package cs3

import (
	"context"
	"crypto/tls"
	"fmt"

	cs3gateway "github.com/cs3org/go-cs3apis/cs3/gateway/v1beta1"
	cs3rpc "github.com/cs3org/go-cs3apis/cs3/rpc/v1beta1"
	"github.com/libregraph/lico"
	"github.com/libregraph/lico/config"
	"github.com/libregraph/lico/identifier/backends"
	"github.com/libregraph/lico/identifier/meta/scopes"
	"github.com/libregraph/lico/identity"
	"github.com/opencloud-eu/reva/v2/pkg/rgrpc/todo/pool"
	cmap "github.com/orcaman/concurrent-map"
	"github.com/sirupsen/logrus"
)

const cs3BackendName = "identifier-cs3"

var cs3SpportedScopes = []string{
	"profile",
	"email",
	lico.ScopeUniqueUserID,
	lico.ScopeRawSubject,
}

// CS3Backend holds the data for the CS3 identifier backend
type CS3Backend struct {
	supportedScopes []string

	logger            logrus.FieldLogger
	tlsConfig         *tls.Config
	gatewayAddr       string
	machineAuthAPIKey string
	insecure          bool

	sessions cmap.ConcurrentMap
}

// NewCS3Backend creates a new CS3 backend identifier backend
func NewCS3Backend(
	c *config.Config,
	tlsConfig *tls.Config,
	gatewayAddr string,
	machineAuthAPIKey string,
	insecure bool,
) (*CS3Backend, error) {

	// Build supported scopes based on default scopes.
	supportedScopes := make([]string, len(cs3SpportedScopes))
	copy(supportedScopes, cs3SpportedScopes)

	b := &CS3Backend{
		supportedScopes: supportedScopes,

		logger:            c.Logger,
		tlsConfig:         tlsConfig,
		gatewayAddr:       gatewayAddr,
		machineAuthAPIKey: machineAuthAPIKey,
		insecure:          insecure,

		sessions: cmap.New(),
	}

	b.logger.Infoln("cs3 backend connection set up")

	return b, nil
}

// RunWithContext implements the Backend interface.
func (b *CS3Backend) RunWithContext(_ context.Context) error {
	return nil
}

// Logon implements the Backend interface, enabling Logon with user name and
// password as provided. Requests are bound to the provided context.
func (b *CS3Backend) Logon(ctx context.Context, audience, username, password string) (bool, *string, *string, backends.UserFromBackend, error) {

	client, err := pool.GetGatewayServiceClient(b.gatewayAddr)
	if err != nil {
		return false, nil, nil, nil, err
	}

	res, err := client.Authenticate(ctx, &cs3gateway.AuthenticateRequest{
		Type:         "basic",
		ClientId:     username,
		ClientSecret: password,
	})
	if err != nil {
		return false, nil, nil, nil, fmt.Errorf("cs3 backend basic authenticate rpc error: %v", err)
	}
	if res.GetStatus().GetCode() != cs3rpc.Code_CODE_OK {
		return false, nil, nil, nil, fmt.Errorf("cs3 backend basic authenticate failed with code %s: %s", res.GetStatus().GetCode().String(), res.GetStatus().GetMessage())
	}

	session := createSession(res.GetUser())

	user, err := newCS3User(res.GetUser())
	if err != nil {
		return false, nil, nil, nil, fmt.Errorf("cs3 backend resolve entry data error: %v", err)
	}

