using Microsoft.EntityFrameworkCore;
using Asp.Versioning;
using FluentValidation;
using Hellang.Middleware.ProblemDetails;
using Microsoft.AspNetCore.SignalR;
using ChatService.API.Application.Behaviors;
using ChatService.API.Hubs;
using ChatService.Infrastructure;
using Serilog;
using StackExchange.Redis;

// EN: Configure Serilog early / VI: Cấu hình Serilog sớm
Log.Logger = new LoggerConfiguration()
    .WriteTo.Console()
    .CreateBootstrapLogger();

try
{
    Log.Information("Starting ChatService API / Khởi động ChatService API");

    var builder = WebApplication.CreateBuilder(args);

    // EN: Configure Serilog / VI: Cấu hình Serilog
    builder.Host.UseSerilog((context, services, configuration) => configuration
        .ReadFrom.Configuration(context.Configuration)
        .ReadFrom.Services(services)
        .Enrich.FromLogContext()
        .WriteTo.Console());

    // EN: Add Infrastructure services / VI: Thêm Infrastructure services
    builder.Services.AddInfrastructure(builder.Configuration);

    // EN: Add MediatR with behaviors / VI: Thêm MediatR với behaviors
    builder.Services.AddMediatR(cfg =>
    {
        cfg.RegisterServicesFromAssemblyContaining<Program>();
        cfg.AddOpenBehavior(typeof(LoggingBehavior<,>));
        cfg.AddOpenBehavior(typeof(ValidatorBehavior<,>));
        cfg.AddOpenBehavior(typeof(TransactionBehavior<,>));
    });

    // EN: Add FluentValidation / VI: Thêm FluentValidation
    builder.Services.AddValidatorsFromAssemblyContaining<Program>();

    // EN: Add SignalR with Redis Backplane and MessagePack
    // VI: Thêm SignalR với Redis Backplane và MessagePack
    var redisConnection = builder.Configuration.GetConnectionString("Redis") ?? "localhost:6379";
    var signalRBuilder = builder.Services.AddSignalR(options =>
    {
        options.EnableDetailedErrors = builder.Environment.IsDevelopment();
        options.KeepAliveInterval = TimeSpan.FromSeconds(
            builder.Configuration.GetValue("SignalR:KeepAliveInterval", 15));
        options.ClientTimeoutInterval = TimeSpan.FromSeconds(
            builder.Configuration.GetValue("SignalR:ClientTimeoutInterval", 30));
        
        // EN: Enable Stateful Reconnect (.NET 8+) / VI: Bật Stateful Reconnect
        options.StatefulReconnectBufferSize = 
            builder.Configuration.GetValue("SignalR:StatefulReconnectBufferSize", 32768);
    });
    
    // EN: Add Redis Backplane for scaling / VI: Thêm Redis Backplane để scale
    signalRBuilder.AddStackExchangeRedis(redisConnection, options =>
    {
        options.Configuration.ChannelPrefix = RedisChannel.Literal("ChatService");
        options.Configuration.AbortOnConnectFail = false;
    });
    
    // EN: Add MessagePack protocol for better performance / VI: Thêm MessagePack cho hiệu năng tốt hơn
    if (builder.Configuration.GetValue("SignalR:EnableMessagePack", true))
    {
        signalRBuilder.AddMessagePackProtocol();
    }
    
    // EN: Add custom User ID provider / VI: Thêm custom User ID provider
    builder.Services.AddSingleton<IUserIdProvider, ClaimsUserIdProvider>();

    // EN: Add API versioning / VI: Thêm API versioning
    builder.Services.AddApiVersioning(options =>
    {
        options.DefaultApiVersion = new ApiVersion(1, 0);
        options.AssumeDefaultVersionWhenUnspecified = true;
        options.ReportApiVersions = true;
        options.ApiVersionReader = ApiVersionReader.Combine(
            new UrlSegmentApiVersionReader(),
            new HeaderApiVersionReader("X-Api-Version"));
    })
    .AddApiExplorer(options =>
    {
        options.GroupNameFormat = "'v'VVV";
        options.SubstituteApiVersionInUrl = true;
    });

    // EN: Add controllers / VI: Thêm controllers
    builder.Services.AddControllers();

    // EN: Add ProblemDetails middleware (RFC 7807) / VI: Thêm ProblemDetails middleware
    builder.Services.AddProblemDetails(options =>
    {
        options.IncludeExceptionDetails = (ctx, ex) =>
            builder.Environment.IsDevelopment();
    });

