using LiteCharms.Features.Models;
using LiteCharms.Features.TechShop.Extensions;
using LiteCharms.Features.TechShop.Postgres;
using LiteCharms.Features.TechShop.Products.Models;

namespace LiteCharms.Features.TechShop.Products;

public class ProductService(IDbContextFactory<ShopDbContext> contextFactory)
{
    public async ValueTask<Result> ChangeProductPriceStatusAsync(Guid productPriceId, bool active, CancellationToken cancellationToken = default)
    {
        try
        {
            using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            var price = await context.ProductPrices.FirstOrDefaultAsync(p => p.Id == productPriceId, cancellationToken);

            if (price is null)
                return Result.Fail($"Could not find product price with ID {productPriceId}");

            price.Active = active;
            price.UpdatedAt = DateTime.UtcNow;

            return await context.SaveChangesAsync(cancellationToken) > 0
                ? Result.Ok()
                : Result.Fail($"Failed to change product price by ID {productPriceId}");

        }
        catch (Exception ex)
        {
            return Result.Fail(new Error(ex.Message).CausedBy(ex));
        }
    }

    public async ValueTask<Result> ChangeProductStatusAsync(Guid productId, bool active, CancellationToken cancellationToken = default)
    {
        try
        {
            using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            var product = await context.Products.FirstOrDefaultAsync(p => p.Id == productId, cancellationToken);

            if (product is null)
                return Result.Fail($"Could not find product with ID {productId}");

            product.Active = active;

            return await context.SaveChangesAsync(cancellationToken) > 0
                ? Result.Ok()
                : Result.Fail($"Failed to change product status by ID {productId}");

        }
        catch (Exception ex)
        {
            return Result.Fail(new Error(ex.Message).CausedBy(ex));
        }
    }

    public async ValueTask<Result<Guid>> CreateProductAsync(CreateProduct request, CancellationToken cancellationToken = default)
    {
        try
        {
            using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            if (!await context.Products.AnyAsync(p => p.Name == request.Name, cancellationToken))
                return Result.Fail<Guid>($"A product by the same name '{request.Name}' already exists");

            var newProduct = context.Products.Add(new Entities.Product
            {
                Name = request.Name,
                Summary = request.Summary,
                Description = request.Description,
                ImageUrl = request.ImageUrl,
                Thumbnails = request.Thumbnails,
                Metadata = request.Metadata
            });

            return await context.SaveChangesAsync(cancellationToken) > 0
                ? Result.Ok(newProduct.Entity.Id)
                : Result.Fail($"Failed to create new product '{request.Name}'");

        }
        catch (Exception ex)
        {
            return Result.Fail(new Error(ex.Message).CausedBy(ex));
        }
    }

    public async ValueTask<Result<Guid>> CreateProductPriceAsync(Guid productId, decimal price, decimal discount = 0, CancellationToken cancellationToken = default)
    {
        try
        {
            using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            var newProductPrice = context.ProductPrices.Add(new Entities.ProductPrice
            {
                Price = price,
                Discount = discount,
                ProductId = productId
            });

            return await context.SaveChangesAsync(cancellationToken) > 0
                ? Result.Ok(newProductPrice.Entity.Id)
                : Result.Fail($"Failed to create new product price for product id {productId}");

        }
        catch (Exception ex)
        {
            return Result.Fail(new Error(ex.Message).CausedBy(ex));
        }
    }

    public async ValueTask<Result<Product>> GetProductAsync(Guid productId, CancellationToken cancellationToken = default)
    {
        try
        {
            using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            var product = await context.Products.FirstOrDefaultAsync(p => p.Id == productId, cancellationToken);

            return product is not null
                ? Result.Ok(product.ToModel())
                : Result.Fail<Product>(new Error($"Product with ID {productId} not found."));
        }
        catch (Exception ex)
        {
            return Result.Fail<Product>(new Error(ex.Message).CausedBy(ex));
        }
    }

    public async ValueTask<Result<ProductPrice>> GetProductPriceAsync(Guid productPriceId, CancellationToken cancellationToken = default)
    {
        try
        {
            using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            if (!await context.Products.AnyAsync(p => p.Id == productPriceId, cancellationToken))
                return Result.Fail<ProductPrice>(new Error($"Product {productPriceId} not found."));

            var productPrice = await context.ProductPrices.AsNoTracking()
                .OrderByDescending(pp => pp.CreatedAt)
                .FirstOrDefaultAsync(pp => pp.Id == productPriceId, cancellationToken);

