// Tests use a global viper instance for configuration,
// making parallel execution unsafe.
//
//nolint:paralleltest
package service_test

import (
	"context"
	"crypto/rand"
	"encoding/json"
	"errors"
	"fmt"
	"os"
	"slices"
	"strings"
	"sync"
	"testing"
	"time"

	"go.uber.org/fx"
	"go.uber.org/fx/fxtest"
	"golang.org/x/crypto/bcrypt"
	"sneak.berlin/go/neoirc/internal/broker"
	"sneak.berlin/go/neoirc/internal/config"
	"sneak.berlin/go/neoirc/internal/db"
	"sneak.berlin/go/neoirc/internal/globals"
	"sneak.berlin/go/neoirc/internal/logger"
	"sneak.berlin/go/neoirc/internal/service"
	"sneak.berlin/go/neoirc/pkg/irc"
)

func TestMain(m *testing.M) {
	db.SetBcryptCost(bcrypt.MinCost)
	os.Exit(m.Run())
}

// testEnv holds all dependencies for a service test.
type testEnv struct {
	svc    *service.Service
	db     *db.Database
	broker *broker.Broker
	app    *fxtest.App
}

func newTestEnv(t *testing.T) *testEnv {
	t.Helper()

	// A random name, so that no other test can share it, not
	// even one that has finished but still holds its database
	// open.
	dbURL := fmt.Sprintf(
		"file:%s?mode=memory&cache=shared",
		rand.Text(),
	)

	var (
		database *db.Database
		svc      *service.Service
	)

	brk := broker.New()

	app := fxtest.New(t,
		fx.Provide(
			func() *globals.Globals {
				return &globals.Globals{
					Appname:   "neoirc-test",
					Version:   "test",
					StartTime: time.Now(),
				}
			},
			logger.New,
			func(
				lifecycle fx.Lifecycle,
				globs *globals.Globals,
				log *logger.Logger,
			) (*config.Config, error) {
				cfg, err := config.New(
					lifecycle, config.Params{ //nolint:exhaustruct
						Globals: globs, Logger: log,
					},
				)
				if err != nil {
					return nil, fmt.Errorf(
						"test config: %w", err,
					)
				}

				cfg.DBURL = dbURL
				cfg.Port = 0
				cfg.OperName = "admin"
				cfg.OperPassword = "secret"

				return cfg, nil
			},
			func(
				lifecycle fx.Lifecycle,
				log *logger.Logger,
				cfg *config.Config,
			) (*db.Database, error) {
				return db.New(lifecycle, db.Params{ //nolint:exhaustruct
					Logger: log, Config: cfg,
				})
			},
			func() *broker.Broker { return brk },
			service.New,
		),
		fx.Populate(&database, &svc),
	)

	app.RequireStart()

	t.Cleanup(func() {
		app.RequireStop()
	})

	return &testEnv{
		svc:    svc,
		db:     database,
		broker: brk,
		app:    app,
	}
}

// createSession is a test helper that creates a session
// and returns the session ID.
func createSession(
	ctx context.Context,
	t *testing.T,
	database *db.Database,
	nick string,
) int64 {
	t.Helper()

	sessionID, _, _, err := database.CreateSession(
		ctx, nick, nick, "localhost", "127.0.0.1",
	)
	if err != nil {
		t.Fatalf("create session %s: %v", nick, err)
	}

	return sessionID
}

// TestEachTestEnvHasItsOwnDatabase checks that a test
// environment starts on an empty database while another one
// is still open.
func TestEachTestEnvHasItsOwnDatabase(t *testing.T) {
	ctx := t.Context()

	first := newTestEnv(t)
	createSession(ctx, t, first.db, "samenick")

	second := newTestEnv(t)
	createSession(ctx, t, second.db, "samenick")
}

func TestFanOut(t *testing.T) {
	env := newTestEnv(t)
	ctx := t.Context()

	sid1 := createSession(ctx, t, env.db, "alice")
	sid2 := createSession(ctx, t, env.db, "bob")

