// Copyright 2016 PingCAP, 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,
// See the License for the specific language governing permissions and
// limitations under the License.

package util

import (
	"crypto/tls"
	"crypto/x509/pkix"
	"fmt"
	"runtime"
	"strconv"
	"strings"
	"time"

	"github.com/pingcap/errors"
	"github.com/pingcap/parser"
	"github.com/pingcap/parser/model"
	"github.com/pingcap/parser/mysql"
	"github.com/pingcap/parser/terror"
	"github.com/pingcap/tidb/util/logutil"
	"go.uber.org/zap"
)

const (
	// DefaultMaxRetries indicates the max retry count.
	DefaultMaxRetries = 30
	// RetryInterval indicates retry interval.
	RetryInterval uint64 = 500
	// GCTimeFormat is the format that gc_worker used to store times.
	GCTimeFormat = "20060102-15:04:05 -0700"
)

// RunWithRetry will run the f with backoff and retry.
// retryCnt: Max retry count
// backoff: When run f failed, it will sleep backoff * triedCount time.Millisecond.
// Function f should have two return value. The first one is an bool which indicate if the err if retryable.
// The second is if the f meet any error.
func RunWithRetry(retryCnt int, backoff uint64, f func() (bool, error)) (err error) {
	for i := 1; i <= retryCnt; i++ {
		var retryAble bool
		retryAble, err = f()
		if err == nil || !retryAble {
			return errors.Trace(err)
		}
		sleepTime := time.Duration(backoff*uint64(i)) * time.Millisecond
		time.Sleep(sleepTime)
	}
	return errors.Trace(err)
}

// GetStack gets the stacktrace.
func GetStack() []byte {
	const size = 4096
	buf := make([]byte, size)
	stackSize := runtime.Stack(buf, false)
	buf = buf[:stackSize]
	return buf
}

// WithRecovery wraps goroutine startup call with force recovery.
// it will dump current goroutine stack into log if catch any recover result.
//   exec:      execute logic function.
//   recoverFn: handler will be called after recover and before dump stack, passing `nil` means noop.
func WithRecovery(exec func(), recoverFn func(r interface{})) {
	defer func() {
		r := recover()
		if recoverFn != nil {
			recoverFn(r)
		}
		if r != nil {
			logutil.BgLogger().Error("panic in the recoverable goroutine",
				zap.Reflect("r", r),
				zap.Stack("stack trace"))
		}
	}()
	exec()
}

// CompatibleParseGCTime parses a string with `GCTimeFormat` and returns a time.Time. If `value` can't be parsed as that
// format, truncate to last space and try again. This function is only useful when loading times that saved by
// gc_worker. We have changed the format that gc_worker saves time (removed the last field), but when loading times it
// should be compatible with the old format.
func CompatibleParseGCTime(value string) (time.Time, error) {
	t, err := time.Parse(GCTimeFormat, value)

	if err != nil {
		// Remove the last field that separated by space
		parts := strings.Split(value, " ")
		prefix := strings.Join(parts[:len(parts)-1], " ")
		t, err = time.Parse(GCTimeFormat, prefix)
	}

	if err != nil {
		err = errors.Errorf("string \"%v\" doesn't has a prefix that matches format \"%v\"", value, GCTimeFormat)
	}
	return t, err
}

const (
	// syntaxErrorPrefix is the common prefix for SQL syntax error in TiDB.
	syntaxErrorPrefix = "You have an error in your SQL syntax; check the manual that corresponds to your TiDB version for the right syntax to use"
)

// SyntaxError converts parser error to TiDB's syntax error.
func SyntaxError(err error) error {
	if err == nil {
		return nil
	}
	logutil.BgLogger().Error("syntax error", zap.Error(err))

	// If the error is already a terror with stack, pass it through.
	if errors.HasStack(err) {
		cause := errors.Cause(err)
		if _, ok := cause.(*terror.Error); ok {
			return err
		}
	}

	return parser.ErrParse.GenWithStackByArgs(syntaxErrorPrefix, err.Error())
}

// SyntaxWarn converts parser warn to TiDB's syntax warn.
func SyntaxWarn(err error) error {
	if err == nil {
		return nil
	}
	return parser.ErrParse.GenWithStackByArgs(syntaxErrorPrefix, err.Error())
}

var (
	// InformationSchemaName is the `INFORMATION_SCHEMA` database name.
	InformationSchemaName = model.NewCIStr("INFORMATION_SCHEMA")
	// PerformanceSchemaName is the `PERFORMANCE_SCHEMA` database name.
	PerformanceSchemaName = model.NewCIStr("PERFORMANCE_SCHEMA")
	// MetricSchemaName is the `METRIC_SCHEMA` database name.
	MetricSchemaName = model.NewCIStr("METRIC_SCHEMA")
	// InspectionSchemaName is the `INSPECTION_SCHEMA` database name
	InspectionSchemaName = model.NewCIStr("INSPECTION_SCHEMA")
)

// IsMemOrSysDB uses to check whether dbLowerName is memory database or system database.
func IsMemOrSysDB(dbLowerName string) bool {
	switch dbLowerName {
	case InformationSchemaName.L,
		InspectionSchemaName.L,
		PerformanceSchemaName.L,
		mysql.SystemDB,
		MetricSchemaName.L:
		return true
	}
	return false
}

