/*
 * Minio Client (C) 2015, 2016, 2017 Minio, Inc.
 *
 * 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 cmd

import (
	"crypto/tls"
	"fmt"
	"io"
	"math/rand"
	"net/url"
	"os"
	"runtime"
	"strings"
	"time"

	"github.com/minio/cli"
	"github.com/minio/mc/pkg/console"
	"github.com/minio/mc/pkg/probe"
)

func isErrIgnored(err *probe.Error) (ignored bool) {
	// For all non critical errors we can continue for the remaining files.
	switch err.ToGoError().(type) {
	// Handle these specifically for filesystem related errors.
	case BrokenSymlink, TooManyLevelsSymlink, PathNotFound, PathInsufficientPermission:
		ignored = true
	// Handle these specifically for object storage related errors.
	case BucketNameEmpty, ObjectMissing, ObjectAlreadyExists:
		ignored = true
	case ObjectAlreadyExistsAsDirectory, BucketDoesNotExist, BucketInvalid, ObjectOnGlacier:
		ignored = true
	default:
		ignored = false
	}
	return ignored
}

// UTCNow - returns current UTC time.
func UTCNow() time.Time {
	return time.Now().UTC()
}

var letters = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")

// newRandomID generates a random id of regular lower case and uppercase english characters.
func newRandomID(n int) string {
	rand.Seed(UTCNow().UnixNano())
	sid := make([]rune, n)
	for i := range sid {
		sid[i] = letters[rand.Intn(len(letters))]
	}
	return string(sid)
}

// dumpTlsCertificates prints some fields of the certificates received from the server.
// Fields will be inspected by the user, so they must be conscise and useful
func dumpTLSCertificates(t *tls.ConnectionState) {
	for _, cert := range t.PeerCertificates {
		console.Debugln("TLS Certificate found: ")
		if len(cert.Issuer.Country) > 0 {
			console.Debugln(" >> Country: " + cert.Issuer.Country[0])
		}
		if len(cert.Issuer.Organization) > 0 {
			console.Debugln(" >> Organization: " + cert.Issuer.Organization[0])
		}
		console.Debugln(" >> Expires: " + cert.NotAfter.String())
	}
}

// isStdIO checks if the input parameter is one of the standard input/output streams
func isStdIO(reader io.Reader) bool {
	return reader == os.Stdin || reader == os.Stdout || reader == os.Stderr
}

// splitStr splits a string into n parts, empty strings are added
// if we are not able to reach n elements
func splitStr(path, sep string, n int) []string {
	splits := strings.SplitN(path, sep, n)
	// Add empty strings if we found elements less than nr
	for i := n - len(splits); i > 0; i-- {
		splits = append(splits, "")
	}
	return splits
}

// parse url usually obtained from env.
func parseEnvURL(envURL string) (*url.URL, string, string, *probe.Error) {
	u, e := url.Parse(envURL)
	if e != nil {
		return nil, "", "", probe.NewError(e).Trace(envURL)
	}

	var accessKey, secretKey string
	// Check if username:password is provided in URL, with no
	// access keys or secret we proceed and perform anonymous
	// requests.
	if u.User != nil {
		accessKey = u.User.Username()
		secretKey, _ = u.User.Password()
	}

	// Look for if URL has invalid values and return error.
	if !((u.Scheme == "http" || u.Scheme == "https") &&
		(u.Path == "/" || u.Path == "") && u.Opaque == "" &&
		u.ForceQuery == false && u.RawQuery == "" && u.Fragment == "") {
		return nil, "", "", errInvalidArgument().Trace(u.String())
	}

	// Now that we have validated the URL to be in expected style.
	u.User = nil

	return u, accessKey, secretKey, nil
}

func buildS3ConfigFromEnv(envURL string) (*Config, *probe.Error) {
	u, accessKey, secretKey, err := parseEnvURL(envURL)
	if err != nil {
		return nil, err.Trace(envURL)
	}

	s3Config, err := newS3Config(cli.Args{u.String(), accessKey, secretKey})
	if err != nil {
		return nil, err.Trace(envURL)
	}

	s3Config.AppName = "mc"
	s3Config.AppVersion = Version
	s3Config.AppComments = []string{os.Args[0], runtime.GOOS, runtime.GOARCH}
	s3Config.Debug = globalDebug
	s3Config.Insecure = globalInsecure

	return s3Config, nil
}

const mcEnvHostsPrefix = "MC_HOSTS_"

// buildS3Config fetches config related to the specified alias
// to create a new config structure
func buildS3Config(alias, urlStr string) (*Config, *probe.Error) {
	// Check if we can get the values from ENV, if not use from `config.json`.
	if alias == "" {
		alias, _ = url2Alias(urlStr)
	}
	if envConfig, ok := os.LookupEnv(mcEnvHostsPrefix + alias); ok {
		return buildS3ConfigFromEnv(envConfig)
	}

	hostCfg := mustGetHostConfig(alias)
	if hostCfg == nil {
		return nil, probe.NewError(fmt.Errorf("The specified alias: %s not found", urlStr))
	}

	// We have a valid alias and hostConfig. We populate the
	// credentials from the match found in the config file.
	s3Config := new(Config)

	s3Config.HostURL = urlStr
	s3Config.AccessKey = hostCfg.AccessKey
	s3Config.SecretKey = hostCfg.SecretKey
	s3Config.Signature = hostCfg.API
	s3Config.AppName = "mc"
	s3Config.AppVersion = Version
	s3Config.AppComments = []string{os.Args[0], runtime.GOOS, runtime.GOARCH}
	s3Config.Debug = globalDebug
	s3Config.Insecure = globalInsecure

	return s3Config, nil
}