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.

// 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()

}