// FIXME: Update this file to be null safe and then delete the line below
#nullable disable

using System.Security.Claims;
using Bit.Core;
using Bit.Core.AdminConsole.Enums;
using Bit.Core.AdminConsole.OrganizationFeatures.Policies;
using Bit.Core.AdminConsole.Services;
using Bit.Core.Auth.Entities;
using Bit.Core.Auth.Enums;
using Bit.Core.Auth.Identity;
using Bit.Core.Auth.Models.Api.Response;
using Bit.Core.Auth.Repositories;
using Bit.Core.Context;
using Bit.Core.Entities;
using Bit.Core.Enums;
using Bit.Core.KeyManagement.Models.Api.Response;
using Bit.Core.KeyManagement.Queries.Interfaces;
using Bit.Core.Models.Api;
using Bit.Core.Models.Api.Response;
using Bit.Core.Repositories;
using Bit.Core.Services;
using Bit.Core.Settings;
using Bit.Core.Utilities;
using Duende.IdentityServer.Validation;
using Microsoft.AspNetCore.Identity;

namespace Bit.Identity.IdentityServer.RequestValidators;

public abstract class BaseRequestValidator<T> where T : class
{
    private UserManager<User> _userManager;
    private readonly IEventService _eventService;
    private readonly IDeviceValidator _deviceValidator;
    private readonly ITwoFactorAuthenticationValidator _twoFactorAuthenticationValidator;
    private readonly IOrganizationUserRepository _organizationUserRepository;
    private readonly ILogger _logger;
    private readonly GlobalSettings _globalSettings;
    private readonly IUserRepository _userRepository;
    private readonly IAuthRequestRepository _authRequestRepository;
    private readonly IMailService _mailService;

    protected ICurrentContext CurrentContext { get; }
    protected IPolicyService PolicyService { get; }
    protected IFeatureService FeatureService { get; }
    protected ISsoConfigRepository SsoConfigRepository { get; }
    protected IUserService _userService { get; }
    protected IUserDecryptionOptionsBuilder UserDecryptionOptionsBuilder { get; }
    protected IPolicyRequirementQuery PolicyRequirementQuery { get; }
    protected IUserAccountKeysQuery _accountKeysQuery { get; }

    public BaseRequestValidator(
        UserManager<User> userManager,
        IUserService userService,
        IEventService eventService,
        IDeviceValidator deviceValidator,
        ITwoFactorAuthenticationValidator twoFactorAuthenticationValidator,
        IOrganizationUserRepository organizationUserRepository,
        ILogger logger,
        ICurrentContext currentContext,
        GlobalSettings globalSettings,
        IUserRepository userRepository,
        IPolicyService policyService,
        IFeatureService featureService,
        ISsoConfigRepository ssoConfigRepository,
        IUserDecryptionOptionsBuilder userDecryptionOptionsBuilder,
        IPolicyRequirementQuery policyRequirementQuery,
        IAuthRequestRepository authRequestRepository,
        IMailService mailService,
        IUserAccountKeysQuery userAccountKeysQuery
        )
    {
        _userManager = userManager;
        _userService = userService;
        _eventService = eventService;
        _deviceValidator = deviceValidator;
        _twoFactorAuthenticationValidator = twoFactorAuthenticationValidator;
        _organizationUserRepository = organizationUserRepository;
        _logger = logger;
        CurrentContext = currentContext;
        _globalSettings = globalSettings;
        PolicyService = policyService;
        _userRepository = userRepository;
        FeatureService = featureService;
        SsoConfigRepository = ssoConfigRepository;
        UserDecryptionOptionsBuilder = userDecryptionOptionsBuilder;
        PolicyRequirementQuery = policyRequirementQuery;
        _authRequestRepository = authRequestRepository;
        _mailService = mailService;
        _accountKeysQuery = userAccountKeysQuery;
    }

    protected async Task ValidateAsync(T context, ValidatedTokenRequest request,
        CustomValidatorRequestContext validatorContext)
    {
        // 1. We need to check if the user's master password hash is correct.
        var valid = await ValidateContextAsync(context, validatorContext);
        var user = validatorContext.User;
        if (!valid)
        {
            await UpdateFailedAuthDetailsAsync(user);

            await BuildErrorResultAsync("Username or password is incorrect. Try again.", false, context, user);
            return;
        }

