package run

import (
	"context"
	"log/slog"

	"gitea.stevedudenhoeffer.com/steve/majordomo/llm"
)

// FinalGuard is the optional host seam consulted when a single-loop run is
// about to finalize SUCCESSFULLY (the model produced a final answer and no run
// error occurred). It exists for the "announce-then-stop" failure: an agent
// renders an artifact into host storage, narrates "Done — sent you the file",
// and ends the run without ever calling the host's delivery tool — so nothing
// reaches the user while the final text claims otherwise (observed live:
// gifsmith run 29170c93 2026-07-12, general run e9e7bf40 2026-07-14).
//
// FinalNudge returns "" to let the run finish as-is (the overwhelmingly common
// case — the host should make its check cheap), or a non-empty nudge message.
// A non-empty nudge sends the loop back for ONE bounded extra round: the nudge
// is appended to the SAME conversation as the next user turn and the agent
// runs again with the same toolbox, capped at finalNudgeMaxSteps steps — enough
// to deliver a stranded artifact (or correct the final text), not enough to
// start a new project. The guard is consulted at most ONCE per run; the nudge
// round's own stop turn is final. Multi-phase runs are not guarded (their
// output contract is the phase pipeline's, not a delivery surface's).
//
// The call runs on the run goroutine, inside the run's deadline, and is
// panic-isolated: a guard panic is logged and treated as "" (the run's
// successful result must never be lost to a guard bug).
type FinalGuard interface {
	FinalNudge(ctx context.Context, info RunInfo, state FinalState) string
}

// FinalState is the snapshot a FinalGuard receives about the finishing run.
type FinalState struct {
	// Output is the run's final answer text (what the host would deliver).
	Output string
	// ToolNames lists the tools that were available to the run, so a guard can
	// skip nudging a run that has no way to act (e.g. no send_attachments).
	ToolNames []string
	// StagedFileIDs are the file ids the executor staged from the invocation's
	// input attachments (Ports.InputFiles). They live under the run's file scope
	// but are the USER's inputs, not run-produced artifacts — a guard checking
	// for undelivered artifacts must exclude them.
	StagedFileIDs []string
}

// finalNudgeMaxSteps caps the nudge round's tool-dispatch steps. Delivering a
// stranded artifact needs at most a file_list + a send_attachments + a final
// text turn; the cap keeps a model that misreads the nudge from launching a
// whole new work spree on the host's budget.
const finalNudgeMaxSteps = 6

// safeFinalNudge consults the guard behind a recover so a guard panic degrades
// to "no nudge" instead of converting a successful run into a panic-error (the
// executor's top-level recover would otherwise stamp res.Err).
func safeFinalNudge(ctx context.Context, g FinalGuard, info RunInfo, state FinalState) (nudge string) {
	defer func() {
		if r := recover(); r != nil {
			slog.Error("run: FinalGuard panicked; skipping nudge",
				"run_id", info.RunID, "panic", r)
			nudge = ""
		}
	}()
	return g.FinalNudge(ctx, info, state)
}

// toolboxNames flattens the run toolbox's tool names for FinalState (nil-safe).
func toolboxNames(b *llm.Toolbox) []string {
	if b == nil {
		return nil
	}
	tools := b.Tools()
	names := make([]string, 0, len(tools))
	for _, t := range tools {
		names = append(names, t.Name)
	}
	return names
}