using Application.Abstractions.Crypto;
using Application.Abstractions.Data;
using Application.Abstractions.Messaging;
using Microsoft.EntityFrameworkCore;
using SharedKernel.Results;
using MemberAddressEntity = Domain.Entities.Store.MemberAddress;

namespace Application.Features.Api.MyPage.Address.Save;

public sealed class Handler(IAppDbContext db, IFieldEncryptor encryptor) : ICommandHandler<Command, Result<int>>
{
    private const int MaxAddressesPerMember = 5;

    public async Task<Result<int>> Handle(Command request, CancellationToken ct)
    {
        // 입력 검증
        if (string.IsNullOrWhiteSpace(request.RecipientName))
        {
            return Result.Failure<int>(Error.Problem("Address.RecipientRequired", "수령인명은 필수입니다."));
        }

        if (string.IsNullOrWhiteSpace(request.Phone))
        {
            return Result.Failure<int>(Error.Problem("Address.PhoneRequired", "연락처는 필수입니다."));
        }

        if (string.IsNullOrWhiteSpace(request.ZipCode) || request.ZipCode.Length > 10)
        {
            return Result.Failure<int>(Error.Problem("Address.InvalidZipCode", "우편번호가 잘못되었습니다."));
        }

        if (string.IsNullOrWhiteSpace(request.Address1) || string.IsNullOrWhiteSpace(request.Address2))
        {
            return Result.Failure<int>(Error.Problem("Address.RequiredFields", "주소를 정확히 입력해주세요."));
        }

        // 암호화
        var recipientEnc = encryptor.Encrypt(request.RecipientName);
        var recipientHash = encryptor.Hash(request.RecipientName);
        var phoneEnc = encryptor.Encrypt(request.Phone);
        var addr1Enc = encryptor.Encrypt(request.Address1);
        var addr2Enc = encryptor.Encrypt(request.Address2);
        var keyVersion = encryptor.CurrentKeyVersion;

        // IsDefault 처리: true 라면 다른 주소의 IsDefault 모두 false 로
        if (request.IsDefault)
        {
            var others = await db.MemberAddress
                .Where(a => a.MemberID == request.MemberID && a.IsDefault)
                .ToListAsync(ct);

            foreach (var o in others)
            {
                if (request.ID.HasValue && o.ID == request.ID.Value)
                {
                    continue;
                }

                o.UnsetDefault();
            }
        }

        if (!request.ID.HasValue || request.ID.Value == 0)
        {
            // 신규 — 회원당 최대 개수 검증
            var count = await db.MemberAddress.CountAsync(a => a.MemberID == request.MemberID, ct);

            if (count >= MaxAddressesPerMember)
            {
                return Result.Failure<int>(Error.Problem("Address.MaxExceeded", $"주소는 회원당 최대 {MaxAddressesPerMember}개까지 등록 가능합니다."));
            }

            // 첫 주소는 자동 default
            var isDefault = request.IsDefault || count == 0;

            var newAddress = MemberAddressEntity.Create(
                memberID: request.MemberID,
                recipientNameEncrypted: recipientEnc,
                recipientNameHash: recipientHash,
                phoneEncrypted: phoneEnc,
                zipCode: request.ZipCode,
                address1Encrypted: addr1Enc,
                address2Encrypted: addr2Enc,
                keyVersion: keyVersion,
                isDefault: isDefault
            );

            db.MemberAddress.Add(newAddress);
            await db.SaveChangesAsync(ct);

            return Result.Success(newAddress.ID);
        }

        // 수정
        var existing = await db.MemberAddress
            .FirstOrDefaultAsync(a => a.ID == request.ID.Value && a.MemberID == request.MemberID, ct);

        if (existing is null)
        {
            return Result.Failure<int>(Error.NotFound("Address.NotFound", "수정할 주소를 찾을 수 없습니다."));
        }

        existing.Update(
            recipientNameEncrypted: recipientEnc,
            recipientNameHash: recipientHash,
            phoneEncrypted: phoneEnc,
            zipCode: request.ZipCode,
            address1Encrypted: addr1Enc,
            address2Encrypted: addr2Enc,
            keyVersion: keyVersion
        );

        if (request.IsDefault && !existing.IsDefault)
        {
            existing.SetAsDefault();
        }
        else if (!request.IsDefault && existing.IsDefault)
        {
            existing.UnsetDefault();
        }

        await db.SaveChangesAsync(ct);

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