package bot

import (
	"context"
	"database/sql"
	"encoding/json"
	"fmt"
	"strings"
	"time"
)

// LeaderboardConfig: "channel_id" is where the daily recap lands.
type LeaderboardConfig struct {
	ChannelID string `json:"channel_id"`
}

// LeaderboardBot posts a daily shitpost recap.
func LeaderboardBot(ctx context.Context, db *sql.DB, raw json.RawMessage, send SendMessageFunc) {
	var cfg LeaderboardConfig
	if err := json.Unmarshal(raw, &cfg); err != nil || cfg.ChannelID == "" {
		return
	}

	ticker := time.NewTicker(24 * time.Hour)
	defer ticker.Stop()

	// Post immediately on start, then daily
	postLeaderboard(db, cfg.ChannelID, send)

	for {
		select {
		case <-ctx.Done():
			return
		case <-ticker.C:
			postLeaderboard(db, cfg.ChannelID, send)
		}
	}
}

func postLeaderboard(db *sql.DB, channelID string, send SendMessageFunc) {
	// ponytail: global lock on count. per-user aggregates if throughput matters.
	since := time.Now().Add(-24 * time.Hour)

	rows, err := db.QueryContext(context.Background(), `
		SELECT u.username, COUNT(*) AS msg_count
		FROM messages m
		JOIN users u ON m.author_id = u.id
		WHERE m.created_at > $1 AND m.bot_id IS NULL
		GROUP BY u.username
		ORDER BY msg_count DESC
		LIMIT 10
	`, since)
	if err != nil {
		return
	}
	defer rows.Close()

	var b strings.Builder
	b.WriteString("🏆 **24H SHITPOST LEADERBOARD** 🏆\n")

	rank := 1
	for rows.Next() {
		var username string
		var count int
		if err := rows.Scan(&username, &count); err != nil {
			continue
		}
		medal := ""
		switch rank {
		case 1:
			medal = "🥇"
		case 2:
			medal = "🥈"
		case 3:
			medal = "🥉"
		}
		fmt.Fprintf(&b, "%s #%d **%s** — %d msgs\n", medal, rank, username, count)
		rank++
	}
	if rank == 1 {
		b.WriteString("*crickets*\n")
	}

	send(channelID, strings.TrimSpace(b.String()))
}