// SPDX-FileCopyrightText: 2026 Echolot contributors
// SPDX-License-Identifier: GPL-3.0-or-later

package adminauth

import (
	"strings"
	"testing"
	"time"
)

// PBKDF2 at 600k iterations is slow on purpose, so these use a reduced count where the test is
// about logic rather than cost.
func fastCredential(t *testing.T, user, pass string) Credential {
	t.Helper()
	c, err := NewCredential(user, pass)
	if err != nil {
		t.Fatal(err)
	}
	return c
}

func TestVerifyAcceptsOnlyTheRightPair(t *testing.T) {
	c := fastCredential(t, "admin", "correct-horse-battery")

	if !c.Verify("admin", "correct-horse-battery") {
		t.Fatal("the correct credentials were rejected")
	}
	for _, tc := range []struct{ user, pass string }{
		{"admin", "wrong-password-here"},
		{"admin", ""},
		{"root", "correct-horse-battery"},
		{"", "correct-horse-battery"},
		{"ADMIN", "correct-horse-battery"}, // usernames are not case-folded
	} {
		if c.Verify(tc.user, tc.pass) {
			t.Errorf("accepted %q/%q", tc.user, tc.pass)
		}
	}
}

// Two credentials with the same password must not share a hash, or one cracked password reveals
// every reuse of it and a precomputed table works against all of them.
func TestSaltsDiffer(t *testing.T) {
	a := fastCredential(t, "admin", "the-same-password-x")
	b := fastCredential(t, "admin", "the-same-password-x")
	if a.Salt == b.Salt {
		t.Fatal("two credentials share a salt")
	}
	if a.Hash == b.Hash {
		t.Fatal("the same password produced the same hash twice")
	}
	// Both must still verify — a salt that is not actually used would also produce differing
	// hashes if it were mixed in wrongly.
	if !a.Verify("admin", "the-same-password-x") || !b.Verify("admin", "the-same-password-x") {
		t.Fatal("a salted credential does not verify")
	}
}

// The stored iteration count is used rather than the current constant, so raising the constant
// later does not silently lock out every existing password.
func TestOldIterationCountsStillVerify(t *testing.T) {
	c := fastCredential(t, "admin", "a-perfectly-fine-pw")
	c.Iterations = iterations // as stored
	if !c.Verify("admin", "a-perfectly-fine-pw") {
		t.Fatal("credential does not verify with its stored iteration count")
	}
	// A credential written before the field existed must not be treated as zero-iteration.
	c.Iterations = 0
	if !c.Verify("admin", "a-perfectly-fine-pw") {
		t.Fatal("a credential with no recorded iteration count failed to verify")
	}
}

func TestWeakInputsAreRefusedAtCreation(t *testing.T) {
	if _, err := NewCredential("", "long-enough-password"); err == nil {
		t.Error("an empty username was accepted")
	}
	if _, err := NewCredential("admin", "short"); err == nil {
		t.Error("a short password was accepted")
	}
}

func TestAnEmptyCredentialNeverVerifies(t *testing.T) {
	var zero Credential
	if zero.Verify("", "") {
		t.Fatal("a server with no local admin configured accepted empty credentials")
	}
	if zero.Verify("admin", "anything") {
		t.Fatal("an unset credential verified")
	}
}

// ---- sessions ----------------------------------------------------------------------------

func TestSessionRoundTrip(t *testing.T) {
	secret, _ := NewSecret()
	s := NewSessions(secret, time.Hour)
	got, err := s.Parse(s.Issue("local:admin", "Admin"))
	if err != nil {
		t.Fatal(err)
	}
	if got.Subject != "local:admin" || got.Display != "Admin" {
		t.Fatalf("session did not round-trip: %+v", got)
	}
}

// The cookie carries its own contents, so the MAC is the only thing standing between a user and
// promoting themselves. Every tampered form must fail.
func TestTamperedSessionsAreRejected(t *testing.T) {
	secret, _ := NewSecret()
	s := NewSessions(secret, time.Hour)
	good := s.Issue("local:admin", "Admin")

	parts := strings.Split(good, ".")
	tampered := []string{
		"",
		"garbage",
		good + "x", // signature altered
		strings.Replace(good, parts[0], "Zm9v", 1), // subject swapped
		strings.Join(parts[:len(parts)-1], "."),    // signature removed
		parts[0] + "." + parts[1] + "." + parts[2], // signature removed, well-formed payload
	}
	for _, v := range tampered {
		if _, err := s.Parse(v); err == nil {
			t.Errorf("accepted a tampered session: %q", v)
		}
	}
}

func TestSessionsFromAnotherSecretAreRejected(t *testing.T) {
	a, _ := NewSecret()
	b, _ := NewSecret()
	issued := NewSessions(a, time.Hour).Issue("local:admin", "Admin")
	if _, err := NewSessions(b, time.Hour).Parse(issued); err == nil {
		t.Fatal("a session signed with a different secret was accepted — rotating the secret " +
			"must invalidate every existing session")
	}
}

func TestExpiredSessionsAreRejected(t *testing.T) {
	secret, _ := NewSecret()
	// A negative TTL is not reachable through NewSessions, so issue with a real one and check
	// the boundary via a session that has already run out.
	s := NewSessions(secret, time.Millisecond)
	v := s.Issue("local:admin", "Admin")
	time.Sleep(10 * time.Millisecond)
	if _, err := s.Parse(v); err == nil {
		t.Fatal("an expired session was accepted")
	}
}

// ---- throttle ------------------------------------------------------------------------------

func TestThrottleGrowsWithFailuresAndResetsOnSuccess(t *testing.T) {
	tr := NewThrottle()
	if d := tr.Delay(); d != 0 {
		t.Fatalf("a first attempt was delayed by %v", d)
	}
	for i := 0; i < 2; i++ {
		tr.Failed()
	}
	first := tr.Delay()
	for i := 0; i < 6; i++ {
		tr.Failed()
	}
	later := tr.Delay()
	if !(later > first && first > 0) {
		t.Fatalf("delay did not grow with failures: %v then %v", first, later)
	}
	tr.Succeeded()
	if d := tr.Delay(); d != 0 {
		t.Fatalf("a successful login did not clear the throttle: %v", d)
	}
}

// A break-glass credential that an attacker can lock out is a denial of service against the one
// person who needs it. The delay must stay bounded rather than becoming a lockout.
func TestThrottleNeverLocksOutPermanently(t *testing.T) {
	tr := NewThrottle()
	for i := 0; i < 1000; i++ {
		tr.Failed()
	}
	if d := tr.Delay(); d > 10*time.Second {
		t.Fatalf("throttle became a lockout: %v", d)
	}
}

func TestThrottleForgivesAfterAQuietPeriod(t *testing.T) {
	tr := NewThrottle()
	now := time.Now()
	tr.now = func() time.Time { return now }
	for i := 0; i < 10; i++ {
		tr.Failed()
	}
	if tr.Delay() == 0 {
		t.Fatal("failures did not register")
	}
	now = now.Add(2 * time.Minute)
	if d := tr.Delay(); d != 0 {
		t.Fatalf("an operator returning later was still throttled: %v", d)
	}
}