package main

import (
	"context"
	"crypto/tls"
	"encoding/json"
	"fmt"
	"net/http"
	"regexp"
	"strconv"
	"strings"

	"github.com/go-irc/irc"
	"github.com/pkg/errors"
	log "github.com/sirupsen/logrus"
)

var regexpHostNotification = regexp.MustCompile(`^(?P<actor>\w+) is now(?: auto)? hosting you(?: for (?P<amount>[0-9]+) viewers)?.$`)

type ircHandler struct {
	conn *tls.Conn
	c    *irc.Client
	user string
}

func newIRCHandler() (*ircHandler, error) {
	h := new(ircHandler)

	username, err := h.fetchTwitchUsername()
	if err != nil {
		return nil, errors.Wrap(err, "fetching username")
	}

	conn, err := tls.Dial("tcp", "irc.chat.twitch.tv:6697", nil)
	if err != nil {
		return nil, errors.Wrap(err, "connect to IRC server")
	}

	h.c = irc.NewClient(conn, irc.ClientConfig{
		Nick:    username,
		Pass:    strings.Join([]string{"oauth", cfg.TwitchToken}, ":"),
		User:    username,
		Name:    username,
		Handler: h,
	})
	h.conn = conn
	h.user = username

	return h, nil
}

func (i ircHandler) Close() error { return i.conn.Close() }

func (i ircHandler) Handle(c *irc.Client, m *irc.Message) {
	switch m.Command {
	case "001":
		// 001 is a welcome event, so we join channels there
		c.WriteMessage(&irc.Message{
			Command: "CAP",
			Params: []string{
				"REQ",
				strings.Join([]string{
					"twitch.tv/commands",
					"twitch.tv/membership",
					"twitch.tv/tags",
				}, " "),
			},
		})
		c.Write(fmt.Sprintf("JOIN #%s", i.user))

	case "NOTICE":
		// NOTICE (Twitch Commands)
		// General notices from the server.
		i.handleTwitchNotice(m)

	case "PRIVMSG":
		i.handleTwitchPrivmsg(m)

	case "RECONNECT":
		// RECONNECT (Twitch Commands)
		// In this case, reconnect and rejoin channels that were on the connection, as you would normally.
		i.Close()

	case "USERNOTICE":
		// USERNOTICE (Twitch Commands)
		// Announces Twitch-specific events to the channel (for example, a user’s subscription notification).
		i.handleTwitchUsernotice(m)

	default:
		log.WithFields(log.Fields{
			"command":  m.Command,
			"tags":     m.Tags,
			"trailing": m.Trailing(),
		}).Trace("Unhandled message")
		// Unhandled message type, not yet needed
	}
}

func (i ircHandler) Run() error { return errors.Wrap(i.c.Run(), "running IRC client") }

func (ircHandler) fetchTwitchUsername() (string, error) {
	ctx, cancel := context.WithTimeout(context.Background(), twitchRequestTimeout)
	defer cancel()

	req, err := http.NewRequestWithContext(ctx, http.MethodGet, fmt.Sprintf("https://api.twitch.tv/helix/users?id=%s", cfg.TwitchID), nil)
	if err != nil {
		return "", errors.Wrap(err, "assemble user request")
	}
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Client-Id", cfg.TwitchClient)
	req.Header.Set("Authorization", "Bearer "+cfg.TwitchToken)

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return "", errors.Wrap(err, "requesting user info")
	}
	defer resp.Body.Close()

	var payload struct {
		Data []struct {
			ID    string `json:"id"`
			Login string `json:"login"`
		} `json:"data"`
	}

	if err = json.NewDecoder(resp.Body).Decode(&payload); err != nil {
		return "", errors.Wrap(err, "parse user info")
	}

	if l := len(payload.Data); l != 1 {
		return "", errors.Errorf("unexpected number of users returned: %d", l)
	}

	if payload.Data[0].ID != cfg.TwitchID {
		return "", errors.Errorf("unexpected user returned: %s", payload.Data[0].ID)
	}

	return payload.Data[0].Login, nil
}

func (ircHandler) handleTwitchNotice(m *irc.Message) {
	log.WithFields(log.Fields{
		"tags":     m.Tags,
		"trailing": m.Trailing,
	}).Debug("IRC NOTICE event")

	switch m.Tags["msg-id"] {
	case "":
		// Notices SHOULD have msg-id tags...
		log.WithField("msg", m).Warn("Received notice without msg-id")

	case "host_success", "host_success_viewers":
		log.WithField("trailing", m.Trailing()).Warn("Incoming host")

		// NOTE: Doesn't work? Need to figure out why, host had no notice
		// This used to work at some time... Maybe? Dunno. Didn't get that to work.

