// package bybit provides rates of cryptocurrencies from bybit exchange orderbook.
package bybit

import (
	"context"
	"fmt"
	"log/slog"
	"net/http"
	"time"

	"gitea.computernetthings.ru/yash/crypto_alert_bot/internal/config"
	"gitea.computernetthings.ru/yash/crypto_alert_bot/internal/entities"
	"gitea.computernetthings.ru/yash/crypto_alert_bot/internal/provider"

	"github.com/shopspring/decimal"
)

const (
	// mainnetURL  = "https://api.bybit.com"
	httpTimeout = time.Second * 10
)

type Bybit struct {
	log    *slog.Logger
	cfg    *config.Bybit
	client *http.Client
}

func New(log *slog.Logger, cfg *config.Bybit) provider.Provider {
	return &Bybit{
		log: log,
		cfg: cfg,
		client: &http.Client{
			Timeout: httpTimeout,
		},
	}
}

func (b *Bybit) symbol(pair *entities.Pair) string {
	return fmt.Sprintf("%s%s", pair.BaseCurrency, pair.QuoteCurrency)
}

// Price returns the current price of the pair (base currency / quote currency).
// e.g. BTC/USDT.
func (b *Bybit) Price(ctx context.Context, pair entities.Pair) (*entities.Price, error) {
	// build request
	req := marketOrderbookReq{
		Category: categorySpot,
		Symbol:   b.symbol(&pair),
	}
	var resp marketOrderbookResp
	// make request
	err := b.makeRequest(ctx, http.MethodGet, "/v5/market/orderbook", req, &resp)
	if err != nil {
		return nil, fmt.Errorf("failed to make request: %w", err)
	}
	// get results
	if len(resp.A) == 0 || len(resp.B) == 0 {
		return nil, fmt.Errorf("incorrect response: nil data")
	}
	if len(resp.A[0]) != 2 || len(resp.B[0]) != 2 {
		return nil, fmt.Errorf("incorrect response: nil prices")
	}

	askPrice := decimal.RequireFromString(resp.A[0][0])
	bidPrice := decimal.RequireFromString(resp.B[0][0])
	spread := askPrice.Sub(bidPrice)

	return &entities.Price{
		Ask:    askPrice,
		Bid:    bidPrice,
		Spread: spread,
		Pair:   pair,
	}, nil
}