package service

import (
	"context"
	"time"

	"github.com/cortezaproject/corteza/server/pkg/actionlog"
	intAuth "github.com/cortezaproject/corteza/server/pkg/auth"
	"github.com/cortezaproject/corteza/server/store"
	"github.com/cortezaproject/corteza/server/system/types"
	"github.com/getsentry/sentry-go"
	"go.uber.org/zap"
)

type (
	reminderSender interface {
		Send(kind string, payload interface{}, userIDs ...uint64) error
	}

	reminder struct {
		ac reminderAccessController

		log            *zap.Logger
		actionlog      actionlog.Recorder
		store          store.Reminders
		reminderSender reminderSender
	}

	reminderAccessController interface {
		CanAssignReminder(ctx context.Context) bool
	}

	ReminderService interface {
		Find(context.Context, types.ReminderFilter) (types.ReminderSet, types.ReminderFilter, error)
		FindByID(context.Context, uint64) (*types.Reminder, error)

		Create(context.Context, *types.Reminder) (*types.Reminder, error)

		Update(context.Context, *types.Reminder) (*types.Reminder, error)

		Dismiss(context.Context, uint64) error
		Undismiss(context.Context, uint64) error
		Snooze(context.Context, uint64, *time.Time) error

		Delete(context.Context, uint64) error

		Watch(ctx context.Context)
	}
)

func Reminder(ctx context.Context, log *zap.Logger, rs reminderSender) ReminderService {
	return &reminder{
		ac:             DefaultAccessControl,
		log:            log,
		store:          DefaultStore,
		reminderSender: rs,
	}
}

func (svc reminder) Find(ctx context.Context, filter types.ReminderFilter) (rr types.ReminderSet, f types.ReminderFilter, err error) {
	var (
		raProps = &reminderActionProps{filter: &filter}
	)

	err = func() (err error) {
		rr, f, err = store.SearchReminders(ctx, svc.store, filter)
		if err != nil {
			return err
		}

		return nil
	}()

	return rr, f, svc.recordAction(ctx, raProps, ReminderActionSearch, err)
}

func (svc reminder) FindByID(ctx context.Context, ID uint64) (r *types.Reminder, err error) {
	var (
		raProps = &reminderActionProps{reminder: &types.Reminder{ID: ID}}
	)

	err = func() (err error) {
		if ID == 0 {
			return ReminderErrInvalidID()
		}

		r, err = store.LookupReminderByID(ctx, svc.store, ID)
		if err != nil {
			return err
		}

		if svc.checkAssignTo(ctx, r) {
			return ReminderErrNotAllowedToRead()
		}

		raProps.setReminder(r)

		return nil
	}()

	return r, svc.recordAction(ctx, raProps, ReminderActionLookup, err)
}

func (svc reminder) FindByIDs(ctx context.Context, IDs ...uint64) (rr types.ReminderSet, err error) {
	if len(IDs) == 0 {
		return nil, nil
	}

	rr, _, err = svc.Find(ctx, types.ReminderFilter{ReminderID: IDs, AssignedTo: svc.currentUser(ctx)})

	return rr, nil
}

func (svc reminder) checkAssignee(ctx context.Context, rm *types.Reminder) (err error) {
	// Check if user is assigning to someone else
	if svc.checkAssignTo(ctx, rm) {
		if !svc.ac.CanAssignReminder(ctx) {
			return ReminderErrNotAllowedToAssign()
		}
	}

	return nil
}

// checkAssignTo compares current user with reminder.AssignedTo and return bool
func (svc reminder) checkAssignTo(ctx context.Context, rm *types.Reminder) (valid bool) {
	return rm.AssignedTo != svc.currentUser(ctx)
}

func (svc reminder) currentUser(ctx context.Context) uint64 {
	return intAuth.GetIdentityFromContext(ctx).Identity()
}

func (svc reminder) Create(ctx context.Context, new *types.Reminder) (r *types.Reminder, err error) {
	var (
		raProps = &reminderActionProps{new: new}
	)

	err = func() (err error) {
		if err := svc.checkAssignee(ctx, new); err != nil {
			return err
		}

		r = new
		r.ID = nextID()
		r.CreatedAt = *now()

		if err = store.CreateReminder(ctx, svc.store, r); err != nil {
			return err
		}

		return nil
	}()

	return r, svc.recordAction(ctx, raProps, ReminderActionUpdate, err)

