package utils

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

/*
The invitation a newly onboarded merchant is emailed.

`setpassword` took a bare userid, which was safe only because the caller had to
reach it through a sign-in — `applogin` answers 409 with the userid for an
account that has no password, and nothing else hands one out.

Mailing that userid as a link changes the threat completely: userids are
sequential, so the link becomes a guessable capability. Walk low numbers and
claim any merchant onboarded but not yet set up, and you own a real business's
admin account. The empty-password check is no defence — an un-set-up account is
precisely what such an attacker is looking for.

So these tests are mostly about what the token REFUSES.
*/

const inviteSecret = "an-invitation-signing-secret-long-enough"

func inviteEnv(t *testing.T) {
	t.Helper()
	t.Setenv("POS_TOKEN_SECRET", inviteSecret)
}

func TestAnInvitationNamesTheAccountItWasIssuedFor(t *testing.T) {
	inviteEnv(t)
	now := time.Now()

	token, expires, err := MintInviteToken(InviteClaims{Userid: 904, Tenantid: 1147}, now)
	if err != nil {
		t.Fatalf("minting: %v", err)
	}

	claims, err := ParseInviteToken(token, now)
	if err != nil {
		t.Fatalf("parsing: %v", err)
	}
	if claims.Userid != 904 || claims.Tenantid != 1147 {
		t.Fatalf("claims came back as %+v", claims)
	}
	if expires.Sub(now) != InviteTokenTTL {
		t.Fatalf("expiry is %v, want %v", expires.Sub(now), InviteTokenTTL)
	}
}

func TestAnEditedInvitationIsRefused(t *testing.T) {
	// The whole point. If the payload could be edited, the link would be a
	// userid in a longer coat and every account would be one base64 edit away.
	inviteEnv(t)
	now := time.Now()

	token, _, err := MintInviteToken(InviteClaims{Userid: 904}, now)
	if err != nil {
		t.Fatalf("minting: %v", err)
	}

	// Re-sign nothing; just change the payload, which is what an attacker who
	// decoded the link and wanted a different userid would do.
	forged, _, err := MintInviteToken(InviteClaims{Userid: 905}, now)
	if err != nil {
		t.Fatalf("minting: %v", err)
	}
	parts := strings.Split(token, ".")
	other := strings.Split(forged, ".")
	swapped := parts[0] + "." + other[1] + "." + parts[2]

	if _, err := ParseInviteToken(swapped, now); err == nil {
		t.Fatal("a payload swapped under an old signature was accepted")
	}
}

func TestAnInvitationSignedWithAnotherSecretIsRefused(t *testing.T) {
	now := time.Now()

	t.Setenv("POS_TOKEN_SECRET", "one-secret-that-is-long-enough-here")
	token, _, err := MintInviteToken(InviteClaims{Userid: 904}, now)
	if err != nil {
		t.Fatalf("minting: %v", err)
	}

	t.Setenv("POS_TOKEN_SECRET", "a-different-secret-also-long-enough")
	if _, err := ParseInviteToken(token, now); err == nil {
		t.Fatal("an invitation from another deployment was accepted")
	}
}

func TestAnExpiredInvitationSaysWhatToDo(t *testing.T) {
	// The one failure here somebody can resolve themselves. "Not valid" would
	// send them to support; naming a resend sends them to whoever onboarded
	// them, which is where the fix actually is.
	inviteEnv(t)
	now := time.Now()

	token, _, err := MintInviteToken(InviteClaims{Userid: 904}, now)
	if err != nil {
		t.Fatalf("minting: %v", err)
	}

	_, err = ParseInviteToken(token, now.Add(InviteTokenTTL+time.Second))
	if err == nil {
		t.Fatal("an expired invitation was accepted")
	}
	// An expired invitation is the one failure here somebody can resolve
	// themselves, so it has to say how. "Invalid" would send them to support
	// instead of to whoever onboarded them.
	if !strings.Contains(err.Error(), "send another") {
		t.Fatalf("the refusal does not say what to do: %v", err)
	}
	// Read by a merchant on `/set-password`, not by a developer in a log. A
	// lowercase fragment in a red banner reads as something that leaked out.
	if !strings.HasPrefix(err.Error(), "This") || !strings.HasSuffix(err.Error(), ".") {
		t.Errorf("the refusal is not written as a sentence: %q", err)
	}
}

func TestAnInvitationIsNotASession(t *testing.T) {
	// They are the same shape signed with the same key. Without the prefix
	// check an invitation would verify as a console session — and it names a
	// userid with no role, no tenant check and a seven-day life, which is a far
	// weaker credential than a session and must never be usable as one.
	inviteEnv(t)
	now := time.Now()

	invite, _, err := MintInviteToken(InviteClaims{Userid: 904, Tenantid: 1147}, now)
	if err != nil {
		t.Fatalf("minting: %v", err)
	}

	if _, err := ParseWebToken(invite, now); err == nil {
		t.Fatal("an invitation was accepted as a console session")
	}
}

func TestASessionIsNotAnInvitation(t *testing.T) {
	// The other direction, which matters less but costs nothing to close: a
	// stolen session should not double as a password-reset link.
	inviteEnv(t)
	now := time.Now()

	session, _, err := MintWebToken(WebClaims{Userid: 904, Tenantid: 1147}, now)
	if err != nil {
		t.Fatalf("minting: %v", err)
	}

	if _, err := ParseInviteToken(session, now); err == nil {
		t.Fatal("a console session was accepted as an invitation")
	}
}

func TestRubbishIsRefusedWithoutPanicking(t *testing.T) {
	inviteEnv(t)
	now := time.Now()

	for _, bad := range []string{
		"", "   ", "i1.", "i1..", "i1.onlyonepart", "not-a-token",
		"i1.!!!not-base64!!!.signature", "w1.something.else",
	} {
		if _, err := ParseInviteToken(bad, now); err == nil {
			t.Fatalf("%q was accepted as an invitation", bad)
		}
	}
}

func TestAnInvitationMustNameSomebody(t *testing.T) {
	// A token naming nobody authorises nothing, and must not be mistaken for
	// one authorising everything — the same rule the session parser applies.
	inviteEnv(t)

	if _, _, err := MintInviteToken(InviteClaims{Userid: 0}, time.Now()); err == nil {
		t.Fatal("an invitation was minted for user 0")
	}
}

func TestNoSigningSecretMeansNoInvitations(t *testing.T) {
	// Rather than issuing something unverifiable. A deployment that cannot sign
	// cannot invite, and saying so at the point of minting is better than an
	// email whose link never works.
	t.Setenv("POS_TOKEN_SECRET", "")
	t.Setenv("JWT_SECRET_KEY", "")

	if _, _, err := MintInviteToken(InviteClaims{Userid: 904}, time.Now()); err == nil {
		t.Fatal("an invitation was minted with no signing secret")
	}
}