	body, _ := json.Marshal([]string{"hello"}) //nolint:errchkjson

	dbID, uuid, err := env.svc.FanOut(
		ctx, irc.CmdPrivmsg, "alice", "#test", 0, 0,
		nil, body, nil,
		[]int64{sid1, sid2},
	)
	if err != nil {
		t.Fatalf("FanOut: %v", err)
	}

	if dbID == 0 {
		t.Error("expected non-zero dbID")
	}

	if uuid == "" {
		t.Error("expected non-empty UUID")
	}
}

func TestJoinChannel(t *testing.T) {
	env := newTestEnv(t)
	ctx := t.Context()

	sid := createSession(ctx, t, env.db, "alice")

	result, err := env.svc.JoinChannel(
		ctx, sid, "alice", "#general", "",
	)
	if err != nil {
		t.Fatalf("JoinChannel: %v", err)
	}

	if result.ChannelID == 0 {
		t.Error("expected non-zero channel ID")
	}

	if !result.IsCreator {
		t.Error("first joiner should be creator")
	}

	// Second user joins — not creator.
	sid2 := createSession(ctx, t, env.db, "bob")

	result2, err := env.svc.JoinChannel(
		ctx, sid2, "bob", "#general", "",
	)
	if err != nil {
		t.Fatalf("JoinChannel bob: %v", err)
	}

	if result2.IsCreator {
		t.Error("second joiner should not be creator")
	}

	if result2.ChannelID != result.ChannelID {
		t.Error("both should join the same channel")
	}
}

func TestPartChannel(t *testing.T) {
	env := newTestEnv(t)
	ctx := t.Context()

	sid := createSession(ctx, t, env.db, "alice")

	_, err := env.svc.JoinChannel(
		ctx, sid, "alice", "#general", "",
	)
	if err != nil {
		t.Fatalf("JoinChannel: %v", err)
	}

	err = env.svc.PartChannel(
		ctx, sid, "alice", "#general", "bye",
	)
	if err != nil {
		t.Fatalf("PartChannel: %v", err)
	}

	// Parting a non-existent channel returns error.
	err = env.svc.PartChannel(
		ctx, sid, "alice", "#nonexistent", "",
	)
	if err == nil {
		t.Error("expected error for non-existent channel")
	}

	var ircErr *service.IRCError
	if !errors.As(err, &ircErr) {
		t.Errorf("expected IRCError, got %T", err)
	}
}

// concurrentJoinTrials is how many times each test of
// concurrent JOINs repeats its race. Before a JOIN ran as
// one transaction, ten trials lost each race every time.
const concurrentJoinTrials = 10

// runConcurrently runs each of funcs in its own goroutine,
// releasing them all at once, and returns their errors in
// the order of funcs.
func runConcurrently(funcs ...func() error) []error {
	start := make(chan struct{})
	errs := make([]error, len(funcs))

	var wg sync.WaitGroup

	for i, run := range funcs {
		wg.Add(1)

		go func() {
			defer wg.Done()

			<-start

			errs[i] = run()
		}()
	}

	close(start)
	wg.Wait()

	return errs
}

// joinConcurrently creates a session for each nick and has
// them all JOIN channel at once. It returns the result and
// error of each JOIN, in the order of nicks.
func joinConcurrently(
	ctx context.Context,
	t *testing.T,
	env *testEnv,
	channel string,
	nicks ...string,
) ([]*service.JoinResult, []error) {
	t.Helper()

	results := make([]*service.JoinResult, len(nicks))
	joins := make([]func() error, len(nicks))

	for i, nick := range nicks {
		sessionID := createSession(ctx, t, env.db, nick)

		joins[i] = func() error {
			result, err := env.svc.JoinChannel(
				ctx, sessionID, nick, channel, "",
			)
			results[i] = result

			return err
		}
	}

	return results, runConcurrently(joins...)
}

// TestConcurrentJoinsRespectUserLimit checks that of two
// concurrent JOINs of a +l 2 channel with one member, one
// gets in and the other gets ERR_CHANNELISFULL.
func TestConcurrentJoinsRespectUserLimit(t *testing.T) {
	const userLimit = 2

	env := newTestEnv(t)
	ctx := t.Context()

	for trial := range concurrentJoinTrials {
		channel := fmt.Sprintf("#full%d", trial)
		opNick := fmt.Sprintf("op%d", trial)
		opSID := createSession(ctx, t, env.db, opNick)

		created, err := env.svc.JoinChannel(
			ctx, opSID, opNick, channel, "",
		)
		if err != nil {
			t.Fatalf("join %s: %v", opNick, err)
		}

		err = env.db.SetChannelUserLimit(
			ctx, created.ChannelID, userLimit,
		)
		if err != nil {
			t.Fatalf("set +l: %v", err)
		}

