using System.Text.Json;
using System.Text.Json.Serialization;
using Journal.AI;
using Journal.Core;
using Journal.WebGateway.Extensions;
using Journal.WebGateway.Infrastructure;
using Journal.WebGateway.Security;
using Microsoft.AspNetCore.Authentication.Cookies;
using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Diagnostics;
using Microsoft.Extensions.FileProviders;

if (TryHandlePasswordHashCommand(args))
    return;

var builder = WebApplication.CreateBuilder(new WebApplicationOptions
{
    Args = args,
    ContentRootPath = AppContext.BaseDirectory
});

// Configuration
var securitySettings = builder.Configuration.GetSection("Security");
var repoRootResolution = PathResolver.ResolveRepoRoot(builder.Configuration);
var repoRoot = repoRootResolution.Root;
var webDistPath = PathResolver.ResolveWebDist(repoRoot, builder.Configuration);
var port = builder.Configuration.GetValue<int?>("PORT") 
           ?? builder.Configuration.GetValue<int?>("GatewaySettings:Port") 
           ?? 5002;

Environment.SetEnvironmentVariable("JOURNAL_PROJECT_ROOT", repoRoot);

builder.WebHost.ConfigureKestrel(options => options.ListenAnyIP(port));

// Services
builder.Services.AddFragmentServices();
builder.Services.AddLlamaSharpServices();
builder.Services.AddSingleton<Entry>();
builder.Services.AddSingleton(new SidecarRootState(repoRootResolution.Root));
builder.Services.AddSingleton(new WebUiState(webDistPath));

builder.Services.AddAuthentication(options => {
        options.DefaultScheme = CookieAuthenticationDefaults.AuthenticationScheme;
        options.DefaultAuthenticateScheme = CookieAuthenticationDefaults.AuthenticationScheme;
        options.DefaultChallengeScheme = CookieAuthenticationDefaults.AuthenticationScheme;
    })
    .AddCookie(CookieAuthenticationDefaults.AuthenticationScheme, options =>
    {
        options.LoginPath = "/gateway/login";
        options.LogoutPath = "/gateway/logout";
        options.Cookie.Name = "Journal.Gateway.Session";
        options.Cookie.HttpOnly = true;
        options.Cookie.SameSite = SameSiteMode.Strict;
        options.Cookie.SecurePolicy = CookieSecurePolicy.SameAsRequest;
        options.ExpireTimeSpan = TimeSpan.FromHours(8);
        options.SlidingExpiration = true;
    })
    .AddScheme<AuthenticationSchemeOptions, ApiKeyAuthenticationHandler>("ApiKey", null);

builder.Services.AddAuthorization(options =>
{
    options.FallbackPolicy = new AuthorizationPolicyBuilder()
        .AddAuthenticationSchemes(CookieAuthenticationDefaults.AuthenticationScheme, "ApiKey")
        .RequireAuthenticatedUser()
        .Build();
});

builder.Services.AddCors(options =>
{
    options.AddPolicy("GatewayCors", policy =>
    {
        var allowedOrigins = securitySettings.GetSection("AllowedOrigins").Get<string[]>() ?? Array.Empty<string>();
        if (allowedOrigins.Length > 0)
        {
            policy.WithOrigins(allowedOrigins).AllowAnyHeader().AllowAnyMethod().AllowCredentials();
        }
        else
        {
            policy.AllowAnyOrigin().AllowAnyHeader().AllowAnyMethod();
        }
    });
});

builder.Services.ConfigureHttpJsonOptions(options =>
{
    options.SerializerOptions.PropertyNamingPolicy = JsonNamingPolicy.CamelCase;
    options.SerializerOptions.PropertyNameCaseInsensitive = true;
    options.SerializerOptions.DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull;
});

var app = builder.Build();

app.Services.GetRequiredService<SidecarRootState>().SetResolved(repoRootResolution.Root, repoRootResolution.IsCustom);

if (string.IsNullOrWhiteSpace(builder.Configuration.GetValue<string>("Security:AccessPasswordHash")))
{
    app.Logger.LogWarning("Security:AccessPasswordHash is not configured. Browser login is disabled until a password hash is set.");
}

app.Logger.LogInformation("Journal.WebGateway starting...");
app.Logger.LogInformation("Content Root: {Path}", app.Environment.ContentRootPath);
app.Logger.LogInformation("Web UI Dist: {Path}", webDistPath);