        // 2. Decide if this user belongs to an organization that requires SSO.
        validatorContext.SsoRequired = await RequireSsoLoginAsync(user, request.GrantType);
        if (validatorContext.SsoRequired)
        {
            SetSsoResult(context,
                new Dictionary<string, object>
                {
                    { "ErrorModel", new ErrorResponseModel("SSO authentication is required.") }
                });
            return;
        }

        // 3. Check if 2FA is required.
        (validatorContext.TwoFactorRequired, var twoFactorOrganization) =
            await _twoFactorAuthenticationValidator.RequiresTwoFactorAsync(user, request);

        // This flag is used to determine if the user wants a rememberMe token sent when
        // authentication is successful.
        var returnRememberMeToken = false;

        if (validatorContext.TwoFactorRequired)
        {
            var twoFactorToken = request.Raw["TwoFactorToken"];
            var twoFactorProvider = request.Raw["TwoFactorProvider"];
            var validTwoFactorRequest = !string.IsNullOrWhiteSpace(twoFactorToken) &&
                                        !string.IsNullOrWhiteSpace(twoFactorProvider);

            // 3a. Response for 2FA required and not provided state.
            if (!validTwoFactorRequest ||
                !Enum.TryParse(twoFactorProvider, out TwoFactorProviderType twoFactorProviderType))
            {
                var resultDict = await _twoFactorAuthenticationValidator
                                        .BuildTwoFactorResultAsync(user, twoFactorOrganization);
                if (resultDict == null)
                {
                    await BuildErrorResultAsync("No two-step providers enabled.", false, context, user);
                    return;
                }

                // Include Master Password Policy in 2FA response.
                resultDict.Add("MasterPasswordPolicy", await GetMasterPasswordPolicyAsync(user));
                SetTwoFactorResult(context, resultDict);
                return;
            }

            var twoFactorTokenValid =
                await _twoFactorAuthenticationValidator
                    .VerifyTwoFactorAsync(user, twoFactorOrganization, twoFactorProviderType, twoFactorToken);

            // 3b. Response for 2FA required but request is not valid or remember token expired state.
            if (!twoFactorTokenValid)
            {
                // The remember me token has expired.
                if (twoFactorProviderType == TwoFactorProviderType.Remember)
                {
                    var resultDict = await _twoFactorAuthenticationValidator
                                            .BuildTwoFactorResultAsync(user, twoFactorOrganization);

                    // Include Master Password Policy in 2FA response
                    resultDict.Add("MasterPasswordPolicy", await GetMasterPasswordPolicyAsync(user));
                    SetTwoFactorResult(context, resultDict);
                }
                else
                {
                    await SendFailedTwoFactorEmail(user, twoFactorProviderType);
                    await UpdateFailedAuthDetailsAsync(user);
                    await BuildErrorResultAsync("Two-step token is invalid. Try again.", true, context, user);
                }
                return;
            }

            // 3c. When the 2FA authentication is successful, we can check if the user wants a
            // rememberMe token.
            var twoFactorRemember = request.Raw["TwoFactorRemember"] == "1";
            // Check if the user wants a rememberMe token.
            if (twoFactorRemember
                // if the 2FA auth was rememberMe do not send another token.
                && twoFactorProviderType != TwoFactorProviderType.Remember)
            {
                returnRememberMeToken = true;
            }
        }

        // 4. Check if the user is logging in from a new device.
        var deviceValid = await _deviceValidator.ValidateRequestDeviceAsync(request, validatorContext);
        if (!deviceValid)
        {
            SetValidationErrorResult(context, validatorContext);
            await LogFailedLoginEvent(validatorContext.User, EventType.User_FailedLogIn);
            return;
        }

        // 5. Force legacy users to the web for migration.
        if (UserService.IsLegacyUser(user) && request.ClientId != "web")
        {
            await FailAuthForLegacyUserAsync(user, context);
            return;
        }

