package main

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"net/http"
	"strconv"
	"strings"
	"sync/atomic"
	"time"

	"golang.org/x/net/websocket"
)

// Slack manages the slack connection and implements API calls
type Slack struct {
	apiToken string
	id       string
	socket   *websocket.Conn
	alive    bool
}

// CreateSlack creates the slack object, opening a websocket
func CreateSlack(token string) (*Slack, error) {
	s := Slack{apiToken: token}
	url := fmt.Sprintf("https://slack.com/api/rtm.start?token=%s", token)
	resp, err := http.Get(url)
	if err != nil {
		return nil, err
	}
	if resp.StatusCode != 200 {
		err = fmt.Errorf("API request failed with code %d", resp.StatusCode)
		return nil, err
	}
	body, err := ioutil.ReadAll(resp.Body)
	resp.Body.Close()
	if err != nil {
		return nil, err
	}
	var respObj responseRtmStart
	err = json.Unmarshal(body, &respObj)
	if err != nil {
		return nil, err
	}

	if !respObj.Ok {
		err = fmt.Errorf("Slack error: %s", respObj.Error)
		return nil, err
	}

	wsurl := respObj.URL
	s.id = respObj.Self.ID

	ws, err := websocket.Dial(wsurl, "", "https://api.slack.com/")
	s.socket = ws
	s.keepAlive()

	return &s, nil
}

func (s *Slack) keepAlive() {
	s.alive = true
	go func() {
		for {
			if s.alive {
				s.ping()
			}
			time.Sleep(time.Second * 30)
		}
	}()
}

var counter uint64

func (s *Slack) ping() error {
	return s.postMessage(Message{Type: "ping"})
}

func (s *Slack) postMessage(m Message) error {
	m.ID = atomic.AddUint64(&counter, 1)
	return websocket.JSON.Send(s.socket, m)
}

func (s *Slack) getMessage() (Message, error) {
	var m Message
	err := websocket.JSON.Receive(s.socket, &m)

	txtArr := strings.Split(m.Ts, ".")
	if t, err := strconv.Atoi(txtArr[0]); err == nil {
		rawts := int64(t)
		m.Time = time.Unix(0, rawts*1000000000)
	}

	return m, err
}

func (s *Slack) sendMessageToUser(uid string, msg string) error {
	// TODO: Actually send a direct message to uid
	return nil
}

func (s *Slack) getUserInfo(uid string) (*User, error) {
	url := fmt.Sprintf("https://slack.com/api/users.info?token=%s&user=%s", s.apiToken, uid)
	resp, err := http.Get(url)
	if err != nil {
		return nil, err
	}
	if resp.StatusCode != 200 {
		err = fmt.Errorf("API request failed with code %d", resp.StatusCode)
		return nil, err
	}
	body, err := ioutil.ReadAll(resp.Body)
	resp.Body.Close()
	if err != nil {
		return nil, err
	}
	var respObj responseUserLookup
	err = json.Unmarshal(body, &respObj)
	if err != nil {
		return nil, err
	}

	if !respObj.Ok {
		err = fmt.Errorf("Slack error: %s", respObj.Error)
		return nil, err
	}
	return respObj.User, nil
}

func (s *Slack) getChannelInfo(cid string) (*Channel, error) {
	url := fmt.Sprintf("https://slack.com/api/channels.info?token=%s&channel=%s", s.apiToken, cid)
	resp, err := http.Get(url)
	if err != nil {
		return nil, err
	}
	if resp.StatusCode != 200 {
		err = fmt.Errorf("API request failed with code %d", resp.StatusCode)
		return nil, err
	}
	body, err := ioutil.ReadAll(resp.Body)
	resp.Body.Close()
	if err != nil {
		return nil, err
	}
	var respObj responseChannelLookup
	err = json.Unmarshal(body, &respObj)
	if err != nil {
		return nil, err
	}

	if !respObj.Ok {
		err = fmt.Errorf("Slack error: %s", respObj.Error)
		return nil, err
	}
	return respObj.Channel, nil
}

func (s *Slack) joinChannel(c *Channel) error {
	url := fmt.Sprintf("https://slack.com/api/channels.join?token=%s&name=%s", s.apiToken, c.Name)
	resp, err := http.Get(url)
	if err != nil {
		return err
	}
	if resp.StatusCode != 200 {
		err = fmt.Errorf("API request failed with code %d", resp.StatusCode)
		return err
	}
	body, err := ioutil.ReadAll(resp.Body)
	resp.Body.Close()
	if err != nil {
		return err
	}
	var respObj responseChannelLookup
	err = json.Unmarshal(body, &respObj)
	if err != nil {
		return err
	}

	if !respObj.Ok {
		err = fmt.Errorf("Slack error: %s", respObj.Error)
		return err
	}
	return err
}

// These structures represent the response of the Slack API events
// Only some fields are included. The rest are ignored by json.Unmarshal.
type responseRtmStart struct {
	Ok    bool         `json:"ok"`
	Error string       `json:"error"`
	URL   string       `json:"url"`
	Self  responseSelf `json:"self"`
}

type responseSelf struct {
	ID string `json:"id"`
}

type responseUserLookup struct {
	Ok    bool   `json:"ok"`
	Error string `json:"error"`
	User  *User  `json:"user"`
}

type responseChannelLookup struct {
	Ok      bool     `json:"ok"`
	Error   string   `json:"error"`
	Channel *Channel `json:"channel"`
}