using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Diagnostics;
using JobTrackerApi.Controllers;
using JobTrackerApi.Data;
using System.Data.Common;
using MySqlConnector;
using Microsoft.AspNetCore.Authentication.JwtBearer;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.DataProtection;
using Microsoft.AspNetCore.RateLimiting;
using Microsoft.IdentityModel.Tokens;
using JobTrackerApi.Models;
using JobTrackerApi.Services;
using System.Diagnostics;
using System.IdentityModel.Tokens.Jwt;
using System.Net;
using System.IO;
using System.Security.Cryptography;
using System.Threading.RateLimiting;
using JobTrackerApi.Services.JobImport;
using JobTrackerApi.Services.JobImport.Plugins;
using JobTrackerApi.Services.JobImport.Translation;

var builder = WebApplication.CreateBuilder(args);

// Avoid Windows EventLog provider issues in local dev environments.
builder.Logging.ClearProviders();
builder.Logging.AddConsole();
builder.Logging.AddDebug();

builder.Services.AddHttpContextAccessor();
builder.Services.AddScoped<ICurrentUserService, CurrentUserService>();
builder.Services.AddScoped<IEmailSettingsResolver, EmailSettingsResolver>();
builder.Services.AddScoped<IAppEmailSender, SmtpEmailSender>();
builder.Services.AddSingleton<ICvProcessingQueue, CvProcessingQueue>();
builder.Services.AddTransient<ProfileCvController>();
builder.Services.AddSingleton<ICvTemplateRenderer, CvTemplateRenderer>();
builder.Services.AddSingleton<ICvPdfExporter, PlaywrightCvPdfExporter>();

builder.Services.AddSingleton<AppPaths>();
builder.Services.AddSingleton<IStartupReadiness, StartupReadiness>();

// Add DbContext
builder.Services.AddDbContext<JobTrackerContext>((sp, options) =>
{
    var cfg = sp.GetRequiredService<IConfiguration>();
    var paths = sp.GetRequiredService<AppPaths>();

    var provider = (cfg["Database:Provider"] ?? "sqlite").Trim().ToLowerInvariant();
    var cs = cfg.GetConnectionString("JobTracker");
    if (string.IsNullOrWhiteSpace(cs))
    {
        cs = $"Data Source={paths.GetDbPath()}";
        provider = "sqlite";
    }

    if (provider is "mysql" or "mariadb")
    {
        // Avoid ServerVersion.AutoDetect here because it forces an immediate DB connection
        // during service registration, which can crash the API if MariaDB is temporarily
        // unavailable or on a different network during deploy startup.
        options.UseMySql(cs, new MariaDbServerVersion(new Version(11, 0, 0)));
    }
    else
    {
        options.UseSqlite(cs);
    }

    // We create Identity tables on startup in environments where `dotnet ef` isn't available.
    // That can cause EF to detect "pending model changes" and throw on Migrate(). Ignore it.
    options.ConfigureWarnings(w => w.Ignore(RelationalEventId.PendingModelChangesWarning));
});

// Enable CORS (allowlist by default)
builder.Services.AddCors(options =>
{
    options.AddPolicy("AllowReact", policy =>
    {
        var origins = builder.Configuration.GetSection("Cors:Origins").Get<string[]>() ?? Array.Empty<string>();
        if (origins.Length == 0)
        {
            origins = new[] { "http://localhost:3000" };
        }

        if (origins.Any(x => x.Trim() == "*"))
        {
            policy.SetIsOriginAllowed(_ => true)
                .AllowAnyMethod()
                .AllowAnyHeader()
                .AllowCredentials();
        }
        else
        {
            policy.WithOrigins(origins.Select(x => x.Trim()).Where(x => x.Length > 0).ToArray())
                .AllowAnyMethod()
                .AllowAnyHeader()
                .AllowCredentials();
        }
    });
});

