package service

import (
	"errors"
	"fmt"
	"sort"
	"strings"
	"time"

	"browser.local/platform/domain"
	"browser.local/platform/repo"
	"browser.local/platform/validator"
)

func (svc *CoreService) ListSCUMUsersForSession(sessionID string, filter domain.SCUMUserFilter) ([]domain.SCUMUser, error) {
	if strings.TrimSpace(filter.ServerInstanceID) == "" {
		return nil, validationError("serverInstanceId is required")
	}
	if _, err := svc.GetServerInstanceForSession(sessionID, filter.ServerInstanceID); err != nil {
		return nil, err
	}
	users, err := svc.store.SCUMUsers().List(filter)
	if err != nil {
		return nil, err
	}
	sort.SliceStable(users, func(i, j int) bool {
		if !users[i].LastActivityAt.Equal(users[j].LastActivityAt) {
			return users[i].LastActivityAt.After(users[j].LastActivityAt)
		}
		return users[i].SteamID < users[j].SteamID
	})
	limit := boundedSCUMLimit(filter.Limit, domain.SCUMDefaultListLimit)
	if len(users) > limit {
		users = users[:limit]
	}
	stamp := svc.now()
	for index := range users {
		if !users[index].LastLoginAt.IsZero() {
			users[index].LastLoginAge = stamp.Sub(users[index].LastLoginAt)
		}
	}
	return domain.CopySCUMUsers(users), nil
}

func (svc *CoreService) ListSCUMUserTrajectoriesForSession(sessionID string, filter domain.SCUMUserTrajectoryFilter) ([]domain.SCUMUserTrajectory, error) {
	if strings.TrimSpace(filter.ServerInstanceID) == "" {
		return nil, validationError("serverInstanceId is required")
	}
	if _, err := svc.GetServerInstanceForSession(sessionID, filter.ServerInstanceID); err != nil {
		return nil, err
	}
	items, err := svc.store.SCUMUserTrajectories().List(filter)
	if err != nil {
		return nil, err
	}
	sort.SliceStable(items, func(i, j int) bool {
		if !items[i].ObservedAt.Equal(items[j].ObservedAt) {
			return items[i].ObservedAt.After(items[j].ObservedAt)
		}
		return items[i].ID < items[j].ID
	})
	limit := boundedSCUMLimit(filter.Limit, domain.SCUMDefaultTrajectoryLimit)
	if len(items) > limit {
		items = items[:limit]
	}
	return domain.CopySCUMUserTrajectories(items), nil
}

func (svc *CoreService) ListSCUMVehiclesForSession(sessionID string, filter domain.SCUMVehicleFilter) ([]domain.SCUMVehicle, error) {
	if strings.TrimSpace(filter.ServerInstanceID) == "" {
		return nil, validationError("serverInstanceId is required")
	}
	if _, err := svc.GetServerInstanceForSession(sessionID, filter.ServerInstanceID); err != nil {
		return nil, err
	}
	vehicles, err := svc.store.SCUMVehicles().List(filter)
	if err != nil {
		return nil, err
	}
	sort.SliceStable(vehicles, func(i, j int) bool {
		if !vehicles[i].LastObservedAt.Equal(vehicles[j].LastObservedAt) {
			return vehicles[i].LastObservedAt.After(vehicles[j].LastObservedAt)
		}
		return vehicles[i].GameVehicleID < vehicles[j].GameVehicleID
	})
	limit := boundedSCUMLimit(filter.Limit, domain.SCUMDefaultListLimit)
	if len(vehicles) > limit {
		vehicles = vehicles[:limit]
	}
	return domain.CopySCUMVehicles(vehicles), nil
}

