CBDDC/samples/ZB.MOM.WW.CBDDC.Sample.Console/SampleDbContext.cs

using System.Text.Json.Serialization;
using System.Security.Cryptography;
using System.Text;
using SurrealDb.Net;
using SurrealDb.Net.Models;
using ZB.MOM.WW.CBDDC.Persistence.Surreal;

namespace ZB.MOM.WW.CBDDC.Sample.Console;

public class SampleDbContext : IDisposable
{
    private const string UsersTable = "sample_users";
    private const string TodoListsTable = "sample_todo_lists";

    private readonly bool _ownsClient;

    /// <summary>
    /// Initializes a new instance of the <see cref="SampleDbContext"/> class.
    /// </summary>
    /// <param name="surrealEmbeddedClient">The embedded SurrealDB client.</param>
    /// <param name="schemaInitializer">The schema initializer.</param>
    public SampleDbContext(
        ICBDDCSurrealEmbeddedClient surrealEmbeddedClient,
        ICBDDCSurrealSchemaInitializer schemaInitializer)
    {
        SurrealEmbeddedClient = surrealEmbeddedClient ?? throw new ArgumentNullException(nameof(surrealEmbeddedClient));
        SchemaInitializer = schemaInitializer ?? throw new ArgumentNullException(nameof(schemaInitializer));

        Users = new SampleSurrealCollection<User>(UsersTable, u => u.Id, SurrealEmbeddedClient, SchemaInitializer);
        TodoLists = new SampleSurrealCollection<TodoList>(TodoListsTable, t => t.Id, SurrealEmbeddedClient, SchemaInitializer);
        OplogEntries = new SampleSurrealReadOnlyCollection<SampleOplogEntry>(
            CBDDCSurrealSchemaNames.OplogEntriesTable,
            SurrealEmbeddedClient,
            SchemaInitializer);
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="SampleDbContext"/> class.
    /// </summary>
    /// <param name="databasePath">The database path used for the embedded store.</param>
    public SampleDbContext(string databasePath)
    {
        string normalizedPath = NormalizeDatabasePath(databasePath);
        string suffix = ComputeDeterministicSuffix(normalizedPath);
        var options = new CBDDCSurrealEmbeddedOptions
        {
            Endpoint = "rocksdb://local",
            DatabasePath = normalizedPath,
            Namespace = $"cbddc_sample_{suffix}",
            Database = $"main_{suffix}"
        };

        SurrealEmbeddedClient = new CBDDCSurrealEmbeddedClient(options);

        _ownsClient = true;
        SchemaInitializer = new SampleSurrealSchemaInitializer(SurrealEmbeddedClient);

        Users = new SampleSurrealCollection<User>(UsersTable, u => u.Id, SurrealEmbeddedClient, SchemaInitializer);
        TodoLists = new SampleSurrealCollection<TodoList>(TodoListsTable, t => t.Id, SurrealEmbeddedClient, SchemaInitializer);
        OplogEntries = new SampleSurrealReadOnlyCollection<SampleOplogEntry>(
            CBDDCSurrealSchemaNames.OplogEntriesTable,
            SurrealEmbeddedClient,
            SchemaInitializer);
    }

    /// <summary>
    /// Gets the embedded SurrealDB client.
    /// </summary>
    public ICBDDCSurrealEmbeddedClient SurrealEmbeddedClient { get; }

    /// <summary>
    /// Gets the schema initializer.
    /// </summary>
    public ICBDDCSurrealSchemaInitializer SchemaInitializer { get; private set; }

    /// <summary>
    /// Gets the users collection.
    /// </summary>
    public SampleSurrealCollection<User> Users { get; private set; }

    /// <summary>
    /// Gets the todo lists collection.
    /// </summary>
    public SampleSurrealCollection<TodoList> TodoLists { get; private set; }

    /// <summary>
    /// Gets the operation log entries collection.
    /// </summary>
    public SampleSurrealReadOnlyCollection<SampleOplogEntry> OplogEntries { get; private set; }

