From 5b941f514e798a20804c5e58db20ce56ec4b7e4a Mon Sep 17 00:00:00 2001
From: Thanatat Tamtan <acoshift@gmail.com>
Date: Tue, 14 Mar 2023 22:57:04 +0700
Subject: [PATCH] add invoke

---
 client.go | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)
 create mode 100644 client.go

diff --git a/client.go b/client.go
new file mode 100644
index 0000000..fab16ff
--- /dev/null
+++ b/client.go
@@ -0,0 +1,59 @@
+package arpc
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"io"
+	"net/http"
+	"strings"
+)
+
+func Invoke[P, R any](ctx context.Context, client *http.Client, endpoint, method string, p *P) (*R, error) {
+	var reqBuff bytes.Buffer
+	err := json.NewEncoder(&reqBuff).Encode(p)
+	if err != nil {
+		return nil, err
+	}
+
+	if !strings.HasSuffix(endpoint, "/") && !strings.HasPrefix(method, "/") {
+		endpoint += "/"
+	}
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, endpoint+method, &reqBuff)
+	if err != nil {
+		return nil, err
+	}
+
+	if client == nil {
+		client = http.DefaultClient
+	}
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	defer io.Copy(io.Discard, resp.Body)
+
+	var res struct {
+		OK    bool `json:"ok"`
+		Error struct {
+			Code    string `json:"code"`
+			Message string `json:"message"`
+		} `json:"error"`
+		Result R `json:"result"`
+	}
+	err = json.NewDecoder(resp.Body).Decode(&res)
+	if err != nil {
+		return nil, err
+	}
+	if !res.OK {
+		if resp.StatusCode == http.StatusInternalServerError {
+			return nil, internalError{}
+		}
+		if resp.StatusCode == http.StatusBadRequest {
+			return nil, NewProtocolError(res.Error.Code, res.Error.Message)
+		}
+		return nil, NewErrorCode(res.Error.Code, res.Error.Message)
+	}
+	return &res.Result, nil
+}