package main

import (
	"errors"
	"fmt"
	"io/ioutil"
	"math/rand"
	"net/http"
	"time"

	"github.com/google/uuid"
	pb "go.wit.com/lib/protobuf/virtbuf"
	"go.wit.com/log"
)

// attempts to create a new virtual machine

func create(w http.ResponseWriter, r *http.Request) (string, error) {
	msg, err := ioutil.ReadAll(r.Body) // Read the body as []byte
	if err != nil {
		result := fmt.Sprintf("ReadAll() error =", err)
		log.Info(result)
		fmt.Fprintln(w, result)
		return result, err
	}

	var d *pb.Droplet
	d = new(pb.Droplet)
	if err := d.UnmarshalJSON(msg); err != nil {
		log.Info("UnmarshalJSON() failed", err)
		if err := d.Unmarshal(msg); err != nil {
			log.Info("droplet protobuf.Unmarshal() failed", err)
			return "", err
		}
	}
	d.StartState = pb.DropletState_OFF
	d.SetState(pb.DropletState_OFF)
	d.Memory = 2048 * 1024 * 1024
	d.Cpus = 2

	log.Info("Got msg:", string(msg))
	log.Info("hostname =", d.Hostname)
	name := d.Hostname

	// don't continue past here if the grid is unstable anyway
	// because this will add the droplet to cluster.Droplets
	if s, err := isClusterStable(); err != nil {
		log.Info(s)
		fmt.Fprintln(w, s)
		return s, err
	}

	tmpd := me.cluster.FindDropletByName(name)
	if tmpd != nil {
		result := "create error: Droplet " + name + " is already defined"
		log.Info(result)
		fmt.Fprintln(w, result)
		return result, errors.New(result)
	}

	if d.Uuid == "" {
		u := uuid.New()
		d.Uuid = u.String()
	}

	if len(d.Networks) == 0 {
		var newNet *pb.Network
		newNet = new(pb.Network)
		newNet.Mac = getNewMac()
		d.Networks = append(d.Networks, newNet)
		// d.AddDefaultNetwork(mac)
	}
	me.cluster.AddDroplet(d)

	result, err := startDroplet(d)
	if err != nil {
		log.Info(result)
		log.Info("startDroplet(d) failed:", err)
		fmt.Fprintln(w, result)
		fmt.Fprintln(w, "startDroplet(d) failed:", err)
		return result, err
	}
	fmt.Fprintln(w, result)
	fmt.Fprintln(w, "START=OK")
	return result, nil
}

// for now, because sometimes this should write to stdout and
// sometimes to http socket, it returns a string
func startDroplet(d *pb.Droplet) (string, error) {
	var result string
	name := d.Hostname
	// validate the droplet
	if err := ValidateDroplet(d); err != nil {
		result = "ValidateDroplet() failed droplet " + d.Hostname
		return result, err
	}

	// is the droplet already on?
	if d.Current.State == pb.DropletState_ON {
		result = "EVENT start droplet " + d.Hostname + " is already ON"
		return result, errors.New(result)
	}

	// how long has the cluster been stable?
	// wait until it is stable. use this to throttle droplet starts
	dur := time.Since(me.unstable)
	result = fmt.Sprintln("should start droplet", name, "here. grid stable for:", pb.FormatDuration(dur))
	if dur < me.unstableTimeout {
		tmp := pb.FormatDuration(me.unstableTimeout)
		result += "grid is still too unstable (unstable timeout = " + tmp + ")"
		return result, errors.New("grid is still unstable")
	}

	// make the list of hypervisors that are active and can start new droplets
	var pool []*HyperT
	for _, h := range me.hypers {
		// this droplet is set to use this and only this hypervisor
		if d.ForceHypervisor == h.pb.Hostname {
			ok, b := h.start(d)
			if ok {
				return result + b, nil
			}
			return result + b, errors.New("start " + name + " on hypervisor " + h.pb.Hostname)
		}

		// skip hypervisors marked inactive
		if h.pb.Active != true {
			result += fmt.Sprintln("hypervisor is inactive:", name, "for", h.pb.Hostname, h.pb.Active)
			continue
		}

		// the config file says this droplet should run on this hypervisor
		// attempt to start the droplet here. use this even if the hypervisor is inactive?
		if d.PreferredHypervisor == h.pb.Hostname {
			ok, b := h.start(d)
			if ok {
				return result + b, nil
			}
			return result + b, errors.New("start " + name + " on hypervisor " + h.pb.Hostname)
		}

		result += fmt.Sprintln("hypervisor ready:", name, "for", h.pb.Hostname, h.pb.Active)
		pool = append(pool, h)
	}

	// left here as an example of how to actually do random numbers
	// it's complete mathematical chaos. Randomness is simple when
	// human interaction occurs -- which is exactly what happens most
	// of the time. most random shit is bullshit. all you really need
	// is exactly this to make sure the random functions work as they
	// should. Probably, just use this everywhere in all cases. --jcarr
	rand.Seed(time.Now().UnixNano())
	a := 0
	b := len(pool)
	n := a + rand.Intn(b-a)
	result += fmt.Sprintln("pool has", len(pool), "members", "rand =", n)
	h := pool[n]

	ok, output := h.start(d)
	if ok {
		return result + output, nil
	}
	return result + output, errors.New("start " + name + " on hypervisor " + h.pb.Hostname)
}