/*
   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 runc

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"io/ioutil"
	"os"
	"os/exec"
	"path/filepath"
	"strconv"
	"strings"
	"syscall"
	"time"

	specs "github.com/opencontainers/runtime-spec/specs-go"
)

// Format is the type of log formatting options avaliable
type Format string

// TopBody represents the structured data of the full ps output
type TopResults struct {
	// Processes running in the container, where each is process is an array of values corresponding to the headers
	Processes [][]string `json:"Processes"`

	// Headers are the names of the columns
	Headers []string `json:"Headers"`
}

const (
	none Format = ""
	JSON Format = "json"
	Text Format = "text"
	// DefaultCommand is the default command for Runc
	DefaultCommand = "runc"
)

// Runc is the client to the runc cli
type Runc struct {
	//If command is empty, DefaultCommand is used
	Command       string
	Root          string
	Debug         bool
	Log           string
	LogFormat     Format
	PdeathSignal  syscall.Signal
	Setpgid       bool
	Criu          string
	SystemdCgroup bool
	Rootless      *bool // nil stands for "auto"
}

// List returns all containers created inside the provided runc root directory
func (r *Runc) List(context context.Context) ([]*Container, error) {
	data, err := cmdOutput(r.command(context, "list", "--format=json"), false)
	defer putBuf(data)
	if err != nil {
		return nil, err
	}
	var out []*Container
	if err := json.Unmarshal(data.Bytes(), &out); err != nil {
		return nil, err
	}
	return out, nil
}

// State returns the state for the container provided by id
func (r *Runc) State(context context.Context, id string) (*Container, error) {
	data, err := cmdOutput(r.command(context, "state", id), true)
	defer putBuf(data)
	if err != nil {
		return nil, fmt.Errorf("%s: %s", err, data.String())
	}
	var c Container
	if err := json.Unmarshal(data.Bytes(), &c); err != nil {
		return nil, err
	}
	return &c, nil
}

type ConsoleSocket interface {
	Path() string
}

type CreateOpts struct {
	IO
	// PidFile is a path to where a pid file should be created
	PidFile       string
	ConsoleSocket ConsoleSocket
	Detach        bool
	NoPivot       bool
	NoNewKeyring  bool
	ExtraFiles    []*os.File
}

func (o *CreateOpts) args() (out []string, err error) {
	if o.PidFile != "" {
		abs, err := filepath.Abs(o.PidFile)
		if err != nil {
			return nil, err
		}
		out = append(out, "--pid-file", abs)
	}
	if o.ConsoleSocket != nil {
		out = append(out, "--console-socket", o.ConsoleSocket.Path())
	}
	if o.NoPivot {
		out = append(out, "--no-pivot")
	}
	if o.NoNewKeyring {
		out = append(out, "--no-new-keyring")
	}
	if o.Detach {
		out = append(out, "--detach")
	}
	if o.ExtraFiles != nil {
		out = append(out, "--preserve-fds", strconv.Itoa(len(o.ExtraFiles)))
	}
	return out, nil
}

// Create creates a new container and returns its pid if it was created successfully
func (r *Runc) Create(context context.Context, id, bundle string, opts *CreateOpts) error {
	args := []string{"create", "--bundle", bundle}
	if opts != nil {
		oargs, err := opts.args()
		if err != nil {
			return err
		}
		args = append(args, oargs...)
	}
	cmd := r.command(context, append(args, id)...)
	if opts != nil && opts.IO != nil {
		opts.Set(cmd)
	}
	cmd.ExtraFiles = opts.ExtraFiles

	if cmd.Stdout == nil && cmd.Stderr == nil {
		data, err := cmdOutput(cmd, true)
		defer putBuf(data)
		if err != nil {
			return fmt.Errorf("%s: %s", err, data.String())
		}
		return nil
	}
	ec, err := Monitor.Start(cmd)
	if err != nil {
		return err
	}
	if opts != nil && opts.IO != nil {
		if c, ok := opts.IO.(StartCloser); ok {
			if err := c.CloseAfterStart(); err != nil {
				return err
			}
		}
	}
	status, err := Monitor.Wait(cmd, ec)
	if err == nil && status != 0 {
		err = fmt.Errorf("%s did not terminate successfully", cmd.Args[0])
	}
	return err
}

