package secrets

import (
	"os"
	"path/filepath"
	"regexp"
	"time"

	"github.com/containers/common/pkg/secrets/filedriver"
	"github.com/containers/storage/pkg/lockfile"
	"github.com/containers/storage/pkg/stringid"
	"github.com/pkg/errors"
)

// maxSecretSize is the max size for secret data - 512kB
const maxSecretSize = 512000

// secretIDLength is the character length of a secret ID - 25
const secretIDLength = 25

// errInvalidPath indicates that the secrets path is invalid
var errInvalidPath = errors.New("invalid secrets path")

// errNoSuchSecret indicates that the secret does not exist
var errNoSuchSecret = errors.New("no such secret")

// errSecretNameInUse indicates that the secret name is already in use
var errSecretNameInUse = errors.New("secret name in use")

// errInvalidSecretName indicates that the secret name is invalid
var errInvalidSecretName = errors.New("invalid secret name")

// errInvalidDriver indicates that the driver type is invalid
var errInvalidDriver = errors.New("invalid driver")

// errInvalidDriverOpt indicates that a driver option is invalid
var errInvalidDriverOpt = errors.New("invalid driver option")

// errAmbiguous indicates that a secret is ambiguous
var errAmbiguous = errors.New("secret is ambiguous")

// errDataSize indicates that the secret data is too large or too small
var errDataSize = errors.New("secret data must be larger than 0 and less than 512000 bytes")

// secretsFile is the name of the file that the secrets database will be stored in
var secretsFile = "secrets.json"

// secretNameRegexp matches valid secret names
// Allowed: 64 [a-zA-Z0-9-_.] characters, and the start and end character must be [a-zA-Z0-9]
var secretNameRegexp = regexp.MustCompile(`^[a-zA-Z0-9][a-zA-Z0-9_.-]*[a-zA-Z0-9]?$`)

// SecretsManager holds information on handling secrets
type SecretsManager struct {
	// secretsPath is the path to the db file where secrets are stored
	secretsDBPath string
	// lockfile is the locker for the secrets file
	lockfile lockfile.Locker
	// db is an in-memory cache of the database of secrets
	db *db
}

// Secret defines a secret
type Secret struct {
	// Name is the name of the secret
	Name string `json:"name"`
	// ID is the unique secret ID
	ID string `json:"id"`
	// Metadata stores other metadata on the secret
	Metadata map[string]string `json:"metadata,omitempty"`
	// CreatedAt is when the secret was created
	CreatedAt time.Time `json:"createdAt"`
	// Driver is the driver used to store secret data
	Driver string `json:"driver"`
	// DriverOptions is other metadata needed to use the driver
	DriverOptions map[string]string `json:"driverOptions"`
}

// SecretsDriver interfaces with the secrets data store.
// The driver stores the actual bytes of secret data, as opposed to
// the secret metadata.
// Currently only the unencrypted filedriver is implemented.
type SecretsDriver interface {
	// List lists all secret ids in the secrets data store
	List() ([]string, error)
	// Lookup gets the secret's data bytes
	Lookup(id string) ([]byte, error)
	// Store stores the secret's data bytes
	Store(id string, data []byte) error
	// Delete deletes a secret's data from the driver
	Delete(id string) error
}

// NewManager creates a new secrets manager
// rootPath is the directory where the secrets data file resides
func NewManager(rootPath string) (*SecretsManager, error) {
	manager := new(SecretsManager)

	if !filepath.IsAbs(rootPath) {
		return nil, errors.Wrapf(errInvalidPath, "path must be absolute: %s", rootPath)
	}
	if _, err := os.Stat(rootPath); os.IsNotExist(err) {
		// the lockfile functions requre that the rootPath dir is executable
		os.MkdirAll(rootPath, 0700)
	}

	lock, err := lockfile.GetLockfile(filepath.Join(rootPath, "secrets.lock"))
	if err != nil {
		return nil, err
	}
	manager.lockfile = lock
	manager.secretsDBPath = filepath.Join(rootPath, secretsFile)
	manager.db = new(db)
	manager.db.Secrets = make(map[string]Secret)
	manager.db.NameToID = make(map[string]string)
	manager.db.IDToName = make(map[string]string)
	return manager, nil
}

