package bans_test

import (
	"net/netip"
	"testing"
	"time"

	"sneak.berlin/go/smallwebwaf/internal/bans"
)

func TestBanWithoutACauseIsAnAdmins(t *testing.T) {
	t.Parallel()

	netblock := netip.MustParsePrefix("203.0.113.0/24")
	ledger := bans.New(defaultRules())
	ledger.Load([]bans.Ban{{Netblock: netblock, Start: midnight()}})

	if got := ledger.Bans(netblock)[0].Cause; got != bans.CauseAdmin {
		t.Errorf("the ban's cause is %q, want admin", got)
	}
}

func TestAdminsBansAreNeverDroppedAndDoNotCountTowardMaxBans(t *testing.T) {
	t.Parallel()

	rules := defaultRules()
	rules.MaxBans = 1
	ledger := bans.New(rules)
	adminsOnly := netip.MustParsePrefix("198.51.100.0/24")
	both := netip.MustParsePrefix("203.0.113.1/32")
	second := netip.MustParsePrefix("203.0.113.2/32")
	third := netip.MustParsePrefix("203.0.113.3/32")

	// Seen longest ago, a netblock with two of an admin's bans alone, and
	// then one with an admin's ban before a ban smallwebwaf made: the one
	// ban counted toward MaxBans.
	ledger.Load([]bans.Ban{
		{Netblock: adminsOnly, Start: midnight().Add(-3 * time.Hour), Cause: bans.CauseAdmin},
		{Netblock: adminsOnly, Start: midnight().Add(-2 * time.Hour), Cause: bans.CauseAdmin},
		{Netblock: both, Start: midnight().Add(-time.Hour), Cause: bans.CauseAdmin},
		{
			Netblock: both,
			Start:    midnight(),
			Expires:  midnight().Add(time.Hour),
			Cause:    bans.CauseLimit,
		},
	})
	wantBans(t, ledger, map[netip.Prefix]int{adminsOnly: 2, both: 2})

	// A new ban drops the ban smallwebwaf made, and only that one.
	ledger.BanForLimit(second, midnight(), bans.Notes{})
	wantBans(t, ledger, map[netip.Prefix]int{adminsOnly: 2, both: 1, second: 1})

	if ledger.Bans(both)[0].Cause != bans.CauseAdmin {
		t.Errorf("%s kept %+v, want the admin's ban", both, ledger.Bans(both))
	}

	// And the next drops that one.
	ledger.BanForLimit(third, midnight(), bans.Notes{})
	wantBans(t, ledger, map[netip.Prefix]int{adminsOnly: 2, both: 1, second: 0, third: 1})
}

func TestReasonOfTheBansSmallwebwafMakes(t *testing.T) {
	t.Parallel()

	ledger := bans.New(defaultRules())

	limit, _ := ledger.BanForLimit(netip.MustParsePrefix("203.0.113.1/32"), midnight(),
		bans.Notes{Limit: 1000, Window: "minute"})
	attack, _ := ledger.BanForAttack(netip.MustParsePrefix("203.0.113.2/32"), midnight(),
		bans.Notes{RuleID: "git-dir", Target: "path"})

	for _, tc := range []struct{ got, want string }{
		{limit.Reason, "requests per minute over the limit of 1000"},
		{attack.Reason, "matched the rule git-dir"},
	} {
		if tc.got != tc.want {
			t.Errorf("the reason is %q, want %q", tc.got, tc.want)
		}
	}
}

func TestLiftedBanForALimitRefusesNothingAndMakesNoBanLonger(t *testing.T) {
	t.Parallel()

	// An hour's ban lifted ten minutes after it started.
	netblock := netip.MustParsePrefix("203.0.113.9/32")
	lifted := bans.Ban{
		Netblock: netblock,
		Start:    midnight(),
		Expires:  midnight().Add(time.Hour),
		Cause:    bans.CauseLimit,
		Lifted:   midnight().Add(10 * time.Minute),
	}

	ledger := bans.New(defaultRules())
	ledger.Load([]bans.Ban{lifted})

	// While it would still last, it refuses nothing, and a limit broken
	// bans for an hour, as a first broken limit does; the lifted ban is
	// kept, and counted among the earlier bans.
	now := midnight().Add(30 * time.Minute)

	_, banned, _ := ledger.Check(netblock.Addr(), now)
	if banned {
		t.Error("the lifted ban refuses")
	}

	ban, _ := ledger.BanForLimit(netblock, now, bans.Notes{})
	if ban.Expires.Sub(ban.Start) != time.Hour ||
		ban.Notes.EarlierBans != (bans.EarlierBans{Limit: 1}) {
		t.Errorf("the next ban lasts %s with earlier bans %+v, want 1h and 1 for a limit",
			ban.Expires.Sub(ban.Start), ban.Notes.EarlierBans)
	}

	held := ledger.Bans(netblock)
	if len(held) != 2 || held[0] != lifted {
		t.Errorf("the ledger holds %+v, want the lifted ban and the new one", held)
	}
}

func TestLiftedBanForAnAttackRefusesNothingAndMakesNoBanLonger(t *testing.T) {
	t.Parallel()

	// A permanent ban for a clear sign of attack, lifted.
	netblock := netip.MustParsePrefix("203.0.113.9/32")
	ledger := bans.New(defaultRules())
	ledger.Load([]bans.Ban{{
		Netblock: netblock,
		Start:    midnight(),
		Cause:    bans.CauseAttack,
		Lifted:   midnight().Add(time.Hour),
	}})

	now := midnight().Add(2 * time.Hour)