app.UseExceptionHandler(exceptionApp =>
{
    exceptionApp.Run(async context =>
    {
        var logger = context.RequestServices.GetRequiredService<ILogger<Program>>();
        var feature = context.Features.Get<IExceptionHandlerPathFeature>();
        logger.LogError(feature?.Error, "Unhandled exception occurred.");
        context.Response.StatusCode = StatusCodes.Status500InternalServerError;
        context.Response.ContentType = "application/json";
        await context.Response.WriteAsJsonAsync(new { ok = false, error = "An internal error occurred." });
    });
});

app.UseCors("GatewayCors");
app.UseAuthentication();
app.UseAuthorization();

app.Use(async (context, next) =>
{
    var path = context.Request.Path;
    var isGatewayAuthPath =
        path.StartsWithSegments("/gateway/login") ||
        path.StartsWithSegments("/gateway/logout");
    var isAnonymousApiPath =
        path.StartsWithSegments("/api/health") ||
        path.StartsWithSegments("/api/web/status");
    var isProtectedUiPath = !path.StartsWithSegments("/api") && !isGatewayAuthPath;

    if (isProtectedUiPath && context.User.Identity?.IsAuthenticated != true)
    {
        await context.ChallengeAsync(CookieAuthenticationDefaults.AuthenticationScheme);
        return;
    }

    if (isAnonymousApiPath)
    {
        await next();
        return;
    }

    await next();
});

// Better handling for 401 challenges on browser requests
app.Use(async (context, next) =>
{
    await next();

    if (context.Response.StatusCode == 401 && 
        !context.Response.HasStarted &&
        context.Request.Path != "/gateway/login" &&
        context.Request.Headers.Accept.ToString().Contains("text/html"))
    {
        context.Response.Redirect("/gateway/login");
    }
});

app.Use(async (context, next) =>
{
    if (securitySettings.GetValue<bool>("EnableAuditLogging"))
    {
        var logger = context.RequestServices.GetRequiredService<ILogger<Program>>();
        var ip = context.Connection.RemoteIpAddress?.ToString() ?? "unknown";
        var userAgent = context.Request.Headers["User-Agent"].ToString();
        var user = context.User.Identity?.Name ?? "Anonymous";

        var timestamp = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss");
        logger.LogInformation("[{Timestamp}] Audit: [{IP}] {Method} {Path} accessed by {User} ({UA})", 
            timestamp, ip, context.Request.Method, context.Request.Path, user, userAgent);
    }
    await next();
});

// Static Files Internal Middleware
if (Directory.Exists(webDistPath))
{
    app.UseDefaultFiles(new DefaultFilesOptions { FileProvider = new PhysicalFileProvider(webDistPath), RequestPath = "" });
    app.UseStaticFiles(new StaticFileOptions { FileProvider = new PhysicalFileProvider(webDistPath), RequestPath = "" });
}

// Map specialized endpoints
app.MapGatewayEndpoints(webDistPath);

app.Run();

static bool TryHandlePasswordHashCommand(string[] args)
{
    if (args.Length == 0 || !string.Equals(args[0], "hash-password", StringComparison.OrdinalIgnoreCase))
        return false;

    string password;
    if (args.Length > 1)
    {
        password = args[1];
    }
    else
    {
        password = PromptForPassword("New gateway password: ");
        var confirm = PromptForPassword("Confirm gateway password: ");
        if (!string.Equals(password, confirm, StringComparison.Ordinal))
        {
            Console.Error.WriteLine("Passwords did not match.");
            Environment.ExitCode = 1;
            return true;
        }
    }

    if (string.IsNullOrWhiteSpace(password))
    {
        Console.Error.WriteLine("Password cannot be empty.");
        Environment.ExitCode = 1;
        return true;
    }

    Console.WriteLine(GatewayPasswordHasher.HashPassword(password));
    return true;
}

static string PromptForPassword(string prompt)
{
    Console.Write(prompt);

    var buffer = new List<char>();
    while (true)
    {
        var key = Console.ReadKey(intercept: true);
        if (key.Key == ConsoleKey.Enter)
        {
            Console.WriteLine();
            return new string([.. buffer]);
        }

        if (key.Key == ConsoleKey.Backspace)
        {
            if (buffer.Count > 0)
                buffer.RemoveAt(buffer.Count - 1);

            continue;
        }

        if (!char.IsControl(key.KeyChar))
            buffer.Add(key.KeyChar);
    }
}