package registry

import (
	"crypto/tls"
	"fmt"
	"net/http"
	"net/url"
	"strings"

	"golang.org/x/net/context"

	"github.com/Sirupsen/logrus"
	"github.com/docker/docker/reference"
	"github.com/docker/engine-api/types"
	registrytypes "github.com/docker/engine-api/types/registry"
)

const (
	// DefaultSearchLimit is the default value for maximum number of returned search results.
	DefaultSearchLimit = 25
)

// Service is the interface defining what a registry service should implement.
type Service interface {
	Auth(ctx context.Context, authConfig *types.AuthConfig, userAgent string) (status, token string, err error)
	LookupPullEndpoints(hostname string) (endpoints []APIEndpoint, err error)
	LookupPushEndpoints(hostname string) (endpoints []APIEndpoint, err error)
	ResolveRepository(name reference.Named) (*RepositoryInfo, error)
	ResolveIndex(name string) (*registrytypes.IndexInfo, error)
	Search(ctx context.Context, term string, limit int, authConfig *types.AuthConfig, userAgent string, headers map[string][]string) (*registrytypes.SearchResults, error)
	ServiceConfig() *registrytypes.ServiceConfig
	TLSConfig(hostname string) (*tls.Config, error)
}

// DefaultService is a registry service. It tracks configuration data such as a list
// of mirrors.
type DefaultService struct {
	config *serviceConfig
}

// NewService returns a new instance of DefaultService ready to be
// installed into an engine.
func NewService(options ServiceOptions) *DefaultService {
	return &DefaultService{
		config: newServiceConfig(options),
	}
}

// ServiceConfig returns the public registry service configuration.
func (s *DefaultService) ServiceConfig() *registrytypes.ServiceConfig {
	return &s.config.ServiceConfig
}

// Auth contacts the public registry with the provided credentials,
// and returns OK if authentication was successful.
// It can be used to verify the validity of a client's credentials.
func (s *DefaultService) Auth(ctx context.Context, authConfig *types.AuthConfig, userAgent string) (status, token string, err error) {
	// TODO Use ctx when searching for repositories
	serverAddress := authConfig.ServerAddress
	if serverAddress == "" {
		serverAddress = IndexServer
	}
	if !strings.HasPrefix(serverAddress, "https://") && !strings.HasPrefix(serverAddress, "http://") {
		serverAddress = "https://" + serverAddress
	}
	u, err := url.Parse(serverAddress)
	if err != nil {
		return "", "", fmt.Errorf("unable to parse server address: %v", err)
	}

	endpoints, err := s.LookupPushEndpoints(u.Host)
	if err != nil {
		return "", "", err
	}

	for _, endpoint := range endpoints {
		login := loginV2
		if endpoint.Version == APIVersion1 {
			login = loginV1
		}

		status, token, err = login(authConfig, endpoint, userAgent)
		if err == nil {
			return
		}
		if fErr, ok := err.(fallbackError); ok {
			err = fErr.err
			logrus.Infof("Error logging in to %s endpoint, trying next endpoint: %v", endpoint.Version, err)
			continue
		}
		return "", "", err
	}

	return "", "", err
}

// splitReposSearchTerm breaks a search term into an index name and remote name
func splitReposSearchTerm(reposName string) (string, string) {
	nameParts := strings.SplitN(reposName, "/", 2)
	var indexName, remoteName string
	if len(nameParts) == 1 || (!strings.Contains(nameParts[0], ".") &&
		!strings.Contains(nameParts[0], ":") && nameParts[0] != "localhost") {
		// This is a Docker Index repos (ex: samalba/hipache or ubuntu)
		// 'docker.io'
		indexName = IndexName
		remoteName = reposName
	} else {
		indexName = nameParts[0]
		remoteName = nameParts[1]
	}
	return indexName, remoteName
}

