using MediatR;
using System.Text.Json;
using TakeoutSaaS.Application.Identity.Abstractions;
using TakeoutSaaS.Application.Identity.Commands;
using TakeoutSaaS.Application.Identity.Contracts;
using TakeoutSaaS.Application.Identity.Events;
using TakeoutSaaS.Application.Identity.Queries;
using TakeoutSaaS.Domain.Identity.Entities;
using TakeoutSaaS.Domain.Identity.Enums;
using TakeoutSaaS.Domain.Identity.Repositories;
using TakeoutSaaS.Shared.Abstractions.Constants;
using TakeoutSaaS.Shared.Abstractions.Exceptions;
using TakeoutSaaS.Shared.Abstractions.Security;

namespace TakeoutSaaS.Application.Identity.Handlers;

/// <summary>
/// 更新用户处理器。
/// </summary>
public sealed class UpdateIdentityUserCommandHandler(
    IIdentityUserRepository identityUserRepository,
    IUserRoleRepository userRoleRepository,
    IRoleRepository roleRepository,
    ICurrentUserAccessor currentUserAccessor,
    IAdminAuthService adminAuthService,
    IIdentityOperationLogPublisher operationLogPublisher,
    IMediator mediator)
    : IRequestHandler<UpdateIdentityUserCommand, UserDetailDto?>
{
    /// <inheritdoc />
    public async Task<UserDetailDto?> Handle(UpdateIdentityUserCommand request, CancellationToken cancellationToken)
    {
        // 1. 获取操作者档案（用于操作日志）
        var operatorProfile = await adminAuthService.GetProfileAsync(currentUserAccessor.UserId, cancellationToken);

        // 2. (空行后) 获取用户实体
        var user = await identityUserRepository.GetForUpdateAsync(request.UserId, cancellationToken);
        if (user == null)
        {
            return null;
        }

        // 3. (空行后) 限定仅允许更新平台管理员账号
        if (user.Portal != PortalType.Admin || user.TenantId is not null)
        {
            return null;
        }

        // 4. (空行后) 规范化输入并校验唯一性
        var portal = PortalType.Admin;
        var displayName = request.DisplayName.Trim();
        var phone = string.IsNullOrWhiteSpace(request.Phone) ? null : request.Phone.Trim();
        var email = string.IsNullOrWhiteSpace(request.Email) ? null : request.Email.Trim();
        var roleIds = request.RoleIds == null ? null : ParseIds(request.RoleIds, "角色");

        if (!string.IsNullOrWhiteSpace(phone)
            && !string.Equals(phone, user.Phone, StringComparison.OrdinalIgnoreCase)
            && await identityUserRepository.ExistsByPhoneAsync(portal, null, phone, user.Id, cancellationToken))
        {
            throw new BusinessException(ErrorCodes.Conflict, "手机号已存在");
        }

        if (!string.IsNullOrWhiteSpace(email)
            && !string.Equals(email, user.Email, StringComparison.OrdinalIgnoreCase)
            && await identityUserRepository.ExistsByEmailAsync(portal, null, email, user.Id, cancellationToken))
        {
            throw new BusinessException(ErrorCodes.Conflict, "邮箱已存在");
        }

        if (roleIds is { Length: > 0 })
        {
            var roles = await roleRepository.GetByIdsAsync(portal, null, roleIds, cancellationToken);
            if (roles.Count != roleIds.Length)
            {
                throw new BusinessException(ErrorCodes.BadRequest, "角色列表包含无效项");
            }
        }

        // 5. 更新用户字段
        user.DisplayName = displayName;
        user.Phone = phone;
        user.Email = email;
        user.Avatar = string.IsNullOrWhiteSpace(request.Avatar) ? null : request.Avatar.Trim();
        user.RowVersion = request.RowVersion;

        // 6. 构建操作日志消息
        var operatorName = string.IsNullOrWhiteSpace(operatorProfile.DisplayName)
            ? operatorProfile.Account
            : operatorProfile.DisplayName;
        if (string.IsNullOrWhiteSpace(operatorName))
        {
            operatorName = $"user:{currentUserAccessor.UserId}";
        }

        var logMessage = new IdentityUserOperationLogMessage
        {
            OperationType = "identity-user:update",
            TargetType = "identity_user",
            TargetIds = JsonSerializer.Serialize(new[] { user.Id }),
            OperatorId = currentUserAccessor.UserId.ToString(),
            OperatorName = operatorName,
            Parameters = JsonSerializer.Serialize(new
            {
                userId = user.Id,
                portal = portal.ToString(),
                displayName,
                phone,
                email,
                roleIds
            }),
            Result = JsonSerializer.Serialize(new { userId = user.Id }),
            Success = true
        };

        // 7. 持久化用户更新并写入 Outbox
        try
        {
            await operationLogPublisher.PublishAsync(logMessage, cancellationToken);
            await identityUserRepository.SaveChangesAsync(cancellationToken);
        }
        catch (Exception ex) when (IsConcurrencyException(ex))
        {
            throw new BusinessException(ErrorCodes.Conflict, "用户数据已被修改，请刷新后重试");
        }

        // 8. 覆盖角色绑定（仅当显式传入时）
        if (roleIds != null)
        {
            await userRoleRepository.ReplaceUserRolesAsync(portal, null, user.Id, roleIds, cancellationToken);
        }

        // 9. 返回用户详情
        return await mediator.Send(new GetIdentityUserDetailQuery { UserId = user.Id }, cancellationToken);
    }

    private static long[] ParseIds(string[] values, string name)
    {
        // 1. 空数组直接返回
        if (values.Length == 0)
        {
            return Array.Empty<long>();
        }

        // 2. 解析并去重
        var ids = new List<long>(values.Length);
        foreach (var value in values)
        {
            if (!long.TryParse(value, out var id) || id <= 0)
            {
                throw new BusinessException(ErrorCodes.BadRequest, $"{name} ID 无效");
            }

            ids.Add(id);
        }

        // 3. 返回去重结果
        return ids.Distinct().ToArray();
    }

    private static bool IsConcurrencyException(Exception exception)
        => string.Equals(exception.GetType().Name, "DbUpdateConcurrencyException", StringComparison.Ordinal);
}