	}
}

func (ircHandler) handleTwitchPrivmsg(m *irc.Message) {
	log.WithFields(log.Fields{
		"name":     m.Name,
		"user":     m.User,
		"tags":     m.Tags,
		"trailing": m.Trailing(),
	}).Trace("Received privmsg")

	// Handle the jtv host message for hosts
	if m.User == "jtv" && regexpHostNotification.MatchString(m.Trailing()) {
		matches := regexpHostNotification.FindStringSubmatch(m.Trailing())
		if matches[2] == "" {
			matches[2] = "0"
		}

		subscriptions.SendAllSockets(msgTypeHost, map[string]interface{}{
			"from":        matches[1],
			"viewerCount": matches[2],
		})
	}
}

func (ircHandler) handleTwitchUsernotice(m *irc.Message) {
	log.WithFields(log.Fields{
		"tags":     m.Tags,
		"trailing": m.Trailing,
	}).Debug("IRC USERNOTICE event")

	displayName, ok := m.Tags["msg-param-displayName"]
	if !ok {
		displayName = m.Tags["login"]
	}

	switch m.Tags["msg-id"] {
	case "":
		// Notices SHOULD have msg-id tags...
		log.WithField("msg", m).Warn("Received usernotice without msg-id")

	case "raid":
		fields := map[string]interface{}{
			"from":        displayName,
			"viewerCount": m.Tags["msg-param-viewerCount"],
		}

		log.WithFields(log.Fields(fields)).Info("Incoming raid")
		subscriptions.SendAllSockets(msgTypeRaid, fields)

	case "sub", "resub":
		fields := map[string]interface{}{
			"from":     displayName,
			"is_resub": m.Tags["msg-id"] == "resub",
			"paid_for": m.Tags["msg-param-multimonth-duration"],
			"streak":   m.Tags["msg-param-streak-months"],
			"tier":     m.Tags["msg-param-sub-plan"],
			"total":    m.Tags["msg-param-cumulative-months"],
		}

		// Update store
		strDisplayName := string(displayName)
		var duration int64
		if v, err := strconv.ParseInt(string(m.Tags["msg-param-cumulative-months"]), 10, 64); err == nil {
			duration = v
		}

		store.Subs.Last = &strDisplayName
		store.Subs.LastDuration = duration

		// Send update to sockets
		log.WithFields(log.Fields(fields)).Info("New subscriber")
		subscriptions.SendAllSockets(msgTypeSub, fields)

		// Execute store save
		if err := store.Save(cfg.StoreFile); err != nil {
			log.WithError(err).Error("Unable to update persistent store")
		}

		if err := subscriptions.SendAllSockets(msgTypeStore, store); err != nil {
			log.WithError(err).Error("Unable to send update to all sockets")
		}

	case "subgift", "anonsubgift":
		toName, ok := m.Tags["msg-param-recipient-display-name"]
		if !ok {
			toName = m.Tags["msg-param-recipient-user-name"]
		}

		fields := map[string]interface{}{
			"from":     displayName,
			"is_anon":  m.Tags["msg-id"] == "anonsubgift",
			"gift_to":  toName,
			"paid_for": m.Tags["msg-param-gift-months"],
			"streak":   m.Tags["msg-param-streak-months"],
			"tier":     m.Tags["msg-param-sub-plan"],
			"total":    m.Tags["msg-param-months"],
		}

		// Update store
		strDisplayName := string(displayName)
		var duration int64
		if v, err := strconv.ParseInt(string(m.Tags["msg-param-months"]), 10, 64); err == nil {
			duration = v
		}

		store.Subs.Last = &strDisplayName
		store.Subs.LastDuration = duration

		// Send update to sockets
		log.WithFields(log.Fields(fields)).Info("New sub-gift")
		subscriptions.SendAllSockets(msgTypeSub, fields)

		// Execute store save
		if err := store.Save(cfg.StoreFile); err != nil {
			log.WithError(err).Error("Unable to update persistent store")
		}

		if err := subscriptions.SendAllSockets(msgTypeStore, store); err != nil {
			log.WithError(err).Error("Unable to send update to all sockets")
		}

	}
}