package events

import (
	"context"
	"fmt"
	"log"
	"strconv"
	"strings"
	"time"

	"velox-bot/internal/db/services"

	"github.com/bwmarrin/discordgo"
)

// HandleBotAddedOnGuild applies safe defaults when this bot is added to a guild
// and DMs setup instructions to the inviter (or guild owner fallback).
func HandleBotAddedOnGuild(s *discordgo.Session, m *discordgo.GuildMemberAdd, svc *services.Services) {
	if s == nil || m == nil || m.Member == nil || m.User == nil || svc == nil {
		return
	}
	if s.State == nil || s.State.User == nil {
		return
	}
	if m.User.ID != s.State.User.ID {
		return
	}

	guildID64, err := strconv.ParseInt(m.GuildID, 10, 64)
	if err != nil {
		return
	}

	// Treat an existing logsettings row as "already onboarded once".
	alreadyOnboarded := false
	if svc.LogSettings != nil {
		exists, err := svc.LogSettings.HasSettings(context.Background(), guildID64)
		if err == nil {
			alreadyOnboarded = exists
		}
	}
	if alreadyOnboarded {
		return
	}

	// Explicitly disable toggleable systems by default.
	if svc.LevelSettings != nil {
		if err := svc.LevelSettings.SetLevelSystemEnabled(context.Background(), guildID64, false); err != nil {
			log.Printf("onboarding: failed to set default level state for guild %s: %v", m.GuildID, err)
		}
	}
	if svc.LogSettings != nil {
		if err := svc.LogSettings.SetEnabled(context.Background(), guildID64, false); err != nil {
			log.Printf("onboarding: failed to set default log state for guild %s: %v", m.GuildID, err)
		}
	}

	recipientID := findRecentBotAdderID(s, m.GuildID)
	if recipientID == "" {
		recipientID = guildOwnerID(s, m.GuildID)
	}
	if recipientID == "" {
		log.Printf("onboarding: unable to resolve DM recipient for guild %s", m.GuildID)
		return
	}

	dmCh, err := s.UserChannelCreate(recipientID)
	if err != nil {
		log.Printf("onboarding: failed creating DM for user %s: %v", recipientID, err)
		return
	}

	guildName := m.GuildID
	if g, err := s.State.Guild(m.GuildID); err == nil && g != nil && strings.TrimSpace(g.Name) != "" {
		guildName = g.Name
	} else if g, err := s.Guild(m.GuildID); err == nil && g != nil && strings.TrimSpace(g.Name) != "" {
		guildName = g.Name
	}

	embed := &discordgo.MessageEmbed{
		Title: "Thanks for adding Velox Bot!",
		Color: 0x5865F2,
		Description: fmt.Sprintf(
			"Server: **%s**\n\nFor safety, toggleable systems start **disabled by default**.\nUse these commands in your server to enable features:",
			guildName,
		),
		Fields: []*discordgo.MessageEmbedField{
			{
				Name: "Level System",
				Value: "`/slvl toggle`",
				Inline: false,
			},
			{
				Name: "Logging System",
				Value: "" +
					"`/config setlogchannel channel:#channel`\n" +
					"`/config enablelogging`",
				Inline: false,
			},
			{
				Name: "Welcome System",
				Value: "" +
					"`/config setwelcomechannel channel:#channel`\n" +
					"`/config setwelcomemessage message:\"...\"`\n" +
					"`/config setwelcomedm message:\"...\"`",
				Inline: false,
			},
		},
		Footer: &discordgo.MessageEmbedFooter{
			Text: "Tip: run /help in any server channel for the full command reference.",
		},
		Timestamp: time.Now().Format(time.RFC3339),
	}

	if _, err := s.ChannelMessageSendEmbed(dmCh.ID, embed); err != nil {
		log.Printf("onboarding: failed sending setup DM to user %s: %v", recipientID, err)
	}
}

func findRecentBotAdderID(s *discordgo.Session, guildID string) string {
	if s == nil || s.State == nil || s.State.User == nil {
		return ""
	}
	logs, err := s.GuildAuditLog(guildID, "", "", int(discordgo.AuditLogActionBotAdd), 10)
	if err != nil || logs == nil {
		return ""
	}

	botID := s.State.User.ID
	now := time.Now().UTC()
	for _, entry := range logs.AuditLogEntries {
		if entry == nil || entry.TargetID != botID || entry.ActionType == nil || *entry.ActionType != discordgo.AuditLogActionBotAdd {
			continue
		}
		ts, err := discordgo.SnowflakeTimestamp(entry.ID)
		if err != nil {
			continue
		}
		if now.Sub(ts) > 10*time.Minute {
			continue
		}
		if entry.UserID != "" {
			return entry.UserID
		}
	}
	return ""
}

func guildOwnerID(s *discordgo.Session, guildID string) string {
	if s == nil || guildID == "" {
		return ""
	}
	if s.State != nil {
		if g, err := s.State.Guild(guildID); err == nil && g != nil && g.OwnerID != "" {
			return g.OwnerID
		}
	}
	if g, err := s.Guild(guildID); err == nil && g != nil {
		return g.OwnerID
	}
	return ""
}