package service

import (
	"context"
	"errors"
	"fmt"
	"sync"
	"time"

	"gitea.dwysokinski.me/twhelp/dcbot/internal/domain"
	"go.uber.org/zap"
)

//counterfeiter:generate -o internal/mock/group_repository.gen.go . GroupRepository
type GroupRepository interface {
	Create(ctx context.Context, params domain.CreateGroupParams) (domain.GroupWithMonitors, error)
	Update(ctx context.Context, id string, params domain.UpdateGroupParams) (domain.GroupWithMonitors, error)
	AddMonitor(ctx context.Context, id string, tribeID int64) (domain.GroupWithMonitors, error)
	DeleteMonitors(ctx context.Context, id string, monitorID ...string) (domain.GroupWithMonitors, error)
	List(ctx context.Context, params domain.ListGroupsParams) ([]domain.GroupWithMonitors, error)
	Get(ctx context.Context, id string) (domain.GroupWithMonitors, error)
	Delete(ctx context.Context, id string) error
	DeleteMany(ctx context.Context, id ...string) error
}

type Group struct {
	repo                GroupRepository
	twhelpSvc           TWHelpService
	logger              *zap.Logger
	maxGroupsPerServer  int
	maxMonitorsPerGroup int
	ennoblementsMu      sync.Mutex           // ennoblementsMu is used by listEnnoblements
	ennoblementsSince   map[string]time.Time // ennoblementsSince is used by listEnnoblements
}

func NewGroup(repo GroupRepository, twhelpSvc TWHelpService, logger *zap.Logger, maxGroupsPerServer, maxMonitorsPerGroup int) *Group {
	return &Group{
		repo:                repo,
		twhelpSvc:           twhelpSvc,
		logger:              logger,
		maxGroupsPerServer:  maxGroupsPerServer,
		maxMonitorsPerGroup: maxMonitorsPerGroup,
	}
}

func (g *Group) Create(ctx context.Context, params domain.CreateGroupParams) (domain.GroupWithMonitors, error) {
	groups, err := g.repo.List(ctx, domain.ListGroupsParams{
		ServerIDs: []string{params.ServerID()},
	})
	if err != nil {
		return domain.GroupWithMonitors{}, fmt.Errorf("GroupRepository.List: %w", err)
	}

	if len(groups) >= g.maxGroupsPerServer {
		return domain.GroupWithMonitors{}, domain.GroupLimitReachedError{
			Current: len(groups),
			Limit:   g.maxGroupsPerServer,
		}
	}

	if _, err = g.twhelpSvc.GetOpenServer(ctx, params.VersionCode(), params.ServerKey()); err != nil {
		return domain.GroupWithMonitors{}, err
	}

	group, err := g.repo.Create(ctx, params)
	if err != nil {
		return domain.GroupWithMonitors{}, fmt.Errorf("GroupRepository.Create: %w", err)
	}

	return group, nil
}

func (g *Group) AddTribe(ctx context.Context, id, serverID, tribeTag string) (domain.GroupWithMonitors, error) {
	// check if group exists
	groupBeforeUpdate, err := g.Get(ctx, id, serverID)
	if err != nil {
		if errors.Is(err, domain.GroupNotFoundError{ID: id}) {
			return domain.GroupWithMonitors{}, domain.GroupDoesNotExistError{ID: id}
		}
		return domain.GroupWithMonitors{}, err
	}

	// check limit
	if len(groupBeforeUpdate.Monitors) >= g.maxMonitorsPerGroup {
		return domain.GroupWithMonitors{}, domain.MonitorLimitReachedError{
			Current: len(groupBeforeUpdate.Monitors),
			Limit:   g.maxMonitorsPerGroup,
		}
	}

	tribe, err := g.twhelpSvc.GetExistingTribeByTag(ctx, groupBeforeUpdate.VersionCode, groupBeforeUpdate.ServerKey, tribeTag)
	if err != nil {
		return domain.GroupWithMonitors{}, err
	}

	group, err := g.repo.AddMonitor(ctx, groupBeforeUpdate.ID, tribe.ID)
	if err != nil {
		return domain.GroupWithMonitors{}, fmt.Errorf("GroupRepository.AddMonitor: %w", err)
	}

