// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: PolyForm-Noncommercial-1.0.0

package password

import (
	"strings"
	"testing"
)

func TestHashAndVerifyRoundTrip(t *testing.T) {
	encoded, err := Hash("correct horse battery staple")
	if err != nil {
		t.Fatalf("Hash: %v", err)
	}
	if !strings.HasPrefix(encoded, "scrypt$16384$8$1$") {
		t.Fatalf("encoded = %q, want scrypt$16384$8$1$ prefix", encoded)
	}
	if !Verify("correct horse battery staple", encoded) {
		t.Fatal("Verify returned false for the correct password")
	}
	if Verify("wrong password", encoded) {
		t.Fatal("Verify returned true for a wrong password")
	}
}

func TestHashRejectsEmpty(t *testing.T) {
	if _, err := Hash(""); err != ErrEmpty {
		t.Fatalf("err = %v, want ErrEmpty", err)
	}
}

func TestHashRejectsTooLong(t *testing.T) {
	if _, err := Hash(strings.Repeat("x", MaxPasswordLength+1)); err == nil {
		t.Fatal("want error for over-long password")
	}
}

func TestVerifyRejectsMalformed(t *testing.T) {
	for _, encoded := range []string{
		"",
		"not-a-hash",
		"bcrypt$16384$8$1$c2FsdA==$aGFzaA==",
		"scrypt$16384$8$c2FsdA==$aGFzaA==",
		"scrypt$abc$8$1$c2FsdA==$aGFzaA==",
		"scrypt$16384$8$1$!!!notb64==$aGFzaA==",
	} {
		if Verify("secret", encoded) {
			t.Fatalf("Verify(%q) = true, want false", encoded)
		}
	}
}

func TestVerifyRejectsWeakParameters(t *testing.T) {
	// N=1024, r=8, p=1 with a well-formed 32-byte hash: below the floor.
	encoded := "scrypt$1024$8$1$c2FsdHNhbHRzYWx0c2E=$aGFzaGhhc2hoYXNoaGFzaGhhc2hoYXNoaGFzaA=="
	if Verify("secret", encoded) {
		t.Fatal("Verify accepted weak scrypt parameters")
	}
	if !NeedsRehash(encoded) {
		t.Fatal("NeedsRehash = false for weak parameters")
	}
}

func TestVerifyRejectsExcessiveMemory(t *testing.T) {
	// N and r parse and clear the floor, but 128*N*r exceeds the bound.
	encoded := "scrypt$1048576$1024$1$c2FsdHNhbHRzYWx0c2E=$aGFzaGhhc2hoYXNoaGFzaGhhc2hoYXNoaGFzaA=="
	if Verify("secret", encoded) {
		t.Fatal("Verify accepted an excessive-memory hash")
	}
}

func TestNeedsRehash(t *testing.T) {
	encoded, err := Hash("password123")
	if err != nil {
		t.Fatalf("Hash: %v", err)
	}
	if NeedsRehash(encoded) {
		t.Fatal("NeedsRehash = true for a current-policy hash")
	}
	if !NeedsRehash("garbage") {
		t.Fatal("NeedsRehash = false for garbage")
	}
}