ServerManagementUtils/robin/Services/Persistence/PositionPersistenceService.cs

using System.Collections.Concurrent;
using System.Core.Extensions;
using System.Text.Json;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using Robin.Options;
using Robin.Serialization;

namespace Robin.Services.Persistence;

public sealed class PositionPersistenceService
{
    private readonly PositionPersistenceOptions options;
    private readonly ConcurrentDictionary<string, long> positions = new();

    public PositionPersistenceService(
        IOptions<PositionPersistenceOptions> options,
        ILogger<PositionPersistenceService> logger
    )
    {
        this.options = options.Value;
        this.options.FilePath.ThrowIfNull();

        try
        {
            if (File.Exists(this.options.FilePath))
            {
                this.positions =
                    JsonSerializer.Deserialize(
                        File.ReadAllText(this.options.FilePath),
                        SerializationContext.Default.ConcurrentDictionaryStringInt64
                    ) ?? new ConcurrentDictionary<string, long>();
            }
        }
        catch (Exception ex)
        {
            logger.LogError(ex, "Failed to load positions from file.");
        }

        this.positions ??= [];
    }

    public async ValueTask SavePositionAsync(
        string source,
        long position,
        CancellationToken cancellationToken
    )
    {
        this.positions[source] = position;
        await File.WriteAllTextAsync(
            this.options.FilePath.ThrowIfNull(),
            JsonSerializer.Serialize(
                this.positions,
                SerializationContext.Default.ConcurrentDictionaryStringInt64
            ),
            cancellationToken
        );
    }

    public long GetPosition(string source)
    {
        return this.positions.GetOrAdd(source, 0);
    }
}