package skillpack

import (
	"context"
	"errors"

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

// Activator adapts the battery to executus/run's SkillPackActivator port: given
// an agent's subscribed pack names, it resolves them to their pinned packs and
// returns the catalog instructions + the skill_use tool the run injects. It
// satisfies run.SkillPackActivator structurally — no import of run — so the
// battery stays run-agnostic (the same inversion as the other batteries).
//
// StagerFor, when set, builds the per-run BundleStager (a host plumbs bundled
// files into its own run-scoped storage from the run + subject ids); nil means
// skill_use lists a pack's bundled filenames without staging them.
type Activator struct {
	Cache     PackCache
	Subs      Store
	StagerFor func(runID, subjectID string) BundleStager
}

// ActivateSkillPacks implements run.SkillPackActivator. Unknown or disabled pack
// names are skipped; it returns "" + nil when nothing resolves.
func (a *Activator) ActivateSkillPacks(ctx context.Context, names []string, runID, subjectID string) (string, []llm.Tool, error) {
	if a == nil || a.Subs == nil || a.Cache == nil || len(names) == 0 {
		return "", nil, nil
	}
	chosen := make([]Subscription, 0, len(names))
	for _, n := range names {
		sub, err := a.Subs.GetByName(ctx, n)
		if errors.Is(err, ErrNotFound) {
			continue
		}
		if err != nil {
			return "", nil, err
		}
		if !sub.Enabled {
			continue
		}
		chosen = append(chosen, *sub)
	}
	packs, err := Resolve(ctx, a.Cache, chosen)
	if err != nil {
		return "", nil, err
	}
	var stager BundleStager
	if a.StagerFor != nil {
		stager = a.StagerFor(runID, subjectID)
	}
	sk := Activate(packs, stager)
	if sk == nil {
		return "", nil, nil
	}
	return sk.Instructions(), sk.Tools().Tools(), nil
}