using Application.Abstractions.Data;
using Application.Abstractions.Messaging;
using Domain.Entities.Store.ValueObject;
using Microsoft.EntityFrameworkCore;
using SharedKernel.Results;
using SharedKernel.Storage;

namespace Application.Features.Admin.Store.Product.Update;

public sealed class Handler(IAppDbContext db, IFileStorage fileStorage) : ICommandHandler<Command, Result>
{
    private static readonly string[] AllowedImageExt = [".jpg", ".jpeg", ".png", ".gif", ".webp"];

    public async Task<Result> Handle(Command request, CancellationToken ct)
    {
        if (!await db.Game.AnyAsync(c => c.ID == request.GameID, ct))
        {
            return Result.Failure(Error.NotFound("Product.GameNotFound", "선택한 게임이 없습니다."));
        }

        if (request.Price < 0)
        {
            return Result.Failure(Error.Problem("Product.InvalidPrice", "가격은 0 이상이어야 합니다."));
        }

        if (request.DiscountType == DiscountType.Percent && (request.DiscountValue < 0 || request.DiscountValue > 99))
        {
            return Result.Failure(Error.Problem("Product.InvalidDiscountPercent", "할인율은 0 ~ 99% 범위로 입력하세요."));
        }

        if (request.DiscountType == DiscountType.Amount && (request.DiscountValue < 0 || request.DiscountValue > request.Price))
        {
            return Result.Failure(Error.Problem("Product.InvalidDiscountAmount", "할인 금액은 0 이상이며 정가 이하로 입력하세요."));
        }

        if (request.Stock < -1)
        {
            return Result.Failure(Error.Problem("Product.InvalidStock", "재고는 -1(무제한) 또는 0 이상이어야 합니다."));
        }

        if (request.MinPurchase < 1 || request.MaxPurchase < request.MinPurchase || request.MaxPurchase > 999)
        {
            return Result.Failure(Error.Problem("Product.InvalidPurchaseRange", "최소/최대 구매 수량 범위가 올바르지 않습니다 (1 ≤ 최소 ≤ 최대 ≤ 999)."));
        }

        if (request.SaleStartAt.HasValue && request.SaleEndAt.HasValue && request.SaleStartAt.Value >= request.SaleEndAt.Value)
        {
            return Result.Failure(Error.Problem("Product.InvalidSalePeriod", "판매 시작일은 종료일보다 이전이어야 합니다."));
        }

        var product = await db.Product.FirstOrDefaultAsync(c => c.ID == request.ID, ct);

        if (product is null)
        {
            return Result.Failure(Error.NotFound("Product.NotFound", "상품을 찾을 수 없습니다."));
        }

        string? newThumbnail = product.Thumbnail;

        if (request.RemoveThumbnail)
        {
            newThumbnail = null;
        }

        if (request.ThumbnailFile is not null)
        {
            var uploadPath = new FileStoragePath(UploadTarget.Upload, UploadFolder.StoreProduct, product.ID);
            var saved = await fileStorage.SaveFileAsync(request.ThumbnailFile, uploadPath, AllowedImageExt, ct);

            if (saved is not null)
            {
                newThumbnail = saved.Url;
            }
        }

        product.Update(
            gameID: request.GameID,
            name: request.Name,
            type: request.Type,
            price: request.Price,
            discountType: request.DiscountType,
            discountValue: request.DiscountValue,
            stock: request.Stock,
            description: request.Description,
            thumbnail: newThumbnail,
            order: request.Order,
            minPurchase: request.MinPurchase,
            maxPurchase: request.MaxPurchase,
            saleStartAt: request.SaleStartAt,
            saleEndAt: request.SaleEndAt,
            isActive: request.IsActive,
            requireDonationChannel: request.RequireDonationChannel
        );

        await db.SaveChangesAsync(ct);

        return Result.Success();
    }
}