// Copyright 2016 The Vanadium 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 discovery

import (
	"fmt"
	"time"

	"v.io/v23/context"
	"v.io/v23/discovery"
)

// update is an implementation of discovery.Update.
type update struct {
	ad        discovery.Advertisement
	hash      AdHash
	dirAddrs  []string
	status    AdStatus
	lost      bool
	timestamp time.Time
}

func (u *update) IsLost() bool          { return u.lost }
func (u *update) Id() discovery.AdId    { return u.ad.Id }
func (u *update) InterfaceName() string { return u.ad.InterfaceName }

func (u *update) Addresses() []string {
	addrs := make([]string, len(u.ad.Addresses))
	copy(addrs, u.ad.Addresses)
	return addrs
}

func (u *update) Attribute(name string) string { return u.ad.Attributes[name] }

func (u *update) Attachment(ctx *context.T, name string) <-chan discovery.DataOrError {
	ch := make(chan discovery.DataOrError, 1)
	if data, ok := u.ad.Attachments[name]; ok {
		var r discovery.DataOrError
		r.Data = make([]byte, len(data))
		copy(r.Data, data)
		ch <- r
		close(ch)
	} else if u.status == AdPartiallyReady {
		go u.fetchAttachment(ctx, name, ch)
	} else {
		close(ch)
	}
	return ch
}

func (u *update) fetchAttachment(ctx *context.T, name string, ch chan<- discovery.DataOrError) {
	defer close(ch)

	dir := newDirClient(u.dirAddrs)
	data, err := dir.GetAttachment(ctx, u.ad.Id, name)
	ch <- discovery.DataOrError{data, err}
}

func (u *update) Advertisement() discovery.Advertisement {
	ad := discovery.Advertisement{
		Id:            u.ad.Id,
		InterfaceName: u.ad.InterfaceName,
	}
	ad.Addresses = make([]string, len(u.ad.Addresses))
	copy(ad.Addresses, u.ad.Addresses)

	ad.Attributes = make(discovery.Attributes, len(u.ad.Attributes))
	for k, v := range u.ad.Attributes {
		ad.Attributes[k] = v
	}

	ad.Attachments = make(discovery.Attachments, len(u.ad.Attachments))
	for k, v := range u.ad.Attachments {
		data := make([]byte, len(v))
		copy(data, v)
		ad.Attachments[k] = data
	}
	return ad
}

func (u *update) Timestamp() time.Time {
	return u.timestamp
}

func (u *update) String() string {
	return fmt.Sprintf("{%v %s %s %v %v}", u.lost, u.ad.Id, u.ad.InterfaceName, u.ad.Addresses, u.ad.Attributes)
}

// NewUpdate returns a new update with the given advertisement information.
func NewUpdate(adinfo *AdInfo) discovery.Update {
	return &update{
		ad:        adinfo.Ad,
		hash:      adinfo.Hash,
		dirAddrs:  adinfo.DirAddrs,
		status:    adinfo.Status,
		lost:      adinfo.Lost,
		timestamp: time.Unix(adinfo.TimestampNs/1e6, adinfo.TimestampNs%1e6),
	}
}