/*
Copyright IBM Corp. All Rights Reserved.

SPDX-License-Identifier: Apache-2.0
*/

package persistence

import (
	"encoding/hex"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
	"strings"

	"github.com/hyperledger/fabric/common/chaincode"
	"github.com/hyperledger/fabric/common/flogging"
	"github.com/hyperledger/fabric/common/util"
	"github.com/pkg/errors"
)

var logger = flogging.MustGetLogger("chaincode.persistence")

// IOReadWriter defines the interface needed for reading, writing, removing, and
// checking for existence of a specified file
type IOReadWriter interface {
	ReadDir(string) ([]os.FileInfo, error)
	ReadFile(string) ([]byte, error)
	Remove(name string) error
	Stat(string) (os.FileInfo, error)
	WriteFile(string, []byte, os.FileMode) error
}

// FilesystemIO is the production implementation of the IOWriter interface
type FilesystemIO struct {
}

// WriteFile writes a file to the filesystem
func (f *FilesystemIO) WriteFile(filename string, data []byte, perm os.FileMode) error {
	return ioutil.WriteFile(filename, data, perm)
}

// Stat checks for existence of the file on the filesystem
func (f *FilesystemIO) Stat(name string) (os.FileInfo, error) {
	return os.Stat(name)
}

// Remove removes a file from the filesystem - used for rolling back an in-flight
// Save operation upon a failure
func (f *FilesystemIO) Remove(name string) error {
	return os.Remove(name)
}

// ReadFile reads a file from the filesystem
func (f *FilesystemIO) ReadFile(filename string) ([]byte, error) {
	return ioutil.ReadFile(filename)
}

// ReadDir reads a directory from the filesystem
func (f *FilesystemIO) ReadDir(dirname string) ([]os.FileInfo, error) {
	return ioutil.ReadDir(dirname)
}

// Store holds the information needed for persisting a chaincode install package
type Store struct {
	Path       string
	ReadWriter IOReadWriter
}

// Save persists chaincode install package bytes with the given name
// and version
func (s *Store) Save(name, version string, ccInstallPkg []byte) ([]byte, error) {
	metadataJSON, err := toJSON(name, version)
	if err != nil {
		return nil, err
	}

	hash := util.ComputeSHA256(ccInstallPkg)
	hashString := hex.EncodeToString(hash)
	metadataPath := filepath.Join(s.Path, hashString+".json")
	if _, err := s.ReadWriter.Stat(metadataPath); err == nil {
		return nil, errors.Errorf("chaincode metadata already exists at %s", metadataPath)
	}

	ccInstallPkgPath := filepath.Join(s.Path, hashString+".bin")
	if _, err := s.ReadWriter.Stat(ccInstallPkgPath); err == nil {
		return nil, errors.Errorf("ChaincodeInstallPackage already exists at %s", ccInstallPkgPath)
	}

	if err := s.ReadWriter.WriteFile(metadataPath, metadataJSON, 0600); err != nil {
		return nil, errors.Wrapf(err, "error writing metadata file to %s", metadataPath)
	}

	if err := s.ReadWriter.WriteFile(ccInstallPkgPath, ccInstallPkg, 0600); err != nil {
		err = errors.Wrapf(err, "error writing chaincode install package to %s", ccInstallPkgPath)
		logger.Error(err.Error())

		// need to roll back metadata write above on error
		if err2 := s.ReadWriter.Remove(metadataPath); err2 != nil {
			logger.Errorf("error removing metadata file at %s: %s", metadataPath, err2)
		}
		return nil, err
	}

	return hash, nil
}

// Load loads a persisted chaincode install package bytes with the given hash
// and also returns the name and version
func (s *Store) Load(hash []byte) (ccInstallPkg []byte, name, version string, err error) {
	hashString := hex.EncodeToString(hash)
	ccInstallPkgPath := filepath.Join(s.Path, hashString+".bin")
	ccInstallPkg, err = s.ReadWriter.ReadFile(ccInstallPkgPath)
	if err != nil {
		err = errors.Wrapf(err, "error reading chaincode install package at %s", ccInstallPkgPath)
		return nil, "", "", err
	}