// Search queries the public registry for images matching the specified
// search terms, and returns the results.
func (s *DefaultService) Search(ctx context.Context, term string, limit int, authConfig *types.AuthConfig, userAgent string, headers map[string][]string) (*registrytypes.SearchResults, error) {
	// TODO Use ctx when searching for repositories
	if err := validateNoScheme(term); err != nil {
		return nil, err
	}

	indexName, remoteName := splitReposSearchTerm(term)

	index, err := newIndexInfo(s.config, indexName)
	if err != nil {
		return nil, err
	}

	// *TODO: Search multiple indexes.
	endpoint, err := NewV1Endpoint(index, userAgent, http.Header(headers))
	if err != nil {
		return nil, err
	}

	r, err := NewSession(endpoint.client, authConfig, endpoint)
	if err != nil {
		return nil, err
	}

	if index.Official {
		localName := remoteName
		if strings.HasPrefix(localName, "library/") {
			// If pull "library/foo", it's stored locally under "foo"
			localName = strings.SplitN(localName, "/", 2)[1]
		}

		return r.SearchRepositories(localName, limit)
	}
	return r.SearchRepositories(remoteName, limit)
}

// ResolveRepository splits a repository name into its components
// and configuration of the associated registry.
func (s *DefaultService) ResolveRepository(name reference.Named) (*RepositoryInfo, error) {
	return newRepositoryInfo(s.config, name)
}

// ResolveIndex takes indexName and returns index info
func (s *DefaultService) ResolveIndex(name string) (*registrytypes.IndexInfo, error) {
	return newIndexInfo(s.config, name)
}

// APIEndpoint represents a remote API endpoint
type APIEndpoint struct {
	Mirror       bool
	URL          *url.URL
	Version      APIVersion
	Official     bool
	TrimHostname bool
	TLSConfig    *tls.Config
}

// ToV1Endpoint returns a V1 API endpoint based on the APIEndpoint
func (e APIEndpoint) ToV1Endpoint(userAgent string, metaHeaders http.Header) (*V1Endpoint, error) {
	return newV1Endpoint(*e.URL, e.TLSConfig, userAgent, metaHeaders)
}

// TLSConfig constructs a client TLS configuration based on server defaults
func (s *DefaultService) TLSConfig(hostname string) (*tls.Config, error) {
	return newTLSConfig(hostname, isSecureIndex(s.config, hostname))
}

func (s *DefaultService) tlsConfigForMirror(mirrorURL *url.URL) (*tls.Config, error) {
	return s.TLSConfig(mirrorURL.Host)
}

// LookupPullEndpoints creates a list of endpoints to try to pull from, in order of preference.
// It gives preference to v2 endpoints over v1, mirrors over the actual
// registry, and HTTPS over plain HTTP.
func (s *DefaultService) LookupPullEndpoints(hostname string) (endpoints []APIEndpoint, err error) {
	return s.lookupEndpoints(hostname)
}

// LookupPushEndpoints creates a list of endpoints to try to push to, in order of preference.
// It gives preference to v2 endpoints over v1, and HTTPS over plain HTTP.
// Mirrors are not included.
func (s *DefaultService) LookupPushEndpoints(hostname string) (endpoints []APIEndpoint, err error) {
	allEndpoints, err := s.lookupEndpoints(hostname)
	if err == nil {
		for _, endpoint := range allEndpoints {
			if !endpoint.Mirror {
				endpoints = append(endpoints, endpoint)
			}
		}
	}
	return endpoints, err
}

func (s *DefaultService) lookupEndpoints(hostname string) (endpoints []APIEndpoint, err error) {
	endpoints, err = s.lookupV2Endpoints(hostname)
	if err != nil {
		return nil, err
	}

	if s.config.V2Only {
		return endpoints, nil
	}

	legacyEndpoints, err := s.lookupV1Endpoints(hostname)
	if err != nil {
		return nil, err
	}
	endpoints = append(endpoints, legacyEndpoints...)

	return endpoints, nil
}