using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Logging;
using Mirea.Api.Security.Common;
using Mirea.Api.Security.Common.Domain;
using Mirea.Api.Security.Common.Interfaces;
using System;
using System.Security;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;

namespace Mirea.Api.Security.Services;

public class AuthService(ICacheService cache, IAccessToken accessTokenService, IRevokedToken revokedToken, ILogger<AuthService> logger, PasswordHashService passwordService)
{
    public TimeSpan Lifetime { private get; init; }
    public TimeSpan LifetimeFirstAuth { private get; init; }

    private static string GenerateRefreshToken() => Guid.NewGuid().ToString().Replace("-", "") +
                                                    GeneratorKey.GenerateString(32);
    private (string Token, DateTime ExpireIn) GenerateAccessToken(string userId) =>
        accessTokenService.GenerateToken(userId);

    private static string GetAuthCacheKey(string fingerprint) => $"{fingerprint}_auth_token";
    private static string GetFirstAuthCacheKey(string fingerprint) => $"{fingerprint}_auth_token_first";

    private Task SetAuthTokenDataToCache(AuthToken data, CancellationToken cancellation) =>
        cache.SetAsync(
            GetAuthCacheKey(data.Fingerprint),
            JsonSerializer.SerializeToUtf8Bytes(data),
            slidingExpiration: Lifetime,
            cancellationToken: cancellation);

    private Task RevokeAccessToken(string token) =>
        revokedToken.AddTokenToRevokedAsync(token, accessTokenService.GetExpireDateTime(token));

    private async Task VerifyUserOrThrowError(RequestContextInfo requestContext, User user, string password,
        CancellationToken cancellation = default)
    {
        if (passwordService.VerifyPassword(password, user.Salt, user.PasswordHash))
            return;

        var failedLoginCacheName = $"{requestContext.Fingerprint}_login_failed";
        var countFailedLogin = await cache.GetAsync<int?>(failedLoginCacheName, cancellation) ?? 1;
        var cacheSaveTime = TimeSpan.FromHours(1);

        await cache.SetAsync(failedLoginCacheName, countFailedLogin + 1, slidingExpiration: cacheSaveTime, cancellationToken: cancellation);

        if (countFailedLogin > 5)
        {
            logger.LogWarning(
                "Multiple failed login attempts detected for user ID {UserId} from IP {UserIp}. Attempt: #{AttemptNumber}. Possible account compromise.",
                user.Id,
                requestContext.Ip,
                countFailedLogin);

            throw new SecurityException($"There are many incorrect attempts to access the account. Try again after {(int)cacheSaveTime.TotalMinutes} minutes.");
        }

        logger.LogInformation(
            "Failed login attempt for user ID {UserId} from IP {UserIp} with User-Agent {UserAgent} and Fingerprint {Fingerprint} Attempt: #{AttemptNumber}.",
            user.Id,
            requestContext.Ip,
            requestContext.UserAgent,
            requestContext.Fingerprint,
            countFailedLogin);

        throw new SecurityException("Invalid username/email or password");
    }

    private async Task GenerateAuthTokensAsync(CookieOptionsParameters cookieOptions, HttpContext context, RequestContextInfo requestContext, string userId, CancellationToken cancellation = default)
    {
        var refreshToken = GenerateRefreshToken();
        var (token, expireIn) = GenerateAccessToken(userId);

        var authToken = new AuthToken(requestContext)
        {
            CreatedAt = DateTime.UtcNow,
            UserId = userId,
            AccessToken = token,
        };

        await SetAuthTokenDataToCache(authToken, cancellation);
        cookieOptions.SetCookie(context, CookieNames.AccessToken, token, expireIn);
        cookieOptions.SetCookie(context, CookieNames.RefreshToken, authToken.RefreshToken, DateTime.UtcNow.Add(Lifetime));

        logger.LogInformation(
            "Successful login attempt for user ID {UserId} from IP {UserIp} with User-Agent {UserAgent} and Fingerprint {Fingerprint}.",
            authToken.UserId,
            authToken.Ip,
            authToken.UserAgent,
            authToken.Fingerprint);
    }

    public async Task<bool> LoginAsync(CookieOptionsParameters cookieOptions, HttpContext context, string code, CancellationToken cancellation = default)
    {
        var requestContext = new RequestContextInfo(context, cookieOptions);

        var firstTokenAuth = await cache.GetAsync<FirstAuthToken?>(GetFirstAuthCacheKey(requestContext.Fingerprint), cancellationToken: cancellation)
                             ?? throw new SecurityException("The session time has expired");