		_, errs := joinConcurrently(
			ctx, t, env, channel,
			fmt.Sprintf("a%d", trial), fmt.Sprintf("b%d", trial),
		)

		refused := 0

		for _, joinErr := range errs {
			var ircErr *service.IRCError

			switch {
			case joinErr == nil:
			case errors.As(joinErr, &ircErr) &&
				ircErr.Code == irc.ErrChannelIsFull:
				refused++
			default:
				t.Errorf("trial %d: JOIN: %v", trial, joinErr)
			}
		}

		members, err := env.db.ChannelMembers(ctx, created.ChannelID)
		if err != nil {
			t.Fatalf("channel members: %v", err)
		}

		if len(members) != userLimit || refused != 1 {
			t.Errorf(
				"trial %d: %d members and %d refused, want %d and 1",
				trial, len(members), refused, userLimit,
			)
		}
	}
}

// TestConcurrentFirstJoinsMakeOneOperator checks that of
// two concurrent JOINs that create a channel, exactly one
// makes its session the operator.
func TestConcurrentFirstJoinsMakeOneOperator(t *testing.T) {
	env := newTestEnv(t)
	ctx := t.Context()

	for trial := range concurrentJoinTrials {
		results, errs := joinConcurrently(
			ctx, t, env, fmt.Sprintf("#new%d", trial),
			fmt.Sprintf("first%d", trial),
			fmt.Sprintf("second%d", trial),
		)

		creators := 0

		for i, err := range errs {
			if err != nil {
				t.Fatalf("trial %d: JOIN: %v", trial, err)
			}

			if results[i].IsCreator {
				creators++
			}
		}

		members, err := env.db.ChannelMembers(
			ctx, results[0].ChannelID,
		)
		if err != nil {
			t.Fatalf("channel members: %v", err)
		}

		operators := 0

		for _, member := range members {
			if member.IsOperator {
				operators++
			}
		}

		if creators != 1 || operators != 1 {
			t.Errorf(
				"trial %d: %d creators and %d operators, want 1 each",
				trial, creators, operators,
			)
		}
	}
}

// TestJoinConcurrentWithLastPart checks that a JOIN
// concurrent with the PART of a channel's only member
// either joins a channel that still exists or gets
// ERR_NOSUCHCHANNEL, and never fails otherwise.
func TestJoinConcurrentWithLastPart(t *testing.T) {
	env := newTestEnv(t)
	ctx := t.Context()

	for trial := range concurrentJoinTrials {
		channel := fmt.Sprintf("#last%d", trial)
		leaverNick := fmt.Sprintf("leaver%d", trial)
		leaverSID := createSession(ctx, t, env.db, leaverNick)
		joinerNick := fmt.Sprintf("joiner%d", trial)
		joinerSID := createSession(ctx, t, env.db, joinerNick)

		_, err := env.svc.JoinChannel(
			ctx, leaverSID, leaverNick, channel, "",
		)
		if err != nil {
			t.Fatalf("join %s: %v", leaverNick, err)
		}

		errs := runConcurrently(
			func() error {
				return env.svc.PartChannel(
					ctx, leaverSID, leaverNick, channel, "",
				)
			},
			func() error {
				_, joinErr := env.svc.JoinChannel(
					ctx, joinerSID, joinerNick, channel, "",
				)

				return joinErr
			},
		)
		if errs[0] != nil {
			t.Fatalf("trial %d: PART: %v", trial, errs[0])
		}

		var ircErr *service.IRCError

		switch {
		case errs[1] == nil:
			chID, lookupErr := env.db.GetChannelByName(ctx, channel)
			isMember, _ := env.db.IsChannelMember(ctx, chID, joinerSID)

			if lookupErr != nil || !isMember {
				t.Errorf(
					"trial %d: JOIN succeeded, but %s is not on %s",
					trial, joinerNick, channel,
				)
			}
		case errors.As(errs[1], &ircErr) &&
			ircErr.Code == irc.ErrNoSuchChannel:
		default:
			t.Errorf(
				"trial %d: JOIN got %v, want success or 403",
				trial, errs[1],
			)
		}
	}
}