    // EN: Add Swagger / VI: Thêm Swagger
    builder.Services.AddEndpointsApiExplorer();
    builder.Services.AddSwaggerGen(options =>
    {
        options.SwaggerDoc("v1", new()
        {
            Title = "ChatService API",
            Version = "v1",
            Description = "Real-time Chat Service with SignalR, AI Integration / Chat Service thời gian thực với SignalR, tích hợp AI"
        });
        
        // EN: Add JWT Bearer security definition / VI: Thêm định nghĩa bảo mật JWT Bearer
        options.AddSecurityDefinition("Bearer", new Microsoft.OpenApi.Models.OpenApiSecurityScheme
        {
            Description = "JWT Authorization header using Bearer scheme. Example: \"Bearer {token}\" / Header Authorization JWT sử dụng scheme Bearer. Ví dụ: \"Bearer {token}\"",
            Name = "Authorization",
            In = Microsoft.OpenApi.Models.ParameterLocation.Header,
            Type = Microsoft.OpenApi.Models.SecuritySchemeType.Http,
            Scheme = "bearer",
            BearerFormat = "JWT"
        });
        
        // EN: Add security requirement / VI: Thêm yêu cầu bảo mật
        options.AddSecurityRequirement(new Microsoft.OpenApi.Models.OpenApiSecurityRequirement
        {
            {
                new Microsoft.OpenApi.Models.OpenApiSecurityScheme
                {
                    Reference = new Microsoft.OpenApi.Models.OpenApiReference
                    {
                        Type = Microsoft.OpenApi.Models.ReferenceType.SecurityScheme,
                        Id = "Bearer"
                    }
                },
                Array.Empty<string>()
            }
        });
    });

    // EN: Add health checks / VI: Thêm health checks
    builder.Services.AddHealthChecks()
        .AddNpgSql(
            builder.Configuration.GetConnectionString("DefaultConnection")
                ?? builder.Configuration["DATABASE_URL"]
                ?? "",
            name: "postgresql",
            tags: ["db", "postgresql"])
        .AddRedis(
            redisConnection,
            name: "redis",
            tags: ["cache", "redis"]);

    // EN: Add CORS for WebSocket / VI: Thêm CORS cho WebSocket
    builder.Services.AddCors(options =>
    {
        options.AddDefaultPolicy(policy =>
        {
            policy.WithOrigins(
                    builder.Configuration.GetSection("AllowedOrigins").Get<string[]>() 
                    ?? ["http://localhost:3000", "http://localhost:5173"])
                  .AllowAnyMethod()
                  .AllowAnyHeader()
                  .AllowCredentials(); // EN: Required for SignalR / VI: Bắt buộc cho SignalR
        });
    });

    var app = builder.Build();

    // EN: Configure middleware pipeline / VI: Cấu hình middleware pipeline
    app.UseSerilogRequestLogging();
    app.UseProblemDetails();

    if (app.Environment.IsDevelopment())
    {
        app.UseSwagger();
        app.UseSwaggerUI(c =>
        {
            c.SwaggerEndpoint("/swagger/v1/swagger.json", "ChatService API v1");
            c.RoutePrefix = "swagger";
        });
    }

    app.UseCors();
    app.UseRouting();

    // EN: Map health check endpoints / VI: Map health check endpoints
    app.MapHealthChecks("/health");
    app.MapHealthChecks("/health/live", new()
    {
        Predicate = _ => false // EN: Just checks app is running / VI: Chỉ kiểm tra app đang chạy
    });
    app.MapHealthChecks("/health/ready");

    // EN: Map controllers / VI: Map controllers
    app.MapControllers();

    // EN: Map SignalR Hub / VI: Map SignalR Hub
    app.MapHub<ChatHub>("/hubs/chat", options =>
    {
        options.AllowStatefulReconnects = true;
    });

    // EN: Run the application / VI: Chạy ứng dụng
    // EN: Auto-apply EF Core migrations on startup
    // VI: Tự động áp dụng EF Core migrations khi khởi động
    try
    {
        using (var scope = app.Services.CreateScope())
        {
            var dbContext = scope.ServiceProvider.GetRequiredService<ChatServiceContext>();
            await dbContext.Database.MigrateAsync();
        }
    }
    catch (Exception ex)
    {
        // EN: Log migration errors but don't crash the app (e.g. PendingModelChangesWarning in EF Core 10)
        // VI: Log lỗi migration nhưng không crash app
        Console.WriteLine($"Warning: EF Core migration issue: {ex.Message}");
    }

    app.Run();
}
catch (Exception ex)
{
    Log.Fatal(ex, "Application terminated unexpectedly / Ứng dụng kết thúc bất ngờ");
    throw;
}
finally
{
    Log.CloseAndFlush();
}

// EN: Make Program class accessible for integration tests
// VI: Làm cho class Program có thể truy cập cho integration tests
public partial class Program { }