	_, banned, _ := ledger.Find(netblock.Addr(), now)
	if banned {
		t.Error("the lifted ban refuses")
	}

	active, permanent := ledger.Count(now)
	if active != 0 || permanent != 0 {
		t.Errorf("%d bans are active and %d permanent, want none", active, permanent)
	}

	// The next clear sign of attack bans for seven days, as a first does.
	ban, _ := ledger.BanForAttack(netblock, now, bans.Notes{})
	if ban.Expires.Sub(ban.Start) != 7*day {
		t.Errorf("the next ban for an attack ends at %s, want seven days on", ban.Expires)
	}
}

func TestLoadEditCountsTheBansAnAdminMade(t *testing.T) {
	t.Parallel()

	ledger := bans.New(defaultRules())
	made, _ := ledger.BanForLimit(netip.MustParsePrefix("203.0.113.1/32"), midnight(),
		bans.Notes{})
	atStart := bans.Ban{
		Netblock: netip.MustParsePrefix("203.0.113.2/32"),
		Start:    midnight(),
	}

	// The bans read at the start were made before it.
	ledger.Load([]bans.Ban{made, atStart})

	if got := ledger.Made(bans.CauseAdmin); got != 0 {
		t.Fatalf("%d bans made by an admin after the start's, want none", got)
	}

	// The admin keeps the ban smallwebwaf made, keeps the one read at the
	// start, and adds one without a cause: that one alone is made.
	kept := made
	kept.Cause = bans.CauseAdmin
	added := bans.Ban{
		Netblock: netip.MustParsePrefix("203.0.113.3/32"),
		Start:    midnight(),
	}
	ledger.LoadEdit([]bans.Ban{kept, atStart, added})

	if ledger.Made(bans.CauseAdmin) != 1 || ledger.Made(bans.CauseLimit) != 1 {
		t.Errorf("%d bans made by an admin and %d for a limit, want 1 of each",
			ledger.Made(bans.CauseAdmin), ledger.Made(bans.CauseLimit))
	}
}

func TestAdminsBanIsMadeWhileAnotherLasts(t *testing.T) {
	t.Parallel()

	netblock := netip.MustParsePrefix("203.0.113.0/24")
	ledger := bans.New(defaultRules())

	// An hour's ban for a broken limit.
	ledger.BanForLimit(netblock, midnight(), bans.Notes{})
	wantChanged(t, ledger, true)

	// A minute later an admin bans the netblock for good, named by an
	// address in it: that ban is made, and counts the other among the
	// earlier bans.
	now := midnight().Add(time.Minute)
	want := bans.Ban{
		Netblock: netblock,
		Start:    now,
		Cause:    bans.CauseAdmin,
		Reason:   "probes for logins",
		Notes:    bans.Notes{EarlierBans: bans.EarlierBans{Limit: 1}},
	}

	got := ledger.BanForAdmin(netip.MustParsePrefix("203.0.113.9/24"), now, time.Time{},
		"probes for logins")
	if got != want {
		t.Errorf("the admin's ban is\n%+v\nwant\n%+v", got, want)
	}

	wantChanged(t, ledger, true)

	if made := ledger.Made(bans.CauseAdmin); made != 1 {
		t.Errorf("%d bans made by an admin, want 1", made)
	}

	// It refuses once the ban for the limit has ended.
	ban, banned, _ := ledger.Find(netblock.Addr(), midnight().Add(2*time.Hour))
	if !banned || ban != want {
		t.Errorf("after the limit's ban the netblock is under %+v (%t), want %+v",
			ban, banned, want)
	}
}

func TestLiftLiftsEveryActiveBanCoveringTheClient(t *testing.T) {
	t.Parallel()

	client := netip.MustParseAddr("203.0.113.9")
	own := netip.MustParsePrefix("203.0.113.9/32")
	wide := netip.MustParsePrefix("203.0.113.0/24")
	other := netip.MustParsePrefix("203.0.113.10/32")

	ledger := bans.New(defaultRules())
	ledger.Load([]bans.Ban{
		// Ended an hour ago.
		{
			Netblock: own, Start: midnight().Add(-2 * time.Hour),
			Expires: midnight().Add(-time.Hour), Cause: bans.CauseLimit,
		},
		// Active, on the client's address and on its /24.
		{
			Netblock: own, Start: midnight(), Expires: midnight().Add(time.Hour),
			Cause: bans.CauseLimit,
		},
		{Netblock: wide, Start: midnight(), Cause: bans.CauseAdmin},
		// Another client's.
		{Netblock: other, Start: midnight(), Cause: bans.CauseAdmin},
	})

	now := midnight().Add(time.Minute)

	lifted := ledger.Lift(client, now)
	if len(lifted) != 2 || lifted[0].Lifted != now || lifted[1].Lifted != now {
		t.Errorf("lifted %+v, want the two active bans covering the client", lifted)
	}

	wantChanged(t, ledger, true)

	if _, banned, _ := ledger.Check(client, now); banned {
		t.Error("the client is still banned")
	}

	if _, banned, _ := ledger.Check(other.Addr(), now); !banned {
		t.Error("the other client's ban was lifted")
	}

	// The lifted bans are kept, and the one that had ended is not lifted.
	covering := ledger.Covering(client)
	if len(covering) != 3 || covering[0].Netblock != wide ||
		!covering[1].Lifted.IsZero() || covering[2].Lifted != now {
		t.Errorf("the bans covering the client are %+v, want the /24's and both "+
			"of its own, the earlier not lifted", covering)
	}

	// With none active, nothing is lifted or changed.
	if lifted = ledger.Lift(client, now); len(lifted) != 0 {
		t.Errorf("lifted %+v again", lifted)
	}

	wantChanged(t, ledger, false)
}