}

func (svc reminder) Update(ctx context.Context, upd *types.Reminder) (r *types.Reminder, err error) {
	var (
		raProps = &reminderActionProps{updated: upd}
	)

	err = func() (err error) {
		if upd.ID == 0 {
			return ReminderErrInvalidID()
		}

		if r, err = store.LookupReminderByID(ctx, svc.store, upd.ID); err != nil {
			return
		}

		if err := svc.checkAssignee(ctx, upd); err != nil {
			return err
		}

		// Assign changed values
		if upd.AssignedTo != r.AssignedTo {
			r.AssignedTo = upd.AssignedTo
			r.AssignedBy = svc.currentUser(ctx)
			r.AssignedAt = time.Now()
		}

		a := r.RemindAt
		if a == nil {
			a = &time.Time{}
		}

		b := upd.RemindAt
		if b == nil {
			b = &time.Time{}
		}
		if !a.Equal(*b) {
			r.SnoozeCount = 0
		}

		r.RemindAt = upd.RemindAt
		r.Payload = upd.Payload
		r.Resource = upd.Resource
		r.UpdatedAt = now()

		if err = store.UpdateReminder(ctx, svc.store, r); err != nil {
			return err
		}

		return nil
	}()

	return r, svc.recordAction(ctx, raProps, ReminderActionUpdate, err)
}

func (svc reminder) Dismiss(ctx context.Context, ID uint64) (err error) {
	var (
		r *types.Reminder

		raProps = &reminderActionProps{reminder: &types.Reminder{ID: ID}}
	)

	err = func() (err error) {
		if ID == 0 {
			return ReminderErrInvalidID()
		}

		if r, err = store.LookupReminderByID(ctx, svc.store, ID); err != nil {
			return ReminderErrNotFound()
		}

		if svc.checkAssignTo(ctx, r) {
			return ReminderErrNotAllowedToDismiss()
		}

		raProps.setReminder(r)

		// Assign changed values
		n := time.Now()
		r.DismissedAt = &n
		r.DismissedBy = svc.currentUser(ctx)

		if err = store.UpdateReminder(ctx, svc.store, r); err != nil {
			return err
		}

		return nil
	}()

	return svc.recordAction(ctx, raProps, ReminderActionDismiss, err)
}

func (svc reminder) Undismiss(ctx context.Context, ID uint64) (err error) {
	var (
		r *types.Reminder

		raProps = &reminderActionProps{reminder: &types.Reminder{ID: ID}}
	)

	err = func() (err error) {
		if ID == 0 {
			return ReminderErrInvalidID()
		}

		if r, err = store.LookupReminderByID(ctx, svc.store, ID); err != nil {
			return ReminderErrNotFound()
		}

		if svc.checkAssignTo(ctx, r) {
			return ReminderErrNotAllowedToUndismiss()
		}

		raProps.setReminder(r)

		// Assign changed values
		r.DismissedAt = nil
		r.DismissedBy = 0

		if err = store.UpdateReminder(ctx, svc.store, r); err != nil {
			return err
		}

		return nil
	}()

	return svc.recordAction(ctx, raProps, ReminderActionDismiss, err)
}

func (svc reminder) Snooze(ctx context.Context, ID uint64, remindAt *time.Time) (err error) {
	var (
		r *types.Reminder

		raProps = &reminderActionProps{reminder: &types.Reminder{ID: ID, RemindAt: remindAt}}
	)

	err = func() (err error) {
		if ID == 0 {
			return ReminderErrInvalidID()
		}

		if r, err = store.LookupReminderByID(ctx, svc.store, ID); err != nil {
			return ReminderErrNotFound()
		}

		raProps.setReminder(r)

		// Assign changed values
		r.SnoozeCount++
		r.RemindAt = remindAt

		if err = store.UpdateReminder(ctx, svc.store, r); err != nil {
			return err
		}

		return nil
	}()

	return svc.recordAction(ctx, raProps, ReminderActionSnooze, err)
}

func (svc reminder) Delete(ctx context.Context, ID uint64) (err error) {
	var (
		r *types.Reminder

		raProps = &reminderActionProps{reminder: &types.Reminder{ID: ID}}
	)

	err = func() (err error) {
		if ID == 0 {
			return ReminderErrInvalidID()
		}

		if r, err = svc.FindByID(ctx, ID); err != nil {
			return ReminderErrNotFound()
		}

		r.DeletedAt = now()

		raProps.setReminder(r)

		return store.UpdateReminder(ctx, svc.store, r)
	}()

	return svc.recordAction(ctx, raProps, ReminderActionDelete, err)
}

func (svc reminder) Watch(ctx context.Context) {
	if svc.reminderSender != nil {
		var (
			interval = time.Minute
			rTicker  = time.NewTicker(interval)
		)

		go func() {
			defer sentry.Recover()
			defer rTicker.Stop()
			defer svc.log.Info("stopped")

			for {
				select {
				case <-ctx.Done():
					return
				case <-rTicker.C:
					// Get scheduled reminders of users
					rr, _, err := svc.Find(ctx, types.ReminderFilter{
						ExcludeDismissed: true,
						ScheduledOnly:    true,
					})

					if err != nil {
						svc.log.Error("failed to get reminders of users", zap.Error(err))
					}

					// Send scheduled reminders to users
					_ = rr.Walk(func(r *types.Reminder) error {
						if r.RemindAt != nil && r.DismissedAt == nil && now().Add(interval).After(*r.RemindAt) {
							if err := svc.reminderSender.Send("reminder", r, r.AssignedTo); err != nil {
								svc.log.Error("failed to send reminder to user", zap.Error(err))
							}
						}
						return nil
					})
				}
			}
		}()
	}
}