// Add controllers
builder.Services.AddControllers();
var dataRoot = (builder.Configuration["Data:Root"] ?? "").Trim();
if (string.IsNullOrWhiteSpace(dataRoot))
{
    dataRoot = builder.Environment.ContentRootPath;
}
if (!Path.IsPathRooted(dataRoot))
{
    dataRoot = Path.Combine(builder.Environment.ContentRootPath, dataRoot);
}
Directory.CreateDirectory(dataRoot);
var dataProtectionKeysPath = Path.Combine(dataRoot, "keys");
Directory.CreateDirectory(dataProtectionKeysPath);

builder.Services.AddDataProtection()
    .PersistKeysToFileSystem(new DirectoryInfo(dataProtectionKeysPath))
    .SetApplicationName("JobTracker");
builder.Services.AddHostedService<RulesHostedService>();
builder.Services.AddHostedService<FollowUpReminderHostedService>();
builder.Services.AddHostedService<DailyExportHostedService>();
builder.Services.AddHostedService<JobEnrichmentHostedService>();
builder.Services.AddHostedService<SummarizerProbeHostedService>();
builder.Services.AddHostedService<CvProcessingHostedService>();

builder.Services.AddHttpClient("jobimport")
    .ConfigurePrimaryHttpMessageHandler(() => new HttpClientHandler
    {
        AutomaticDecompression = DecompressionMethods.All,
        AllowAutoRedirect = false
    });

// Local AI service (FastAPI). Supports summarization and OCR/text extraction.
builder.Services.AddHttpClient("ai-service", client =>
{
    var baseUrl = builder.Configuration["Ai:BaseUrl"]
        ?? builder.Configuration["Summarizer:BaseUrl"]
        ?? "http://127.0.0.1:8001";
    client.BaseAddress = new Uri(baseUrl);
    client.Timeout = TimeSpan.FromSeconds(30);
});

builder.Services.AddMemoryCache();
builder.Services.AddSingleton<ISummarizerService, SummarizerService>();
builder.Services.AddSingleton<ICvAiClassifier, CvAiClassifier>();
builder.Services.AddSingleton<ICvAiNormalizer, CvAiNormalizer>();
builder.Services.AddSingleton<IGoogleTokenValidator, GoogleTokenValidator>();
builder.Services.AddScoped<IGmailOAuthService, GmailOAuthService>();
builder.Services.AddSingleton<IGmailJobMatchingService, GmailJobMatchingService>();
builder.Services.AddSingleton<IGmailCorrespondenceEnrichmentService, NoOpGmailCorrespondenceEnrichmentService>();

builder.Services.AddIdentityCore<ApplicationUser>(options =>
    {
        options.User.RequireUniqueEmail = true;
        options.Password.RequireDigit = true;
        options.Password.RequireLowercase = true;
        options.Password.RequireUppercase = false;
        options.Password.RequireNonAlphanumeric = false;
        options.Password.RequiredLength = 8;
    })
    .AddRoles<IdentityRole>()
    .AddEntityFrameworkStores<JobTrackerContext>()
    .AddSignInManager();

builder.Services.AddScoped<ITokenService, TokenService>();

builder.Services.AddSingleton<UniversalJobParser>();
builder.Services.AddSingleton<IHostAddressResolver, DnsHostAddressResolver>();
builder.Services.AddSingleton<IJobSitePlugin, FinnPlugin>();
builder.Services.AddSingleton<IJobSitePlugin, NavPlugin>();
builder.Services.AddSingleton<IJobSitePlugin, LinkedInPlugin>();
builder.Services.AddSingleton<IJobSitePlugin, JobbnorgePlugin>();

var translationProvider = (builder.Configuration["Translation:Provider"] ?? "none").Trim().ToLowerInvariant();
builder.Services.AddSingleton<ITranslationService>(sp =>
{
    return translationProvider switch
    {
        "libretranslate" => new LibreTranslateService(sp.GetRequiredService<IHttpClientFactory>(), sp.GetRequiredService<IConfiguration>()),
        _ => new NoOpTranslationService()
    };
});
builder.Services.AddScoped<JobImportService>();

var requireAuth = builder.Configuration.GetValue("Auth:Require", false);
var googleClientId = (builder.Configuration["Auth:GoogleClientId"] ?? "").Trim();