// Start will start an already created container
func (r *Runc) Start(context context.Context, id string) error {
	return r.runOrError(r.command(context, "start", id))
}

type ExecOpts struct {
	IO
	PidFile       string
	ConsoleSocket ConsoleSocket
	Detach        bool
}

func (o *ExecOpts) args() (out []string, err error) {
	if o.ConsoleSocket != nil {
		out = append(out, "--console-socket", o.ConsoleSocket.Path())
	}
	if o.Detach {
		out = append(out, "--detach")
	}
	if o.PidFile != "" {
		abs, err := filepath.Abs(o.PidFile)
		if err != nil {
			return nil, err
		}
		out = append(out, "--pid-file", abs)
	}
	return out, nil
}

// Exec executres and additional process inside the container based on a full
// OCI Process specification
func (r *Runc) Exec(context context.Context, id string, spec specs.Process, opts *ExecOpts) error {
	f, err := ioutil.TempFile(os.Getenv("XDG_RUNTIME_DIR"), "runc-process")
	if err != nil {
		return err
	}
	defer os.Remove(f.Name())
	err = json.NewEncoder(f).Encode(spec)
	f.Close()
	if err != nil {
		return err
	}
	args := []string{"exec", "--process", f.Name()}
	if opts != nil {
		oargs, err := opts.args()
		if err != nil {
			return err
		}
		args = append(args, oargs...)
	}
	cmd := r.command(context, append(args, id)...)
	if opts != nil && opts.IO != nil {
		opts.Set(cmd)
	}
	if cmd.Stdout == nil && cmd.Stderr == nil {
		data, err := cmdOutput(cmd, true)
		defer putBuf(data)
		if err != nil {
			return fmt.Errorf("%s: %s", err, data.String())
		}
		return nil
	}
	ec, err := Monitor.Start(cmd)
	if err != nil {
		return err
	}
	if opts != nil && opts.IO != nil {
		if c, ok := opts.IO.(StartCloser); ok {
			if err := c.CloseAfterStart(); err != nil {
				return err
			}
		}
	}
	status, err := Monitor.Wait(cmd, ec)
	if err == nil && status != 0 {
		err = fmt.Errorf("%s did not terminate successfully", cmd.Args[0])
	}
	return err
}

// Run runs the create, start, delete lifecycle of the container
// and returns its exit status after it has exited
func (r *Runc) Run(context context.Context, id, bundle string, opts *CreateOpts) (int, error) {
	args := []string{"run", "--bundle", bundle}
	if opts != nil {
		oargs, err := opts.args()
		if err != nil {
			return -1, err
		}
		args = append(args, oargs...)
	}
	cmd := r.command(context, append(args, id)...)
	if opts != nil && opts.IO != nil {
		opts.Set(cmd)
	}
	ec, err := Monitor.Start(cmd)
	if err != nil {
		return -1, err
	}
	status, err := Monitor.Wait(cmd, ec)
	if err == nil && status != 0 {
		err = fmt.Errorf("%s did not terminate successfully", cmd.Args[0])
	}
	return status, err
}

type DeleteOpts struct {
	Force bool
}

func (o *DeleteOpts) args() (out []string) {
	if o.Force {
		out = append(out, "--force")
	}
	return out
}

// Delete deletes the container
func (r *Runc) Delete(context context.Context, id string, opts *DeleteOpts) error {
	args := []string{"delete"}
	if opts != nil {
		args = append(args, opts.args()...)
	}
	return r.runOrError(r.command(context, append(args, id)...))
}

