package rolereactions

import (
	"io/ioutil"
	"log"

	"git.annabunch.es/annabunches/urizen/lib/util"

	"github.com/bwmarrin/discordgo"
	"gopkg.in/yaml.v2"
)

type roleReactionConfig struct {
	Channel     string
	Message     string
	MessageText string               `yaml:"message_text"`
	RoleMap     map[string]emojiData `yaml:"role_map"`
}

type emojiData struct {
	CustomEmojiID string `yaml:"custom_emoji_id"`
	RoleID        string `yaml:"role_id"`
}

var config []roleReactionConfig

// Init initializes the module, installing the handlers into the provided
// discord session and setting up the role mapping via the config file.
func Init(session *discordgo.Session, configFile string) {
	// TODO: should config be added/stored dynamically?
	config = make([]roleReactionConfig, 0)
	util.ParseFile(configFile, initConfig)
	changed := initMessages(session)
	if changed {
		writeConfig(configFile)
	}
	session.AddHandler(handleReactAdd)
	session.AddHandler(handleReactRemove)
}

func initConfig(data []byte) int {
	err := yaml.Unmarshal(data, &config)
	if err != nil {
		log.Panicf("[RoleReactions] Failed to parse role reaction config: %v", err)
	}
	return 1
}

func writeConfig(filename string) {
	data, err := yaml.Marshal(&config)
	if err != nil {
		log.Printf("[RoleReactions] Failed to convert config back to yaml. Couldn't save config. This will probably break something: %v", err)
		return
	}

	err = ioutil.WriteFile(filename, data, 0644)
	if err != nil {
		log.Printf("[RoleReactions] Failed to save changes to config. This will probably break something on future runs: %v", err)
		return
	}

	log.Printf("[RoleReactions] Wrote new config.")
}

// Iterate over the message IDs, first removing all reactions from the
// bot, then adding the available reactions.
// This will log an error if a message ID is not found, but program
// execution will continue.
func initMessages(session *discordgo.Session) bool {
	changed := false
	for i, data := range config {
		// if message ID is empty, create a new message and flag that we need to write
		// out the new config
		if data.Message == "" {
			msgID, err := postMessage(session, data)
			if err != nil {
				log.Printf("[RoleReactions] Couldn't post message to channel '%s'. This config entry will be ignored.", data.Channel)
				continue
			}
			config[i].Message = msgID
			data.Message = msgID // we have to set this one so that the rest of this loop iteration works as expected
			changed = true
		}

		// delete any self-made reactions from previous runs. We iterate over all of them
		// in case the options have changed
		deleteOwnReactions(session, data.Message, data.Channel)

		// Add the new reacts
		for name, eData := range data.RoleMap {
			emojiString := name
			if eData.CustomEmojiID != "" {
				emojiString += ":" + eData.CustomEmojiID
			}
			err := session.MessageReactionAdd(data.Channel, data.Message, emojiString)
			if err != nil {
				log.Printf("[RoleReactions] Couldn't add reaction '%s' on message '%s': %v", emojiString, data.Message, err)
				continue
			}
		}
		log.Printf("[RoleReactions] listening to message %s", data.Message)
		log.Printf("[RoleReactions] role map: %v", data.RoleMap)
	}

	return changed
}

func postMessage(session *discordgo.Session, data roleReactionConfig) (string, error) {
	log.Printf("Posting a new message to channel '%s'", data.Channel)
	msg, err := session.ChannelMessageSend(data.Channel, data.MessageText)
	if err != nil {
		return "", err
	}
	return msg.ID, nil
}

func deleteOwnReactions(session *discordgo.Session, message string, channel string) {
	// Clean up the old reacts
	msg, err := session.ChannelMessage(channel, message)
	if err != nil {
		log.Printf("[RoleReactions] Error retrieving message to clean reacts: %v", err)
		return
	}

	for _, react := range msg.Reactions {
		if react.Me != true {
			continue
		}

		session.MessageReactionRemove(channel, message, react.Emoji.Name, "@me")
	}
}

func handleReactAdd(s *discordgo.Session, m *discordgo.MessageReactionAdd) {
	for _, target := range config {
		if m.MessageID != target.Message {
			continue
		}

		eData, ok := target.RoleMap[m.Emoji.Name]
		if !ok {
			log.Printf("[RoleReactions] Unmapped react added to message '%s': %s", target.Message, m.Emoji.Name)
			return
		}

		// add the role to the user
		s.GuildMemberRoleAdd(m.GuildID, m.UserID, eData.RoleID)
		log.Printf("[RoleReactions] Added role '%s' to user '%s'", m.UserID, eData.RoleID)
		return
	}
}

func handleReactRemove(s *discordgo.Session, m *discordgo.MessageReactionRemove) {
	for _, target := range config {
		if m.MessageID != target.Message {
			continue
		}

		eData, ok := target.RoleMap[m.Emoji.Name]
		if !ok {
			return
		}

		s.GuildMemberRoleRemove(m.GuildID, m.UserID, eData.RoleID)
		log.Printf("[RoleReactions] Removed role '%s' from user '%s'", m.UserID, eData.RoleID)
		return
	}
}