package pool

import (
	"math/rand"
	"testing"
)

func TestHash_OrderIndependence(t *testing.T) {
	flags1 := []string{"--a", "1", "--b", "2", "--c", "3"}
	h1 := Hash("foo", flags1)

	for i := 0; i < 5; i++ {
		shuffled := make([]string, len(flags1))
		copy(shuffled, flags1)
		// Shuffle pairs (each pair is 2 tokens)
		pairs := make([][2]string, 0)
		for j := 0; j < len(shuffled); j += 2 {
			pairs = append(pairs, [2]string{shuffled[j], shuffled[j+1]})
		}
		rand.Shuffle(len(pairs), func(a, b int) { pairs[a], pairs[b] = pairs[b], pairs[a] })
		var flat []string
		for _, p := range pairs {
			flat = append(flat, p[0], p[1])
		}
		h := Hash("foo", flat)
		if h != h1 {
			t.Errorf("iteration %d: hash %s != %s for order %v", i, h, h1, flat)
		}
	}
}

func TestHash_SeparatorCollision(t *testing.T) {
	h1 := Hash("foo", []string{"--a\x1eb", "1"})
	h2 := Hash("foo", []string{"--ab", "1"})
	if h1 == h2 {
		t.Error("separator collision: hashes should differ")
	}
}

func TestHash_Length(t *testing.T) {
	h := Hash("model", []string{"--top-k", "20"})
	if len(h) != 16 {
		t.Errorf("expected 16 hex chars, got %d: %s", len(h), h)
	}
}

func TestHash_DifferentModels(t *testing.T) {
	h1 := Hash("model-a", []string{"--top-k", "20"})
	h2 := Hash("model-b", []string{"--top-k", "20"})
	if h1 == h2 {
		t.Error("different models should produce different hashes")
	}
}