func (svc *CoreService) ListSCUMVehicleTrajectoriesForSession(sessionID string, filter domain.SCUMVehicleTrajectoryFilter) ([]domain.SCUMVehicleTrajectory, error) {
	if strings.TrimSpace(filter.ServerInstanceID) == "" {
		return nil, validationError("serverInstanceId is required")
	}
	if _, err := svc.GetServerInstanceForSession(sessionID, filter.ServerInstanceID); err != nil {
		return nil, err
	}
	items, err := svc.store.SCUMVehicleTrajectories().List(filter)
	if err != nil {
		return nil, err
	}
	sort.SliceStable(items, func(i, j int) bool {
		if !items[i].ObservedAt.Equal(items[j].ObservedAt) {
			return items[i].ObservedAt.After(items[j].ObservedAt)
		}
		return items[i].ID < items[j].ID
	})
	limit := boundedSCUMLimit(filter.Limit, domain.SCUMDefaultTrajectoryLimit)
	if len(items) > limit {
		items = items[:limit]
	}
	return domain.CopySCUMVehicleTrajectories(items), nil
}

func (svc *CoreService) ListSCUMVehicleLocksForSession(sessionID string, filter domain.SCUMVehicleLockFilter) ([]domain.SCUMVehicleLock, error) {
	if strings.TrimSpace(filter.ServerInstanceID) == "" {
		return nil, validationError("serverInstanceId is required")
	}
	if _, err := svc.GetServerInstanceForSession(sessionID, filter.ServerInstanceID); err != nil {
		return nil, err
	}
	items, err := svc.store.SCUMVehicleLocks().List(filter)
	if err != nil {
		return nil, err
	}
	sort.SliceStable(items, func(i, j int) bool {
		if !items[i].LockedAt.Equal(items[j].LockedAt) {
			return items[i].LockedAt.After(items[j].LockedAt)
		}
		return items[i].ID < items[j].ID
	})
	limit := boundedSCUMLimit(filter.Limit, domain.SCUMDefaultTrajectoryLimit)
	if len(items) > limit {
		items = items[:limit]
	}
	return domain.CopySCUMVehicleLocks(items), nil
}

func (svc *CoreService) IngestSCUMFacts(batch domain.SCUMFactIngest) (domain.SCUMFactIngestResult, error) {
	batch = domain.CopySCUMFactIngest(batch)
	if strings.TrimSpace(batch.ServerInstanceID) == "" {
		return domain.SCUMFactIngestResult{}, validationError("serverInstanceId is required")
	}
	if len(batch.Users) == 0 && len(batch.Vehicles) == 0 {
		return domain.SCUMFactIngestResult{}, validationError("SCUM facts are required")
	}
	if len(batch.Users) > 1000 || len(batch.Vehicles) > 1000 {
		return domain.SCUMFactIngestResult{}, validationError("SCUM fact batch is too large")
	}
	if err := svc.validateRunSession(batch.RunEndpointID, batch.SessionToken); err != nil {
		return domain.SCUMFactIngestResult{}, err
	}
	instance, err := svc.store.ServerInstances().Get(batch.ServerInstanceID)
	if err != nil {
		return domain.SCUMFactIngestResult{}, err
	}
	if instance.RunEndpointID != batch.RunEndpointID {
		return domain.SCUMFactIngestResult{}, ErrForbidden
	}
	stamp := svc.now()
	welcomeCount := 0
	for _, fact := range batch.Users {
		if err := svc.ingestSCUMUserFact(instance, fact, stamp, &welcomeCount); err != nil {
			return domain.SCUMFactIngestResult{}, err
		}
	}
	for _, fact := range batch.Vehicles {
		if err := svc.ingestSCUMVehicleFact(instance, fact, stamp); err != nil {
			return domain.SCUMFactIngestResult{}, err
		}
	}
	return domain.SCUMFactIngestResult{Accepted: true, AcceptedUserCount: len(batch.Users), AcceptedVehicleCount: len(batch.Vehicles), WelcomeQueuedCount: welcomeCount, ServerTime: stamp}, nil
}