	return group, nil
}

const listTribesLimit = 200

func (g *Group) RemoveTribe(ctx context.Context, id, serverID, tribeTag string) (domain.GroupWithMonitors, error) {
	// check if group exists
	groupBeforeUpdate, err := g.Get(ctx, id, serverID)
	if err != nil {
		return domain.GroupWithMonitors{}, err
	}

	tribes, err := g.twhelpSvc.ListTribesTag(ctx, groupBeforeUpdate.VersionCode, groupBeforeUpdate.ServerKey, []string{tribeTag}, 0, listTribesLimit)
	if err != nil {
		return domain.GroupWithMonitors{}, fmt.Errorf("TWHelpClient.ListTribes: %w", err)
	}
	if len(tribes) == 0 {
		return domain.GroupWithMonitors{}, domain.TribeTagNotFoundError{
			Tag: tribeTag,
		}
	}

	var ids []string
	for _, t := range tribes {
		for _, m := range groupBeforeUpdate.Monitors {
			if m.TribeID == t.ID {
				ids = append(ids, m.ID)
			}
		}
	}

	group, err := g.repo.DeleteMonitors(ctx, groupBeforeUpdate.ID, ids...)
	if err != nil {
		return domain.GroupWithMonitors{}, fmt.Errorf("GroupRepository.DeleteMonitors: %w", err)
	}

	return group, nil
}

func (g *Group) SetChannelGains(ctx context.Context, id, serverID, channel string) (domain.GroupWithMonitors, error) {
	return g.update(ctx, id, serverID, domain.UpdateGroupParams{
		ChannelGains: domain.NullString{
			String: channel,
			Valid:  true,
		},
	})
}

func (g *Group) SetChannelLosses(ctx context.Context, id, serverID, channel string) (domain.GroupWithMonitors, error) {
	return g.update(ctx, id, serverID, domain.UpdateGroupParams{
		ChannelLosses: domain.NullString{
			String: channel,
			Valid:  true,
		},
	})
}

func (g *Group) SetInternals(ctx context.Context, id, serverID string, internals bool) (domain.GroupWithMonitors, error) {
	return g.update(ctx, id, serverID, domain.UpdateGroupParams{
		Internals: domain.NullBool{
			Bool:  internals,
			Valid: true,
		},
	})
}

func (g *Group) SetBarbarians(ctx context.Context, id, serverID string, barbarians bool) (domain.GroupWithMonitors, error) {
	return g.update(ctx, id, serverID, domain.UpdateGroupParams{
		Barbarians: domain.NullBool{
			Bool:  barbarians,
			Valid: true,
		},
	})
}

func (g *Group) SetLanguageTag(ctx context.Context, id, serverID, languageTag string) (domain.GroupWithMonitors, error) {
	return g.update(ctx, id, serverID, domain.UpdateGroupParams{
		LanguageTag: domain.NullString{
			String: languageTag,
			Valid:  true,
		},
	})
}

func (g *Group) update(ctx context.Context, id, serverID string, params domain.UpdateGroupParams) (domain.GroupWithMonitors, error) {
	// check if group exists
	if _, err := g.Get(ctx, id, serverID); err != nil {
		return domain.GroupWithMonitors{}, err
	}

	group, err := g.repo.Update(ctx, id, params)
	if err != nil {
		return domain.GroupWithMonitors{}, fmt.Errorf("GroupRepository.Update: %w", err)
	}

	return group, nil
}

func (g *Group) ListServer(ctx context.Context, serverID string) ([]domain.GroupWithMonitors, error) {
	groups, err := g.repo.List(ctx, domain.ListGroupsParams{
		ServerIDs: []string{serverID},
	})
	if err != nil {
		return nil, fmt.Errorf("GroupRepository.List: %w", err)
	}
	return groups, nil
}

func (g *Group) Get(ctx context.Context, id, serverID string) (domain.GroupWithMonitors, error) {
	group, err := g.repo.Get(ctx, id)
	if err != nil {
		return domain.GroupWithMonitors{}, fmt.Errorf("GroupRepository.Get: %w", err)
	}