// TestJoinConcurrentWithLastQuit checks that a user who
// sends JOIN without the key to a +k channel, again after
// each ERR_BADCHANNELKEY, while the channel's only member
// quits, gets in only once the channel is deleted, into a
// new channel of that name with no key.
func TestJoinConcurrentWithLastQuit(t *testing.T) {
	env := newTestEnv(t)
	ctx := t.Context()

	for trial := range concurrentJoinTrials {
		channel := fmt.Sprintf("#keyed%d", trial)
		leaverNick := fmt.Sprintf("leaver%d", trial)
		leaverSID := createSession(ctx, t, env.db, leaverNick)
		joinerNick := fmt.Sprintf("joiner%d", trial)
		joinerSID := createSession(ctx, t, env.db, joinerNick)

		created, err := env.svc.JoinChannel(
			ctx, leaverSID, leaverNick, channel, "",
		)
		if err != nil {
			t.Fatalf("join %s: %v", leaverNick, err)
		}

		err = env.db.SetChannelKey(ctx, created.ChannelID, "secret")
		if err != nil {
			t.Fatalf("set +k: %v", err)
		}

		var joined *service.JoinResult

		errs := runConcurrently(
			func() error {
				env.svc.BroadcastQuit(ctx, leaverSID, leaverNick, "")

				return nil
			},
			// The database has one connection, so retried
			// JOINs take turns with the QUIT's statements
			// and land between any two that are not in one
			// transaction. A JOIN after the QUIT gets in, so
			// the loop ends.
			func() error {
				for {
					var (
						joinErr error
						ircErr  *service.IRCError
					)

					joined, joinErr = env.svc.JoinChannel(
						ctx, joinerSID, joinerNick, channel, "",
					)
					if !errors.As(joinErr, &ircErr) ||
						ircErr.Code != irc.ErrBadChannelKey {
						return joinErr
					}
				}
			},
		)
		if errs[1] != nil {
			t.Fatalf("trial %d: JOIN: %v", trial, errs[1])
		}

		key, _ := env.db.GetChannelKey(ctx, joined.ChannelID)
		if key != "" {
			t.Errorf(
				"trial %d: %s got into +k %s without the key",
				trial, joinerNick, channel,
			)
		}
	}
}

// TestJoinUsesUpInvite checks that the JOIN an invite let
// into a +i channel uses the invite up, so that a JOIN
// after leaving gets ERR_INVITEONLYCHAN.
func TestJoinUsesUpInvite(t *testing.T) {
	const channel = "#club"

	env := newTestEnv(t)
	ctx := t.Context()

	opSID := createSession(ctx, t, env.db, "op")
	guestSID := createSession(ctx, t, env.db, "guest")

	created, err := env.svc.JoinChannel(ctx, opSID, "op", channel, "")
	if err != nil {
		t.Fatalf("join op: %v", err)
	}

	err = env.db.SetChannelInviteOnly(ctx, created.ChannelID, true)
	if err != nil {
		t.Fatalf("set +i: %v", err)
	}

	_, err = env.svc.InviteUser(ctx, opSID, "op", "guest", channel)
	if err != nil {
		t.Fatalf("invite guest: %v", err)
	}

	_, err = env.svc.JoinChannel(ctx, guestSID, "guest", channel, "")
	if err != nil {
		t.Fatalf("invited join: %v", err)
	}

	err = env.svc.PartChannel(ctx, guestSID, "guest", channel, "")
	if err != nil {
		t.Fatalf("part guest: %v", err)
	}

	_, err = env.svc.JoinChannel(ctx, guestSID, "guest", channel, "")

	var ircErr *service.IRCError
	if !errors.As(err, &ircErr) || ircErr.Code != irc.ErrInviteOnlyChan {
		t.Fatalf("second join: want ERR_INVITEONLYCHAN, got %v", err)
	}
}

