package hash_test

import (
	"bytes"
	"testing"

	"git.akyoto.dev/go/hash"
)

var hashes = map[uint64][]byte{}

func TestTinyCollisions(t *testing.T) {
	for size := 1; size < 8; size++ {
		tmp := make([]byte, size)
		index := 0

		for i := 0; i < 256; i++ {
			tmp[index] += 1
			h := hash.Bytes(tmp)
			previous, found := hashes[h]

			if found && !bytes.Equal(tmp, previous) {
				t.Fatalf("collision between %v and %v:\nhash %064b", previous, tmp, h)
			}

			save := make([]byte, size)
			copy(save, tmp)
			hashes[h] = save
			index = (index + 1) % size
		}
	}
}

func TestZeroedCollisions(t *testing.T) {
	zero := make([]byte, 8192)

	for size := 1; size <= len(zero); size++ {
		tmp := zero[:size]
		h := hash.Bytes(tmp)
		previous, found := hashes[h]

		if found && !bytes.Equal(tmp, previous) {
			t.Fatalf("collision between %v and %v:\nhash %064b", previous, tmp, h)
		}

		hashes[h] = tmp
	}
}