// +build !windows

package main

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"path/filepath"
	"runtime"
	"strconv"
	"strings"

	"github.com/Sirupsen/logrus"
	"github.com/containerd/containerd/api/services/execution"
	protobuf "github.com/gogo/protobuf/types"
	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
	specs "github.com/opencontainers/runtime-spec/specs-go"
	"github.com/urfave/cli"
)

const (
	rwm        = "rwm"
	rootfsPath = "rootfs"
)

var capabilities = []string{
	"CAP_CHOWN",
	"CAP_DAC_OVERRIDE",
	"CAP_FSETID",
	"CAP_FOWNER",
	"CAP_MKNOD",
	"CAP_NET_RAW",
	"CAP_SETGID",
	"CAP_SETUID",
	"CAP_SETFCAP",
	"CAP_SETPCAP",
	"CAP_NET_BIND_SERVICE",
	"CAP_SYS_CHROOT",
	"CAP_KILL",
	"CAP_AUDIT_WRITE",
}

func spec(id string, config *ocispec.ImageConfig, context *cli.Context) (*specs.Spec, error) {
	env := []string{
		"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
	}
	env = append(env, config.Env...)
	cmd := config.Cmd
	if v := context.Args().Tail(); len(v) > 0 {
		cmd = v
	}
	var (
		// TODO: support overriding entrypoint
		args     = append(config.Entrypoint, cmd...)
		tty      = context.Bool("tty")
		uid, gid uint32
	)
	if config.User != "" {
		parts := strings.Split(config.User, ":")
		switch len(parts) {
		case 1:
			v, err := strconv.ParseUint(parts[0], 0, 10)
			if err != nil {
				return nil, err
			}
			uid, gid = uint32(v), uint32(v)
		case 2:
			v, err := strconv.ParseUint(parts[0], 0, 10)
			if err != nil {
				return nil, err
			}
			uid = uint32(v)
			if v, err = strconv.ParseUint(parts[1], 0, 10); err != nil {
				return nil, err
			}
			gid = uint32(v)
		default:
			return nil, fmt.Errorf("invalid USER value %s", config.User)
		}
	}
	if tty {
		env = append(env, "TERM=xterm")
	}
	cwd := config.WorkingDir
	if cwd == "" {
		cwd = "/"
	}
	return &specs.Spec{
		Version: specs.Version,
		Platform: specs.Platform{
			OS:   runtime.GOOS,
			Arch: runtime.GOARCH,
		},
		Root: specs.Root{
			Path:     rootfsPath,
			Readonly: context.Bool("readonly"),
		},
		Process: specs.Process{
			Args:            args,
			Env:             env,
			Terminal:        tty,
			Cwd:             cwd,
			NoNewPrivileges: true,
			User: specs.User{
				UID: uid,
				GID: gid,
			},
			Capabilities: &specs.LinuxCapabilities{
				Bounding:    capabilities,
				Permitted:   capabilities,
				Inheritable: capabilities,
				Effective:   capabilities,
				Ambient:     capabilities,
			},
			Rlimits: []specs.LinuxRlimit{
				{
					Type: "RLIMIT_NOFILE",
					Hard: uint64(1024),
					Soft: uint64(1024),
				},
			},
		},
		Mounts: []specs.Mount{
			{
				Destination: "/proc",
				Type:        "proc",
				Source:      "proc",
			},
			{
				Destination: "/dev",
				Type:        "tmpfs",
				Source:      "tmpfs",
				Options:     []string{"nosuid", "strictatime", "mode=755", "size=65536k"},
			},
			{
				Destination: "/dev/pts",
				Type:        "devpts",
				Source:      "devpts",
				Options:     []string{"nosuid", "noexec", "newinstance", "ptmxmode=0666", "mode=0620", "gid=5"},
			},
			{
				Destination: "/dev/shm",
				Type:        "tmpfs",
				Source:      "shm",
				Options:     []string{"nosuid", "noexec", "nodev", "mode=1777", "size=65536k"},
			},
			{
				Destination: "/dev/mqueue",
				Type:        "mqueue",
				Source:      "mqueue",
				Options:     []string{"nosuid", "noexec", "nodev"},
			},
			{
				Destination: "/sys",
				Type:        "sysfs",
				Source:      "sysfs",
				Options:     []string{"nosuid", "noexec", "nodev", "ro"},
			},
			{
				Destination: "/run",
				Type:        "tmpfs",
				Source:      "tmpfs",
				Options:     []string{"nosuid", "strictatime", "mode=755", "size=65536k"},
			},
			{
				Destination: "/etc/resolv.conf",
				Type:        "bind",
				Source:      "/etc/resolv.conf",
				Options:     []string{"rbind", "ro"},
			},
			{
				Destination: "/etc/hosts",
				Type:        "bind",
				Source:      "/etc/hosts",
				Options:     []string{"rbind", "ro"},
			},
			{
				Destination: "/etc/localtime",
				Type:        "bind",
				Source:      "/etc/localtime",
				Options:     []string{"rbind", "ro"},
			},
		},
		Hostname: id,
		Linux: &specs.Linux{
			Resources: &specs.LinuxResources{
				Devices: []specs.LinuxDeviceCgroup{
					{
						Allow:  false,
						Access: rwm,
					},
				},
			},
			Namespaces: []specs.LinuxNamespace{
				{
					Type: "pid",
				},
				{
					Type: "ipc",
				},
				{
					Type: "uts",
				},
				{
					Type: "mount",
				},
				{
					Type: "network",
				},
			},
		},
	}, nil
}

func customSpec(configPath string) (*specs.Spec, error) {
	b, err := ioutil.ReadFile(configPath)
	if err != nil {
		return nil, err
	}
	var s specs.Spec
	if err := json.Unmarshal(b, &s); err != nil {
		return nil, err
	}
	if s.Root.Path != rootfsPath {
		logrus.Warnf("ignoring Root.Path %q, setting %q forcibly", s.Root.Path, rootfsPath)
		s.Root.Path = rootfsPath
	}
	return &s, nil
}

func getConfig(context *cli.Context, imageConfig *ocispec.ImageConfig) (*specs.Spec, error) {
	config := context.String("runtime-config")
	if config == "" {
		return spec(context.String("id"), imageConfig, context)
	}

	return customSpec(config)
}

func newCreateRequest(context *cli.Context, imageConfig *ocispec.ImageConfig, id, tmpDir string) (*execution.CreateRequest, error) {
	s, err := getConfig(context, imageConfig)
	if err != nil {
		return nil, err
	}
	data, err := json.Marshal(s)
	if err != nil {
		return nil, err
	}
	create := &execution.CreateRequest{
		ID: id,
		Spec: &protobuf.Any{
			TypeUrl: specs.Version,
			Value:   data,
		},
		Runtime:  context.String("runtime"),
		Terminal: context.Bool("tty"),
		Stdin:    filepath.Join(tmpDir, "stdin"),
		Stdout:   filepath.Join(tmpDir, "stdout"),
		Stderr:   filepath.Join(tmpDir, "stderr"),
	}

	return create, nil
}