// TestJoinRefusedByHostmaskBan checks that a ban naming a
// session's nick, username and hostname refuses its JOIN
// with ERR_BANNEDFROMCHAN.
func TestJoinRefusedByHostmaskBan(t *testing.T) {
	const channel = "#club"

	env := newTestEnv(t)
	ctx := t.Context()

	opSID := createSession(ctx, t, env.db, "op")

	created, err := env.svc.JoinChannel(ctx, opSID, "op", channel, "")
	if err != nil {
		t.Fatalf("join op: %v", err)
	}

	err = env.db.AddChannelBan(
		ctx, created.ChannelID, "guest!user@host.example", "op",
	)
	if err != nil {
		t.Fatalf("add ban: %v", err)
	}

	guestSID, _, _, err := env.db.CreateSession(
		ctx, "guest", "user", "host.example", "127.0.0.1",
	)
	if err != nil {
		t.Fatalf("create session guest: %v", err)
	}

	_, err = env.svc.JoinChannel(ctx, guestSID, "guest", channel, "")

	var ircErr *service.IRCError
	if !errors.As(err, &ircErr) || ircErr.Code != irc.ErrBannedFromChan {
		t.Fatalf("want ERR_BANNEDFROMCHAN, got %v", err)
	}
}

// TestPartDeletesChannelOnlyWhenEmpty checks that a PART
// keeps a channel other members are still on and deletes
// the channel when its last member parts.
func TestPartDeletesChannelOnlyWhenEmpty(t *testing.T) {
	const channel = "#room"

	env := newTestEnv(t)
	ctx := t.Context()

	aliceSID := createSession(ctx, t, env.db, "alice")
	bobSID := createSession(ctx, t, env.db, "bob")

	_, err := env.svc.JoinChannel(ctx, aliceSID, "alice", channel, "")
	if err != nil {
		t.Fatalf("join alice: %v", err)
	}

	_, err = env.svc.JoinChannel(ctx, bobSID, "bob", channel, "")
	if err != nil {
		t.Fatalf("join bob: %v", err)
	}

	err = env.svc.PartChannel(ctx, aliceSID, "alice", channel, "")
	if err != nil {
		t.Fatalf("part alice: %v", err)
	}

	chID, err := env.db.GetChannelByName(ctx, channel)
	if err != nil {
		t.Fatalf("channel gone while bob is on it: %v", err)
	}

	isMember, _ := env.db.IsChannelMember(ctx, chID, bobSID)
	if !isMember {
		t.Fatal("bob is not on the channel after alice parted")
	}

	err = env.svc.PartChannel(ctx, bobSID, "bob", channel, "")
	if err != nil {
		t.Fatalf("part bob: %v", err)
	}

	_, err = env.db.GetChannelByName(ctx, channel)
	if err == nil {
		t.Fatal("channel still exists after its last member parted")
	}
}

// TestKickOfLastMemberDeletesChannel checks that a KICK
// that leaves a channel with no members deletes it.
func TestKickOfLastMemberDeletesChannel(t *testing.T) {
	const channel = "#room"

	env := newTestEnv(t)
	ctx := t.Context()

	sid := createSession(ctx, t, env.db, "alice")

	_, err := env.svc.JoinChannel(ctx, sid, "alice", channel, "")
	if err != nil {
		t.Fatalf("join alice: %v", err)
	}

	err = env.svc.KickUser(ctx, sid, "alice", channel, "alice", "")
	if err != nil {
		t.Fatalf("kick alice: %v", err)
	}

	_, err = env.db.GetChannelByName(ctx, channel)
	if err == nil {
		t.Fatal("channel still exists after its last member was kicked")
	}
}

func TestSendChannelMessage(t *testing.T) {
	env := newTestEnv(t)
	ctx := t.Context()

	sid1 := createSession(ctx, t, env.db, "alice")
	sid2 := createSession(ctx, t, env.db, "bob")

	_, err := env.svc.JoinChannel(
		ctx, sid1, "alice", "#chat", "",
	)
	if err != nil {
		t.Fatalf("join alice: %v", err)
	}

