using w4c_workflows.Models.Nodes;

namespace w4c_workflows.Services.Nodes;

/// <summary>
/// Maps a blueprint type id to the <see cref="INodeExecutor"/> that can run it.
/// Blueprints may exist without an executor (catalogue-only, e.g. a connector
/// that is listed but not installed); the compiler and API decide how to surface
/// that, the registry only answers whether a runner exists.
/// </summary>
public class NodeExecutorRegistry
{
    private readonly IReadOnlyDictionary<string, INodeExecutor> _executors;

    public NodeExecutorRegistry(IEnumerable<INodeExecutor> executors)
    {
        var map = new Dictionary<string, INodeExecutor>(StringComparer.Ordinal);
        foreach (var executor in executors)
        {
            if (string.IsNullOrWhiteSpace(executor.Type))
                throw new InvalidOperationException("a node executor is missing its type id");
            if (!map.TryAdd(executor.Type, executor))
                throw new InvalidOperationException($"duplicate node executor for type '{executor.Type}'");
        }

        _executors = map;
    }

    public IReadOnlyCollection<string> Types => (IReadOnlyCollection<string>)_executors.Keys;

    public INodeExecutor? Resolve(string type)
        => _executors.TryGetValue(type, out var executor) ? executor : null;

    public bool CanRun(string type) => _executors.ContainsKey(type);

    public bool CanRun(NodeBlueprint blueprint) => CanRun(blueprint.Type);
}