using System.Text.Json;

namespace NucleicBroker;

/// <summary>
/// The `ai.generate` seam (docs/WINDOWS_PORT.md §9.2): Phi Silica via Windows AI Foundry is
/// WinRT-only, so hostd routes on-device-AI requests through this broker rather than a
/// second helper process. Capability-probed: on non-Copilot+ hardware (or off-Windows) the
/// provider is unavailable and hostd's Intelligence seam falls back to its heuristics —
/// identical UX to a Mac without Apple Intelligence.
/// </summary>
public interface IAiProvider
{
    bool IsAvailable { get; }
    /// <summary>Generate text for `prompt`; when `schema` is present the result must be JSON
    /// conforming to it (guided generation). Throws WslcError(AiUnavailable) when absent.</summary>
    Task<string> GenerateAsync(string prompt, JsonElement? schema, CancellationToken ct);
}

/// <summary>Default provider: no on-device model. The real Foundry-backed provider lands
/// with work item 16 behind the same interface.</summary>
public sealed class UnavailableAiProvider : IAiProvider
{
    public bool IsAvailable => false;

    public Task<string> GenerateAsync(string prompt, JsonElement? schema, CancellationToken ct) =>
        throw new WslcError(WslcError.AiUnavailable, "no on-device AI provider on this machine");
}