package fetcher

import (
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"net/url"
	"strings"
)

type AlchemyClient struct {
	apiKey string
	http  *http.Client
}

func NewAlchemyClient(apiKey string) *AlchemyClient {
	return &AlchemyClient{apiKey: apiKey, http: &http.Client{}}
}

// FetchOwnerTokens returns tokenIDs (as strings) for the owner for a single contract.
// network: e.g. "arb" (arbitrum one) -> uses arb-mainnet endpoint.
func (c *AlchemyClient) FetchOwnerTokens(network, contract, owner string) ([]string, error) {
	if c.apiKey == "" {
		return nil, errors.New("missing ALCHEMY_API_KEY")
	}
	base := networkBase(network)
	if base == "" {
		return nil, fmt.Errorf("unsupported network: %s", network)
	}
	endpoint := fmt.Sprintf("%s/nft/v3/%s/getNFTsForOwner", base, c.apiKey)
	q := url.Values{}
	q.Set("owner", owner)
	q.Add("contractAddresses[]", contract)
	q.Set("withMetadata", "false")
	url := endpoint + "?" + q.Encode()

	resp, err := c.http.Get(url)
	if err != nil { return nil, err }
	defer resp.Body.Close()
	if resp.StatusCode != 200 {
		return nil, fmt.Errorf("alchemy error: %s", resp.Status)
	}
	var parsed struct {
		OwnedNfts []struct {
			Id struct { TokenId string `json:"tokenId"` } `json:"id"`
		} `json:"ownedNfts"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&parsed); err != nil { return nil, err }
	ids := make([]string, 0, len(parsed.OwnedNfts))
	for _, n := range parsed.OwnedNfts {
		ids = append(ids, stripHexPrefix(n.Id.TokenId))
	}
	return ids, nil
}

func stripHexPrefix(s string) string {
	s = strings.TrimPrefix(s, "0x")
	// Alchemy may return hex with leading zeros; keep as-is (frontend can parse)
	return s
}

func networkBase(network string) string {
	switch strings.ToLower(network) {
	case "arb", "arbitrum", "arbitrum-one":
		return "https://arb-mainnet.g.alchemy.com"
	case "arb-sepolia", "arbitrum-sepolia":
		return "https://arb-sepolia.g.alchemy.com"
	case "eth", "mainnet", "ethereum":
		return "https://eth-mainnet.g.alchemy.com"
	default:
		return ""
	}
}