var jwtKey = (builder.Configuration["Auth:JwtKey"] ?? "").Trim();
var ephemeralJwtKey = false;
if (string.IsNullOrWhiteSpace(jwtKey))
{
    if (requireAuth)
        throw new InvalidOperationException("Auth is required but Auth:JwtKey is not configured.");

    jwtKey = Convert.ToBase64String(RandomNumberGenerator.GetBytes(64));
    builder.Configuration.AddInMemoryCollection(new Dictionary<string, string?> { ["Auth:JwtKey"] = jwtKey });
    ephemeralJwtKey = true;
}

var issuer = (builder.Configuration["Auth:JwtIssuer"] ?? "JobTrackerApi").Trim();
var audience = (builder.Configuration["Auth:JwtAudience"] ?? "job-tracker-ui").Trim();

builder.Services.AddAuthentication(options =>
    {
        options.DefaultScheme = "smart";
        options.DefaultChallengeScheme = "smart";
    })
    .AddPolicyScheme("smart", "Smart JWT", options =>
    {
        options.ForwardDefaultSelector = ctx =>
        {
            if (string.IsNullOrWhiteSpace(googleClientId))
                return "local";

            var auth = ctx.Request.Headers.Authorization.ToString();
            if (!auth.StartsWith("Bearer ", StringComparison.OrdinalIgnoreCase))
                return "local";

            var token = auth["Bearer ".Length..].Trim();
            var handler = new JwtSecurityTokenHandler();
            if (!handler.CanReadToken(token))
                return "local";

            try
            {
                var jwt = handler.ReadJwtToken(token);
                var iss = jwt.Issuer ?? "";
                return iss is "accounts.google.com" or "https://accounts.google.com"
                    ? "google"
                    : "local";
            }
            catch
            {
                return "local";
            }
        };
    })
    .AddJwtBearer("local", options =>
    {
        options.Events = new JwtBearerEvents
        {
            OnMessageReceived = context =>
            {
                if (!string.IsNullOrWhiteSpace(context.Token))
                {
                    return Task.CompletedTask;
                }

                if (context.Request.Cookies.TryGetValue(AuthSessionOptions.SessionCookieName, out var cookieToken) && !string.IsNullOrWhiteSpace(cookieToken))
                {
                    context.Token = cookieToken;
                }

                return Task.CompletedTask;
            }
        };
        options.TokenValidationParameters = new TokenValidationParameters
        {
            ValidateIssuer = true,
            ValidIssuer = issuer,
            ValidateAudience = true,
            ValidAudience = audience,
            ValidateIssuerSigningKey = true,
            IssuerSigningKey = new SymmetricSecurityKey(System.Text.Encoding.UTF8.GetBytes(jwtKey)),
            ValidateLifetime = true,
            ClockSkew = TimeSpan.FromMinutes(2),
            NameClaimType = System.Security.Claims.ClaimTypes.Name,
            RoleClaimType = System.Security.Claims.ClaimTypes.Role,
        };
    });

if (!string.IsNullOrWhiteSpace(googleClientId))
{
    builder.Services.AddAuthentication().AddJwtBearer("google", options =>
    {
        // Validate Google ID tokens (sent from the frontend) as bearer tokens.
        options.Authority = "https://accounts.google.com";
        options.TokenValidationParameters = new TokenValidationParameters
        {
            ValidateIssuer = true,
            ValidIssuers = new[] { "accounts.google.com", "https://accounts.google.com" },
            ValidateAudience = true,
            ValidAudience = googleClientId,
            ValidateLifetime = true,
        };
    });
}

builder.Services.AddAuthorization(options =>
{
    if (requireAuth)
    {
        options.FallbackPolicy = new AuthorizationPolicyBuilder()
            .RequireAuthenticatedUser()
            .Build();
    }
});

builder.Services.AddRateLimiter(options =>
{
    options.RejectionStatusCode = StatusCodes.Status429TooManyRequests;

    options.AddPolicy("auth-login", context =>
        RateLimitPartition.GetFixedWindowLimiter(
            partitionKey: $"login:{context.Connection.RemoteIpAddress?.ToString() ?? "unknown"}",
            factory: _ => new FixedWindowRateLimiterOptions
            {
                PermitLimit = 10,
                Window = TimeSpan.FromMinutes(5),
                QueueProcessingOrder = QueueProcessingOrder.OldestFirst,
                QueueLimit = 0,
            }));

