using TaskStatus = ClaudeDo.Data.Models.TaskStatus;

namespace ClaudeDo.Worker.External;

/// <summary>
/// Renders the `blockedReason` string shared by <see cref="ExternalMcpService"/> and
/// <see cref="TaskWaitMcpTools"/>. Lives here so the two can't drift on the wording an agent
/// parses.
/// </summary>
internal static class TaskBlocking
{
    /// <summary>
    /// The predecessors of <paramref name="dependencyIds"/> that have not reached Done — an id
    /// missing from <paramref name="statuses"/> counts as unmet (the picker treats a dangling
    /// edge as blocking too).
    /// </summary>
    public static List<(string Id, TaskStatus? Status)> Unmet(
        IEnumerable<string> dependencyIds, IReadOnlyDictionary<string, TaskStatus> statuses)
    {
        var unmet = new List<(string Id, TaskStatus? Status)>();
        foreach (var id in dependencyIds)
        {
            if (statuses.TryGetValue(id, out var status))
            {
                if (status != TaskStatus.Done) unmet.Add((id, status));
            }
            else
            {
                unmet.Add((id, null));
            }
        }
        return unmet;
    }

    /// <summary>Names every open predecessor, not just the first — a task can wait on n of them.</summary>
    public static string Describe(IReadOnlyList<(string Id, TaskStatus? Status)> unmet)
    {
        var noun = unmet.Count == 1 ? "task" : "tasks";
        var parts = unmet.Select(u => $"{u.Id} (status: {(u.Status?.ToString() ?? "not found")})");
        return $"Blocked: depends on {noun} {string.Join(", ", parts)}.";
    }
}