	// Use the users subject as user id.
	userID := user.Subject()

	sessionRef := identity.GetSessionRef(b.Name(), audience, userID)
	b.sessions.Set(*sessionRef, session)
	b.logger.WithFields(logrus.Fields{
		"session":  session,
		"ref":      *sessionRef,
		"username": user.Username(),
		"id":       userID,
	}).Debugln("cs3 backend logon")

	return true, &userID, sessionRef, user, nil
}

// GetUser implements the Backend interface, providing user meta data retrieval
// for the user specified by the userID. Requests are bound to the provided
// context.
func (b *CS3Backend) GetUser(ctx context.Context, userEntryID string, sessionRef *string, _ map[string]bool) (backends.UserFromBackend, error) {

	var session *cs3Session
	if s, ok := b.sessions.Get(*sessionRef); ok {
		// We have a cached session
		session = s.(*cs3Session)
		if session != nil {
			user, err := newCS3User(session.User())
			if err != nil {
				return nil, fmt.Errorf("cs3 backend get user failed to process user: %v", err)
			}
			return user, nil
		}
	}

	// rebuild session

	client, err := pool.GetGatewayServiceClient(b.gatewayAddr)
	if err != nil {
		return nil, err
	}

	res, err := client.Authenticate(ctx, &cs3gateway.AuthenticateRequest{
		Type:         "machine",
		ClientId:     "userid:" + userEntryID,
		ClientSecret: b.machineAuthAPIKey,
	})
	if err != nil {
		return nil, fmt.Errorf("cs3 backend get user machine authenticate rpc error: %v", err)
	}
	if res.GetStatus().GetCode() != cs3rpc.Code_CODE_OK {
		return nil, fmt.Errorf("cs3 backend get user machine authenticate failed with code %s: %s", res.GetStatus().GetCode().String(), res.GetStatus().GetMessage())
	}

	// cache session
	session = createSession(res.GetUser())
	b.sessions.Set(*sessionRef, session)

	user, err := newCS3User(res.GetUser())
	if err != nil {
		return nil, fmt.Errorf("cs3 backend get user data error: %v", err)
	}

	return user, nil
}

// ResolveUserByUsername implements the Backend interface, providing lookup for
// user by providing the username. Requests are bound to the provided context.
func (b *CS3Backend) ResolveUserByUsername(ctx context.Context, username string) (backends.UserFromBackend, error) {

	client, err := pool.GetGatewayServiceClient(b.gatewayAddr)
	if err != nil {
		return nil, err
	}

	res, err := client.Authenticate(ctx, &cs3gateway.AuthenticateRequest{
		Type:         "machine",
		ClientId:     "username:" + username,
		ClientSecret: b.machineAuthAPIKey,
	})
	if err != nil {
		return nil, fmt.Errorf("cs3 backend machine authenticate rpc error: %v", err)
	}
	if res.GetStatus().GetCode() != cs3rpc.Code_CODE_OK {
		return nil, fmt.Errorf("cs3 backend machine authenticate failed with code %s: %s", res.GetStatus().GetCode().String(), res.GetStatus().GetMessage())
	}

	user, err := newCS3User(res.GetUser())
	if err != nil {
		return nil, fmt.Errorf("cs3 backend resolve username data error: %v", err)
	}

	return user, nil
}

// RefreshSession implements the Backend interface.
func (b *CS3Backend) RefreshSession(_ context.Context, _ string, _ *string, _ map[string]any) error {
	return nil
}

// DestroySession implements the Backend interface providing destroy CS3 session.
func (b *CS3Backend) DestroySession(_ context.Context, sessionRef *string) error {
	b.sessions.Remove(*sessionRef)
	return nil
}

// UserClaims implements the Backend interface, providing user specific claims
// for the user specified by the userID.
func (b *CS3Backend) UserClaims(_ string, _ map[string]bool) map[string]any {
	return nil
}

// ScopesSupported implements the Backend interface, providing supported scopes
// when running this backend.
func (b *CS3Backend) ScopesSupported() []string {
	return b.supportedScopes
}

// ScopesMeta implements the Backend interface, providing meta data for
// supported scopes.
func (b *CS3Backend) ScopesMeta() *scopes.Scopes {
	return nil
}

// Name implements the Backend interface.
func (b *CS3Backend) Name() string {
	return cs3BackendName
}