package live

import (
	"crypto/md5"
	cryptorand "crypto/rand"
	"encoding/hex"
	"fmt"
	"strconv"
	"time"
)

type DisabledAdapter struct{}

func (DisabledAdapter) Provider() string { return "disabled" }
func (DisabledAdapter) CreateStream(StreamRequest) (StreamCredentials, error) {
	return StreamCredentials{}, ErrDisabled
}
func (DisabledAdapter) CreatePlayURLs(PlayRequest) (PlayURLs, error) { return PlayURLs{}, ErrDisabled }
func (DisabledAdapter) QueryOnline(string) (OnlineStatus, error)     { return OnlineStatus{}, ErrDisabled }

// FakeAdapter is a local provider that never contacts a cloud service.
type FakeAdapter struct {
	PlayDomain string
	PushDomain string
	AppName    string
}

func (f FakeAdapter) Provider() string { return "fake" }
func (f FakeAdapter) CreateStream(req StreamRequest) (StreamCredentials, error) {
	return StreamCredentials{
		Provider:  f.Provider(),
		PushURL:   "fake://" + f.PushDomain + "/" + f.AppName + "/" + req.StreamName,
		ExpiresAt: req.ExpiresAt,
	}, nil
}
func (f FakeAdapter) CreatePlayURLs(req PlayRequest) (PlayURLs, error) {
	return PlayURLs{
		HLS:       "fake://" + f.PlayDomain + "/" + f.AppName + "/" + req.StreamName + ".m3u8",
		ExpiresAt: req.ExpiresAt,
	}, nil
}
func (f FakeAdapter) QueryOnline(string) (OnlineStatus, error) {
	return OnlineStatus{Online: true}, nil
}

type AliyunAdapter struct {
	cfg    Config
	client *aliyunLiveClient
}

func NewAliyunAdapter(cfg Config) (Adapter, error) {
	if !cfg.AllowRealCloud || cfg.PushDomain == "" || cfg.PlayDomain == "" || cfg.AppName == "" || cfg.AuthKey == "" || cfg.PlayAuthKey == "" || cfg.AccessKeyID == "" || cfg.AccessKeySecret == "" || cfg.RegionID == "" {
		return nil, ErrInvalidConfig
	}
	if cfg.Protocol == "" {
		cfg.Protocol = "srt"
	}
	if cfg.Protocol != "srt" && cfg.Protocol != "rtmps" {
		return nil, ErrInvalidConfig
	}
	if cfg.SRTPort <= 0 {
		cfg.SRTPort = 1105
	}
	client, err := newAliyunLiveClient(cfg)
	if err != nil {
		return nil, err
	}
	return AliyunAdapter{cfg: cfg, client: client}, nil
}

func (a AliyunAdapter) Provider() string { return "aliyun" }
func (a AliyunAdapter) CreateStream(req StreamRequest) (StreamCredentials, error) {
	return StreamCredentials{Provider: a.Provider(), PushURL: a.pushURL(req.StreamName, req.ExpiresAt), ExpiresAt: req.ExpiresAt}, nil
}
func (a AliyunAdapter) CreatePlayURLs(req PlayRequest) (PlayURLs, error) {
	expires := req.ExpiresAt
	path := "/" + a.cfg.AppName + "/" + req.StreamName
	// Alibaba Live authenticates the complete playback path. HLS and FLV
	// therefore need independent signatures because their file extensions are
	// part of the URI used by the CDN auth check.
	hlsPath := path + ".m3u8"
	flvPath := path + ".flv"
	hlsSignature := sign(hlsPath, expires.Unix(), a.cfg.PlayAuthKey)
	flvSignature := sign(flvPath, expires.Unix(), a.cfg.PlayAuthKey)
	base := "http://" + a.cfg.PlayDomain + "/" + a.cfg.AppName + "/" + req.StreamName
	rtmpPath := path
	rtmpSignature := sign(rtmpPath, expires.Unix(), a.cfg.PlayAuthKey)
	rtmp := "rtmp://" + a.cfg.PlayDomain + "/" + a.cfg.AppName + "/" + req.StreamName + "?auth_key=" + rtmpSignature
	return PlayURLs{
		HLS:       base + ".m3u8?auth_key=" + hlsSignature,
		FLV:       base + ".flv?auth_key=" + flvSignature,
		RTMP:      rtmp,
		ExpiresAt: expires,
	}, nil
}
func (a AliyunAdapter) QueryOnline(streamName string) (OnlineStatus, error) {
	return a.client.queryOnline(streamName)
}

func sign(path string, expiresAt int64, key string) string {
	var random [4]byte
	if _, err := cryptorand.Read(random[:]); err != nil {
		panic(fmt.Sprintf("generate live URL nonce: %v", err))
	}
	rand := strconv.FormatUint(uint64(random[0])<<24|uint64(random[1])<<16|uint64(random[2])<<8|uint64(random[3]), 10)
	sum := md5.Sum([]byte(fmt.Sprintf("%s-%d-%s-0-%s", path, expiresAt, rand, key)))
	return fmt.Sprintf("%d-%s-0-%s", expiresAt, rand, hex.EncodeToString(sum[:]))
}

func (a AliyunAdapter) pushURL(streamName string, expires time.Time) string {
	path := "/" + a.cfg.AppName + "/" + streamName
	auth := sign(path, expires.Unix(), a.cfg.AuthKey)
	if a.cfg.Protocol == "srt" {
		return "srt://" + a.cfg.PushDomain + ":" + strconv.Itoa(a.cfg.SRTPort) + "?streamid=#!::h=" + a.cfg.PushDomain + ",r=" + path + "?auth_key=" + auth + ",m=publish"
	}
	return "rtmps://" + a.cfg.PushDomain + "/" + a.cfg.AppName + "/" + streamName + "?auth_key=" + auth
}