a301_server/internal/chain/client.go

package chain

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"sync/atomic"
	"time"
)

type rpcRequest struct {
	JSONRPC string `json:"jsonrpc"`
	ID      int64  `json:"id"`
	Method  string `json:"method"`
	Params  any    `json:"params"`
}

type rpcResponse struct {
	JSONRPC string          `json:"jsonrpc"`
	ID      any             `json:"id"`
	Result  json.RawMessage `json:"result,omitempty"`
	Error   *rpcError       `json:"error,omitempty"`
}

type rpcError struct {
	Code    int    `json:"code"`
	Message string `json:"message"`
}

func (e *rpcError) Error() string {
	return fmt.Sprintf("RPC error %d: %s", e.Code, e.Message)
}

// Client is a JSON-RPC 2.0 client for the TOL Chain node.
type Client struct {
	nodeURL string
	http    *http.Client
	idSeq   atomic.Int64
}

func NewClient(nodeURL string) *Client {
	return &Client{
		nodeURL: nodeURL,
		http:    &http.Client{Timeout: 10 * time.Second},
	}
}

// Call invokes a JSON-RPC method and unmarshals the result into out.
func (c *Client) Call(method string, params any, out any) error {
	reqBody := rpcRequest{
		JSONRPC: "2.0",
		ID:      c.idSeq.Add(1),
		Method:  method,
		Params:  params,
	}
	data, err := json.Marshal(reqBody)
	if err != nil {
		return fmt.Errorf("marshal RPC request: %w", err)
	}

	resp, err := c.http.Post(c.nodeURL, "application/json", bytes.NewReader(data))
	if err != nil {
		return fmt.Errorf("RPC network error: %w", err)
	}
	defer resp.Body.Close()

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return fmt.Errorf("read RPC response: %w", err)
	}

	var rpcResp rpcResponse
	if err := json.Unmarshal(body, &rpcResp); err != nil {
		return fmt.Errorf("unmarshal RPC response: %w", err)
	}
	if rpcResp.Error != nil {
		return rpcResp.Error
	}
	if out != nil {
		if err := json.Unmarshal(rpcResp.Result, out); err != nil {
			return fmt.Errorf("unmarshal RPC result: %w", err)
		}
	}
	return nil
}

// --- Typed convenience methods ---

type BalanceResult struct {
	Address string `json:"address"`
	Balance uint64 `json:"balance"`
	Nonce   uint64 `json:"nonce"`
}

func (c *Client) GetBalance(address string) (*BalanceResult, error) {
	var result BalanceResult
	err := c.Call("getBalance", map[string]string{"address": address}, &result)
	return &result, err
}

func (c *Client) GetAsset(id string) (json.RawMessage, error) {
	var result json.RawMessage
	err := c.Call("getAsset", map[string]string{"id": id}, &result)
	return result, err
}

func (c *Client) GetAssetsByOwner(owner string, offset, limit int) (json.RawMessage, error) {
	var result json.RawMessage
	err := c.Call("getAssetsByOwner", map[string]any{
		"owner": owner, "offset": offset, "limit": limit,
	}, &result)
	return result, err
}

func (c *Client) GetInventory(owner string) (json.RawMessage, error) {
	var result json.RawMessage
	err := c.Call("getInventory", map[string]string{"owner": owner}, &result)
	return result, err
}

func (c *Client) GetActiveListings(offset, limit int) (json.RawMessage, error) {
	var result json.RawMessage
	err := c.Call("getActiveListings", map[string]any{
		"offset": offset, "limit": limit,
	}, &result)
	return result, err
}

func (c *Client) GetListing(id string) (json.RawMessage, error) {
	var result json.RawMessage
	err := c.Call("getListing", map[string]string{"id": id}, &result)
	return result, err
}

type SendTxResult struct {
	TxID string `json:"tx_id"`
}

func (c *Client) SendTx(tx any) (*SendTxResult, error) {
	var result SendTxResult
	err := c.Call("sendTx", tx, &result)
	return &result, err
}