using MongoDB.Bson;
using MongoDB.Driver;

namespace Htmx.ApiDemo.Data;

/// <summary>
/// Scoped service wrapping the AppUser MongoDB collection.
/// All operations use MongoDB's native async API — no EF, no LINQ-to-SQL
/// translation, no RelationalModel, fully NativeAOT safe.
/// </summary>
public sealed class MongoDbService
{
    private readonly IMongoCollection<AppUser> _users;

    public MongoDbService(IMongoClient client, IConfiguration configuration)
    {
        var db = client.GetDatabase(configuration["MongoDbName"] ?? "HtmxAppDb");
        _users = db.GetCollection<AppUser>("users");
    }

    /// <summary>Ensures the unique index on NormalizedEmail exists (idempotent).</summary>
    public async Task EnsureIndexesAsync(CancellationToken ct = default)
    {
        var indexKeys = Builders<AppUser>.IndexKeys.Ascending(u => u.NormalizedEmail);
        var indexOptions = new CreateIndexOptions { Unique = true, Name = "uq_normalizedEmail" };
        var model = new CreateIndexModel<AppUser>(indexKeys, indexOptions);
        await _users.Indexes.CreateOneAsync(model, cancellationToken: ct);
    }

    /// <summary>Returns true if a user with the given normalised email already exists.</summary>
    public async Task<bool> EmailExistsAsync(string normalizedEmail, CancellationToken ct = default)
    {
        var filter = Builders<AppUser>.Filter.Eq(u => u.NormalizedEmail, normalizedEmail);
        return await _users.Find(filter).AnyAsync(ct);
    }

    /// <summary>Returns the user matching the normalised email, or null.</summary>
    public async Task<AppUser?> FindByNormalizedEmailAsync(string normalizedEmail, CancellationToken ct = default)
    {
        var filter = Builders<AppUser>.Filter.Eq(u => u.NormalizedEmail, normalizedEmail);
        return await _users.Find(filter).FirstOrDefaultAsync(ct);
    }

    /// <summary>Inserts a new user document.</summary>
    public Task InsertAsync(AppUser user, CancellationToken ct = default) =>
        _users.InsertOneAsync(user, cancellationToken: ct);
}