	_, err = env.svc.JoinChannel(
		ctx, sid2, "bob", "#chat", "",
	)
	if err != nil {
		t.Fatalf("join bob: %v", err)
	}

	body, _ := json.Marshal([]string{"hello world"}) //nolint:errchkjson

	dbID, uuid, err := env.svc.SendChannelMessage(
		ctx, sid1, "alice",
		irc.CmdPrivmsg, "#chat", body, nil,
	)
	if err != nil {
		t.Fatalf("SendChannelMessage: %v", err)
	}

	if dbID == 0 {
		t.Error("expected non-zero dbID")
	}

	if uuid == "" {
		t.Error("expected non-empty UUID")
	}

	// Non-member cannot send.
	sid3 := createSession(ctx, t, env.db, "charlie")

	_, _, err = env.svc.SendChannelMessage(
		ctx, sid3, "charlie",
		irc.CmdPrivmsg, "#chat", body, nil,
	)
	if err == nil {
		t.Error("expected error for non-member send")
	}
}

func TestBroadcastQuit(t *testing.T) {
	env := newTestEnv(t)
	ctx := t.Context()

	sid1 := createSession(ctx, t, env.db, "alice")
	sid2 := createSession(ctx, t, env.db, "bob")

	_, err := env.svc.JoinChannel(
		ctx, sid1, "alice", "#room", "",
	)
	if err != nil {
		t.Fatalf("join alice: %v", err)
	}

	_, err = env.svc.JoinChannel(
		ctx, sid2, "bob", "#room", "",
	)
	if err != nil {
		t.Fatalf("join bob: %v", err)
	}

	// BroadcastQuit should not panic and should clean up.
	env.svc.BroadcastQuit(
		ctx, sid1, "alice", "Goodbye",
	)

	// Session should be deleted.
	_, lookupErr := env.db.GetSessionByNick(ctx, "alice")
	if lookupErr == nil {
		t.Error("expected session to be deleted after quit")
	}
}

// TestSendDirectMessageTargetQuits checks that a DM whose
// target quits after its nick is looked up gets the same
// error as a DM to an unknown nick. The trigger deletes the
// target's session just before the DM is stored.
func TestSendDirectMessageTargetQuits(t *testing.T) {
	env := newTestEnv(t)
	ctx := t.Context()

	sid := createSession(ctx, t, env.db, "alice")
	createSession(ctx, t, env.db, "bob")

	_, err := env.db.GetDB().ExecContext(ctx,
		`CREATE TRIGGER delete_recipient
		 BEFORE INSERT ON messages
		 BEGIN
		   DELETE FROM sessions WHERE id = NEW.to_session_id;
		 END`)
	if err != nil {
		t.Fatalf("create trigger: %v", err)
	}

	body, _ := json.Marshal([]string{"hi"}) //nolint:errchkjson

	_, err = env.svc.SendDirectMessage(
		ctx, sid, "alice", irc.CmdPrivmsg, "bob", body, nil,
	)

	var ircErr *service.IRCError
	if !errors.As(err, &ircErr) || ircErr.Code != irc.ErrNoSuchNick {
		t.Fatalf("want ERR_NOSUCHNICK, got %v", err)
	}
}

// TestSendChannelMessageChannelDeleted checks that a channel
// message whose channel is deleted after it is looked up gets
// the same error as a message to an unknown channel. The
// trigger deletes the channel just before the message is
// stored.
func TestSendChannelMessageChannelDeleted(t *testing.T) {
	env := newTestEnv(t)
	ctx := t.Context()

	sid := createSession(ctx, t, env.db, "alice")

	_, err := env.svc.JoinChannel(ctx, sid, "alice", "#gone", "")
	if err != nil {
		t.Fatalf("join alice: %v", err)
	}

