//go:build integration

package inttest

import (
	"context"
	"testing"
	"time"

	"github.com/google/uuid"
	"go.opentelemetry.io/otel/metric/noop"
	"go.uber.org/zap"

	"scrabble/backend/internal/account"
	"scrabble/backend/internal/engine"
	"scrabble/backend/internal/game"
	"scrabble/backend/internal/lobby"
	"scrabble/backend/internal/robot"
)

// newRobotService builds a robot service over games (shared so its moves and the
// test's human moves use the same live-game cache and per-game locks), a fresh
// social service for nudges, and a no-op meter.
func newRobotService(t *testing.T, games *game.Service) *robot.Service {
	t.Helper()
	return robot.NewService(games, account.NewStore(testDB), newSocialService(), noop.NewMeterProvider().Meter("robot-test"), zap.NewNop())
}

// newMatchmaker builds a matchmaker starting real games and substituting from
// robots after wait.
func newMatchmaker(t *testing.T, robots lobby.RobotProvider, wait time.Duration) *lobby.Matchmaker {
	t.Helper()
	return lobby.NewMatchmaker(newGameService(), robots, wait, zap.NewNop())
}

// setTurnStarted rewrites a game's turn clock so a robot turn can be made due (or
// idle) at a chosen instant, independent of wall time.
func setTurnStarted(t *testing.T, id uuid.UUID, at time.Time) {
	t.Helper()
	if _, err := testDB.ExecContext(context.Background(),
		`UPDATE backend.games SET turn_started_at = $2 WHERE game_id = $1`, id, at); err != nil {
		t.Fatalf("set turn_started_at: %v", err)
	}
}

// isRobotAccount reports whether the account carries a robot identity.
func isRobotAccount(t *testing.T, id uuid.UUID) bool {
	t.Helper()
	var n int
	if err := testDB.QueryRowContext(context.Background(),
		`SELECT count(*) FROM backend.identities WHERE account_id = $1 AND kind = 'robot'`, id).Scan(&n); err != nil {
		t.Fatalf("count robot identity: %v", err)
	}
	return n > 0
}

// countNudges counts the nudges senderID has sent in a game.
func countNudges(t *testing.T, gameID, senderID uuid.UUID) int {
	t.Helper()
	var n int
	if err := testDB.QueryRowContext(context.Background(),
		`SELECT count(*) FROM backend.chat_messages WHERE game_id = $1 AND sender_id = $2 AND kind = 'nudge'`,
		gameID, senderID).Scan(&n); err != nil {
		t.Fatalf("count nudges: %v", err)
	}
	return n
}

// daytime is a fixed instant whose hour is awake for every sleep drift (the
// always-awake band is [10,21) local), used to drive robot moves deterministically.
var daytime = time.Date(2024, 1, 1, 14, 0, 0, 0, time.UTC)

// TestRobotPoolProvisionsRobotAccounts checks EnsurePool creates durable,
// chat/friend-blocked robot accounts (exercising the kind='robot' migration) and
// is idempotent.
func TestRobotPoolProvisionsRobotAccounts(t *testing.T) {
	ctx := context.Background()
	r := newRobotService(t, newGameService())
	if err := r.EnsurePool(ctx); err != nil {
		t.Fatalf("ensure pool: %v", err)
	}
	if err := r.EnsurePool(ctx); err != nil {
		t.Fatalf("ensure pool (idempotent): %v", err)
	}
	id, err := r.Pick()
	if err != nil {
		t.Fatalf("pick: %v", err)
	}
	if !isRobotAccount(t, id) {
		t.Errorf("picked account %s is not a robot identity", id)
	}
	acc, err := account.NewStore(testDB).GetByID(ctx, id)
	if err != nil {
		t.Fatalf("get robot account: %v", err)
	}
	if acc.DisplayName == "" || !acc.BlockChat || !acc.BlockFriendRequests {
		t.Errorf("robot profile not set: name=%q chat=%v friends=%v", acc.DisplayName, acc.BlockChat, acc.BlockFriendRequests)
	}
}

// TestRobotPlaysAutoMatchToEnd drives a robot through a full two-player game (the
// human plays greedily) and checks it finishes with a robot statistics row. The
// robot is forced due each turn by resetting the turn clock and driving at a fixed
// daytime instant, so the game does not depend on wall time.
func TestRobotPlaysAutoMatchToEnd(t *testing.T) {
	ctx := context.Background()
	svc := newGameService()
	robots := newRobotService(t, svc)
	if err := robots.EnsurePool(ctx); err != nil {
		t.Fatalf("ensure pool: %v", err)
	}
	robotID, err := robots.Pick()
	if err != nil {
		t.Fatalf("pick: %v", err)
	}
	human := provisionAccount(t)
	seed := openingSeed(t)

	g, err := svc.Create(ctx, game.CreateParams{
		Variant: engine.VariantEnglish, Seats: []uuid.UUID{human, robotID},
		TurnTimeout: 24 * time.Hour, Seed: seed,
	})
	if err != nil {
		t.Fatalf("create: %v", err)
	}
	robotSeat := 1 // seats = [human, robot]

