package main

// RFC 5869 HKDF-SHA256 test vector harness.
// Proves that hkdf.Expand produces byte-identical output to the published
// vectors — i.e. that the realloc-leak refactor in web/common/crypto/hkdf
// did not alter observable behaviour.

import (
	"smesh.lol/web/common/crypto/hkdf"
	"smesh.lol/web/common/helpers"
)

type vec struct {
	name       string
	ikm        string
	salt       string
	info       string
	length     int
	expectPRK  string
	expectOKM  string
}

var vectors = []vec{
	{
		name:      "RFC5869 #1",
		ikm:       "0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b",
		salt:      "000102030405060708090a0b0c",
		info:      "f0f1f2f3f4f5f6f7f8f9",
		length:    42,
		expectPRK: "077709362c2e32df0ddc3f0dc47bba6390b6c73bb50f9c3122ec844ad7c2b3e5",
		expectOKM: "3cb25f25faacd57a90434f64d0362f2a2d2d0a90cf1a5a4c5db02d56ecc4c5bf34007208d5b887185865",
	},
	{
		name:      "RFC5869 #2 (82-byte OKM, 3 HMAC blocks)",
		ikm:       "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f",
		salt:      "606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f808182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3a4a5a6a7a8a9aaabacadaeaf",
		info:      "b0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6c7c8c9cacbcccdcecfd0d1d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9eaebecedeeeff0f1f2f3f4f5f6f7f8f9fafbfcfdfeff",
		length:    82,
		expectPRK: "06a6b88c5853361a06104c9ceb35b45cef760014904671014a193f40c15fc244",
		expectOKM: "b11e398dc80327a1c8e7f78c596a49344f012eda2d4efad8a050cc4c19afa97c59045a99cac7827271cb41c65e590e09da3275600c2f09b8367793a9aca3db71cc30c58179ec3e87c14c01d5c1f3434f1d87",
	},
	{
		name:      "RFC5869 #3 (no salt, no info)",
		ikm:       "0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b",
		salt:      "",
		info:      "",
		length:    42,
		expectPRK: "19ef24a32c717b167f33a91d6f648bdf96596776afdb6377ac434c1c293ccb04",
		expectOKM: "8da4e775a563c18f715f802a063c5a31b8a11f5c5ee1879ec3454e5f3c738d2d9d201395faa4b61a96c8",
	},
}

func main() {
	pass := 0
	fail := 0
	for i := 0; i < len(vectors); i++ {
		v := vectors[i]
		ikm := helpers.HexDecode(v.ikm)
		salt := helpers.HexDecode(v.salt)
		info := helpers.HexDecode(v.info)

		prk := hkdf.Extract(salt, ikm)
		prkHex := helpers.HexEncode(prk[:])
		if prkHex != v.expectPRK {
			println("FAIL", v.name, "PRK:")
			println("  got     ", prkHex)
			println("  expected", v.expectPRK)
			fail++
			continue
		}

		okm := hkdf.Expand(prk[:], info, v.length)
		okmHex := helpers.HexEncode(okm)
		if okmHex != v.expectOKM {
			println("FAIL", v.name, "OKM:")
			println("  got     ", okmHex)
			println("  expected", v.expectOKM)
			fail++
			continue
		}
		if len(okm) != v.length {
			println("FAIL", v.name, "length mismatch:", len(okm), "vs", v.length)
			fail++
			continue
		}
		println("PASS", v.name)
		pass++
	}
	println("---")
	println("total pass:", pass, "fail:", fail)
	if fail > 0 {
		panic("hkdf test vectors failed")
	}
}