        // TODO: PM-24324 - This should be its own validator at some point.
        // 6. Auth request handling
        if (validatorContext.ValidatedAuthRequest != null)
        {
            validatorContext.ValidatedAuthRequest.AuthenticationDate = DateTime.UtcNow;
            await _authRequestRepository.ReplaceAsync(validatorContext.ValidatedAuthRequest);
        }

        await BuildSuccessResultAsync(user, context, validatorContext.Device, returnRememberMeToken);
    }

    protected async Task FailAuthForLegacyUserAsync(User user, T context)
    {
        await BuildErrorResultAsync(
            $"Legacy encryption without a userkey is no longer supported. To recover your account, please contact support",
            false, context, user);
    }

    protected abstract Task<bool> ValidateContextAsync(T context, CustomValidatorRequestContext validatorContext);


    /// <summary>
    /// Responsible for building the response to the client when the user has successfully authenticated.
    /// </summary>
    /// <param name="user">The authenticated user.</param>
    /// <param name="context">The current request context.</param>
    /// <param name="device">The device used for authentication.</param>
    /// <param name="sendRememberToken">Whether to send a 2FA remember token.</param>
    protected async Task BuildSuccessResultAsync(User user, T context, Device device, bool sendRememberToken)
    {
        await _eventService.LogUserEventAsync(user.Id, EventType.User_LoggedIn);

        var claims = this.BuildSubjectClaims(user, context, device);

        var customResponse = await BuildCustomResponse(user, context, device, sendRememberToken);

        await ResetFailedAuthDetailsAsync(user);

        // Once we've built the claims and custom response, we can set the success result.
        // We delegate this to the derived classes, as the implementation varies based on the grant type.
        await SetSuccessResult(context, user, claims, customResponse);
    }

    /// <summary>
    /// This does two things, it sets the error result for the current ValidatorContext _and_ it logs error.
    /// These two things should be seperated to maintain single concerns.
    /// </summary>
    /// <param name="message">Error message for the error result</param>
    /// <param name="twoFactorRequest">bool that controls how the error is logged</param>
    /// <param name="context">used to set the error result in the current validator</param>
    /// <param name="user">used to associate the failed login with a user</param>
    /// <returns>void</returns>
    [Obsolete("Consider using SetValidationErrorResult to set the validation result, and LogFailedLoginEvent " +
        "to log the failure.")]
    protected async Task BuildErrorResultAsync(string message, bool twoFactorRequest, T context, User user)
    {
        if (user != null)
        {
            await _eventService.LogUserEventAsync(user.Id,
                twoFactorRequest ? EventType.User_FailedLogIn2fa : EventType.User_FailedLogIn);
        }

        if (_globalSettings.SelfHosted)
        {
            _logger.LogWarning(Constants.BypassFiltersEventId,
                string.Format("Failed login attempt{0}{1}", twoFactorRequest ? ", 2FA invalid." : ".",
                    $" {CurrentContext.IpAddress}"));
        }

        await Task.Delay(2000); // Delay for brute force.
        SetErrorResult(context,
            new Dictionary<string, object> { { "ErrorModel", new ErrorResponseModel(message) } });
    }

    protected async Task LogFailedLoginEvent(User user, EventType eventType)
    {
        if (user != null)
        {
            await _eventService.LogUserEventAsync(user.Id, eventType);
        }

        if (_globalSettings.SelfHosted)
        {
            string formattedMessage;
            switch (eventType)
            {
                case EventType.User_FailedLogIn:
                    formattedMessage = string.Format("Failed login attempt. {0}", $" {CurrentContext.IpAddress}");
                    break;
                case EventType.User_FailedLogIn2fa:
                    formattedMessage = string.Format("Failed login attempt, 2FA invalid.{0}", $" {CurrentContext.IpAddress}");
                    break;
                default:
                    formattedMessage = "Failed login attempt.";
                    break;
            }
            _logger.LogWarning(Constants.BypassFiltersEventId, formattedMessage);
        }
        await Task.Delay(2000); // Delay for brute force.
    }

