// Copyright 2009 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.

// Fork, exec, wait, etc.

package windows

import (

	errorspkg "errors"

	"unsafe"

)

// EscapeArg rewrites command line argument s as prescribed

// in http://msdn.microsoft.com/en-us/library/ms880421.

// This function returns "" (2 double quotes) if s is empty.

// Alternatively, these transformations are done:

//   - every back slash (\) is doubled, but only if immediately

//     followed by double quote (");

//   - every double quote (") is escaped by back slash (\);

//   - finally, s is wrapped with double quotes (arg -> "arg"),

//     but only if there is space or tab inside s.

func EscapeArg(s string) string {

	if len(s) == 0 {

		return "\"\""

	}

	n := len(s)

	hasSpace := false

	for i := 0; i < len(s); i++ {

		switch s[i] {

		case '"', '\\':

			n++

		case ' ', '\t':

			hasSpace = true

		}

	}

	if hasSpace {

		n += 2

	}

	if n == len(s) {

		return s

	}

	qs := make([]byte, n)

	j := 0

	if hasSpace {

		qs[j] = '"'

		j++

	}

	slashes := 0

	for i := 0; i < len(s); i++ {

		switch s[i] {

		default:

			slashes = 0

			qs[j] = s[i]

		case '\\':

			slashes++

			qs[j] = s[i]

		case '"':

			for ; slashes > 0; slashes-- {

				qs[j] = '\\'

				j++

			}

			qs[j] = '\\'

			j++

			qs[j] = s[i]

		}

		j++

	}

	if hasSpace {

		for ; slashes > 0; slashes-- {

			qs[j] = '\\'

			j++

		}

		qs[j] = '"'

		j++

	}

	return string(qs[:j])

}

// ComposeCommandLine escapes and joins the given arguments suitable for use as a Windows command line,

// in CreateProcess's CommandLine argument, CreateService/ChangeServiceConfig's BinaryPathName argument,

// or any program that uses CommandLineToArgv.

func ComposeCommandLine(args []string) string {

	var commandLine string

	for i := range args {

		if i > 0 {

			commandLine += " "

		}

		commandLine += EscapeArg(args[i])

	}

	return commandLine

}

// DecomposeCommandLine breaks apart its argument command line into unescaped parts using CommandLineToArgv,

// as gathered from GetCommandLine, QUERY_SERVICE_CONFIG's BinaryPathName argument, or elsewhere that

// command lines are passed around.

func DecomposeCommandLine(commandLine string) ([]string, error) {

	if len(commandLine) == 0 {

		return []string{}, nil

	}

	var argc int32

	argv, err := CommandLineToArgv(StringToUTF16Ptr(commandLine), &argc)

	if err != nil {

		return nil, err

	}

	defer LocalFree(Handle(unsafe.Pointer(argv)))

	var args []string

	for _, v := range (*argv)[:argc] {

		args = append(args, UTF16ToString((*v)[:]))

	}

	return args, nil

}

func CloseOnExec(fd Handle) {

	SetHandleInformation(Handle(fd), HANDLE_FLAG_INHERIT, 0)

}

// FullPath retrieves the full path of the specified file.

func FullPath(name string) (path string, err error) {

	p, err := UTF16PtrFromString(name)

	if err != nil {

		return "", err

	}

	n := uint32(100)

	for {

		buf := make([]uint16, n)

		n, err = GetFullPathName(p, uint32(len(buf)), &buf[0], nil)

		if err != nil {

			return "", err

		}

		if n <= uint32(len(buf)) {

			return UTF16ToString(buf[:n]), nil

		}

	}

}

// NewProcThreadAttributeList allocates a new ProcThreadAttributeListContainer, with the requested maximum number of attributes.

func NewProcThreadAttributeList(maxAttrCount uint32) (*ProcThreadAttributeListContainer, error) {

	var size uintptr

	err := initializeProcThreadAttributeList(nil, maxAttrCount, 0, &size)

	if err != ERROR_INSUFFICIENT_BUFFER {

		if err == nil {

			return nil, errorspkg.New("unable to query buffer size from InitializeProcThreadAttributeList")

		}

		return nil, err

	}

	alloc, err := LocalAlloc(LMEM_FIXED, uint32(size))

	if err != nil {

		return nil, err

	}

	// size is guaranteed to be ≥1 by InitializeProcThreadAttributeList.

	al := &ProcThreadAttributeListContainer{data: (*ProcThreadAttributeList)(unsafe.Pointer(alloc))}

	err = initializeProcThreadAttributeList(al.data, maxAttrCount, 0, &size)

	if err != nil {

		return nil, err

	}

	return al, err

}

// Update modifies the ProcThreadAttributeList using UpdateProcThreadAttribute.

func (al *ProcThreadAttributeListContainer) Update(attribute uintptr, value unsafe.Pointer, size uintptr) error {

	al.pointers = append(al.pointers, value)

	return updateProcThreadAttribute(al.data, 0, attribute, value, size, nil, nil)

}

// Delete frees ProcThreadAttributeList's resources.

func (al *ProcThreadAttributeListContainer) Delete() {

	deleteProcThreadAttributeList(al.data)

	LocalFree(Handle(unsafe.Pointer(al.data)))

	al.data = nil

	al.pointers = nil

}

// List returns the actual ProcThreadAttributeList to be passed to StartupInfoEx.

func (al *ProcThreadAttributeListContainer) List() *ProcThreadAttributeList {

	return al.data

}