	if group.ServerID != serverID {
		return domain.GroupWithMonitors{}, domain.GroupNotFoundError{
			ID: id,
		}
	}

	return group, nil
}

type getTribeResult struct {
	index   int
	monitor domain.Monitor
	tribe   domain.Tribe
	err     error
}

func (g *Group) GetWithTribes(ctx context.Context, id, serverID string) (domain.GroupWithMonitorsAndTribes, error) {
	group, err := g.Get(ctx, id, serverID)
	if err != nil {
		return domain.GroupWithMonitorsAndTribes{}, err
	}

	var wg sync.WaitGroup
	ch := make(chan getTribeResult)
	ctx, cancel := context.WithCancel(ctx)
	defer cancel()

	for i, monitor := range group.Monitors {
		wg.Add(1)
		go func(i int, monitor domain.Monitor) {
			defer wg.Done()

			res := getTribeResult{
				index:   i,
				monitor: monitor,
			}
			res.tribe, res.err = g.twhelpSvc.GetTribeByID(
				ctx,
				group.VersionCode,
				group.ServerKey,
				monitor.TribeID,
			)
			ch <- res
		}(i, monitor)
	}

	go func() {
		wg.Wait()
		close(ch)
	}()

	var firstErr error
	monitors := make([]domain.MonitorWithTribe, len(group.Monitors))
	for res := range ch {
		if res.err != nil && firstErr == nil {
			firstErr = fmt.Errorf("couldn't load tribe (monitorID=%s): %w", res.monitor.ID, res.err)
			cancel()
			continue
		}
		if res.err != nil {
			continue
		}

		monitors[res.index] = domain.MonitorWithTribe{
			Monitor: res.monitor,
			Tribe:   res.tribe,
		}
	}
	if firstErr != nil {
		return domain.GroupWithMonitorsAndTribes{}, firstErr
	}

	return domain.GroupWithMonitorsAndTribes{
		Group:    group.Group,
		Monitors: monitors,
	}, nil
}

func (g *Group) Delete(ctx context.Context, id, serverID string) error {
	// check if group exists
	if _, err := g.Get(ctx, id, serverID); err != nil {
		return err
	}

	if err := g.repo.Delete(ctx, id); err != nil {
		return fmt.Errorf("GroupRepository.Delete: %w", err)
	}

	return nil
}

func (g *Group) Execute(ctx context.Context) ([]domain.EnnoblementNotification, error) {
	groups, err := g.repo.List(ctx, domain.ListGroupsParams{
		EnabledNotifications: domain.NullBool{
			Bool:  true,
			Valid: true,
		},
	})
	if err != nil {
		return nil, fmt.Errorf("GroupRepository.List: %w", err)
	}

	res, err := g.listEnnoblements(ctx, groups)
	if err != nil {
		return nil, err
	}

	return ennoblementNotificationBuilder{
		groups:       groups,
		ennoblements: res,
	}.build(), nil
}

type listEnnoblementsSingleResult struct {
	versionCode  string
	serverKey    string
	ennoblements []domain.Ennoblement
}

type listEnnoblementsResult []listEnnoblementsSingleResult

func (r listEnnoblementsResult) find(versionCode, serverKey string) []domain.Ennoblement {
	for _, res := range r {
		if res.serverKey == serverKey && res.versionCode == versionCode {
			return res.ennoblements
		}
	}
	return nil
}

const listEnnoblementsLimit = 200

func (g *Group) listEnnoblements(ctx context.Context, groups []domain.GroupWithMonitors) (listEnnoblementsResult, error) {
	g.ennoblementsMu.Lock()
	defer g.ennoblementsMu.Unlock()

	var wg sync.WaitGroup
	ch := make(chan listEnnoblementsSingleResult)
	ennoblementsSince := g.ennoblementsSince
	skip := make(map[string]struct{}, len(ennoblementsSince))

	for _, group := range groups {
		key := g.buildEnnoblementsSinceKey(group.VersionCode, group.ServerKey)

