/*
Copyright 2016 The Fission Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package utils

import (
	"context"
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"io"
	"net"
	"net/http"
	"os"
	"path/filepath"
	"strconv"
	"strings"

	"github.com/mholt/archiver/v3"
	"github.com/pkg/errors"
	uuid "github.com/satori/go.uuid"
	"golang.org/x/net/context/ctxhttp"
	apiv1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"

	fv1 "github.com/fission/fission/pkg/apis/core/v1"
)

func UrlForFunction(name, namespace string) string {
	prefix := "/fission-function"
	if namespace != metav1.NamespaceDefault {
		prefix = fmt.Sprintf("/fission-function/%s", namespace)
	}
	return fmt.Sprintf("%s/%s", prefix, name)
}

// IsNetworkError returns true if an error is a network error, and false otherwise.
func IsNetworkError(err error) bool {
	_, ok := err.(net.Error)
	return ok
}

// GetFunctionIstioServiceName return service name of function for istio feature
func GetFunctionIstioServiceName(fnName, fnNamespace string) string {
	return fmt.Sprintf("istio-%s-%s", fnName, fnNamespace)
}

// GetTempDir creates and return a temporary directory
func GetTempDir() (string, error) {
	id, err := uuid.NewV4()
	if err != nil {
		return "", err
	}
	tmpDir := id.String()
	dir, err := os.MkdirTemp("", tmpDir)
	return dir, err
}

// FindAllGlobs returns a list of globs of input list.
func FindAllGlobs(paths ...string) ([]string, error) {
	files := make([]string, 0)
	for _, p := range paths {
		// use absolute path to find files
		path, err := filepath.Abs(p)
		if err != nil {
			return nil, errors.Wrapf(err, "error getting absolute path of path '%s'", p)
		}
		globs, err := filepath.Glob(path)
		if err != nil {
			return nil, errors.Errorf("invalid glob %s: %s", path, err)
		}
		files = append(files, globs...)
		// xxx handle excludeGlobs here
	}
	return files, nil
}

func MakeZipArchive(targetName string, globs ...string) (string, error) {
	files, err := FindAllGlobs(globs...)
	if err != nil {
		return "", err
	}

	// zip up the file list
	err = archiver.DefaultZip.Archive(files, targetName)
	if err != nil {
		return "", err
	}

	return filepath.Abs(targetName)
}

// RemoveZeroBytes remove empty byte(\x00) from input byte slice and return a new byte slice
// This function is trying to fix the problem that empty byte will fail os.Openfile
// For more information, please visit:
// 1. https://github.com/golang/go/issues/24195
// 2. https://play.golang.org/p/5F9ykC2tlbc
func RemoveZeroBytes(src []byte) []byte {
	var bs []byte
	for _, v := range src {
		if v != 0 {
			bs = append(bs, v)
		}
	}
	return bs
}

// GetImagePullPolicy returns the image pull policy base on the input value.
func GetImagePullPolicy(policy string) apiv1.PullPolicy {
	switch policy {
	case "Always":
		return apiv1.PullAlways
	case "Never":
		return apiv1.PullNever
	default:
		return apiv1.PullIfNotPresent
	}
}

func FileSize(filePath string) (int64, error) {
	info, err := os.Stat(filePath)
	if err != nil {
		return 0, err
	}
	return info.Size(), err
}

func GetFileChecksum(fileName string) (*fv1.Checksum, error) {
	f, err := os.Open(fileName)
	if err != nil {
		return nil, fmt.Errorf("failed to open file %v: %v", fileName, err)
	}
	defer f.Close()

	sum, err := GetChecksum(f)
	if err != nil {
		return nil, fmt.Errorf("failed to calculate checksum for %v", fileName)
	}

	return sum, nil
}

func GetChecksum(src io.Reader) (*fv1.Checksum, error) {
	if src == nil {
		return nil, errors.New("cannot read from nil reader")
	}

	h := sha256.New()

	_, err := io.Copy(h, src)
	if err != nil {
		return nil, err
	}

	return &fv1.Checksum{
		Type: fv1.ChecksumTypeSHA256,
		Sum:  hex.EncodeToString(h.Sum(nil)),
	}, nil
}

func IsURL(str string) bool {
	return strings.HasPrefix(str, "http://") || strings.HasPrefix(str, "https://")
}

func DownloadUrl(ctx context.Context, httpClient *http.Client, url string, localPath string) error {
	resp, err := ctxhttp.Get(ctx, httpClient, url)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	w, err := os.Create(localPath)
	if err != nil {
		return err
	}
	defer w.Close()

	_, err = io.Copy(w, resp.Body)
	if err != nil {
		return err
	}

	// flushing write buffer to file
	err = w.Sync()
	if err != nil {
		return err
	}

	err = os.Chmod(localPath, 0600)
	if err != nil {
		return err
	}

	return nil
}

func IsZip(filename string) (bool, error) {
	f, err := os.Open(filename)
	if err != nil {
		return false, nil
	}
	defer f.Close()
	return archiver.DefaultZip.Match(f)
}

// GetCurrentNamespace returns Kubernetes namespace of current Pod
func GetCurrentNamespace() (string, error) {

	// This file contains the namespace and can be found in each container.
	body, err := os.ReadFile("/var/run/secrets/kubernetes.io/serviceaccount/namespace")
	if err != nil {
		return "", err
	}
	return string(body), nil
}

func GetStringValueFromEnv(envVar string) (string, error) {
	v := os.Getenv(envVar)
	if v == "" {
		return v, errors.New(fmt.Sprintf("Еnvironment variable %s empty", envVar))
	}
	return v, nil
}

func GetUIntValueFromEnv(envVar string) (uint, error) {
	s, err := GetStringValueFromEnv(envVar)
	if err != nil {
		return 0, err
	}
	value, err := strconv.ParseUint(s, 10, 32)
	if err != nil {
		return 0, err
	}
	return uint(value), nil
}