package main

import (
	"bufio"
	"errors"
	"fmt"
	"io"
	"io/ioutil"
	"os"
	"os/exec"
	"path"
	"strconv"
	"strings"

	log "github.com/Sirupsen/logrus"
	ps "github.com/mitchellh/go-ps"
	"github.com/rneugeba/iso9660wrap"

	"github.com/docker/infrakit/pkg/spi/instance"
	"github.com/docker/infrakit/pkg/template"
	"github.com/docker/infrakit/pkg/types"
)

// NewHyperKitPlugin creates an instance plugin for hyperkit.
func NewHyperKitPlugin(vmDir, hyperkit, vpnkitSock string, thyper, tkern *template.Template) instance.Plugin {
	return &hyperkitPlugin{VMDir: vmDir,
		HyperKit:   hyperkit,
		VPNKitSock: vpnkitSock,

		HyperKitTmpl: thyper,
		KernelTmpl:   tkern,
	}
}

type hyperkitPlugin struct {
	// VMDir is the path to a directory where per VM state is kept
	VMDir string

	// Hyperkit is the path to the hyperkit executable
	HyperKit string

	// VPNKitSock is the path to the VPNKit Unix domain socket.
	VPNKitSock string

	HyperKitTmpl *template.Template
	KernelTmpl   *template.Template
}

const (
	hyperkitPid = "hyperkit.pid"
)

// Validate performs local validation on a provision request.
func (v hyperkitPlugin) Validate(req *types.Any) error {
	return nil
}

// Provision creates a new instance.
func (v hyperkitPlugin) Provision(spec instance.Spec) (*instance.ID, error) {

	var properties map[string]interface{}

	if spec.Properties != nil {
		if err := spec.Properties.Decode(&properties); err != nil {
			return nil, fmt.Errorf("Invalid instance properties: %s", err)
		}
	}

	if properties["Moby"] == nil {
		return nil, errors.New("Property 'Moby' must be set")
	}
	if properties["CPUs"] == nil {
		properties["CPUs"] = 1
	}
	if properties["Memory"] == nil {
		properties["Memory"] = 512
	}
	if properties["Disk"] == nil {
		properties["Disk"] = float64(256)
	}

	instanceDir, err := ioutil.TempDir(v.VMDir, "infrakit-")
	if err != nil {
		return nil, err
	}
	id := instance.ID(path.Base(instanceDir))

	// Apply parameters
	params := map[string]interface{}{
		"VMLocation": instanceDir,
		"VPNKitSock": v.VPNKitSock,
		"Properties": properties,
	}

	err = v.execHyperKit(spec, params)
	if err != nil {
		v.Destroy(id)
		return nil, err
	}

	tagData, err := types.AnyValue(spec.Tags)
	if err != nil {
		return nil, err
	}

	if err := ioutil.WriteFile(path.Join(instanceDir, "tags"), tagData.Bytes(), 0666); err != nil {
		return nil, err
	}

	return &id, nil
}

// Label labels the instance
func (v hyperkitPlugin) Label(instance instance.ID, labels map[string]string) error {
	instanceDir := path.Join(v.VMDir, string(instance))
	tagFile := path.Join(instanceDir, "tags")
	buff, err := ioutil.ReadFile(tagFile)
	if err != nil {
		return err
	}

	tags := map[string]string{}
	err = types.AnyBytes(buff).Decode(&tags)
	if err != nil {
		return err
	}

	for k, v := range labels {
		tags[k] = v
	}

	encoded, err := types.AnyValue(tags)
	if err != nil {
		return err
	}
	return ioutil.WriteFile(tagFile, encoded.Bytes(), 0666)
}

// Destroy terminates an existing instance.
func (v hyperkitPlugin) Destroy(id instance.ID) error {
	fmt.Println("Destroying ", id)

	instanceDir := path.Join(v.VMDir, string(id))
	_, err := os.Stat(instanceDir)
	if err != nil {
		if os.IsNotExist(err) {
			return errors.New("Instance does not exist")
		}
	}

	p, err := getProcess(instanceDir)
	if err != nil {
		log.Warningln("Can't find processes: ", err)
	} else {
		err = p.Kill()
		if err != nil {
			log.Warningln("Can't kill processes with pid: ", p.Pid, err)
			return err
		}
	}

	if err := os.RemoveAll(instanceDir); err != nil {
		return err
	}

	return nil
}

// DescribeInstances returns descriptions of all instances matching all of the provided tags.
func (v hyperkitPlugin) DescribeInstances(tags map[string]string) ([]instance.Description, error) {
	files, err := ioutil.ReadDir(v.VMDir)
	if err != nil {
		return nil, err
	}

	descriptions := []instance.Description{}

	for _, file := range files {
		if !file.IsDir() {
			continue
		}

		instanceDir := path.Join(v.VMDir, file.Name())

		tagData, err := ioutil.ReadFile(path.Join(instanceDir, "tags"))
		if err != nil {
			if os.IsNotExist(err) {
				continue
			}

			return nil, err
		}

		instanceTags := map[string]string{}
		if err := types.AnyBytes(tagData).Decode(&instanceTags); err != nil {
			return nil, err
		}

		allMatched := true
		for k, v := range tags {
			value, exists := instanceTags[k]
			if !exists || v != value {
				allMatched = false
				break
			}
		}

		if allMatched {
			var logicalID *instance.LogicalID
			id := instance.ID(file.Name())

			pidData, err := ioutil.ReadFile(path.Join(instanceDir, hyperkitPid))
			if err == nil {
				lid := instance.LogicalID(pidData)
				logicalID = &lid
			} else {
				if !os.IsNotExist(err) {
					return nil, err
				}
			}