func (svc *CoreService) ingestSCUMUserFact(instance domain.ServerInstance, fact domain.SCUMUserFact, stamp time.Time, welcomeCount *int) error {
	steamID := strings.TrimSpace(fact.SteamID)
	if steamID == "" {
		return validationError("SCUM user steamId is required")
	}
	observedAt := nonZeroTime(fact.ObservedAt, stamp)
	loginAt := nonZeroTime(fact.LoginObservedAt, observedAt)
	userID := scumUserID(instance.ID, steamID)
	user, err := svc.store.SCUMUsers().Get(userID)
	created := false
	if errors.Is(err, repo.ErrNotFound) {
		created = true
		user = domain.SCUMUser{ID: userID, ServerInstanceID: instance.ID, SteamID: steamID, RegisteredAt: loginAt, CreatedAt: stamp}
	} else if err != nil {
		return err
	}
	previousActivity := user.LastActivityAt
	freshLogin := created || (fact.Login && (previousActivity.IsZero() || loginAt.Sub(previousActivity) > domain.SCUMUserOfflineAfter))
	moved := fact.Online && fact.Position != nil && userPositionMoved(user, fact.Position)
	if fact.Login || created {
		user.LastLoginAt = loginAt
	}
	user.DisplayName = firstNonBlank(fact.DisplayName, user.DisplayName)
	if fact.SquadID != nil {
		user.SquadID = *fact.SquadID
	}
	user.LastLoginIP = firstNonBlank(fact.LoginIP, user.LastLoginIP)
	user.Online = fact.Online
	user.LastActivityAt = latestTime(user.LastActivityAt, observedAt)
	if fact.Position != nil {
		user.X, user.Y, user.Z = floatPtr(fact.Position.X), floatPtr(fact.Position.Y), floatPtr(fact.Position.Z)
	}
	if fact.BankBalance != nil {
		user.BankBalance = int64Ptr(*fact.BankBalance)
	}
	if fact.GoldBars != nil {
		user.GoldBars = int64Ptr(*fact.GoldBars)
	}
	user.GameVehicleID = strings.TrimSpace(fact.RiddenGameVehicleID)
	if user.GameVehicleID != "" {
		user.RiddenVehicleID = scumVehicleID(instance.ID, user.GameVehicleID)
	} else {
		user.RiddenVehicleID = ""
	}
	user.UpdatedAt = stamp
	if created {
		if err := svc.store.SCUMUsers().Create(user); err != nil {
			return err
		}
	} else if err := svc.store.SCUMUsers().Update(user); err != nil {
		return err
	}
	if moved {
		track := domain.SCUMUserTrajectory{ID: scumTrajectoryID("scum-user-track", instance.ID, steamID, observedAt), ServerInstanceID: instance.ID, SCUMUserID: user.ID, SteamID: steamID, DisplayName: user.DisplayName, X: fact.Position.X, Y: fact.Position.Y, Z: fact.Position.Z, RiddenVehicleID: user.RiddenVehicleID, GameVehicleID: user.GameVehicleID, ObservedAt: observedAt, CreatedAt: stamp}
		if err := createUnlessDuplicate(svc.store.SCUMUserTrajectories(), track); err != nil {
			return err
		}
	}
	if freshLogin {
		queued, queueErr := svc.queueSCUMWelcomeMessage(instance, user, stamp)
		if queueErr != nil {
			user.WelcomeLastError = queueErr.Error()
		} else if queued {
			user.WelcomeQueuedAt = stamp.Add(domain.SCUMWelcomeMessageDelay)
			*welcomeCount = *welcomeCount + 1
		}
		user.UpdatedAt = stamp
		if err := svc.store.SCUMUsers().Update(user); err != nil {
			return err
		}
	}
	return nil
}