    options.AddPolicy("auth-email", context =>
        RateLimitPartition.GetFixedWindowLimiter(
            partitionKey: $"email:{context.Connection.RemoteIpAddress?.ToString() ?? "unknown"}",
            factory: _ => new FixedWindowRateLimiterOptions
            {
                PermitLimit = 5,
                Window = TimeSpan.FromMinutes(15),
                QueueProcessingOrder = QueueProcessingOrder.OldestFirst,
                QueueLimit = 0,
            }));
});

var app = builder.Build();

if (ephemeralJwtKey)
{
    app.Logger.LogWarning("Auth:JwtKey was not configured. Generated an ephemeral key; local login tokens will be invalid after restart.");
}

var enableHttpsRedirect = app.Configuration.GetValue("HttpsRedirection:Enabled", false);
var enableHsts = app.Configuration.GetValue("HttpsRedirection:Hsts", false);
if (enableHsts) app.UseHsts();
if (enableHttpsRedirect) app.UseHttpsRedirection();

// Structured request logging for easy diagnosis.
app.Use(async (ctx, next) =>
{
    var sw = Stopwatch.StartNew();
    try
    {
        await next();
        sw.Stop();

        var sub = ctx.User?.Claims?.FirstOrDefault(c => c.Type is "sub" or "http://schemas.xmlsoap.org/ws/2005/05/identity/claims/nameidentifier")?.Value;
        app.Logger.LogInformation(
            "HTTP {Method} {Path} {StatusCode} {ElapsedMs}ms trace={TraceId} sub={Sub}",
            ctx.Request.Method,
            ctx.Request.Path.Value ?? "",
            ctx.Response.StatusCode,
            sw.ElapsedMilliseconds,
            ctx.TraceIdentifier,
            sub ?? ""
        );
    }
    catch (Exception ex)
    {
        sw.Stop();
        app.Logger.LogError(
            ex,
            "HTTP {Method} {Path} 500 {ElapsedMs}ms trace={TraceId}",
            ctx.Request.Method,
            ctx.Request.Path.Value ?? "",
            sw.ElapsedMilliseconds,
            ctx.TraceIdentifier
        );
        throw;
    }
});

await app.InitializeJobTrackerAsync();

app.UseCors("AllowReact");
app.UseRateLimiter();

app.Use(async (ctx, next) =>
{
    if (HttpMethods.IsGet(ctx.Request.Method) || HttpMethods.IsHead(ctx.Request.Method) || HttpMethods.IsOptions(ctx.Request.Method) || HttpMethods.IsTrace(ctx.Request.Method))
    {
        await next();
        return;
    }

    if (!ctx.Request.Cookies.ContainsKey(AuthSessionOptions.SessionCookieName))
    {
        await next();
        return;
    }

    if (ctx.Request.Path.StartsWithSegments("/api/auth/login")
        || ctx.Request.Path.StartsWithSegments("/api/auth/register")
        || ctx.Request.Path.StartsWithSegments("/api/auth/google/exchange")
        || ctx.Request.Path.StartsWithSegments("/api/auth/request-password-reset")
        || ctx.Request.Path.StartsWithSegments("/api/auth/reset-password")
        || ctx.Request.Path.StartsWithSegments("/api/auth/csrf"))
    {
        await next();
        return;
    }

    var csrfCookie = ctx.Request.Cookies[AuthSessionOptions.CsrfCookieName];
    var csrfHeader = ctx.Request.Headers[AuthSessionOptions.CsrfHeaderName].ToString();
    if (string.IsNullOrWhiteSpace(csrfCookie) || string.IsNullOrWhiteSpace(csrfHeader) || !string.Equals(csrfCookie, csrfHeader, StringComparison.Ordinal))
    {
        ctx.Response.StatusCode = StatusCodes.Status403Forbidden;
        await ctx.Response.WriteAsync("CSRF validation failed.");
        return;
    }

    await next();
});

app.UseAuthentication();
app.UseAuthorization();
app.MapControllers();

app.Run();