		if _, ok := skip[key]; ok {
			continue
		}
		skip[key] = struct{}{}

		since := ennoblementsSince[key]
		if since.IsZero() {
			since = time.Now().Add(-1 * time.Minute)
		}

		wg.Add(1)
		go func(group domain.GroupWithMonitors, since time.Time) {
			defer wg.Done()

			ennoblements, err := g.twhelpSvc.ListEnnoblementsSince(ctx, group.VersionCode, group.ServerKey, since, 0, listEnnoblementsLimit)
			if err != nil {
				g.logger.Warn(
					"couldn't list ennoblements",
					zap.String("versionCode", group.VersionCode),
					zap.String("serverKey", group.ServerKey),
					zap.Error(err),
				)
				return
			}
			ch <- listEnnoblementsSingleResult{
				versionCode:  group.VersionCode,
				serverKey:    group.ServerKey,
				ennoblements: ennoblements,
			}
		}(group, since)
	}

	go func() {
		wg.Wait()
		close(ch)
	}()

	// reinitialize ennoblementsSince
	g.ennoblementsSince = make(map[string]time.Time)

	results := make(listEnnoblementsResult, 0, len(skip))
	for res := range ch {
		key := g.buildEnnoblementsSinceKey(res.versionCode, res.serverKey)
		if l := len(res.ennoblements); l > 0 {
			g.ennoblementsSince[key] = res.ennoblements[l-1].CreatedAt.Add(time.Second)
		} else {
			g.ennoblementsSince[key] = ennoblementsSince[key]
		}
		results = append(results, res)
	}

	return results, nil
}

func (g *Group) buildEnnoblementsSinceKey(versionCode, serverKey string) string {
	return versionCode + ":" + serverKey
}

func (g *Group) CleanUp(ctx context.Context) error {
	if err := g.deleteAllWithDisabledNotifications(ctx); err != nil {
		return err
	}

	if err := g.deleteAllWithClosedTWServers(ctx); err != nil {
		return err
	}

	return nil
}

func (g *Group) deleteAllWithDisabledNotifications(ctx context.Context) error {
	groups, err := g.repo.List(ctx, domain.ListGroupsParams{
		EnabledNotifications: domain.NullBool{
			Bool:  false,
			Valid: true,
		},
		CreatedAtLTE: time.Now().Add(-24 * time.Hour),
	})
	if err != nil {
		return fmt.Errorf("couldn't find groups with disabled notifications: %w", err)
	}

	ids := make([]string, 0, len(groups))
	for _, group := range groups {
		ids = append(ids, group.ID)
	}

	if err = g.repo.DeleteMany(ctx, ids...); err != nil {
		return fmt.Errorf("couldn't delete groups with disabled notifications: %w", err)
	}

	return nil
}

const listServersLimit = 500

func (g *Group) deleteAllWithClosedTWServers(ctx context.Context) error {
	versions, err := g.twhelpSvc.ListVersions(ctx)
	if err != nil {
		return err
	}

	for _, v := range versions {
		servers, err := g.twhelpSvc.ListClosedServers(ctx, v.Code, 0, listServersLimit)
		if err != nil {
			g.logger.Warn("couldn't list closed servers", zap.Error(err), zap.String("versionCode", v.Code))
			continue
		}

		if len(servers) == 0 {
			continue
		}

		params := domain.ListGroupsParams{
			VersionCode: domain.NullString{
				String: v.Code,
				Valid:  true,
			},
			ServerKeys: make([]string, 0, len(servers)),
		}
		for _, s := range servers {
			params.ServerKeys = append(params.ServerKeys, s.Key)
		}

		groups, err := g.repo.List(ctx, params)
		if err != nil {
			g.logger.Warn("couldn't list groups", zap.Error(err), zap.String("versionCode", v.Code))
			continue
		}

		if len(groups) == 0 {
			continue
		}

		ids := make([]string, 0, len(groups))
		for _, group := range groups {
			ids = append(ids, group.ID)
		}

		if err = g.repo.DeleteMany(ctx, ids...); err != nil {
			g.logger.Warn("couldn't delete groups", zap.Error(err), zap.String("versionCode", v.Code))
			continue
		}
	}

	return nil
}