// Store takes a name, creates a secret and stores the secret metadata and the secret payload.
// It returns a generated ID that is associated with the secret.
// The max size for secret data is 512kB.
func (s *SecretsManager) Store(name string, data []byte, driverType string, driverOpts map[string]string) (string, error) {
	err := validateSecretName(name)
	if err != nil {
		return "", err
	}

	if !(len(data) > 0 && len(data) < maxSecretSize) {
		return "", errDataSize
	}

	s.lockfile.Lock()
	defer s.lockfile.Unlock()

	exist, err := s.secretExists(name)
	if err != nil {
		return "", err
	}
	if exist {
		return "", errors.Wrapf(errSecretNameInUse, name)
	}

	secr := new(Secret)
	secr.Name = name

	for {
		newID := stringid.GenerateNonCryptoID()
		// GenerateNonCryptoID() gives 64 characters, so we truncate to correct length
		newID = newID[0:secretIDLength]
		_, err := s.lookupSecret(newID)
		if err != nil {
			if errors.Cause(err) == errNoSuchSecret {
				secr.ID = newID
				break
			} else {
				return "", err
			}
		}
	}

	secr.Driver = driverType
	secr.Metadata = make(map[string]string)
	secr.CreatedAt = time.Now()
	secr.DriverOptions = driverOpts

	driver, err := getDriver(driverType, driverOpts)
	if err != nil {
		return "", err
	}
	err = driver.Store(secr.ID, data)
	if err != nil {
		return "", errors.Wrapf(err, "error creating secret %s", name)
	}

	err = s.store(secr)
	if err != nil {
		return "", errors.Wrapf(err, "error creating secret %s", name)
	}

	return secr.ID, nil
}

// Delete removes all secret metadata and secret data associated with the specified secret.
// Delete takes a name, ID, or partial ID.
func (s *SecretsManager) Delete(nameOrID string) (string, error) {
	err := validateSecretName(nameOrID)
	if err != nil {
		return "", err
	}

	s.lockfile.Lock()
	defer s.lockfile.Unlock()

	secret, err := s.lookupSecret(nameOrID)
	if err != nil {
		return "", err
	}
	secretID := secret.ID

	driver, err := getDriver(secret.Driver, secret.DriverOptions)
	if err != nil {
		return "", err
	}

	err = driver.Delete(secretID)
	if err != nil {
		return "", errors.Wrapf(err, "error deleting secret %s", nameOrID)
	}

	err = s.delete(secretID)
	if err != nil {
		return "", errors.Wrapf(err, "error deleting secret %s", nameOrID)
	}
	return secretID, nil
}

// Lookup gives a secret's metadata given its name, ID, or partial ID.
func (s *SecretsManager) Lookup(nameOrID string) (*Secret, error) {
	s.lockfile.Lock()
	defer s.lockfile.Unlock()

	return s.lookupSecret(nameOrID)
}

// List lists all secrets.
func (s *SecretsManager) List() ([]Secret, error) {
	s.lockfile.Lock()
	defer s.lockfile.Unlock()

	secrets, err := s.lookupAll()
	if err != nil {
		return nil, err
	}
	var ls []Secret
	for _, v := range secrets {
		ls = append(ls, v)

	}
	return ls, nil
}

// LookupSecretData returns secret metadata as well as secret data in bytes.
// The secret data can be looked up using its name, ID, or partial ID.
func (s *SecretsManager) LookupSecretData(nameOrID string) (*Secret, []byte, error) {
	s.lockfile.Lock()
	defer s.lockfile.Unlock()

	secret, err := s.lookupSecret(nameOrID)
	if err != nil {
		return nil, nil, err
	}
	driver, err := getDriver(secret.Driver, secret.DriverOptions)
	if err != nil {
		return nil, nil, err
	}
	data, err := driver.Lookup(secret.ID)
	if err != nil {
		return nil, nil, err
	}
	return secret, data, nil
}

// validateSecretName checks if the secret name is valid.
func validateSecretName(name string) error {
	if !secretNameRegexp.MatchString(name) || len(name) > 64 {
		return errors.Wrapf(errInvalidSecretName, "only 64 [a-zA-Z0-9-_.] characters allowed, and the start and end character must be [a-zA-Z0-9]: %s", name)
	}
	return nil
}

// getDriver creates a new driver.
func getDriver(name string, opts map[string]string) (SecretsDriver, error) {
	if name == "file" {
		if path, ok := opts["path"]; ok {
			return filedriver.NewDriver(path)
		} else {
			return nil, errors.Wrap(errInvalidDriverOpt, "need path for filedriver")
		}
	}
	return nil, errInvalidDriver
}