	finished := false
	for i := 0; i < 400 && !finished; i++ {
		_, toMove, status, err := svc.Participants(ctx, g.ID)
		if err != nil {
			t.Fatalf("participants: %v", err)
		}
		if status != game.StatusActive {
			finished = true
			break
		}
		if toMove == robotSeat {
			setTurnStarted(t, g.ID, daytime.Add(-2*time.Hour)) // well past any sampled delay
			robots.Drive(ctx, daytime)
			continue
		}
		playHuman(t, ctx, svc, g.ID, human)
	}
	if !finished {
		t.Fatal("robot game did not finish within the move budget")
	}

	if _, _, _, mg, _, ok := readStats(t, robotID); !ok || mg < 0 {
		t.Errorf("robot must have a statistics row after a finished game (found=%v, maxGame=%d)", ok, mg)
	}
}

// TestMatchmakerSubstitutesRobotEndToEnd checks a waiting human is paired with a
// real robot account after the wait window, discoverable through Poll.
func TestMatchmakerSubstitutesRobotEndToEnd(t *testing.T) {
	ctx := context.Background()
	robots := newRobotService(t, newGameService())
	if err := robots.EnsurePool(ctx); err != nil {
		t.Fatalf("ensure pool: %v", err)
	}
	mm := newMatchmaker(t, robots, 10*time.Second)
	human := provisionAccount(t)

	before := time.Now()
	r, err := mm.Enqueue(ctx, human, engine.VariantEnglish)
	if err != nil {
		t.Fatalf("enqueue: %v", err)
	}
	if r.Matched {
		t.Fatal("first enqueue must wait")
	}

	mm.Reap(ctx, before.Add(11*time.Second))
	got, err := mm.Poll(ctx, human)
	if err != nil {
		t.Fatalf("poll: %v", err)
	}
	if !got.Matched {
		t.Fatal("expected a substituted game after the wait window")
	}

	seats, _, status, err := newGameService().Participants(ctx, got.Game.ID)
	if err != nil {
		t.Fatalf("participants: %v", err)
	}
	if status != game.StatusActive || len(seats) != 2 {
		t.Fatalf("substituted game: status %q seats %v", status, seats)
	}
	var human0, robot0 bool
	for _, s := range seats {
		switch {
		case s == human:
			human0 = true
		case isRobotAccount(t, s):
			robot0 = true
		}
	}
	if !human0 || !robot0 {
		t.Errorf("substituted seats must be the human and a robot, got %v", seats)
	}
}

// TestRobotProactiveNudge checks the robot nudges the human after the idle
// threshold on the human's turn.
func TestRobotProactiveNudge(t *testing.T) {
	ctx := context.Background()
	svc := newGameService()
	robots := newRobotService(t, svc)
	if err := robots.EnsurePool(ctx); err != nil {
		t.Fatalf("ensure pool: %v", err)
	}
	robotID, err := robots.Pick()
	if err != nil {
		t.Fatalf("pick: %v", err)
	}
	human := provisionAccount(t)
	seed := openingSeed(t)

	// Seat the human first so it is the human's turn and the robot is the awaiter.
	g, err := svc.Create(ctx, game.CreateParams{
		Variant: engine.VariantEnglish, Seats: []uuid.UUID{human, robotID},
		TurnTimeout: 24 * time.Hour, Seed: seed,
	})
	if err != nil {
		t.Fatalf("create: %v", err)
	}

	// Midnight start, driven 13 hours later (>12h idle) at a daytime hour awake for
	// every drift.
	start := time.Date(2024, 1, 1, 0, 0, 0, 0, time.UTC)
	setTurnStarted(t, g.ID, start)
	robots.Drive(ctx, start.Add(13*time.Hour))

	if n := countNudges(t, g.ID, robotID); n != 1 {
		t.Errorf("robot nudges = %d, want 1 after 13h idle on the human's turn", n)
	}
}

// playHuman makes a greedy human move: the top candidate, else an exchange, else a
// pass.
func playHuman(t *testing.T, ctx context.Context, svc *game.Service, gameID, human uuid.UUID) {
	t.Helper()
	cands, err := svc.Candidates(ctx, gameID, human)
	if err != nil {
		t.Fatalf("human candidates: %v", err)
	}
	if len(cands) > 0 {
		if _, err := svc.SubmitPlay(ctx, gameID, human, cands[0].Dir, cands[0].Tiles); err != nil {
			t.Fatalf("human play: %v", err)
		}
		return
	}
	st, err := svc.GameState(ctx, gameID, human)
	if err != nil {
		t.Fatalf("human state: %v", err)
	}
	if len(st.Rack) > 0 && st.BagLen >= len(st.Rack) {
		if _, err := svc.Exchange(ctx, gameID, human, st.Rack); err != nil {
			t.Fatalf("human exchange: %v", err)
		}
		return
	}
	if _, err := svc.Pass(ctx, gameID, human); err != nil {
		t.Fatalf("human pass: %v", err)
	}
}