// KillOpts specifies options for killing a container and its processes
type KillOpts struct {
	All bool
}

func (o *KillOpts) args() (out []string) {
	if o.All {
		out = append(out, "--all")
	}
	return out
}

// Kill sends the specified signal to the container
func (r *Runc) Kill(context context.Context, id string, sig int, opts *KillOpts) error {
	args := []string{
		"kill",
	}
	if opts != nil {
		args = append(args, opts.args()...)
	}
	return r.runOrError(r.command(context, append(args, id, strconv.Itoa(sig))...))
}

// Stats return the stats for a container like cpu, memory, and io
func (r *Runc) Stats(context context.Context, id string) (*Stats, error) {
	cmd := r.command(context, "events", "--stats", id)
	rd, err := cmd.StdoutPipe()
	if err != nil {
		return nil, err
	}
	ec, err := Monitor.Start(cmd)
	if err != nil {
		return nil, err
	}
	defer func() {
		rd.Close()
		Monitor.Wait(cmd, ec)
	}()
	var e Event
	if err := json.NewDecoder(rd).Decode(&e); err != nil {
		return nil, err
	}
	return e.Stats, nil
}

// Events returns an event stream from runc for a container with stats and OOM notifications
func (r *Runc) Events(context context.Context, id string, interval time.Duration) (chan *Event, error) {
	cmd := r.command(context, "events", fmt.Sprintf("--interval=%ds", int(interval.Seconds())), id)
	rd, err := cmd.StdoutPipe()
	if err != nil {
		return nil, err
	}
	ec, err := Monitor.Start(cmd)
	if err != nil {
		rd.Close()
		return nil, err
	}
	var (
		dec = json.NewDecoder(rd)
		c   = make(chan *Event, 128)
	)
	go func() {
		defer func() {
			close(c)
			rd.Close()
			Monitor.Wait(cmd, ec)
		}()
		for {
			var e Event
			if err := dec.Decode(&e); err != nil {
				if err == io.EOF {
					return
				}
				e = Event{
					Type: "error",
					Err:  err,
				}
			}
			c <- &e
		}
	}()
	return c, nil
}

// Pause the container with the provided id
func (r *Runc) Pause(context context.Context, id string) error {
	return r.runOrError(r.command(context, "pause", id))
}

// Resume the container with the provided id
func (r *Runc) Resume(context context.Context, id string) error {
	return r.runOrError(r.command(context, "resume", id))
}

// Ps lists all the processes inside the container returning their pids
func (r *Runc) Ps(context context.Context, id string) ([]int, error) {
	data, err := cmdOutput(r.command(context, "ps", "--format", "json", id), true)
	defer putBuf(data)
	if err != nil {
		return nil, fmt.Errorf("%s: %s", err, data.String())
	}
	var pids []int
	if err := json.Unmarshal(data.Bytes(), &pids); err != nil {
		return nil, err
	}
	return pids, nil
}

// Top lists all the processes inside the container returning the full ps data
func (r *Runc) Top(context context.Context, id string, psOptions string) (*TopResults, error) {
	data, err := cmdOutput(r.command(context, "ps", "--format", "table", id, psOptions), true)
	defer putBuf(data)
	if err != nil {
		return nil, fmt.Errorf("%s: %s", err, data.String())
	}

	topResults, err := ParsePSOutput(data.Bytes())
	if err != nil {
		return nil, fmt.Errorf("%s: ", err)
	}
	return topResults, nil
}

type CheckpointOpts struct {
	// ImagePath is the path for saving the criu image file
	ImagePath string
	// WorkDir is the working directory for criu
	WorkDir string
	// ParentPath is the path for previous image files from a pre-dump
	ParentPath string
	// AllowOpenTCP allows open tcp connections to be checkpointed
	AllowOpenTCP bool
	// AllowExternalUnixSockets allows external unix sockets to be checkpointed
	AllowExternalUnixSockets bool
	// AllowTerminal allows the terminal(pty) to be checkpointed with a container
	AllowTerminal bool
	// CriuPageServer is the address:port for the criu page server
	CriuPageServer string
	// FileLocks handle file locks held by the container
	FileLocks bool
	// Cgroups is the cgroup mode for how to handle the checkpoint of a container's cgroups
	Cgroups CgroupMode
	// EmptyNamespaces creates a namespace for the container but does not save its properties
	// Provide the namespaces you wish to be checkpointed without their settings on restore
	EmptyNamespaces []string
}