	metadataPath := filepath.Join(s.Path, hashString+".json")
	name, version, err = s.LoadMetadata(metadataPath)
	if err != nil {
		return nil, "", "", err
	}

	return ccInstallPkg, name, version, nil
}

// LoadMetadata loads the chaincode metadata stored at the specified path
func (s *Store) LoadMetadata(path string) (name, version string, err error) {
	metadataBytes, err := s.ReadWriter.ReadFile(path)
	if err != nil {
		err = errors.Wrapf(err, "error reading metadata at %s", path)
		return "", "", err
	}
	ccMetadata := &ChaincodeMetadata{}
	err = json.Unmarshal(metadataBytes, ccMetadata)
	if err != nil {
		err = errors.Wrapf(err, "error unmarshaling metadata at %s", path)
		return "", "", err
	}

	return ccMetadata.Name, ccMetadata.Version, nil
}

// CodePackageNotFoundErr is the error returned when a code package cannot
// be found in the persistence store
type CodePackageNotFoundErr struct {
	Name    string
	Version string
}

func (e *CodePackageNotFoundErr) Error() string {
	return fmt.Sprintf("chaincode install package not found with name '%s', version '%s'", e.Name, e.Version)
}

// RetrieveHash retrieves the hash of a chaincode install package given the
// name and version of the chaincode
func (s *Store) RetrieveHash(name string, version string) ([]byte, error) {
	installedChaincodes, err := s.ListInstalledChaincodes()
	if err != nil {
		return nil, errors.WithMessage(err, "error getting installed chaincodes")
	}

	for _, installedChaincode := range installedChaincodes {
		if installedChaincode.Name == name && installedChaincode.Version == version {
			return installedChaincode.Id, nil
		}
	}

	err = &CodePackageNotFoundErr{
		Name:    name,
		Version: version,
	}

	return nil, err
}

// ListInstalledChaincodes returns an array with information about the
// chaincodes installed in the persistence store
func (s *Store) ListInstalledChaincodes() ([]chaincode.InstalledChaincode, error) {
	files, err := s.ReadWriter.ReadDir(s.Path)
	if err != nil {
		return nil, errors.Wrapf(err, "error reading chaincode directory at %s", s.Path)
	}

	installedChaincodes := []chaincode.InstalledChaincode{}
	for _, file := range files {
		if strings.HasSuffix(file.Name(), ".json") {
			metadataPath := filepath.Join(s.Path, file.Name())
			ccName, ccVersion, err := s.LoadMetadata(metadataPath)
			if err != nil {
				logger.Warning(err.Error())
				continue
			}

			// split the file name and get just the hash
			hashString := strings.Split(file.Name(), ".")[0]
			hash, err := hex.DecodeString(hashString)
			if err != nil {
				return nil, errors.Wrapf(err, "error decoding hash from hex string: %s", hashString)
			}
			installedChaincode := chaincode.InstalledChaincode{
				Name:    ccName,
				Version: ccVersion,
				Id:      hash,
			}
			installedChaincodes = append(installedChaincodes, installedChaincode)
		}
	}
	return installedChaincodes, nil
}

// GetChaincodeInstallPath returns the path where chaincodes
// are installed
func (s *Store) GetChaincodeInstallPath() string {
	return s.Path
}

// ChaincodeMetadata holds the name and version of a chaincode
type ChaincodeMetadata struct {
	Name    string `json:"Name"`
	Version string `json:"Version"`
}

func toJSON(name, version string) ([]byte, error) {
	metadata := &ChaincodeMetadata{
		Name:    name,
		Version: version,
	}

	metadataBytes, err := json.Marshal(metadata)
	if err != nil {
		return nil, errors.Wrap(err, "error marshaling name and version into JSON")
	}

	return metadataBytes, nil
}