package autocleanup

import (
	"github.com/mattermost/mattermost/server/public/pluginapi"
	"github.com/pkg/errors"
)

const listKeysPageSize = 1000

// Store persists per-channel automatic cleanup configuration.
type Store struct {
	client *pluginapi.Client
}

func NewStore(client *pluginapi.Client) *Store {
	return &Store{client: client}
}

func (s *Store) Get(channelID string) (*Config, error) {
	var config Config
	if err := s.client.KV.Get(kvKey(channelID), &config); err != nil {
		return nil, errors.Wrap(err, "failed to get auto cleanup config")
	}
	if config.OffsetDays <= 0 {
		return nil, nil
	}

	config.ChannelID = channelID
	return &config, nil
}

func (s *Store) Set(channelID string, offsetDays int) error {
	if offsetDays <= 0 {
		return errors.New("offset_days must be greater than zero")
	}

	config := Config{
		ChannelID:  channelID,
		OffsetDays: offsetDays,
	}
	_, err := s.client.KV.Set(kvKey(channelID), config)
	return errors.Wrap(err, "failed to set auto cleanup config")
}

func (s *Store) Delete(channelID string) error {
	if err := s.client.KV.Delete(kvKey(channelID)); err != nil {
		return errors.Wrap(err, "failed to delete auto cleanup config")
	}
	return nil
}

func (s *Store) List() ([]Config, error) {
	configs := make([]Config, 0)
	for page := 0; ; page++ {
		keys, err := s.client.KV.ListKeys(page, listKeysPageSize, pluginapi.WithPrefix(kvKeyPrefix))
		if err != nil {
			return nil, errors.Wrap(err, "failed to list auto cleanup configs")
		}
		if len(keys) == 0 {
			break
		}

		for _, key := range keys {
			channelID := key[len(kvKeyPrefix):]
			config, err := s.Get(channelID)
			if err != nil {
				return nil, err
			}
			if config != nil {
				configs = append(configs, *config)
			}
		}

		if len(keys) < listKeysPageSize {
			break
		}
	}

	return configs, nil
}