public static async Task RunAsync(string connectionString)
    {
        var options = new DbContextOptionsBuilder<AppDbContext>().UseNpgsql(connectionString).Options;
        await using var db = new AppDbContext(options);
        await db.Database.EnsureDeletedAsync();
        await db.Database.EnsureCreatedAsync();
        db.ChangeTracker.AutoDetectChangesEnabled = false;

        var stopwatch = Stopwatch.StartNew();
        var random = new Random(220);
        string[] countries = ["RS", "DE", "US", "GB", "NL", "FR", "PL", "ES"];
        string[] statuses = ["Pending", "Paid", "Shipped", "Delivered"];
        string[] methods = ["Card", "PayPal", "Bank"];

        var customers = Enumerable.Range(1, Customers)
            .Select(i => new Customer
            {
                Name = $"Customer {i}",
                Email = $"customer{i}@example.com",
                Country = countries[random.Next(countries.Length)]
            })
            .ToList();
        var products = Enumerable.Range(1, Products)
            .Select(i => new Product
            {
                Sku = $"SKU-{i:D5}",
                Name = $"Product {i}",
                Price = Math.Round((decimal)(random.NextDouble() * 190 + 10), 2)
            })
            .ToList();
        var carriers = new[] { "DHL", "UPS", "FedEx", "GLS", "DPD", "PostNL", "USPS", "Royal Mail" }
            .Select(name => new Carrier { Name = name })
            .ToList();
        db.AddRange(carriers);
        db.AddRange(customers);
        db.AddRange(products);
        await db.SaveChangesAsync();
        db.ChangeTracker.Clear();

        // The extra references draw from their own generator, so the orders, lines and payments
        // are the same rows as before the references were added.
        var extra = new Random(221);
        string[] cities = ["Belgrade", "Berlin", "Austin", "London", "Utrecht", "Lyon", "Gdansk", "Valencia"];
        Address NewAddress() => new()
        {
            Street = $"{extra.Next(1, 400)} Street {extra.Next(1, 900)}",
            City = cities[extra.Next(cities.Length)],
            PostalCode = extra.Next(10_000, 99_999).ToString(),
            Country = countries[extra.Next(countries.Length)]
        };

        const int chunk = 2_000;
        for (var start = 0; start < Orders; start += chunk)
        {
            var orders = new List<Order>(chunk);
            for (var i = 0; i < chunk; i++)
            {
                var customer = customers[random.Next(customers.Count)];
                var orderedAt = FirstDay.AddSeconds(random.NextInt64(Days * 86_400L));
                var order = new Order
                {
                    CustomerId = customer.Id,
                    OrderedAt = orderedAt,
                    Status = statuses[random.Next(statuses.Length)]
                };

                // Every order ships somewhere, half are billed to a second address,
                // and a pending order has no carrier yet.
                order.ShippingAddress = NewAddress();
                order.BillingAddress = extra.Next(2) == 0 ? NewAddress() : null;
                order.CarrierId = order.Status == "Pending" ? null : carriers[extra.Next(carriers.Count)].Id;

                for (var l = 0; l < LinesPerOrder; l++)
                {
                    var product = products[random.Next(products.Count)];
                    order.Lines.Add(new OrderLine
                    {
                        ProductId = product.Id,
                        Quantity = random.Next(1, 5),
                        UnitPrice = product.Price
                    });
                }

                var total = order.Lines.Sum(x => x.Quantity * x.UnitPrice);
                var paymentCount = random.Next(1, 3);
                for (var p = 0; p < paymentCount; p++)
                {
                    order.Payments.Add(new Payment
                    {
                        Amount = Math.Round(total / paymentCount, 2),
                        PaidAt = orderedAt.AddMinutes(random.Next(1, 600)),
                        Method = methods[random.Next(methods.Length)]
                    });
                }

                orders.Add(order);
            }

            db.AddRange(orders);
            await db.SaveChangesAsync();
            db.ChangeTracker.Clear();
        }

        await db.Database.ExecuteSqlRawAsync("VACUUM ANALYZE");

        Console.WriteLine(
            $"Seeded {Customers} customers, {Products} products, {Orders} orders, " +
            $"{Orders * LinesPerOrder} lines in {stopwatch.Elapsed.TotalSeconds:F1} s.");
    }
}