/*
Copyright The containerd Authors.
Copyright 2018 Google LLC

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

    https://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 runsc

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

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

var Monitor runc.ProcessMonitor = runc.Monitor

// DefaultCommand is the default command for Runsc
const DefaultCommand = "runsc"

// Runsc is the client to the runsc cli
type Runsc struct {
	Command      string
	PdeathSignal syscall.Signal
	Setpgid      bool
	Root         string
	Log          string
	LogFormat    runc.Format
	Config       map[string]string
}

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

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

type CreateOpts struct {
	runc.IO
	// PidFile is a path to where a pid file should be created
	PidFile       string
	ConsoleSocket runc.ConsoleSocket
	// UserLog is a path to where runsc user log should be generated.
	UserLog string
}

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.UserLog != "" {
		out = append(out, "--user-log", o.UserLog)
	}
	return out, nil
}

// Create creates a new container and returns its pid if it was created successfully
func (r *Runsc) 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)
	}

	if cmd.Stdout == nil && cmd.Stderr == nil {
		data, err := cmdOutput(cmd, true)
		if err != nil {
			return fmt.Errorf("%s: %s", err, data)
		}
		return nil
	}
	ec, err := Monitor.Start(cmd)
	if err != nil {
		return err
	}
	if opts != nil && opts.IO != nil {
		if c, ok := opts.IO.(runc.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 sucessfully", cmd.Args[0])
	}

	return err
}

// Start will start an already created container
func (r *Runsc) Start(context context.Context, id string, cio runc.IO) error {
	cmd := r.command(context, "start", id)
	if cio != nil {
		cio.Set(cmd)
	}

	if cmd.Stdout == nil && cmd.Stderr == nil {
		data, err := cmdOutput(cmd, true)
		if err != nil {
			return fmt.Errorf("%s: %s", err, data)
		}
		return nil
	}

	ec, err := Monitor.Start(cmd)
	if err != nil {
		return err
	}
	if cio != nil {
		if c, ok := cio.(runc.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 sucessfully", cmd.Args[0])
	}

	return err
}

type waitResult struct {
	ID         string `json:"id"`
	ExitStatus int    `json:"exitStatus"`
}

// Wait will wait for a running container, and return its exit status.
// TODO(random-liu): Add exec process support.
func (r *Runsc) Wait(context context.Context, id string) (int, error) {
	data, err := cmdOutput(r.command(context, "wait", id), true)
	if err != nil {
		return 0, fmt.Errorf("%s: %s", err, data)
	}
	var res waitResult
	if err := json.Unmarshal(data, &res); err != nil {
		return 0, err
	}
	return res.ExitStatus, nil
}

type ExecOpts struct {
	runc.IO
	PidFile         string
	InternalPidFile string
	ConsoleSocket   runc.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)
	}
	if o.InternalPidFile != "" {
		abs, err := filepath.Abs(o.InternalPidFile)
		if err != nil {
			return nil, err
		}
		out = append(out, "--internal-pid-file", abs)
	}
	return out, nil
}

// Exec executres and additional process inside the container based on a full
// OCI Process specification
func (r *Runsc) Exec(context context.Context, id string, spec specs.Process, opts *ExecOpts) error {
	f, err := ioutil.TempFile(os.Getenv("XDG_RUNTIME_DIR"), "runsc-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)
		if err != nil {
			return fmt.Errorf("%s: %s", err, data)
		}
		return nil
	}
	ec, err := Monitor.Start(cmd)
	if err != nil {
		return err
	}
	if opts != nil && opts.IO != nil {
		if c, ok := opts.IO.(runc.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 sucessfully", 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 *Runsc) 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
	}
	return Monitor.Wait(cmd, ec)
}

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 *Runsc) 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
	Pid int
}

func (o *KillOpts) args() (out []string) {
	if o.All {
		out = append(out, "--all")
	}
	if o.Pid != 0 {
		out = append(out, "--pid", strconv.Itoa(o.Pid))
	}
	return out
}

// Kill sends the specified signal to the container
func (r *Runsc) 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 *Runsc) Stats(context context.Context, id string) (*runc.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 runc.Event
	if err := json.NewDecoder(rd).Decode(&e); err != nil {
		return nil, err
	}
	return e.Stats, nil
}

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

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

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

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

func (r *Runsc) args() []string {
	var args []string
	if r.Root != "" {
		args = append(args, fmt.Sprintf("--root=%s", r.Root))
	}
	if r.Log != "" {
		args = append(args, fmt.Sprintf("--log=%s", r.Log))
	}
	if r.LogFormat != "" {
		args = append(args, fmt.Sprintf("--log-format=%s", r.LogFormat))
	}
	for k, v := range r.Config {
		args = append(args, fmt.Sprintf("--%s=%s", k, v))
	}
	return args
}

// 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 *Runsc) 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 sucessfully", cmd.Args[0])
		}
		return err
	}
	data, err := cmdOutput(cmd, true)
	if err != nil {
		return fmt.Errorf("%s: %s", err, data)
	}
	return nil
}

func (r *Runsc) command(context context.Context, args ...string) *exec.Cmd {
	command := r.Command
	if command == "" {
		command = DefaultCommand
	}
	cmd := exec.CommandContext(context, command, append(r.args(), args...)...)
	cmd.SysProcAttr = &syscall.SysProcAttr{
		Setpgid: r.Setpgid,
	}
	if r.PdeathSignal != 0 {
		cmd.SysProcAttr.Pdeathsig = r.PdeathSignal
	}

	return cmd
}

func cmdOutput(cmd *exec.Cmd, combined bool) ([]byte, error) {
	b := getBuf()
	defer putBuf(b)

	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 sucessfully", cmd.Args[0])
	}

	return b.Bytes(), err
}