package help

import (
	"log"
	"unicode/utf8"

	"github.com/bwmarrin/discordgo"
)

var Help = &discordgo.ApplicationCommand{
	Name:        "help",
	Description: "Get help with the bot",
}

// A message's embeds share a limit of 6000 characters, and one embed holds at
// most 25 fields of 1024 characters. The reference is longer than that, so it
// is sent as a few messages.
const (
	maxEmbedChars = 5000
	maxFieldChars = 1024
)

// docsURL is where each command is explained in full, with its options and
// who may use it.
const docsURL = "https://velox.fernandovideira.com/docs/commands"

// col is one short column of the help: a list of commands, no descriptions.
// Fields are inline, so Discord lays three of them side by side and the help
// is wide and short instead of narrow and long.
func col(name string, lines ...string) *discordgo.MessageEmbedField {
	v := ""
	for i, l := range lines {
		if i > 0 {
			v += "\n"
		}
		v += l
	}
	return &discordgo.MessageEmbedField{Name: name, Value: v, Inline: true}
}

func fields() []*discordgo.MessageEmbedField {
	return []*discordgo.MessageEmbedField{
		col("Fun",
			"`/ping` `/joke` `/coinflip`", "`/dice` `/rps` `/rpsstats`", "`/rpsleaderboard`"),
		col("Music (DJ role)",
			"`/play` `/queue` `/volume`", "`/music skip` `pause` `resume`", "`/music stop` `repeat`", "`/music remove` `move`", "`/music toggle` (Manage Server)"),
		col("Sessions and time",
			"`/schedule create`", "`/schedule list`", "`/schedule reschedule`", "`/timezone set` `show`"),
		col("Tickets",
			"Open one from the panel.", "`/ticket add` `close`", "`/ticket claim` `remove` (staff)", "`/tickets setup` `settings`", "`/tickets category` `panel` `list`"),
		col("Security",
			"`/security status` `settings` `history`", "`/security toggle`", "`/security joingate` `words` `raid`", "`/security antinuke` `heat` `alert-dms`", "`/security trust` `release` `end-raid`", "`/security alerts` `quarantine-role`", "`/security snapshot` `restore`", "`/lockdown` `/unlock`"),
		col("Moderation",
			"`/moderation purge`", "`/moderation timeout` `untimeout`", "`/moderation kick` `ban` `unban`", "`/moderation slowmode`", "`/moderation bans` `timeouts`"),
		col("Meeting rooms",
			"`/meeting add-lobby`", "`/meeting remove-lobby` `lobbies`", "`/meeting lock` `lock-private`", "`/meeting unlock`", "`/meeting invite` `uninvite`"),
		col("Leveling",
			"`/rank` `/leaderboard` `/rewards`", "`/slvl toggle` `status`", "`/slvl set` `set-channel`", "`/slvl set-message`", "`/slvl set-reward` `remove-reward`"),
		col("Projects",
			"`/projects list`", "`/projects create`", "`/projects add-helper`", "`/projects close`"),
		col("Welcome and roles",
			"`/config setwelcomechannel`", "`/config setwelcomemessage`", "`/config setwelcomedm`", "`/config setwelcomegif`", "`/config setdefaultrole`"),
		col("Logging and Twitch",
			"`/config setlogchannel`", "`/config enablelogging` `disablelogging`", "`/config addstreamer` `removestreamer`", "`/config streamers`", "`/config toggletwitch`", "`/config settwitchnotificationchannel`"),
		col("Settings and beta",
			"`/config view` `clear`", "`/config beta-features` (server owner)", "Bot owner, in a DM with me:", "`/beta set` `off` `status`"),
		{
			Name:  "Everything in detail",
			Value: "Options, permissions and what each command does: " + docsURL + "\nMost setup commands need **Manage Server**. `/help` shows this list again.",
		},
	}
}

func fieldSize(f *discordgo.MessageEmbedField) int {
	return utf8.RuneCountInString(f.Name) + utf8.RuneCountInString(f.Value)
}

// embeds splits the reference into embeds that fit Discord's limits.
func embeds(author *discordgo.MessageEmbedAuthor) []*discordgo.MessageEmbed {
	var out []*discordgo.MessageEmbed
	cur := &discordgo.MessageEmbed{
		Title:       "Velox Bot Help",
		Description: "Every command, by area. Some need server permissions or a role.",
		Color:       0xFFA500,
		Author:      author,
	}
	size := utf8.RuneCountInString(cur.Title) + utf8.RuneCountInString(cur.Description) + utf8.RuneCountInString(author.Name)
	for _, f := range fields() {
		if size+fieldSize(f) > maxEmbedChars || len(cur.Fields) >= 25 {
			out = append(out, cur)
			cur = &discordgo.MessageEmbed{Title: "Velox Bot Help (continued)", Color: 0xFFA500}
			size = utf8.RuneCountInString(cur.Title)
		}
		cur.Fields = append(cur.Fields, f)
		size += fieldSize(f)
	}
	return append(out, cur)
}

func HelpHandler(s *discordgo.Session, i *discordgo.InteractionCreate) {
	s.InteractionRespond(i.Interaction, &discordgo.InteractionResponse{
		Type: discordgo.InteractionResponseChannelMessageWithSource,
		Data: &discordgo.InteractionResponseData{
			Content: "Check your DMs for help.",
			Flags:   discordgo.MessageFlagsEphemeral,
		},
	})

	userID := ""

	// check if command is run in a guild
	if i.Member != nil {
		userID = i.Member.User.ID
	} else {
		userID = i.Interaction.User.ID
	}

	dmChannel, err := s.UserChannelCreate(userID)
	if err != nil {
		log.Printf("Error creating DM channel: %v", err)
		return
	}

	author := discordgo.MessageEmbedAuthor{
		Name: "Velox Bot",
		URL:  "https://gitea.fernandovideira.com/FernandoJVideira/velox-bot",
	}

	for _, e := range embeds(&author) {
		if _, err := s.ChannelMessageSendEmbed(dmChannel.ID, e); err != nil {
			log.Printf("Error sending help: %v", err)
			return
		}
	}
}