    /// <summary>
    /// Ensures schema changes are applied before persisting updates.
    /// </summary>
    /// <param name="cancellationToken">A cancellation token.</param>
    public async Task SaveChangesAsync(CancellationToken cancellationToken = default)
    {
        await SchemaInitializer.EnsureInitializedAsync(cancellationToken);
    }

    /// <inheritdoc />
    public void Dispose()
    {
        Users.Dispose();
        TodoLists.Dispose();

        if (_ownsClient) SurrealEmbeddedClient.Dispose();
    }

    private static string NormalizeDatabasePath(string databasePath)
    {
        if (string.IsNullOrWhiteSpace(databasePath))
            throw new ArgumentException("Database path is required.", nameof(databasePath));

        return Path.GetFullPath(databasePath);
    }

    private static string ComputeDeterministicSuffix(string value)
    {
        byte[] bytes = SHA256.HashData(Encoding.UTF8.GetBytes(value));
        return Convert.ToHexString(bytes).ToLowerInvariant()[..12];
    }
}

public sealed class SampleSurrealSchemaInitializer : ICBDDCSurrealSchemaInitializer
{
    private const string SampleSchemaSql = """
                                           DEFINE TABLE OVERWRITE sample_users SCHEMALESS CHANGEFEED 7d;
                                           DEFINE TABLE OVERWRITE sample_todo_lists SCHEMALESS CHANGEFEED 7d;
                                           """;
    private readonly ICBDDCSurrealEmbeddedClient _client;
    private int _initialized;

    /// <summary>
    /// Initializes a new instance of the <see cref="SampleSurrealSchemaInitializer"/> class.
    /// </summary>
    /// <param name="client">The embedded SurrealDB client.</param>
    public SampleSurrealSchemaInitializer(ICBDDCSurrealEmbeddedClient client)
    {
        _client = client ?? throw new ArgumentNullException(nameof(client));
    }

    /// <inheritdoc />
    public async Task EnsureInitializedAsync(CancellationToken cancellationToken = default)
    {
        if (Volatile.Read(ref _initialized) == 1) return;
        await _client.InitializeAsync(cancellationToken);
        await _client.RawQueryAsync(SampleSchemaSql, cancellationToken: cancellationToken);
        Volatile.Write(ref _initialized, 1);
    }
}

public sealed class SampleSurrealCollection<TEntity> : ISurrealWatchableCollection<TEntity>, IDisposable
    where TEntity : class
{
    private readonly SurrealCollectionChangeFeed<TEntity> _changeFeed = new();
    private readonly ISurrealDbClient _client;
    private readonly Func<TEntity, string> _keySelector;
    private readonly ICBDDCSurrealSchemaInitializer _schemaInitializer;
    private readonly string _tableName;

    /// <summary>
    /// Initializes a new instance of the <see cref="SampleSurrealCollection{TEntity}"/> class.
    /// </summary>
    /// <param name="tableName">The backing table name.</param>
    /// <param name="keySelector">The key selector for entities.</param>
    /// <param name="surrealEmbeddedClient">The embedded SurrealDB client.</param>
    /// <param name="schemaInitializer">The schema initializer.</param>
    public SampleSurrealCollection(
        string tableName,
        Func<TEntity, string> keySelector,
        ICBDDCSurrealEmbeddedClient surrealEmbeddedClient,
        ICBDDCSurrealSchemaInitializer schemaInitializer)
    {
        if (string.IsNullOrWhiteSpace(tableName))
            throw new ArgumentException("Table name is required.", nameof(tableName));

        _tableName = tableName;
        _keySelector = keySelector ?? throw new ArgumentNullException(nameof(keySelector));
        _client = (surrealEmbeddedClient ?? throw new ArgumentNullException(nameof(surrealEmbeddedClient))).Client;
        _schemaInitializer = schemaInitializer ?? throw new ArgumentNullException(nameof(schemaInitializer));
    }

