using Microsoft.AspNetCore.Identity;
using Microsoft.Extensions.Options;
using MongoDB.Driver;
using WorkTracker.Configuration;

namespace WorkTracker.Services.Auth;

public sealed class MongoAuthService : IMongoAuthService
{
    private const string UsersCollectionName = "users";

    private readonly IMongoCollection<MongoAuthUser> users;
    private readonly PasswordHasher<MongoAuthUser> passwordHasher = new();
    private readonly IOptions<SingleUserOptions> options;
    private readonly ILogger<MongoAuthService> logger;

    public MongoAuthService(
        IMongoDatabase database,
        IOptions<SingleUserOptions> options,
        ILogger<MongoAuthService> logger)
    {
        users = database.GetCollection<MongoAuthUser>(UsersCollectionName);
        this.options = options;
        this.logger = logger;
    }

    public async Task EnsureSeedUserAsync(CancellationToken cancellationToken)
    {
        var email = options.Value.Email.Trim();
        var normalizedEmail = NormalizeEmail(email);

        var existingUser = await users
            .Find(x => x.EmailNormalized == normalizedEmail)
            .FirstOrDefaultAsync(cancellationToken);

        if (existingUser is not null)
        {
            return;
        }

        var user = new MongoAuthUser
        {
            Email = email,
            EmailNormalized = normalizedEmail,
            PasswordHash = string.Empty
        };

        var passwordHash = passwordHasher.HashPassword(user, options.Value.Password);
        var userToCreate = new MongoAuthUser
        {
            Email = email,
            EmailNormalized = normalizedEmail,
            PasswordHash = passwordHash
        };

        await users.InsertOneAsync(userToCreate, cancellationToken: cancellationToken);
        logger.LogInformation("Seeded single user account {Email} in MongoDB", email);
    }

    public async Task<MongoAuthUser?> ValidateCredentialsAsync(string email, string password, CancellationToken cancellationToken)
    {
        var normalizedEmail = NormalizeEmail(email);
        var user = await users
            .Find(x => x.EmailNormalized == normalizedEmail)
            .FirstOrDefaultAsync(cancellationToken);

        if (user is null)
        {
            return null;
        }

        var result = passwordHasher.VerifyHashedPassword(user, user.PasswordHash, password);
        return result == PasswordVerificationResult.Failed ? null : user;
    }

    private static string NormalizeEmail(string email) => email.Trim().ToUpperInvariant();
}