// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
package main

import (
	"context"
	"encoding/json"
	"flag"
	"fmt"
	"io"
	"io/ioutil"
	"net"
	"os"
	"time"

	"fuchsia.googlesource.com/tools/botanist"
	"fuchsia.googlesource.com/tools/botanist/target"
	"fuchsia.googlesource.com/tools/build"
	"fuchsia.googlesource.com/tools/command"
	"fuchsia.googlesource.com/tools/logger"
	"fuchsia.googlesource.com/tools/runner"
	"fuchsia.googlesource.com/tools/serial"
	"fuchsia.googlesource.com/tools/sshutil"

	"github.com/google/subcommands"
)

const (
	netstackTimeout time.Duration = 1 * time.Minute
)

// Target represents a fuchsia instance.
type Target interface {
	// Nodename returns the name of the target node.
	Nodename() string

	// IPv4Addr returns the IPv4 address of the target.
	IPv4Addr() (net.IP, error)

	// Serial returns the serial device associated with the target for serial i/o.
	Serial() string

	// SSHKey returns the private key corresponding an authorized SSH key of the target.
	SSHKey() string

	// Start starts the target.
	Start(ctx context.Context, images build.Images, args []string) error

	// Restart restarts the target.
	Restart(ctx context.Context) error

	// Stop stops the target.
	Stop(ctx context.Context) error

	// Wait waits for the target to finish running.
	Wait(ctx context.Context) error
}

// RunCommand is a Command implementation for booting a device and running a
// given command locally.
type RunCommand struct {
	// ConfigFile is the path to the target configurations.
	configFile string

	// ImageManifests is a list of paths to image manifests (e.g., images.json)
	imageManifests command.StringsFlag

	// Netboot tells botanist to netboot (and not to pave).
	netboot bool

	// ZirconArgs are kernel command-line arguments to pass on boot.
	zirconArgs command.StringsFlag

	// Timeout is the duration allowed for the command to finish execution.
	timeout time.Duration

	// CmdStdout is the file to which the command's stdout will be redirected.
	cmdStdout string

	// CmdStderr is the file to which the command's stderr will be redirected.
	cmdStderr string

	// SysloggerFile, if nonempty, is the file to where the system's logs will be written.
	syslogFile string

	// SshKey is the path to a private SSH user key.
	sshKey string

	// SerialLogFile, if nonempty, is the file where the system's serial logs will be written.
	serialLogFile string
}

func (*RunCommand) Name() string {
	return "run"
}

func (*RunCommand) Usage() string {
	return `
botanist run [flags...] [command...]

flags:
`
}

func (*RunCommand) Synopsis() string {
	return "boots a device and runs a local command"
}

func (r *RunCommand) SetFlags(f *flag.FlagSet) {
	f.StringVar(&r.configFile, "config", "/etc/botanist/device.json", "path to file of device config")
	f.Var(&r.imageManifests, "images", "paths to image manifests")
	f.BoolVar(&r.netboot, "netboot", false, "if set, botanist will not pave; but will netboot instead")
	f.Var(&r.zirconArgs, "zircon-args", "kernel command-line arguments")
	f.DurationVar(&r.timeout, "timeout", 10*time.Minute, "duration allowed for the command to finish execution.")
	f.StringVar(&r.cmdStdout, "stdout", "", "file to redirect the command's stdout into; if unspecified, it will be redirected to the process' stdout")
	f.StringVar(&r.cmdStderr, "stderr", "", "file to redirect the command's stderr into; if unspecified, it will be redirected to the process' stderr")
	f.StringVar(&r.syslogFile, "syslog", "", "file to write the systems logs to")
	f.StringVar(&r.sshKey, "ssh", "", "file containing a private SSH user key; if not provided, a private key will be generated.")
	f.StringVar(&r.serialLogFile, "serial-log", "", "file to write the serial logs to.")
}

func (r *RunCommand) runCmd(ctx context.Context, args []string, t Target, syslog io.Writer) error {
	nodename := t.Nodename()
	// If having paved, SSH in and stream syslogs back to a file sink.
	if !r.netboot && syslog != nil {
		p, err := ioutil.ReadFile(t.SSHKey())
		if err != nil {
			return err
		}
		config, err := sshutil.DefaultSSHConfig(p)
		if err != nil {
			return err
		}
		client, err := sshutil.ConnectToNode(ctx, nodename, config)
		if err != nil {
			return err
		}
		syslogger, err := botanist.NewSyslogger(client)
		if err != nil {
			return err
		}
		go func() {
			syslogger.Stream(ctx, syslog)
			syslogger.Close()
		}()
	}

	ip, err := t.IPv4Addr()
	if err == nil {
		logger.Infof(ctx, "IPv4 address of %s found: %s", nodename, ip)
	} else {
		logger.Errorf(ctx, "could not resolve IPv4 address of %s: %v", nodename, err)
	}

	env := append(
		os.Environ(),
		fmt.Sprintf("FUCHSIA_NODENAME=%s", nodename),
		fmt.Sprintf("FUCHSIA_IPV4_ADDR=%v", ip),
		fmt.Sprintf("FUCHSIA_SSH_KEY=%s", t.SSHKey()),
	)

	ctx, cancel := context.WithTimeout(ctx, r.timeout)
	defer cancel()

