using Agent.Core.Tasks;

namespace Agent.Core.Tests;

public sealed class TaskRegistryTests
{
    [Fact]
    public async Task Explicit_task_id_can_be_cancelled_and_observed_as_terminal()
    {
        var registry = new TaskRegistry();
        Guid taskId = Guid.NewGuid();
        TaskSnapshot queued = registry.Enqueue("work", null, null, requestedTaskId: taskId);
        Assert.Equal(taskId, queued.TaskId);
        Assert.True(registry.Cancel(taskId));
        TaskSnapshot terminal = await registry.WaitForTerminalAsync(taskId, TestContext.Current.CancellationToken);
        Assert.Equal(AgentTaskState.Cancelled, terminal.State);
        Assert.True(registry.GetCancellationToken(taskId).IsCancellationRequested);
    }

    [Fact]
    public void NewTaskGetsUniqueTaskAndSessionIds()
    {
        var registry = new TaskRegistry();
        TaskSnapshot first = registry.Enqueue("one", null, null);
        TaskSnapshot second = registry.Enqueue("two", null, 0.2);
        Assert.NotEqual(first.TaskId, second.TaskId);
        Assert.NotEqual(first.SessionId, second.SessionId);
        Assert.Equal(AgentTaskState.Queued, first.State);
    }

    [Fact]
    public void UnknownSessionIsRejected()
    {
        var registry = new TaskRegistry();
        Assert.Throws<KeyNotFoundException>(() => registry.Enqueue("request", Guid.NewGuid(), null));
    }

    [Fact]
    public void TerminalTaskCannotTransition()
    {
        var registry = new TaskRegistry();
        TaskSnapshot task = registry.Enqueue("request", null, null);
        Assert.True(registry.Transition(task.TaskId, AgentTaskState.Planning));
        Assert.True(registry.Transition(task.TaskId, AgentTaskState.Running));
        Assert.True(registry.Transition(task.TaskId, AgentTaskState.Completed));
        Assert.False(registry.Transition(task.TaskId, AgentTaskState.Running));
    }
}