// Copyright 2010 The Go Authors. All rights reserved.

// Use of this source code is governed by a BSD-style

// license that can be found in the LICENSE file.

// Windows environment variables.

package windows

import (

	"syscall"

	"unicode/utf16"

	"unsafe"

)

func Getenv(key string) (value string, found bool) {

	return syscall.Getenv(key)

}

func Setenv(key, value string) error {

	return syscall.Setenv(key, value)

}

func Clearenv() {

	syscall.Clearenv()

}

func Environ() []string {

	return syscall.Environ()

}

// Returns a default environment associated with the token, rather than the current

// process. If inheritExisting is true, then this environment also inherits the

// environment of the current process.

func (token Token) Environ(inheritExisting bool) (env []string, err error) {

	var block *uint16

	err = CreateEnvironmentBlock(&block, token, inheritExisting)

	if err != nil {

		return nil, err

	}

	defer DestroyEnvironmentBlock(block)

	blockp := uintptr(unsafe.Pointer(block))

	for {

		entry := (*[(1 << 30) - 1]uint16)(unsafe.Pointer(blockp))[:]

		for i, v := range entry {

			if v == 0 {

				entry = entry[:i]

				break

			}

		}

		if len(entry) == 0 {

			break

		}

		env = append(env, string(utf16.Decode(entry)))

		blockp += 2 * (uintptr(len(entry)) + 1)

	}

	return env, nil

}

func Unsetenv(key string) error {

	return syscall.Unsetenv(key)

}