// Copyright 2011 Google Inc. All rights reserved. 
// Use of this source code is governed by the Apache 2.0
// license that can be found in the LICENSE file. 

package internal

import (
	"os"

	netcontext "golang.org/x/net/context"
)

var (
	// This is set to true in identity_classic.go, which is behind the appengine build tag. 
	// The appengine build tag is set for the first generation runtimes (<= Go 1.9) but not
	// the second generation runtimes (>= Go 1.11), so this indicates whether we're on a
	// first-gen runtime.  See IsStandard below for the second-gen check. 
	appengineStandard bool

	// This is set to true in identity_flex.go, which is behind the appenginevm build tag. 
	appengineFlex bool
)

// AppID is the implementation of the wrapper function of the same name in
// ../identity.go.  See that file for commentary. 
func AppID(c netcontext. Context) string {
	return appID(FullyQualifiedAppID(c))
}

// IsStandard is the implementation of the wrapper function of the same name in
// ../appengine.go.  See that file for commentary. 
func IsStandard() bool {
	// appengineStandard will be true for first-gen runtimes (<= Go 1.9) but not
	// second-gen (>= Go 1.11). 
	return appengineStandard || IsSecondGen()
}

// IsStandard is the implementation of the wrapper function of the same name in
// ../appengine.go.  See that file for commentary. 
func IsSecondGen() bool {
	// Second-gen runtimes set $GAE_ENV so we use that to check if we're on a second-gen runtime. 
	return os. Getenv("GAE_ENV") == "standard"
}

// IsFlex is the implementation of the wrapper function of the same name in
// ../appengine.go.  See that file for commentary. 
func IsFlex() bool {
	return appengineFlex
}

// IsAppEngine is the implementation of the wrapper function of the same name in
// ../appengine.go.  See that file for commentary. 
func IsAppEngine() bool {
	return IsStandard() || IsFlex()
}