            return productPrice is not null
                ? Result.Ok(productPrice.ToModel())
                : Result.Fail<ProductPrice>(new Error($"Product price {productPriceId} not found."));
        }
        catch (Exception ex)
        {
            return Result.Fail<ProductPrice>(new Error(ex.Message).CausedBy(ex));
        }
    }

    public async ValueTask<Result<ProductPrice[]>> GetProductPricesAsync(int maxRecords = 1000, CancellationToken cancellationToken = default)
    {
        try
        {
            using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            var products = await context.ProductPrices.AsNoTracking()
                .OrderByDescending(o => o.Id)
                .Take(maxRecords)
                .ToArrayAsync(cancellationToken);

            return Result.Ok(products.Select(p => p.ToModel()).ToArray());
        }
        catch (Exception ex)
        {
            return Result.Fail<ProductPrice[]>(new Error(ex.Message).CausedBy(ex));
        }
    }

    public async ValueTask<Result<Product[]>> GetProductsAsync(int maxRecords = 1000, CancellationToken cancellationToken = default)
    {
        try
        {
            using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            var products = await context.Products.AsNoTracking()
                .OrderByDescending(o => o.Id)
                .Take(maxRecords)
                .ToArrayAsync(cancellationToken);

            return Result.Ok(products.Select(p => p.ToModel()).ToArray());
        }
        catch (Exception ex)
        {
            return Result.Fail<Product[]>(new Error(ex.Message).CausedBy(ex));
        }
    }

    public async ValueTask<Result<Guid>> ReplaceProductPriceAsync(Guid productPriceId, decimal price, decimal discount = 0, CancellationToken cancellationToken = default)
    {
        try
        {
            using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            var existingPrice = await context.ProductPrices.FirstOrDefaultAsync(p => p.Id == productPriceId, cancellationToken);

            if (existingPrice is null)
                return Result.Fail($"Could not find product price with ID {productPriceId}");

            existingPrice.Active = false;
            existingPrice.UpdatedAt = DateTime.UtcNow;

            if (!(await context.SaveChangesAsync(cancellationToken) > 0))
                return Result.Fail<Guid>($"Failed to deactivate existing price of ID {productPriceId}, try again later");

            var result = await CreateProductPriceAsync(existingPrice.ProductId, price, discount, cancellationToken);

            if (result.IsFailed)
            {
                var deactivatedPrice = await context.ProductPrices.FirstOrDefaultAsync(p => p.Id == productPriceId, cancellationToken);

                existingPrice.Active = true;
                existingPrice.UpdatedAt = DateTime.UtcNow;

                return await context.SaveChangesAsync(cancellationToken) > 0
                    ? Result.Fail<Guid>("Reverted to old price, creation of new price failed")
                    : Result.Fail<Guid>($"Failed to reactivate price of ID {productPriceId} after new price creation failed");
            }

            return Result.Ok(result.Value);
        }
        catch (Exception ex)
        {
            return Result.Fail(new Error(ex.Message).CausedBy(ex));
        }
    }

    public async ValueTask<Result> SetProductPriceStatusAsync(Guid productPriceId, bool active, CancellationToken cancellationToken = default)
    {
        try
        {
            using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            var productPrice = await context.ProductPrices.FirstOrDefaultAsync(p => p.Id == productPriceId, cancellationToken);

            if (productPrice is null)
                return Result.Fail($"Could not find product price with ID {productPriceId}");

            productPrice.Active = active;
            productPrice.UpdatedAt = DateTime.UtcNow;

            return await context.SaveChangesAsync(cancellationToken) > 0
                ? Result.Ok()
                : Result.Fail($"Failed to change product price status by ID {productPriceId}");
        }
        catch (Exception ex)
        {
            return Result.Fail(new Error(ex.Message).CausedBy(ex));
        }
    }

    public async ValueTask<Result> UpdateProductMetadataAsync(Guid productId, ProductMetadata metadata, CancellationToken cancellationToken = default)
    {
        try
        {
            using var context = await contextFactory.CreateDbContextAsync(cancellationToken);
            
            var product = await context.Products.FirstOrDefaultAsync(p => p.Id == productId, cancellationToken);
            
            if (product is null)
                return Result.Fail($"Could not find product with ID {productId}");
            
            product.Metadata = metadata;
            product.UpdatedAt = DateTime.UtcNow;

            return await context.SaveChangesAsync(cancellationToken) > 0
                ? Result.Ok()
                : Result.Fail($"Failed to update product metadata by ID {productId}");
        }
        catch (Exception ex)
        {
            return Result.Fail(new Error(ex.Message).CausedBy(ex));
        }
    }
}