package filter

import (
	"errors"

	log "github.com/Sirupsen/logrus"
	"github.com/docker/swarm/cluster"
	"github.com/samalba/dockerclient"
)

type Filter interface {
	// Return a subset of nodes that were accepted by the filtering policy.
	Filter(*dockerclient.ContainerConfig, []*cluster.Node) ([]*cluster.Node, error)
}

var (
	filters         map[string]Filter
	ErrNotSupported = errors.New("filter not supported")
)

func init() {
	filters = map[string]Filter{
		"affinity":   &AffinityFilter{},
		"health":     &HealthFilter{},
		"constraint": &ConstraintFilter{},
		"port":       &PortFilter{},
	}
}

func New(names []string) ([]Filter, error) {
	var selectedFilters []Filter

	for _, name := range names {
		if filter, exists := filters[name]; exists {
			log.Debugf("Initializing %q filter", name)
			selectedFilters = append(selectedFilters, filter)
		} else {
			return nil, ErrNotSupported
		}
	}
	return selectedFilters, nil
}

// Apply a set of filters in batch.
func ApplyFilters(filters []Filter, config *dockerclient.ContainerConfig, nodes []*cluster.Node) ([]*cluster.Node, error) {
	var err error

	for _, filter := range filters {
		nodes, err = filter.Filter(config, nodes)
		if err != nil {
			return nil, err
		}
	}
	return nodes, nil
}