/*
   Copyright The containerd Authors.

   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.
*/

package v2

import (
	"context"
	"fmt"
	"net"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"time"

	"github.com/containerd/containerd/namespaces"
	"github.com/pkg/errors"
)

const shimBinaryFormat = "containerd-shim-%s-%s"

func shimCommand(ctx context.Context, runtime, containerdAddress string, bundle *Bundle, cmdArgs ...string) (*exec.Cmd, error) {
	ns, err := namespaces.NamespaceRequired(ctx)
	if err != nil {
		return nil, err
	}
	self, err := os.Executable()
	if err != nil {
		return nil, err
	}
	args := []string{
		"-namespace", ns,
		"-address", containerdAddress,
		"-publish-binary", self,
	}
	args = append(args, cmdArgs...)
	name := getShimBinaryName(runtime)
	if _, err := exec.LookPath(name); err != nil {
		if eerr, ok := err.(*exec.Error); ok {
			if eerr.Err == exec.ErrNotFound {
				return nil, errors.Wrapf(os.ErrNotExist, "runtime %q binary not installed %q", runtime, name)
			}
		}
	}
	cmd := exec.Command(name, args...)
	cmd.Dir = bundle.Path
	cmd.Env = append(os.Environ(), "GOMAXPROCS=2")
	cmd.SysProcAttr = getSysProcAttr()
	return cmd, nil
}

func getShimBinaryName(runtime string) string {
	parts := strings.Split(runtime, ".")
	// TODO: add validation for runtime
	return fmt.Sprintf(shimBinaryFormat, parts[len(parts)-2], parts[len(parts)-1])
}

func abstractAddress(ctx context.Context, id string) (string, error) {
	ns, err := namespaces.NamespaceRequired(ctx)
	if err != nil {
		return "", err
	}
	return filepath.Join(string(filepath.Separator), "containerd-shim", ns, id, "shim.sock"), nil
}

func connect(address string, d func(string, time.Duration) (net.Conn, error)) (net.Conn, error) {
	return d(address, 100*time.Second)
}

func annonDialer(address string, timeout time.Duration) (net.Conn, error) {
	address = strings.TrimPrefix(address, "unix://")
	return net.DialTimeout("unix", "\x00"+address, timeout)
}

func newSocket(address string) (*net.UnixListener, error) {
	if len(address) > 106 {
		return nil, errors.Errorf("%q: unix socket path too long (> 106)", address)
	}
	l, err := net.Listen("unix", "\x00"+address)
	if err != nil {
		return nil, errors.Wrapf(err, "failed to listen to abstract unix socket %q", address)
	}
	return l.(*net.UnixListener), nil
}

func writePidFile(path string, pid int) error {
	path, err := filepath.Abs(path)
	if err != nil {
		return err
	}
	tempPath := filepath.Join(filepath.Dir(path), fmt.Sprintf(".%s", filepath.Base(path)))
	f, err := os.OpenFile(tempPath, os.O_RDWR|os.O_CREATE|os.O_EXCL|os.O_SYNC, 0666)
	if err != nil {
		return err
	}
	_, err = fmt.Fprintf(f, "%d", pid)
	f.Close()
	if err != nil {
		return err
	}
	return os.Rename(tempPath, path)
}