	_, err = env.db.GetDB().ExecContext(ctx,
		`CREATE TRIGGER delete_recipient
		 BEFORE INSERT ON messages
		 BEGIN
		   DELETE FROM channels WHERE id = NEW.to_channel_id;
		 END`)
	if err != nil {
		t.Fatalf("create trigger: %v", err)
	}

	body, _ := json.Marshal([]string{"hi"}) //nolint:errchkjson

	_, _, err = env.svc.SendChannelMessage(
		ctx, sid, "alice", irc.CmdPrivmsg, "#gone", body, nil,
	)

	var ircErr *service.IRCError
	if !errors.As(err, &ircErr) ||
		ircErr.Code != irc.ErrNoSuchChannel {
		t.Fatalf("want ERR_NOSUCHCHANNEL, got %v", err)
	}
}

func TestSendChannelMessage_Moderated(t *testing.T) {
	env := newTestEnv(t)
	ctx := t.Context()

	sid1 := createSession(ctx, t, env.db, "alice")
	sid2 := createSession(ctx, t, env.db, "bob")

	result, err := env.svc.JoinChannel(
		ctx, sid1, "alice", "#modchat", "",
	)
	if err != nil {
		t.Fatalf("join alice: %v", err)
	}

	_, err = env.svc.JoinChannel(
		ctx, sid2, "bob", "#modchat", "",
	)
	if err != nil {
		t.Fatalf("join bob: %v", err)
	}

	// Set channel to moderated.
	chID := result.ChannelID
	_ = env.svc.SetChannelFlag(ctx, chID, 'm', true)

	body, _ := json.Marshal([]string{"test"}) //nolint:errchkjson

	// Bob (non-op, non-voiced) should fail to send.
	_, _, err = env.svc.SendChannelMessage(
		ctx, sid2, "bob",
		irc.CmdPrivmsg, "#modchat", body, nil,
	)
	if err == nil {
		t.Error("expected error for non-voiced user in moderated channel")
	}

	// Alice (operator) should succeed.
	_, _, err = env.svc.SendChannelMessage(
		ctx, sid1, "alice",
		irc.CmdPrivmsg, "#modchat", body, nil,
	)
	if err != nil {
		t.Errorf("operator should be able to send in moderated channel: %v", err)
	}
}

func TestQueryUserMode(t *testing.T) {
	env := newTestEnv(t)
	ctx := t.Context()

	sid := createSession(ctx, t, env.db, "alice")

	modes, err := env.svc.QueryUserMode(ctx, sid)
	if err != nil {
		t.Fatalf("query user mode: %v", err)
	}

	if modes != "+" {
		t.Errorf("expected +, got %s", modes)
	}

	setUserModes(ctx, t, env.db, sid, userModes{wallops: true})

	modes, err = env.svc.QueryUserMode(ctx, sid)
	if err != nil {
		t.Fatalf("query user mode: %v", err)
	}

	if modes != "+w" {
		t.Errorf("expected +w, got %s", modes)
	}

	setUserModes(
		ctx, t, env.db, sid, userModes{oper: true, wallops: true},
	)

	modes, err = env.svc.QueryUserMode(ctx, sid)
	if err != nil {
		t.Fatalf("query user mode: %v", err)
	}

	if modes != "+ow" {
		t.Errorf("expected +ow, got %s", modes)
	}

	// A flag that cannot be read is an error, not a flag
	// that is unset.
	cancelled, cancel := context.WithCancel(ctx)
	cancel()

	_, err = env.svc.QueryUserMode(cancelled, sid)
	if !errors.Is(err, context.Canceled) {
		t.Errorf("expected the read's error, got %v", err)
	}
}

func TestUserhostReply(t *testing.T) {
	env := newTestEnv(t)
	ctx := t.Context()

	createSession(ctx, t, env.db, "alice")
	bobID := createSession(ctx, t, env.db, "bob")

	// No username or hostname, and an operator.
	operID, _, _, err := env.db.CreateSession(
		ctx, "oper", "", "", "",
	)
	if err != nil {
		t.Fatal(err)
	}

	setUserModes(ctx, t, env.db, operID, userModes{oper: true})

	_, err = env.svc.SetAway(ctx, bobID, "gone fishing")
	if err != nil {
		t.Fatal(err)
	}

	reply, err := env.svc.UserhostReply(ctx, []string{
		"alice", "bob", "nobody", "oper",
	}, "srv")
	if err != nil {
		t.Fatal(err)
	}

	want := "alice=+alice@localhost bob=-bob@localhost " +
		"oper*=+oper@srv"
	if reply != want {
		t.Errorf("want %q, got %q", want, reply)
	}

	reply, err = env.svc.UserhostReply(
		ctx, slices.Repeat([]string{"bob"}, 6), "srv",
	)
	if err != nil {
		t.Fatal(err)
	}

	if strings.Count(reply, "bob=") != 5 {
		t.Errorf("want 5 entries for 6 nicks, got %q", reply)
	}