func (svc *CoreService) ingestSCUMVehicleFact(instance domain.ServerInstance, fact domain.SCUMVehicleFact, stamp time.Time) error {
	gameVehicleID := strings.TrimSpace(fact.GameVehicleID)
	if gameVehicleID == "" {
		return validationError("SCUM vehicle gameVehicleId is required")
	}
	observedAt := nonZeroTime(fact.ObservedAt, stamp)
	vehicleID := scumVehicleID(instance.ID, gameVehicleID)
	vehicle, err := svc.store.SCUMVehicles().Get(vehicleID)
	created := false
	if errors.Is(err, repo.ErrNotFound) {
		created = true
		vehicle = domain.SCUMVehicle{ID: vehicleID, ServerInstanceID: instance.ID, GameVehicleID: gameVehicleID, Exists: true, CreatedAt: stamp}
	} else if err != nil {
		return err
	}
	moved := fact.Position != nil && vehiclePositionMoved(vehicle, fact.Position)
	vehicle.VehicleClass = firstNonBlank(fact.VehicleClass, vehicle.VehicleClass)
	vehicle.DisplayName = firstNonBlank(fact.DisplayName, vehicle.DisplayName)
	if fact.Exists != nil {
		vehicle.Exists = *fact.Exists
	}
	if fact.Locked != nil {
		vehicle.Locked = *fact.Locked
	}
	if fact.Position != nil {
		vehicle.X, vehicle.Y, vehicle.Z = floatPtr(fact.Position.X), floatPtr(fact.Position.Y), floatPtr(fact.Position.Z)
	}
	vehicle.LastObservedAt = latestTime(vehicle.LastObservedAt, observedAt)
	vehicle.UpdatedAt = stamp
	if created {
		if err := svc.store.SCUMVehicles().Create(vehicle); err != nil {
			return err
		}
	} else if err := svc.store.SCUMVehicles().Update(vehicle); err != nil {
		return err
	}
	if moved {
		track := domain.SCUMVehicleTrajectory{ID: scumTrajectoryID("scum-vehicle-track", instance.ID, gameVehicleID, observedAt), ServerInstanceID: instance.ID, SCUMVehicleID: vehicle.ID, GameVehicleID: gameVehicleID, VehicleClass: vehicle.VehicleClass, X: fact.Position.X, Y: fact.Position.Y, Z: fact.Position.Z, ObservedAt: observedAt, CreatedAt: stamp}
		if err := createUnlessDuplicate(svc.store.SCUMVehicleTrajectories(), track); err != nil {
			return err
		}
	}
	if strings.TrimSpace(fact.LockedBySteamID) != "" && !fact.LockedAt.IsZero() {
		lockUserID := scumUserID(instance.ID, strings.TrimSpace(fact.LockedBySteamID))
		lock := domain.SCUMVehicleLock{ID: scumTrajectoryID("scum-vehicle-lock", instance.ID, gameVehicleID+":"+fact.LockedBySteamID, fact.LockedAt), ServerInstanceID: instance.ID, SCUMVehicleID: vehicle.ID, GameVehicleID: gameVehicleID, SCUMUserID: lockUserID, SteamID: strings.TrimSpace(fact.LockedBySteamID), LockedAt: fact.LockedAt, CreatedAt: stamp}
		if err := createUnlessDuplicate(svc.store.SCUMVehicleLocks(), lock); err != nil {
			return err
		}
	}
	return nil
}

