package db

import (
	"crypto/x509"
	"encoding/json"
	"time"

	"github.com/pkg/errors"
	"github.com/smallstep/nosql"
)

var (
	certsTable        = []byte("x509_certs")
	revokedCertsTable = []byte("revoked_x509_certs")
	usedOTTTable      = []byte("used_ott")
)

// ErrAlreadyExists can be returned if the DB attempts to set a key that has
// been previously set.
var ErrAlreadyExists = errors.New("already exists")

// Config represents the JSON attributes used for configuring a step-ca DB.
type Config struct {
	Type       string `json:"type"`
	DataSource string `json:"dataSource"`
	ValueDir   string `json:"valueDir,omitempty"`
	Database   string `json:"database,omitempty"`
}

// AuthDB is an interface over an Authority DB client that implements a nosql.DB interface.
type AuthDB interface {
	IsRevoked(sn string) (bool, error)
	Revoke(rci *RevokedCertificateInfo) error
	StoreCertificate(crt *x509.Certificate) error
	UseToken(id, tok string) (bool, error)
	Shutdown() error
}

// DB is a wrapper over the nosql.DB interface.
type DB struct {
	nosql.DB
	isUp bool
}

// New returns a new database client that implements the AuthDB interface.
func New(c *Config) (AuthDB, error) {
	if c == nil {
		return newSimpleDB(c)
	}

	db, err := nosql.New(c.Type, c.DataSource, nosql.WithDatabase(c.Database),
		nosql.WithValueDir(c.ValueDir))
	if err != nil {
		return nil, errors.Wrapf(err, "Error opening database of Type %s with source %s", c.Type, c.DataSource)
	}

	tables := [][]byte{revokedCertsTable, certsTable}
	for _, b := range tables {
		if err := db.CreateTable(b); err != nil {
			return nil, errors.Wrapf(err, "error creating table %s",
				string(b))
		}
	}

	return &DB{db, true}, nil
}

// RevokedCertificateInfo contains information regarding the certificate
// revocation action.
type RevokedCertificateInfo struct {
	Serial        string
	ProvisionerID string
	ReasonCode    int
	Reason        string
	RevokedAt     time.Time
	TokenID       string
	MTLS          bool
}

// IsRevoked returns whether or not a certificate with the given identifier
// has been revoked.
// In the case of an X509 Certificate the `id` should be the Serial Number of
// the Certificate.
func (db *DB) IsRevoked(sn string) (bool, error) {
	// If the DB is nil then act as pass through.
	if db == nil {
		return false, nil
	}

	// If the error is `Not Found` then the certificate has not been revoked.
	// Any other error should be propagated to the caller.
	if _, err := db.Get(revokedCertsTable, []byte(sn)); err != nil {
		if nosql.IsErrNotFound(err) {
			return false, nil
		}
		return false, errors.Wrap(err, "error checking revocation bucket")
	}

	// This certificate has been revoked.
	return true, nil
}

// Revoke adds a certificate to the revocation table.
func (db *DB) Revoke(rci *RevokedCertificateInfo) error {
	isRvkd, err := db.IsRevoked(rci.Serial)
	if err != nil {
		return err
	}
	if isRvkd {
		return ErrAlreadyExists
	}
	rcib, err := json.Marshal(rci)
	if err != nil {
		return errors.Wrap(err, "error marshaling revoked certificate info")
	}

	if err = db.Set(revokedCertsTable, []byte(rci.Serial), rcib); err != nil {
		return errors.Wrap(err, "database Set error")
	}
	return nil
}

// StoreCertificate stores a certificate PEM.
func (db *DB) StoreCertificate(crt *x509.Certificate) error {
	if err := db.Set(certsTable, []byte(crt.SerialNumber.String()), crt.Raw); err != nil {
		return errors.Wrap(err, "database Set error")
	}
	return nil
}

// UseToken returns true if we were able to successfully store the token for
// for the first time, false otherwise.
func (db *DB) UseToken(id, tok string) (bool, error) {
	_, swapped, err := db.CmpAndSwap(usedOTTTable, []byte(id), nil, []byte(tok))
	switch {
	case err != nil:
		return false, errors.Wrapf(err, "error storing used token %s/%s",
			string(usedOTTTable), id)
	case !swapped:
		return false, nil
	default:
		return true, nil
	}
}

// Shutdown sends a shutdown message to the database.
func (db *DB) Shutdown() error {
	if db.isUp {
		if err := db.Close(); err != nil {
			return errors.Wrap(err, "database shutdown error")
		}
		db.isUp = false
	}
	return nil
}