package intentflow

import (
	"os"
	"strings"
	"sync"
)

// PlanTier is the intentflow rollout switch. It must not be stored on
// intent.ActionSpec or intent.FeatureFlags.
type PlanTier string

const (
	TierLegacy   PlanTier = "legacy"
	TierShadow   PlanTier = "shadow"
	TierAutoRead PlanTier = "auto_read"
	TierConfirm  PlanTier = "confirm"
	TierFull     PlanTier = "full"
)

type FeatureFlags struct {
	PlanTier PlanTier
}

var (
	flagsMu     sync.RWMutex
	activeFlags = defaultFeatureFlags()
)

func defaultFeatureFlags() FeatureFlags {
	return FeatureFlags{PlanTier: parsePlanTier(os.Getenv("MULTI_INTENT_PLAN_TIER"))}
}

func parsePlanTier(raw string) PlanTier {
	switch strings.ToLower(strings.TrimSpace(raw)) {
	case "", "legacy":
		return TierLegacy
	case "shadow":
		return TierShadow
	case "auto_read", "autoread":
		return TierAutoRead
	case "confirm":
		return TierConfirm
	case "full":
		return TierFull
	default:
		return TierLegacy
	}
}

func CurrentFeatureFlags() FeatureFlags {
	flagsMu.RLock()
	defer flagsMu.RUnlock()
	return activeFlags
}

func SetFeatureFlagsForTest(f FeatureFlags) {
	flagsMu.Lock()
	activeFlags = f
	flagsMu.Unlock()
}

func ResetFeatureFlagsForTest() {
	flagsMu.Lock()
	activeFlags = defaultFeatureFlags()
	flagsMu.Unlock()
}

// Allows reports whether the current (or supplied) tier may activate a policy row.
func (t PlanTier) Allows(min PlanTier) bool {
	return tierRank(t) >= tierRank(min)
}

func tierRank(t PlanTier) int {
	switch t {
	case TierLegacy:
		return 0
	case TierShadow:
		return 1
	case TierAutoRead:
		return 2
	case TierConfirm:
		return 3
	case TierFull:
		return 4
	default:
		return 0
	}
}