	// A nick that cannot be looked up is an error, not a nick
	// with no session.
	cancelled, cancel := context.WithCancel(ctx)
	cancel()

	_, err = env.svc.UserhostReply(cancelled, []string{"alice"}, "srv")
	if !errors.Is(err, context.Canceled) {
		t.Errorf("want the lookup's error, got %v", err)
	}
}

// userModes is the stored state of a session's user mode
// flags.
type userModes struct {
	oper    bool
	wallops bool
}

// applyUserModeTest is one mode string, the flags stored
// before it is applied, and the expected outcome. An empty
// wantModes means the string is rejected with
// ERR_UMODEUNKNOWNFLAG, and then after must equal before.
type applyUserModeTest struct {
	modeStr   string
	before    userModes
	wantModes string
	after     userModes
}

func applyUserModeTests() []applyUserModeTest {
	none := userModes{}
	oper := userModes{oper: true}
	wallops := userModes{wallops: true}
	both := userModes{oper: true, wallops: true}

	return []applyUserModeTest{
		{"+w", none, "+w", wallops},
		{"-w", wallops, "+", none},
		{"-o", oper, "+", none},
		{"-wo", both, "+", none},
		{"+w-o", oper, "+w", wallops},
		{"-w+w", none, "+w", wallops},
		{"+w-w", wallops, "+", none},
		{"-w+o", both, "", both},
		{"+o-w+w", both, "", both},
		{"+wo", none, "", none},
		{"+wz", none, "", none},
		{"+z", none, "", none},
		{"-x+y", none, "", none},
		{"+y-x", none, "", none},
		{"w", none, "", none},
		{"xw", wallops, "", wallops},
		{"", none, "", none},
		{"+", none, "", none},
		{"-", none, "", none},
		{"+-+", none, "", none},
	}
}

func TestApplyUserMode(t *testing.T) {
	env := newTestEnv(t)

	for i, test := range applyUserModeTests() {
		t.Run(test.modeStr, func(t *testing.T) {
			ctx := t.Context()
			sid := createSession(
				ctx, t, env.db, fmt.Sprintf("user%d", i),
			)
			setUserModes(ctx, t, env.db, sid, test.before)

			modes, err := env.svc.ApplyUserMode(
				ctx, sid, test.modeStr,
			)
			checkApplyUserModeResult(t, test.wantModes, modes, err)

			got := getUserModes(ctx, t, env.db, sid)
			if got != test.after {
				t.Errorf(
					"stored modes: want %+v, got %+v",
					test.after, got,
				)
			}
		})
	}
}

func checkApplyUserModeResult(
	t *testing.T,
	wantModes, modes string,
	err error,
) {
	t.Helper()

	if wantModes == "" {
		var ircErr *service.IRCError
		if !errors.As(err, &ircErr) ||
			ircErr.Code != irc.ErrUmodeUnknownFlag {
			t.Fatalf("want ERR_UMODEUNKNOWNFLAG, got %v", err)
		}

		return
	}

	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	if modes != wantModes {
		t.Errorf("modes: want %q, got %q", wantModes, modes)
	}
}

func setUserModes(
	ctx context.Context,
	t *testing.T,
	database *db.Database,
	sid int64,
	modes userModes,
) {
	t.Helper()

	err := database.SetSessionUserModes(
		ctx, sid, &modes.wallops, &modes.oper,
	)
	if err != nil {
		t.Fatalf("set user modes: %v", err)
	}
}

func getUserModes(
	ctx context.Context,
	t *testing.T,
	database *db.Database,
	sid int64,
) userModes {
	t.Helper()

	oper, err := database.IsSessionOper(ctx, sid)
	if err != nil {
		t.Fatalf("read oper: %v", err)
	}

	wallops, err := database.IsSessionWallops(ctx, sid)
	if err != nil {
		t.Fatalf("read wallops: %v", err)
	}

	return userModes{oper: oper, wallops: wallops}
}