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

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

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

    public async Task<Result<int>> Handle(Command request, CancellationToken ct)
    {
        // Game 존재 검증 (사용자 정책: GameID 필수)
        if (!await db.Game.AnyAsync(c => c.ID == request.GameID && c.IsActive, ct))
        {
            return Result.Failure<int>(Error.NotFound("Product.GameNotFound", "선택한 게임이 없거나 비활성 상태입니다."));
        }

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

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

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

        if (request.Stock < -1)
        {
            return Result.Failure<int>(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<int>(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<int>(Error.Problem("Product.InvalidSalePeriod", "판매 시작일은 종료일보다 이전이어야 합니다."));
        }

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

        if (!request.IsActive)
        {
            product.Deactivate();
        }

        db.Product.Add(product);
        await db.SaveChangesAsync(ct);

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

                await db.SaveChangesAsync(ct);
            }
        }

        return Result.Success(product.ID);
    }
}