package library

import (
	"math/rand/v2"
	"testing"
)

func randomPrint(r *rand.Rand, n int) []uint32 {
	out := make([]uint32, n)
	for i := range out {
		out[i] = r.Uint32()
	}
	return out
}

func TestSimilarity(t *testing.T) {
	r := rand.New(rand.NewPCG(1, 2))
	a := randomPrint(r, 950) // ~2 мин
	if s := Similarity(a, a); s != 1 {
		t.Fatalf("same print: %v", s)
	}

	// Перекодирование: другое вступление (сдвиг на 20 точек) и ~8% перевёрнутых бит.
	b := append(randomPrint(r, 20), a...)
	for i := range b {
		for bit := range 32 {
			if r.IntN(100) < 8 {
				b[i] ^= 1 << bit
			}
		}
	}
	if s := Similarity(a, b); s < SameRecording {
		t.Fatalf("re-encoded copy: %v < %v", s, SameRecording)
	}

	if s := Similarity(a, randomPrint(r, 950)); s >= SameRecording {
		t.Fatalf("different recordings: %v >= %v", s, SameRecording)
	}
	if s := Similarity(a, a[:40]); s != 0 {
		t.Fatalf("too short overlap must not match: %v", s)
	}
}

func TestParseFPCalc(t *testing.T) {
	fp, err := parseFPCalc([]byte(`{"duration": 215.4, "fingerprint": [4294967295, 1, 2]}`))
	if err != nil {
		t.Fatal(err)
	}
	if fp.DurationMs != 215400 || len(fp.Points) != 3 || fp.Points[0] != 4294967295 {
		t.Fatalf("parsed %+v", fp)
	}
	if fp.Prefix() != int64(-4294967295) { // 0xFFFFFFFF_00000001 как int64
		t.Fatalf("prefix %d", fp.Prefix())
	}
	if _, err := parseFPCalc([]byte(`{"duration": 1, "fingerprint": []}`)); err == nil {
		t.Fatal("empty fingerprint must fail")
	}
}