			// Check if process is running
			if _, err := getProcess(instanceDir); err != nil {
				log.Warningln("Process not running: Instance ", id)
				v.Destroy(id)
				continue
			}

			descriptions = append(descriptions, instance.Description{
				ID:        id,
				LogicalID: logicalID,
				Tags:      instanceTags,
			})
		}
	}

	return descriptions, nil
}

const hyperkitArgs = "-A -u -F {{.VMLocation}}/hyperkit.pid " +
	"-c {{.Properties.CPUs}} -m {{.Properties.Memory}}M " +
	"-s 0:0,hostbridge -s 31,lpc -s 5,virtio-rnd " +
	"-s 4,virtio-blk,{{.VMLocation}}/disk.img " +
	"-s 2:0,virtio-vpnkit,path={{.VPNKitSock}} " +
	"-l com1,autopty={{.VMLocation}}/tty,log={{.VMLocation}}/console-ring"
const hyperkitKernArgs = "kexec," +
	"{{.Properties.Moby}}-bzImage," +
	"{{.Properties.Moby}}-initrd.img," +
	"earlyprintk=serial console=ttyS0 panic=1 vsyscall=emulate page_poison=1 ntp=gateway"

func (v hyperkitPlugin) execHyperKit(spec instance.Spec, params map[string]interface{}) error {

	instanceDir := params["VMLocation"].(string)

	args, err := v.HyperKitTmpl.Render(params)
	if err != nil {
		return err
	}
	kernArgs, err := v.KernelTmpl.Render(params)
	if err != nil {
		return err
	}

	// Build arguments
	c := []string{v.HyperKit}
	c = append(c, strings.Split(args, " ")...)
	c = append(c, "-f", kernArgs)

	// Write command line to state
	if err := ioutil.WriteFile(path.Join(instanceDir, "cmdline"), []byte(strings.Join(c, " ")), 0666); err != nil {
		return err
	}

	prop := params["Properties"].(map[string]interface{})
	sz, ok := prop["Disk"].(float64)
	if !ok {
		return fmt.Errorf("Unable to extract Disk Size: %s", prop["Disk"])
	}
	err = createDisk(instanceDir, int(sz))
	if err != nil {
		return err
	}

	if len(spec.Init) != 0 {
		err = createConfigISO(instanceDir, spec.Init)
		if err != nil {
			return err
		}
	}

	cmd := exec.Command(c[0], c[1:]...)
	cmd.Env = os.Environ()

	stdoutChan := make(chan string)
	stderrChan := make(chan string)

	stdout, err := cmd.StdoutPipe()
	if err != nil {
		return err
	}

	stderr, err := cmd.StderrPipe()
	if err != nil {
		return err
	}

	stream(stdout, stdoutChan)
	stream(stderr, stderrChan)

	done := make(chan struct{})
	go func() {
		for {
			select {
			case stderrl := <-stderrChan:
				log.Warning("HyperKit STDERR: ", stderrl)
			case stdoutl := <-stdoutChan:
				log.Info("HyperKit STDOUT: ", stdoutl)
			case <-done:
				return
			}
		}
	}()

	log.Infoln("Starting: ", c)

	err = cmd.Start()

	return err
}

func createDisk(instanceDir string, diskSz int) error {
	f, err := os.Create(path.Join(instanceDir, "disk.img"))
	if err != nil {
		return err
	}
	defer f.Close()

	buf := make([]byte, 1048676)
	for i := 0; i < len(buf); i++ {
		buf[i] = 0
	}

	for i := 0; i < diskSz; i++ {
		f.Write(buf)
	}
	return nil
}

func createConfigISO(instanceDir, init string) error {
	inName := path.Join(instanceDir, "config")

	if err := ioutil.WriteFile(inName, []byte(init), 0666); err != nil {
		return err
	}

	outfh, err := os.OpenFile(inName+".iso", os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0666)
	if err != nil {
		return err
	}
	infh, err := os.Open(inName)
	if err != nil {
		return err
	}
	err = iso9660wrap.WriteFile(outfh, infh)
	if err != nil {
		log.Fatalf("writing file failed with %s", err)
	}

	return nil
}

func stream(r io.ReadCloser, dest chan<- string) {
	go func() {
		defer r.Close()
		reader := bufio.NewReader(r)
		for {
			line, err := reader.ReadString('\n')
			if err != nil {
				return
			}
			dest <- line
		}
	}()
}

func getProcess(instanceDir string) (*os.Process, error) {
	pidData, err := ioutil.ReadFile(path.Join(instanceDir, hyperkitPid))
	if err != nil {
		log.Warningln("Can't read pid file: ", err)
		return nil, err
	}
	pid, err := strconv.Atoi(string(pidData[:]))
	if err != nil {
		log.Warningln("Can't convert pidData: ", pidData, err)
		return nil, err
	}

	p, err := os.FindProcess(pid)
	if err != nil {
		log.Warningln("Can't find process with pid: ", pid)
		return nil, err
	}
	// os.FindProcess on Unix always returns a process object even
	// if the process does not exists. There does not seem to be
	// a call to find out if the process is running either, so we
	// use another package to find out.
	proc, err := ps.FindProcess(p.Pid)
	if err != nil {
		log.Warningln("Can't find process", err)
		return nil, err
	}
	if proc == nil {
		return nil, errors.New("Process not found")
	}
	return p, nil
}