// X509NameOnline prints pkix.Name into old X509_NAME_oneline format.
// https://www.openssl.org/docs/manmaster/man3/X509_NAME_oneline.html
func X509NameOnline(n pkix.Name) string {
	s := make([]string, 0, len(n.Names))
	for _, name := range n.Names {
		oid := name.Type.String()
		// unlike MySQL, TiDB only support check pkixAttributeTypeNames fields
		if n, exist := pkixAttributeTypeNames[oid]; exist {
			s = append(s, n+"="+fmt.Sprint(name.Value))
		}
	}
	if len(s) == 0 {
		return ""
	}
	return "/" + strings.Join(s, "/")
}

const (
	// Country is type name for country.
	Country = "C"
	// Organization is type name for organization.
	Organization = "O"
	// OrganizationalUnit is type name for organizational unit.
	OrganizationalUnit = "OU"
	// Locality is type name for locality.
	Locality = "L"
	// Email is type name for email.
	Email = "emailAddress"
	// CommonName is type name for common name.
	CommonName = "CN"
	// Province is type name for province or state.
	Province = "ST"
)

// see go/src/crypto/x509/pkix/pkix.go:attributeTypeNames
var pkixAttributeTypeNames = map[string]string{
	"2.5.4.6":              Country,
	"2.5.4.10":             Organization,
	"2.5.4.11":             OrganizationalUnit,
	"2.5.4.3":              CommonName,
	"2.5.4.5":              "SERIALNUMBER",
	"2.5.4.7":              Locality,
	"2.5.4.8":              Province,
	"2.5.4.9":              "STREET",
	"2.5.4.17":             "POSTALCODE",
	"1.2.840.113549.1.9.1": Email,
}

var pkixTypeNameAttributes = make(map[string]string)

// MockPkixAttribute generates mock AttributeTypeAndValue.
// only used for test.
func MockPkixAttribute(name, value string) pkix.AttributeTypeAndValue {
	n, exists := pkixTypeNameAttributes[name]
	if !exists {
		panic(fmt.Sprintf("unsupport mock type: %s", name))
	}
	var vs []int
	for _, v := range strings.Split(n, ".") {
		i, err := strconv.Atoi(v)
		if err != nil {
			panic(err)
		}
		vs = append(vs, i)
	}
	return pkix.AttributeTypeAndValue{
		Type:  vs,
		Value: value,
	}
}

// CheckSupportX509NameOneline parses and validate input str is X509_NAME_oneline format
// and precheck check-item is supported by TiDB
// https://www.openssl.org/docs/manmaster/man3/X509_NAME_oneline.html
func CheckSupportX509NameOneline(oneline string) (err error) {
	entries := strings.Split(oneline, `/`)
	for _, entry := range entries {
		if len(entry) == 0 {
			continue
		}
		kvs := strings.Split(entry, "=")
		if len(kvs) != 2 {
			err = errors.Errorf("invalid X509_NAME input: %s", oneline)
			return
		}
		k := kvs[0]
		if _, support := pkixTypeNameAttributes[k]; !support {
			err = errors.Errorf("Unsupport check '%s' in current version TiDB", k)
			return
		}
	}
	return
}

var tlsCipherString = map[uint16]string{
	tls.TLS_RSA_WITH_RC4_128_SHA:                "RC4-SHA",
	tls.TLS_RSA_WITH_3DES_EDE_CBC_SHA:           "DES-CBC3-SHA",
	tls.TLS_RSA_WITH_AES_128_CBC_SHA:            "AES128-SHA",
	tls.TLS_RSA_WITH_AES_256_CBC_SHA:            "AES256-SHA",
	tls.TLS_RSA_WITH_AES_128_CBC_SHA256:         "AES128-SHA256",
	tls.TLS_RSA_WITH_AES_128_GCM_SHA256:         "AES128-GCM-SHA256",
	tls.TLS_RSA_WITH_AES_256_GCM_SHA384:         "AES256-GCM-SHA384",
	tls.TLS_ECDHE_ECDSA_WITH_RC4_128_SHA:        "ECDHE-ECDSA-RC4-SHA",
	tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA:    "ECDHE-ECDSA-AES128-SHA",
	tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA:    "ECDHE-ECDSA-AES256-SHA",
	tls.TLS_ECDHE_RSA_WITH_RC4_128_SHA:          "ECDHE-RSA-RC4-SHA",
	tls.TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA:     "ECDHE-RSA-DES-CBC3-SHA",
	tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA:      "ECDHE-RSA-AES128-SHA",
	tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA:      "ECDHE-RSA-AES256-SHA",
	tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256: "ECDHE-ECDSA-AES128-SHA256",
	tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256:   "ECDHE-RSA-AES128-SHA256",
	tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256:   "ECDHE-RSA-AES128-GCM-SHA256",
	tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256: "ECDHE-ECDSA-AES128-GCM-SHA256",
	tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384:   "ECDHE-RSA-AES256-GCM-SHA384",
	tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384: "ECDHE-ECDSA-AES256-GCM-SHA384",
	tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305:    "ECDHE-RSA-CHACHA20-POLY1305",
	tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305:  "ECDHE-ECDSA-CHACHA20-POLY1305",
	// TLS 1.3 cipher suites, compatible with mysql using '_'.
	tls.TLS_AES_128_GCM_SHA256:       "TLS_AES_128_GCM_SHA256",
	tls.TLS_AES_256_GCM_SHA384:       "TLS_AES_256_GCM_SHA384",
	tls.TLS_CHACHA20_POLY1305_SHA256: "TLS_CHACHA20_POLY1305_SHA256",
}

// SupportCipher maintains cipher supported by TiDB.
var SupportCipher = make(map[string]struct{}, len(tlsCipherString))

// TLSCipher2String convert tls num to string.
// Taken from https://testssl.sh/openssl-rfc.mapping.html .
func TLSCipher2String(n uint16) string {
	s, ok := tlsCipherString[n]
	if !ok {
		return ""
	}
	return s
}

func init() {
	for _, value := range tlsCipherString {
		SupportCipher[value] = struct{}{}
	}
	for key, value := range pkixAttributeTypeNames {
		pkixTypeNameAttributes[value] = key
	}
}