type CgroupMode string

const (
	Soft   CgroupMode = "soft"
	Full   CgroupMode = "full"
	Strict CgroupMode = "strict"
)

func (o *CheckpointOpts) args() (out []string) {
	if o.ImagePath != "" {
		out = append(out, "--image-path", o.ImagePath)
	}
	if o.WorkDir != "" {
		out = append(out, "--work-path", o.WorkDir)
	}
	if o.ParentPath != "" {
		out = append(out, "--parent-path", o.ParentPath)
	}
	if o.AllowOpenTCP {
		out = append(out, "--tcp-established")
	}
	if o.AllowExternalUnixSockets {
		out = append(out, "--ext-unix-sk")
	}
	if o.AllowTerminal {
		out = append(out, "--shell-job")
	}
	if o.CriuPageServer != "" {
		out = append(out, "--page-server", o.CriuPageServer)
	}
	if o.FileLocks {
		out = append(out, "--file-locks")
	}
	if string(o.Cgroups) != "" {
		out = append(out, "--manage-cgroups-mode", string(o.Cgroups))
	}
	for _, ns := range o.EmptyNamespaces {
		out = append(out, "--empty-ns", ns)
	}
	return out
}

type CheckpointAction func([]string) []string

// LeaveRunning keeps the container running after the checkpoint has been completed
func LeaveRunning(args []string) []string {
	return append(args, "--leave-running")
}

// PreDump allows a pre-dump of the checkpoint to be made and completed later
func PreDump(args []string) []string {
	return append(args, "--pre-dump")
}

// Checkpoint allows you to checkpoint a container using criu
func (r *Runc) Checkpoint(context context.Context, id string, opts *CheckpointOpts, actions ...CheckpointAction) error {
	args := []string{"checkpoint"}
	if opts != nil {
		args = append(args, opts.args()...)
	}
	for _, a := range actions {
		args = a(args)
	}
	return r.runOrError(r.command(context, append(args, id)...))
}

type RestoreOpts struct {
	CheckpointOpts
	IO

	Detach        bool
	PidFile       string
	NoSubreaper   bool
	NoPivot       bool
	ConsoleSocket ConsoleSocket
}

func (o *RestoreOpts) args() ([]string, error) {
	out := o.CheckpointOpts.args()
	if o.Detach {
		out = append(out, "--detach")
	}
	if o.PidFile != "" {
		abs, err := filepath.Abs(o.PidFile)
		if err != nil {
			return nil, err
		}
		out = append(out, "--pid-file", abs)
	}
	if o.ConsoleSocket != nil {
		out = append(out, "--console-socket", o.ConsoleSocket.Path())
	}
	if o.NoPivot {
		out = append(out, "--no-pivot")
	}
	if o.NoSubreaper {
		out = append(out, "-no-subreaper")
	}
	return out, nil
}

// Restore restores a container with the provide id from an existing checkpoint
func (r *Runc) Restore(context context.Context, id, bundle string, opts *RestoreOpts) (int, error) {
	args := []string{"restore"}
	if opts != nil {
		oargs, err := opts.args()
		if err != nil {
			return -1, err
		}
		args = append(args, oargs...)
	}
	args = append(args, "--bundle", bundle)
	cmd := r.command(context, append(args, id)...)
	if opts != nil && opts.IO != nil {
		opts.Set(cmd)
	}
	ec, err := Monitor.Start(cmd)
	if err != nil {
		return -1, err
	}
	if opts != nil && opts.IO != nil {
		if c, ok := opts.IO.(StartCloser); ok {
			if err := c.CloseAfterStart(); err != nil {
				return -1, err
			}
		}
	}
	status, err := Monitor.Wait(cmd, ec)
	if err == nil && status != 0 {
		err = fmt.Errorf("%s did not terminate successfully", cmd.Args[0])
	}
	return status, err
}