	stdout := os.Stdout
	if r.cmdStdout != "" {
		f, err := os.Create(r.cmdStdout)
		if err != nil {
			return err
		}
		defer f.Close()
		stdout = f
	}
	stderr := os.Stderr
	if r.cmdStderr != "" {
		f, err := os.Create(r.cmdStderr)
		if err != nil {
			return err
		}
		defer f.Close()
		stderr = f
	}

	runner := runner.SubprocessRunner{
		Env: env,
	}
	if err := runner.Run(ctx, args, stdout, stderr); err != nil {
		if ctx.Err() != nil {
			return fmt.Errorf("command timed out after %v", r.timeout)
		}
		return err
	}
	return nil
}

func (r *RunCommand) execute(ctx context.Context, args []string) error {
	imgs, err := build.LoadImages(r.imageManifests...)
	if err != nil {
		return fmt.Errorf("failed to load images: %v", err)
	}

	opts := target.Options{
		Netboot:  r.netboot,
		SSHKey:   r.sshKey,
	}

	data, err := ioutil.ReadFile(r.configFile)
	if err != nil {
		return fmt.Errorf("could not open config file: %v", err)
	}
	var objs []json.RawMessage
	if err := json.Unmarshal(data, &objs); err != nil {
		return fmt.Errorf("could not unmarshal config file as a JSON list: %v", err)
	}

	var targets []Target
	for _, obj := range objs {
		t, err := DeriveTarget(obj, opts)
		if err != nil {
			return err
		}
		targets = append(targets, t)
	}

	if len(targets) != 1 {
		return fmt.Errorf("`botanist run` only supports configuration for a single target")
	}
	t := targets[0]

	var syslog io.WriteCloser
	if r.syslogFile != "" {
		syslog, err = os.Create(r.syslogFile)
		if err != nil {
			return err
		}
		defer syslog.Close()
	}

	if t.Serial() != "" && r.serialLogFile != "" {
		serialLog, err := os.Create(r.serialLogFile)
		if err != nil {
			return err
		}
		defer serialLog.Close()

		serialDevice, err := serial.Open(t.Serial())
		if err != nil {
			return fmt.Errorf("unable to open %s: %v", t.Serial(), err)
		}
		defer serialDevice.Close()

		// Here we invoke the `dlog` command over serial to tail the existing log buffer into the
		// output file.  This should give us everything since Zedboot boot, and new messages should
		// be written to directly to the serial port without needing to tail with `dlog -f`.
		if _, err = io.WriteString(serialDevice, "\ndlog\n"); err != nil {
			logger.Errorf(ctx, "failed to tail zedboot dlog: %v", err)
		}

		go func() {
			_, err := io.Copy(serialLog, serialDevice)
			if err != nil {
				logger.Errorf(ctx, "failed to write serial log: %v", err)
			}
		}()

		// Modify the zirconArgs passed to the kernel on boot to enable serial logging on x64.
		// arm64 devices should already be enabling kernel.serial at compile time.
		r.zirconArgs = append(r.zirconArgs, "kernel.bypass-debuglog=true", "kernel.serial=legacy")
	}

	defer func() {
		logger.Debugf(ctx, "stopping or rebooting the node %q\n", t.Nodename())
		if err := t.Stop(ctx); err == target.ErrUnimplemented {
			t.Restart(ctx)
		}
	}()

	ctx, cancel := context.WithCancel(ctx)
	defer cancel()
	errs := make(chan error)
	go func() {
		if err := t.Start(ctx, imgs, r.zirconArgs); err != nil {
			errs <- err
		}
		if err := t.Wait(ctx); err != nil && err != target.ErrUnimplemented {
			errs <- err
		}
	}()
	go func() {
		errs <- r.runCmd(ctx, args, t, syslog)
	}()

	select {
	case err := <-errs:
		return err
	case <-ctx.Done():
	}
	return nil
}

func (r *RunCommand) Execute(ctx context.Context, f *flag.FlagSet, _ ...interface{}) subcommands.ExitStatus {
	args := f.Args()
	if len(args) == 0 {
		return subcommands.ExitUsageError
	}
	if err := r.execute(ctx, args); err != nil {
		logger.Errorf(ctx, "%v\n", err)
		return subcommands.ExitFailure
	}
	return subcommands.ExitSuccess
}

func DeriveTarget(obj []byte, opts target.Options) (Target, error) {
	type typed struct {
		Type string `json:"type"`
	}
	var x typed

	if err := json.Unmarshal(obj, &x); err != nil {
		return nil, fmt.Errorf("object in list has no \"type\" field: %v", err)
	}
	switch x.Type {
	case "qemu":
		var cfg target.QEMUConfig
		if err := json.Unmarshal(obj, &cfg); err != nil {
			return nil, fmt.Errorf("invalid QEMU config found: %v", err)
		}
		return target.NewQEMUTarget(cfg, opts), nil
	case "device":
		var cfg target.DeviceConfig
		if err := json.Unmarshal(obj, &cfg); err != nil {
			return nil, fmt.Errorf("invalid device config found: %v", err)
		}
		t, err := target.NewDeviceTarget(cfg, opts)
		return t, err
	default:
		return nil, fmt.Errorf("unknown type found: %q", x.Type)
	}
}