// Copyright 2016-2018, Pulumi Corporation.
//
// 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,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//+build windows

package main

import (
	"fmt"
	"io"
	"net"
	"os"
	"time"

	winio "github.com/Microsoft/go-winio"

	"github.com/pulumi/pulumi/sdk/v2/go/common/util/logging"
)

// Windows specific pipe implementation. Slightly complex as it sits on top of a pair of named pipes
// that have to asynchronously accept connections to.  But also fairly simple as windows will take
// care of cleaning things up once our processes complete.
func createPipes() (pipes, error) {
	// Generate a random pipe name so that we don't collide with other pipes made by other pulumi
	// instances.
	rand := uint32(time.Now().UnixNano() + int64(os.Getpid()))
	dir := fmt.Sprintf(`\\.\pipe\pulumi%v`, rand)

	reqPipeName := dir + `\invoke_req`
	resPipeName := dir + `\invoke_res`
	reqListener, err := winio.ListenPipe(reqPipeName, nil)
	if err != nil {
		logging.V(10).Infof("createPipes: Received error trying to create request pipe %s: %s\n", reqPipeName, err)
		return nil, err
	}

	resListener, err := winio.ListenPipe(resPipeName, nil)
	if err != nil {
		logging.V(10).Infof("createPipes: Received error trying to create response pipe %s: %s\n", resPipeName, err)
		return nil, err
	}
	return &windowsPipes{
		dir:         dir,
		reqListener: reqListener,
		resListener: resListener,
	}, nil
}

type windowsPipes struct {
	dir                      string
	reqListener, resListener net.Listener
	reqConn, resConn         net.Conn
}

func (p *windowsPipes) directory() string {
	return p.dir
}

func (p *windowsPipes) reader() io.Reader {
	return p.reqConn
}

func (p *windowsPipes) writer() io.Writer {
	return p.resConn
}

func (p *windowsPipes) connect() error {
	acceptDone := make(chan error)
	defer close(acceptDone)

	go func() {
		reqConn, err := p.reqListener.Accept()
		if err != nil {
			acceptDone <- err
		}
		p.reqConn = reqConn
		acceptDone <- nil
	}()

	go func() {
		resConn, err := p.resListener.Accept()
		if err != nil {
			acceptDone <- err
		}
		p.resConn = resConn
		acceptDone <- nil
	}()

	res1 := <-acceptDone
	res2 := <-acceptDone

	if res1 != nil {
		return res1
	}

	return res2
}

func (p *windowsPipes) shutdown() {
	// Don't need to do anything here.  Named pipes are cleaned up when all processes that are using
	// them terminate.
}
