dolittle/DotNET.SDK

// Copyright (c) Dolittle. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.

using System;
using System.Linq;
using System.Threading.Tasks;
using Dolittle.SDK.Tenancy;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace Dolittle.SDK.Extensions.AspNet;

/// <summary>
/// Represents a middleware that intercepts <see cref="HttpRequest"/> and sets the <see cref="IServiceProvider"/> to a scoped
/// <see cref="IServiceProvider"/> that knows about the tenant services for the tenant supplied by the Tenant-Id header on the <see cref="HttpRequest"/>.
/// </summary>
public partial class TenantScopedServiceProviderMiddleware
{
    const string TenantIdHeader = "Tenant-ID";
    readonly RequestDelegate _next;
    readonly IDolittleClient _client;
    readonly IHostEnvironment _env;
    readonly ILogger<TenantScopedServiceProviderMiddleware> _logger;

    /// <summary>
    /// Initializes a new instance of the <see cref="TenantScopedServiceProviderMiddleware"/> class.
    /// </summary>
    /// <param name="next">The <see cref="RequestDelegate"/>.</param>
    /// <param name="client">The <see cref="IDolittleClient"/>.</param>
    /// <param name="env">The <see cref="IHostEnvironment"/>.</param>
    /// <param name="logger">The <see cref="ILogger"/>.</param>
    public TenantScopedServiceProviderMiddleware(RequestDelegate next, IDolittleClient client, IHostEnvironment env, ILogger<TenantScopedServiceProviderMiddleware> logger)
    {
        _next = next;
        _client = client;
        _env = env;
        _logger = logger;
    }

    /// <summary>
    /// Invokes the middleware.
    /// </summary>
    /// <param name="context">The <see cref="HttpContext"/>.</param>
    /// <returns>A <see cref="Task"/> representing the asynchronous operation.</returns>
    public async Task InvokeAsync(HttpContext context)
    {
        if (_client is not { IsConnected: true })
        {
            DolittleClientNotReady();
            await _next(context).ConfigureAwait(false);
            return;
        }
        TenantId tenantId;
        if (Guid.TryParse(context.Request.Headers[TenantIdHeader], out var tenantGuid))
        {
            tenantId = tenantGuid;
        }
        else
        {
            if (!_env.IsDevelopment())
            {
                NoTenantIdInNonDevelopmentEnvironment();
                await _next(context).ConfigureAwait(false);
                return;
            }

            var availableTenantIds = _client.Tenants.Select(_ => _.Id).ToArray();
            if (!availableTenantIds.Any())
            {
                NoTenantsConfigured();
                await _next(context).ConfigureAwait(false);
                return;
            }

            if (availableTenantIds.Contains(TenantId.Development))
            {
                DefaultingToDevelopmentTenant();
                tenantId = TenantId.Development;
            }
            else
            {
                tenantId = availableTenantIds.Select(_ => _.ToString()).OrderBy(_ => _).First();
                DefaultingToFirstTenant(tenantId);
            }
        }

        using var scope = _client.Services.ForTenant(tenantId).CreateScope();
        context.RequestServices = scope.ServiceProvider;
        await _next(context).ConfigureAwait(false);
    }

    [LoggerMessage(0, LogLevel.Debug, "No tenant configured in the Tenant-ID header. Falling back to the development tenant")]
    partial void DefaultingToDevelopmentTenant();

    [LoggerMessage(0, LogLevel.Debug, "No tenant configured in the Tenant-ID header. Falling back to the first tenant in the tenant list ordered: {Tenant}")]
    partial void DefaultingToFirstTenant(TenantId tenant);
        
    [LoggerMessage(0, LogLevel.Error, "No Tenant ID provided by header in non-development environment")]
    partial void NoTenantIdInNonDevelopmentEnvironment();

    [LoggerMessage(0, LogLevel.Error, "No tenant configured in the Tenant-ID header and there are no tenants configured for the Dolittle Client")]
    partial void NoTenantsConfigured();

    [LoggerMessage(0, LogLevel.Error, "Dolittle client is not ready. Thr resources will not be set on the request")]
    partial void DolittleClientNotReady();
}