func (svc *CoreService) queueSCUMWelcomeMessage(instance domain.ServerInstance, user domain.SCUMUser, stamp time.Time) (bool, error) {
	if instance.State != domain.ServerInstanceStateRunning {
		return false, nil
	}
	resolution, err := svc.resolveSourceRCONDispatch(instance)
	if err != nil {
		return false, err
	}
	message := fmt.Sprintf("欢迎 %s 回到服务器", firstNonBlank(user.DisplayName, user.SteamID))
	request := domain.SourceRCONCommandRequest{ServerInstanceID: instance.ID, Kind: domain.SourceRCONCommandKindChat, ChatType: 4, Message: message, IdempotencyKey: scumWelcomeIdempotencyKey(instance.ID, user.SteamID, user.LastLoginAt)}
	if err := validator.ValidateSourceRCONCommandRequest(request); err != nil {
		return false, err
	}
	if existing, err := svc.store.Jobs().GetByIdempotency(instance.RunEndpointID, request.IdempotencyKey); err == nil {
		return existing.QueueEligibleAt.Equal(stamp.Add(domain.SCUMWelcomeMessageDelay)) || !existing.QueueEligibleAt.IsZero(), nil
	} else if !errors.Is(err, repo.ErrNotFound) {
		return false, err
	}
	command := sourceRCONCommandText(request)
	jobID := jobIDFromParts("job-source-rcon", instance.ID, request.IdempotencyKey)
	if err := svc.sourceRCONCommands.Put(jobID, command); err != nil {
		return false, err
	}
	job := domain.Job{ID: jobID, ServerInstanceID: instance.ID, RunEndpointID: instance.RunEndpointID, Capability: domain.JobCapabilityRemoteRunRCONCommand, TargetKey: resolution.transport.TargetKey, InputRef: "input://source-rcon/" + jobID, IdempotencyKey: request.IdempotencyKey, State: domain.JobStateQueued, Progress: domain.JobProgress{Percent: 0, Message: "SCUM welcome message queued"}, RetryPolicy: domain.JobRetryPolicy{MaxAttempts: 1, InitialBackoffSeconds: 1, MaxBackoffSeconds: 1}, QueueEligibleAt: stamp.Add(domain.SCUMWelcomeMessageDelay), ExecutionInput: domain.JobExecutionInput{WorkspaceScope: resolution.binding.ProfileKey, RemoteAdapterKey: resolution.transport.Key, RemoteAdapterKind: string(domain.RemoteAdapterRCON), TimeoutSeconds: sourceRCONTimeoutSeconds, PluginID: resolution.plugin.ID, SourceRCON: resolution.plan}}
	created, err := svc.CreateJob(job)
	if err != nil {
		svc.sourceRCONCommands.Delete(jobID)
		return false, err
	}
	return created.ID == jobID, nil
}

func userPositionMoved(user domain.SCUMUser, position *domain.SCUMPosition) bool {
	if position == nil || user.X == nil || user.Y == nil || user.Z == nil {
		return true
	}
	return *user.X != position.X || *user.Y != position.Y || *user.Z != position.Z
}

func vehiclePositionMoved(vehicle domain.SCUMVehicle, position *domain.SCUMPosition) bool {
	if position == nil || vehicle.X == nil || vehicle.Y == nil || vehicle.Z == nil {
		return true
	}
	return *vehicle.X != position.X || *vehicle.Y != position.Y || *vehicle.Z != position.Z
}

func boundedSCUMLimit(requested int, fallback int) int {
	if requested <= 0 {
		return fallback
	}
	if requested > 1000 {
		return 1000
	}
	return requested
}

func scumUserID(serverID string, steamID string) string {
	return "scum-user-" + fingerprintID(serverID, strings.TrimSpace(steamID))
}

func scumVehicleID(serverID string, gameVehicleID string) string {
	return "scum-vehicle-" + fingerprintID(serverID, strings.TrimSpace(gameVehicleID))
}

func scumTrajectoryID(prefix string, serverID string, subjectID string, observedAt time.Time) string {
	return prefix + "-" + fingerprintID(serverID, strings.TrimSpace(subjectID)+"\x00"+observedAt.UTC().Format(time.RFC3339Nano))
}

func scumWelcomeIdempotencyKey(serverID string, steamID string, loginAt time.Time) string {
	return "scum-welcome:" + fingerprintID(serverID, strings.TrimSpace(steamID)+"\x00"+loginAt.UTC().Format(time.RFC3339Nano))
}

func nonZeroTime(value time.Time, fallback time.Time) time.Time {
	if value.IsZero() {
		return fallback
	}
	return value.UTC()
}

func latestTime(left time.Time, right time.Time) time.Time {
	if left.IsZero() || right.After(left) {
		return right
	}
	return left
}

func firstNonBlank(values ...string) string {
	for _, value := range values {
		if strings.TrimSpace(value) != "" {
			return strings.TrimSpace(value)
		}
	}
	return ""
}

func floatPtr(value float64) *float64 { return &value }
func int64Ptr(value int64) *int64     { return &value }

type scumCreateOnlyRepository[T any] interface {
	Create(T) error
}

func createUnlessDuplicate[T any](repository scumCreateOnlyRepository[T], value T) error {
	if err := repository.Create(value); err != nil && !errors.Is(err, repo.ErrDuplicate) {
		return err
	}
	return nil
}