package flags

import (
	"testing"

	"github.com/google/uuid"
)

// nilStore returns enabled for everything — handy for hot paths where
// the store isn't wired (tests, init).
func TestNilStoreAllows(t *testing.T) {
	var s *Store
	if !s.Enabled("anything", uuid.New()) {
		t.Fatal("nil *Store must report Enabled=true so absent infra never disables behaviour")
	}
}

// Unknown keys default to enabled — the safe default for "we just
// added a gate; ship code first, write the row later if needed".
func TestUnknownKeyDefaultsOn(t *testing.T) {
	s := New(nil, nil)
	if !s.Enabled("never_seeded", uuid.New()) {
		t.Errorf("unknown key should be enabled by default")
	}
}

func TestExplicitlyDisabledKey(t *testing.T) {
	s := New(nil, nil)
	s.flags["kill"] = Flag{Key: "kill", Enabled: false, PercentRollout: 100}
	if s.Enabled("kill", uuid.New()) {
		t.Errorf("disabled flag must be off regardless of percent")
	}
}

func TestPercentRolloutZeroDisablesForUsers(t *testing.T) {
	s := New(nil, nil)
	s.flags["k"] = Flag{Key: "k", Enabled: true, PercentRollout: 0}
	if s.Enabled("k", uuid.New()) {
		t.Errorf("0%% rollout should be off for any user")
	}
}

// Stable bucketing — same (key, user) must always return the same
// decision so a user doesn't flap on and off across requests.
func TestPercentBucketIsStable(t *testing.T) {
	s := New(nil, nil)
	s.flags["k"] = Flag{Key: "k", Enabled: true, PercentRollout: 50}
	u := uuid.New()
	first := s.Enabled("k", u)
	for i := 0; i < 20; i++ {
		if s.Enabled("k", u) != first {
			t.Fatalf("flag decision for user %v flapped on iteration %d", u, i)
		}
	}
}

// Anonymous callers (uuid.Nil) skip percent-rollout splits — they're
// treated as the public path. Otherwise a 25%-rollout flag would 75%
// of the time refuse anonymous traffic, which is the wrong default
// for a public endpoint.
func TestAnonymousIsAlwaysOn(t *testing.T) {
	s := New(nil, nil)
	s.flags["k"] = Flag{Key: "k", Enabled: true, PercentRollout: 1}
	if !s.Enabled("k", uuid.Nil) {
		t.Errorf("uuid.Nil subject should be Enabled=true for partial rollouts")
	}
}