    [Obsolete("Consider using SetValidationErrorResult instead.")]
    protected abstract void SetTwoFactorResult(T context, Dictionary<string, object> customResponse);
    [Obsolete("Consider using SetValidationErrorResult instead.")]
    protected abstract void SetSsoResult(T context, Dictionary<string, object> customResponse);
    [Obsolete("Consider using SetValidationErrorResult instead.")]
    protected abstract void SetErrorResult(T context, Dictionary<string, object> customResponse);

    /// <summary>
    /// This consumes the ValidationErrorResult property in the CustomValidatorRequestContext and sets
    /// it appropriately in the response object for the token and grant validators.
    /// </summary>
    /// <param name="context">The current grant or token context</param>
    /// <param name="requestContext">The modified request context containing material used to build the response object</param>
    protected abstract void SetValidationErrorResult(T context, CustomValidatorRequestContext requestContext);
    protected abstract Task SetSuccessResult(T context, User user, List<Claim> claims,
        Dictionary<string, object> customResponse);

    protected abstract ClaimsPrincipal GetSubject(T context);

    /// <summary>
    /// Check if the user is required to authenticate via SSO. If the user requires SSO, but they are
    /// logging in using an API Key (client_credentials) then they are allowed to bypass the SSO requirement.
    /// If the GrantType is authorization_code or client_credentials we know the user is trying to login
    /// using the SSO flow so they are allowed to continue.
    /// </summary>
    /// <param name="user">user trying to login</param>
    /// <param name="grantType">magic string identifying the grant type requested</param>
    /// <returns>true if sso required; false if not required or already in process</returns>
    private async Task<bool> RequireSsoLoginAsync(User user, string grantType)
    {
        if (grantType == "authorization_code" || grantType == "client_credentials")
        {
            // Already using SSO to authenticate, or logging-in via api key to skip SSO requirement
            // allow to authenticate successfully
            return false;
        }

        // Check if user belongs to any organization with an active SSO policy
        var ssoRequired = FeatureService.IsEnabled(FeatureFlagKeys.PolicyRequirements)
            ? (await PolicyRequirementQuery.GetAsync<RequireSsoPolicyRequirement>(user.Id))
                .SsoRequired
            : await PolicyService.AnyPoliciesApplicableToUserAsync(
                user.Id, PolicyType.RequireSso, OrganizationUserStatusType.Confirmed);
        if (ssoRequired)
        {
            return true;
        }

        // Default - SSO is not required
        return false;
    }

    private async Task ResetFailedAuthDetailsAsync(User user)
    {
        // Early escape if db hit not necessary
        if (user == null || user.FailedLoginCount == 0)
        {
            return;
        }

        user.FailedLoginCount = 0;
        user.RevisionDate = DateTime.UtcNow;
        await _userRepository.ReplaceAsync(user);
    }

    private async Task UpdateFailedAuthDetailsAsync(User user)
    {
        if (user == null)
        {
            return;
        }

        var utcNow = DateTime.UtcNow;
        user.FailedLoginCount = ++user.FailedLoginCount;
        user.LastFailedLoginDate = user.RevisionDate = utcNow;
        await _userRepository.ReplaceAsync(user);
    }

    private async Task SendFailedTwoFactorEmail(User user, TwoFactorProviderType failedAttemptType)
    {
        if (FeatureService.IsEnabled(FeatureFlagKeys.FailedTwoFactorEmail))
        {
            await _mailService.SendFailedTwoFactorAttemptEmailAsync(user.Email, failedAttemptType, DateTime.UtcNow, CurrentContext.IpAddress);
        }
    }

    private async Task<MasterPasswordPolicyResponseModel> GetMasterPasswordPolicyAsync(User user)
    {
        // Check current context/cache to see if user is in any organizations, avoids extra DB call if not
        var orgs = (await CurrentContext.OrganizationMembershipAsync(_organizationUserRepository, user.Id))
            .ToList();

        if (orgs.Count == 0)
        {
            return null;
        }

        return new MasterPasswordPolicyResponseModel(await PolicyService.GetMasterPasswordPolicyForUserAsync(user));
    }