    /// <inheritdoc />
    public IDisposable Subscribe(IObserver<SurrealCollectionChange<TEntity>> observer)
    {
        return _changeFeed.Subscribe(observer);
    }

    /// <inheritdoc />
    public async Task InsertAsync(TEntity entity, CancellationToken cancellationToken = default)
    {
        await UpsertAsync(entity, cancellationToken);
    }

    /// <inheritdoc />
    public async Task UpdateAsync(TEntity entity, CancellationToken cancellationToken = default)
    {
        await UpsertAsync(entity, cancellationToken);
    }

    /// <inheritdoc />
    public async Task DeleteAsync(string id, CancellationToken cancellationToken = default)
    {
        if (string.IsNullOrWhiteSpace(id))
            throw new ArgumentException("Document id is required.", nameof(id));

        await EnsureReadyAsync(cancellationToken);
        await _client.Delete(RecordId.From(_tableName, id), cancellationToken);
        _changeFeed.PublishDelete(id);
    }

    /// <summary>
    /// Finds an entity by identifier.
    /// </summary>
    /// <param name="id">The entity identifier.</param>
    /// <returns>The matching entity when found; otherwise <see langword="null"/>.</returns>
    public TEntity? FindById(string id)
    {
        return FindByIdAsync(id).GetAwaiter().GetResult();
    }

    /// <summary>
    /// Finds an entity by identifier asynchronously.
    /// </summary>
    /// <param name="id">The entity identifier.</param>
    /// <param name="cancellationToken">A cancellation token.</param>
    /// <returns>The matching entity when found; otherwise <see langword="null"/>.</returns>
    public async Task<TEntity?> FindByIdAsync(string id, CancellationToken cancellationToken = default)
    {
        if (string.IsNullOrWhiteSpace(id))
            throw new ArgumentException("Document id is required.", nameof(id));

        await EnsureReadyAsync(cancellationToken);
        var record = await _client.Select<SampleEntityRecord<TEntity>>(RecordId.From(_tableName, id), cancellationToken);
        return record?.Entity;
    }

    /// <inheritdoc />
    public IEnumerable<TEntity> FindAll()
    {
        return FindAllAsync().GetAwaiter().GetResult();
    }

    /// <inheritdoc />
    public async Task<IReadOnlyList<TEntity>> FindAllAsync(CancellationToken cancellationToken = default)
    {
        await EnsureReadyAsync(cancellationToken);
        var rows = await _client.Select<SampleEntityRecord<TEntity>>(_tableName, cancellationToken);
        return rows?
                   .Where(r => r.Entity != null)
                   .Select(r => r.Entity!)
                   .ToList()
               ?? [];
    }

    /// <inheritdoc />
    public IEnumerable<TEntity> Find(Func<TEntity, bool> predicate)
    {
        ArgumentNullException.ThrowIfNull(predicate);
        return FindAll().Where(predicate);
    }

    /// <inheritdoc />
    public void Dispose()
    {
        _changeFeed.Dispose();
    }

    private async Task UpsertAsync(TEntity entity, CancellationToken cancellationToken)
    {
        ArgumentNullException.ThrowIfNull(entity);

        string key = _keySelector(entity);
        if (string.IsNullOrWhiteSpace(key))
            throw new InvalidOperationException("Entity key cannot be null or empty.");

        await EnsureReadyAsync(cancellationToken);
        await _client.Upsert<SampleEntityRecord<TEntity>, SampleEntityRecord<TEntity>>(
            RecordId.From(_tableName, key),
            new SampleEntityRecord<TEntity> { Entity = entity },
            cancellationToken);
        _changeFeed.PublishPut(entity, key);
    }

    private async Task EnsureReadyAsync(CancellationToken cancellationToken)
    {
        await _schemaInitializer.EnsureInitializedAsync(cancellationToken);
    }
}

public sealed class SampleSurrealReadOnlyCollection<TEntity>
    where TEntity : class
{
    private readonly ISurrealDbClient _client;
    private readonly ICBDDCSurrealSchemaInitializer _schemaInitializer;
    private readonly string _tableName;

