package watchlists

import (
	"context"
	"fmt"

	"github.com/jackc/pgx/v5/pgxpool"
)

// WatchlistService handles watchlist operations
type WatchlistService struct {
	db *pgxpool.Pool
}

// NewWatchlistService creates a new watchlist service
func NewWatchlistService(db *pgxpool.Pool) *WatchlistService {
	return &WatchlistService{db: db}
}

// AddToWatchlist adds an address to a user's watchlist
func (w *WatchlistService) AddToWatchlist(ctx context.Context, userID string, chainID int, address, label string) error {
	query := `
		INSERT INTO watchlists (user_id, chain_id, address, label)
		VALUES ($1, $2, $3, $4)
		ON CONFLICT (user_id, chain_id, address) DO UPDATE SET
			label = $4
	`

	_, err := w.db.Exec(ctx, query, userID, chainID, address, label)
	return err
}

// RemoveFromWatchlist removes an address from watchlist
func (w *WatchlistService) RemoveFromWatchlist(ctx context.Context, userID string, chainID int, address string) error {
	query := `DELETE FROM watchlists WHERE user_id = $1 AND chain_id = $2 AND address = $3`
	_, err := w.db.Exec(ctx, query, userID, chainID, address)
	return err
}

// GetWatchlist gets a user's watchlist
func (w *WatchlistService) GetWatchlist(ctx context.Context, userID string, chainID int) ([]WatchlistItem, error) {
	query := `
		SELECT chain_id, address, label, created_at
		FROM watchlists
		WHERE user_id = $1 AND chain_id = $2
		ORDER BY created_at DESC
	`

	rows, err := w.db.Query(ctx, query, userID, chainID)
	if err != nil {
		return nil, fmt.Errorf("failed to query watchlist: %w", err)
	}
	defer rows.Close()

	var items []WatchlistItem
	for rows.Next() {
		var item WatchlistItem
		if err := rows.Scan(&item.ChainID, &item.Address, &item.Label, &item.CreatedAt); err != nil {
			continue
		}
		items = append(items, item)
	}

	return items, nil
}

// WatchlistItem represents a watchlist item
type WatchlistItem struct {
	ChainID   int
	Address   string
	Label     string
	CreatedAt string
}