    /// <summary>
    /// Builds the claims that will be stored on the persisted grant.
    /// These claims are supplemented by the claims in the ProfileService when the access token is returned to the client.
    /// </summary>
    /// <param name="user">The authenticated user.</param>
    /// <param name="context">The current request context.</param>
    /// <param name="device">The device used for authentication.</param>
    private List<Claim> BuildSubjectClaims(User user, T context, Device device)
    {
        // We are adding the security stamp claim to the list of claims that will be stored in the persisted grant.
        // We need this because we check for changes in the stamp to determine if we need to invalidate token refresh requests,
        // in the `ProfileService.IsActiveAsync` method.
        // If we don't store the security stamp in the persisted grant, we won't have the previous value to compare against.
        var claims = new List<Claim>
        {
            new Claim(Claims.SecurityStamp, user.SecurityStamp)
        };

        if (device != null)
        {
            claims.Add(new Claim(Claims.Device, device.Identifier));
            claims.Add(new Claim(Claims.DeviceType, device.Type.ToString()));
        }
        return claims;
    }

    /// <summary>
    /// Builds the custom response that will be sent to the client upon successful authentication, which
    /// includes the information needed for the client to initialize the user's account in state.
    /// </summary>
    /// <param name="user">The authenticated user.</param>
    /// <param name="context">The current request context.</param>
    /// <param name="device">The device used for authentication.</param>
    /// <param name="sendRememberToken">Whether to send a 2FA remember token.</param>
    private async Task<Dictionary<string, object>> BuildCustomResponse(User user, T context, Device device, bool sendRememberToken)
    {
        var customResponse = new Dictionary<string, object>();
        if (!string.IsNullOrWhiteSpace(user.PrivateKey))
        {
            customResponse.Add("PrivateKey", user.PrivateKey);
            var accountKeys = await _accountKeysQuery.Run(user);
            customResponse.Add("AccountKeys", new PrivateKeysResponseModel(accountKeys));
        }

        if (!string.IsNullOrWhiteSpace(user.Key))
        {
            customResponse.Add("Key", user.Key);
        }

        customResponse.Add("MasterPasswordPolicy", await GetMasterPasswordPolicyAsync(user));
        customResponse.Add("ForcePasswordReset", user.ForcePasswordReset);
        customResponse.Add("ResetMasterPassword", string.IsNullOrWhiteSpace(user.MasterPassword));
        customResponse.Add("Kdf", (byte)user.Kdf);
        customResponse.Add("KdfIterations", user.KdfIterations);
        customResponse.Add("KdfMemory", user.KdfMemory);
        customResponse.Add("KdfParallelism", user.KdfParallelism);
        customResponse.Add("UserDecryptionOptions", await CreateUserDecryptionOptionsAsync(user, device, GetSubject(context)));

        if (sendRememberToken)
        {
            var token = await _userManager.GenerateTwoFactorTokenAsync(user,
                CoreHelpers.CustomProviderName(TwoFactorProviderType.Remember));
            customResponse.Add("TwoFactorToken", token);
        }
        return customResponse;
    }

#nullable enable
    /// <summary>
    /// Used to create a list of all possible ways the newly authenticated user can decrypt their vault contents
    /// </summary>
    private async Task<UserDecryptionOptions> CreateUserDecryptionOptionsAsync(User user, Device device, ClaimsPrincipal subject)
    {
        var ssoConfig = await GetSsoConfigurationDataAsync(subject);
        return await UserDecryptionOptionsBuilder
            .ForUser(user)
            .WithDevice(device)
            .WithSso(ssoConfig)
            .BuildAsync();
    }

    private async Task<SsoConfig?> GetSsoConfigurationDataAsync(ClaimsPrincipal subject)
    {
        var organizationClaim = subject?.FindFirstValue("organizationId");

        if (organizationClaim == null || !Guid.TryParse(organizationClaim, out var organizationId))
        {
            return null;
        }

        var ssoConfig = await SsoConfigRepository.GetByOrganizationIdAsync(organizationId);
        if (ssoConfig == null)
        {
            return null;
        }

        return ssoConfig;
    }
}