// Update updates the current container with the provided resource spec
func (r *Runc) Update(context context.Context, id string, resources *specs.LinuxResources) error {
	buf := getBuf()
	defer putBuf(buf)

	if err := json.NewEncoder(buf).Encode(resources); err != nil {
		return err
	}
	args := []string{"update", "--resources", "-", id}
	cmd := r.command(context, args...)
	cmd.Stdin = buf
	return r.runOrError(cmd)
}

var ErrParseRuncVersion = errors.New("unable to parse runc version")

type Version struct {
	Runc   string
	Commit string
	Spec   string
}

// Version returns the runc and runtime-spec versions
func (r *Runc) Version(context context.Context) (Version, error) {
	data, err := cmdOutput(r.command(context, "--version"), false)
	defer putBuf(data)
	if err != nil {
		return Version{}, err
	}
	return parseVersion(data.Bytes())
}

func parseVersion(data []byte) (Version, error) {
	var v Version
	parts := strings.Split(strings.TrimSpace(string(data)), "\n")

	if len(parts) > 0 {
		if !strings.HasPrefix(parts[0], "runc version ") {
			return v, nil
		}
		v.Runc = parts[0][13:]

		for _, part := range parts[1:] {
			if strings.HasPrefix(part, "commit: ") {
				v.Commit = part[8:]
			} else if strings.HasPrefix(part, "spec: ") {
				v.Spec = part[6:]
			}
		}
	}

	return v, nil
}

func (r *Runc) args() (out []string) {
	if r.Root != "" {
		out = append(out, "--root", r.Root)
	}
	if r.Debug {
		out = append(out, "--debug")
	}
	if r.Log != "" {
		out = append(out, "--log", r.Log)
	}
	if r.LogFormat != none {
		out = append(out, "--log-format", string(r.LogFormat))
	}
	if r.Criu != "" {
		out = append(out, "--criu", r.Criu)
	}
	if r.SystemdCgroup {
		out = append(out, "--systemd-cgroup")
	}
	if r.Rootless != nil {
		// nil stands for "auto" (differs from explicit "false")
		out = append(out, "--rootless="+strconv.FormatBool(*r.Rootless))
	}
	return out
}

// runOrError will run the provided command.  If an error is
// encountered and neither Stdout or Stderr was set the error and the
// stderr of the command will be returned in the format of <error>:
// <stderr>
func (r *Runc) runOrError(cmd *exec.Cmd) error {
	if cmd.Stdout != nil || cmd.Stderr != nil {
		ec, err := Monitor.Start(cmd)
		if err != nil {
			return err
		}
		status, err := Monitor.Wait(cmd, ec)
		if err == nil && status != 0 {
			err = fmt.Errorf("%s did not terminate successfully", cmd.Args[0])
		}
		return err
	}
	data, err := cmdOutput(cmd, true)
	defer putBuf(data)
	if err != nil {
		return fmt.Errorf("%s: %s", err, data.String())
	}
	return nil
}

// callers of cmdOutput are expected to call putBuf on the returned Buffer
// to ensure it is released back to the shared pool after use.
func cmdOutput(cmd *exec.Cmd, combined bool) (*bytes.Buffer, error) {
	b := getBuf()

	cmd.Stdout = b
	if combined {
		cmd.Stderr = b
	}
	ec, err := Monitor.Start(cmd)
	if err != nil {
		return nil, err
	}

	status, err := Monitor.Wait(cmd, ec)
	if err == nil && status != 0 {
		err = fmt.Errorf("%s did not terminate successfully", cmd.Args[0])
	}

	return b, err
}