        switch (firstTokenAuth.SecondFactor)
        {
            case SecondFactor.Totp:
                {
                    if (string.IsNullOrEmpty(firstTokenAuth.Secret))
                        throw new InvalidOperationException("The user's secrets for data processing were not transferred.");

                    var totp = new TotpService(firstTokenAuth.Secret);

                    if (!totp.VerifyToken(code))
                        throw new SecurityException("The entered code is incorrect.");
                }
                break;
            default:
                throw new InvalidOperationException("The system failed to understand the authorization method.");
        }

        await GenerateAuthTokensAsync(cookieOptions, context, requestContext, firstTokenAuth.UserId, cancellation);
        return true;
    }

    public async Task<bool> LoginAsync(CookieOptionsParameters cookieOptions, User user, HttpContext context, string password, CancellationToken cancellation = default)
    {
        var requestContext = new RequestContextInfo(context, cookieOptions);

        await VerifyUserOrThrowError(requestContext, user, password, cancellation);

        if (user.SecondFactor == SecondFactor.None)
        {
            await GenerateAuthTokensAsync(cookieOptions, context, requestContext, user.Id.ToString(), cancellation);
            return true;
        }

        var firstAuthToken = new FirstAuthToken(requestContext)
        {
            UserId = user.Id.ToString(),
            Secret = user.SecondFactorToken,
            SecondFactor = user.SecondFactor
        };

        await cache.SetAsync(GetFirstAuthCacheKey(requestContext.Fingerprint), firstAuthToken, absoluteExpirationRelativeToNow: LifetimeFirstAuth, cancellationToken: cancellation);

        return false;
    }

    public async Task RefreshTokenAsync(CookieOptionsParameters cookieOptions, HttpContext context, CancellationToken cancellation = default)
    {
        var requestContext = new RequestContextInfo(context, cookieOptions);
        var authToken = await cache.GetAsync<AuthToken>(GetAuthCacheKey(requestContext.Fingerprint), cancellation)
                        ?? throw new SecurityException("The session time has expired");

        if (authToken.RefreshToken != requestContext.RefreshToken ||
            authToken.UserAgent != requestContext.UserAgent &&
            authToken.Ip != requestContext.Ip)
        {
            await RevokeAccessToken(authToken.AccessToken);
            await cache.RemoveAsync(GetAuthCacheKey(requestContext.Fingerprint), cancellation);
            cookieOptions.DropCookie(context, CookieNames.AccessToken);
            cookieOptions.DropCookie(context, CookieNames.RefreshToken);

            logger.LogWarning("Token validation failed for user ID {UserId}. Invalid token used from IP {UserIp} with User-Agent {UserAgent} and Fingerprint {Fingerprint}. Possible account compromise. Reason: {Reason}.",
                authToken.UserId,
                authToken.Ip,
                authToken.UserAgent,
                authToken.Fingerprint,
                authToken.RefreshToken != requestContext.RefreshToken ?
                    $"Cached refresh token '{authToken.RefreshToken}' does not match the provided refresh token '{requestContext.RefreshToken}'" :
                    $"User-Agent '{authToken.UserAgent}' and IP '{authToken.Ip}' in cache do not match the provided User-Agent '{requestContext.UserAgent}' and IP '{requestContext.Ip}'");

            throw new SecurityException("The session time has expired");
        }

        var (token, expireIn) = GenerateAccessToken(authToken.UserId);
        await RevokeAccessToken(authToken.AccessToken);

        var newRefreshToken = GenerateRefreshToken();

        authToken.AccessToken = token;
        authToken.RefreshToken = newRefreshToken;

        await SetAuthTokenDataToCache(authToken, cancellation);
        cookieOptions.SetCookie(context, CookieNames.AccessToken, token, expireIn);
        cookieOptions.SetCookie(context, CookieNames.RefreshToken, authToken.RefreshToken, DateTime.UtcNow.Add(Lifetime));
    }

    public async Task LogoutAsync(CookieOptionsParameters cookieOptions, HttpContext context, CancellationToken cancellation = default)
    {
        var requestContext = new RequestContextInfo(context, cookieOptions);
        var authTokenStruct = await cache.GetAsync<AuthToken>(GetAuthCacheKey(requestContext.Fingerprint), cancellation);

        if (authTokenStruct == null)
            return;

        await RevokeAccessToken(authTokenStruct.AccessToken);
        await cache.RemoveAsync(requestContext.Fingerprint, cancellation);
        cookieOptions.DropCookie(context, CookieNames.AccessToken);
        cookieOptions.DropCookie(context, CookieNames.RefreshToken);
    }
}