    /// <summary>
    /// Initializes a new instance of the <see cref="SampleSurrealReadOnlyCollection{TEntity}"/> class.
    /// </summary>
    /// <param name="tableName">The backing table name.</param>
    /// <param name="surrealEmbeddedClient">The embedded SurrealDB client.</param>
    /// <param name="schemaInitializer">The schema initializer.</param>
    public SampleSurrealReadOnlyCollection(
        string tableName,
        ICBDDCSurrealEmbeddedClient surrealEmbeddedClient,
        ICBDDCSurrealSchemaInitializer schemaInitializer)
    {
        if (string.IsNullOrWhiteSpace(tableName))
            throw new ArgumentException("Table name is required.", nameof(tableName));

        _tableName = tableName;
        _client = (surrealEmbeddedClient ?? throw new ArgumentNullException(nameof(surrealEmbeddedClient))).Client;
        _schemaInitializer = schemaInitializer ?? throw new ArgumentNullException(nameof(schemaInitializer));
    }

    /// <summary>
    /// Returns all entities from the collection.
    /// </summary>
    /// <returns>The entities in the collection.</returns>
    public IEnumerable<TEntity> FindAll()
    {
        return FindAllAsync().GetAwaiter().GetResult();
    }

    /// <summary>
    /// Returns all entities from the collection asynchronously.
    /// </summary>
    /// <param name="cancellationToken">A cancellation token.</param>
    /// <returns>The entities in the collection.</returns>
    public async Task<IReadOnlyList<TEntity>> FindAllAsync(CancellationToken cancellationToken = default)
    {
        await _schemaInitializer.EnsureInitializedAsync(cancellationToken);
        var rows = await _client.Select<TEntity>(_tableName, cancellationToken);
        return rows?.ToList() ?? [];
    }

    /// <summary>
    /// Returns entities that match the provided predicate.
    /// </summary>
    /// <param name="predicate">The predicate used to filter entities.</param>
    /// <returns>The entities that satisfy the predicate.</returns>
    public IEnumerable<TEntity> Find(Func<TEntity, bool> predicate)
    {
        ArgumentNullException.ThrowIfNull(predicate);
        return FindAll().Where(predicate);
    }
}

public sealed class SampleEntityRecord<TEntity> : Record
    where TEntity : class
{
    /// <summary>
    /// Gets or sets the stored entity payload.
    /// </summary>
    [JsonPropertyName("entity")]
    public TEntity? Entity { get; set; }
}

public sealed class SampleOplogEntry : Record
{
    /// <summary>
    /// Gets or sets the collection name.
    /// </summary>
    [JsonPropertyName("collection")]
    public string Collection { get; set; } = "";

    /// <summary>
    /// Gets or sets the entity key.
    /// </summary>
    [JsonPropertyName("key")]
    public string Key { get; set; } = "";

    /// <summary>
    /// Gets or sets the operation code.
    /// </summary>
    [JsonPropertyName("operation")]
    public int Operation { get; set; }

    /// <summary>
    /// Gets or sets the node identifier portion of the timestamp.
    /// </summary>
    [JsonPropertyName("timestampNodeId")]
    public string TimestampNodeId { get; set; } = "";

    /// <summary>
    /// Gets or sets the physical time portion of the timestamp.
    /// </summary>
    [JsonPropertyName("timestampPhysicalTime")]
    public long TimestampPhysicalTime { get; set; }

    /// <summary>
    /// Gets or sets the logical counter portion of the timestamp.
    /// </summary>
    [JsonPropertyName("timestampLogicalCounter")]
    public int TimestampLogicalCounter { get; set; }

    /// <summary>
    /// Gets or sets the hash for the operation entry.
    /// </summary>
    [JsonPropertyName("hash")]
    public string Hash { get; set; } = "";
}