From 427cc77fa3633aca7c4c3377fa26b0e70921a7b5 Mon Sep 17 00:00:00 2001
From: Julien Dessaux
Date: Mon, 6 May 2024 00:18:22 +0200
Subject: [golang] bootstrapped a client in yet another language

---
 golang/pkg/api/agents.go         | 14 +++++++
 golang/pkg/api/api.go            | 87 ++++++++++++++++++++++++++++++++++++++++
 golang/pkg/api/client.go         | 75 ++++++++++++++++++++++++++++++++++
 golang/pkg/api/errors.go         | 23 +++++++++++
 golang/pkg/api/priority_queue.go | 44 ++++++++++++++++++++
 golang/pkg/api/register.go       | 20 +++++++++
 6 files changed, 263 insertions(+)
 create mode 100644 golang/pkg/api/agents.go
 create mode 100644 golang/pkg/api/api.go
 create mode 100644 golang/pkg/api/client.go
 create mode 100644 golang/pkg/api/errors.go
 create mode 100644 golang/pkg/api/priority_queue.go
 create mode 100644 golang/pkg/api/register.go

(limited to 'golang/pkg/api')

diff --git a/golang/pkg/api/agents.go b/golang/pkg/api/agents.go
new file mode 100644
index 0000000..aa8107a
--- /dev/null
+++ b/golang/pkg/api/agents.go
@@ -0,0 +1,14 @@
+package api
+
+type AgentMessage struct {
+	AccountID       string `json:"accountId"`
+	Credits         int    `json:"credits"`
+	Headquarters    string `json:"headquarters"`
+	ShipCount       int    `json:"shipCount"`
+	StartingFaction string `json:"startingFaction"`
+	Symbol          string `json:"symbol"`
+}
+
+func (c *Client) MyAgent() (APIMessage[AgentMessage, any], error) {
+	return Send[AgentMessage](c, "GET", "/my/agent", nil)
+}
diff --git a/golang/pkg/api/api.go b/golang/pkg/api/api.go
new file mode 100644
index 0000000..662bb87
--- /dev/null
+++ b/golang/pkg/api/api.go
@@ -0,0 +1,87 @@
+package api
+
+import (
+	"bytes"
+	"encoding/json"
+	"io"
+	"log/slog"
+	"net/http"
+	"time"
+)
+
+type Error[T any] struct {
+	Code    int    `json:"code"`
+	Data    T      `json:"data"`
+	Message string `json:"message"`
+}
+
+type APIMessage[T any, E any] struct {
+	Data  T        `json:"data"`
+	Error Error[E] `json:"error"`
+	//meta
+}
+
+type Response struct {
+	Response []byte
+	Err      error
+}
+
+func Send[T any](c *Client, method, path string, payload any) (message APIMessage[T, any], err error) {
+	resp := make(chan *Response)
+	c.channel <- &Request{
+		method:   method,
+		path:     path,
+		payload:  payload,
+		priority: 10,
+		resp:     resp,
+	}
+	res := <-resp
+	if res.Err != nil {
+		return message, res.Err
+	}
+	err = json.Unmarshal(res.Response, &message)
+	return message, err
+}
+
+func (c *Client) sendOne(method, path string, payload any) (body []byte, err error) {
+	slog.Debug("Request", "method", method, "path", path, "payload", payload)
+	var req *http.Request
+	if payload != nil {
+		body, err = json.Marshal(payload)
+		if err == nil {
+			req, err = http.NewRequest(method, c.baseURL+path, bytes.NewBuffer(body))
+		} else {
+			return nil, err
+		}
+	} else {
+		req, err = http.NewRequest(method, c.baseURL+path, nil)
+	}
+	if err != nil {
+		return nil, err
+	}
+	req.Header = *c.headers
+	req = req.WithContext(c.ctx)
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		slog.Error("sendOne Do", "method", method, "path", path, "error", err)
+		return nil, err
+	}
+	defer func() {
+		if e := resp.Body.Close(); err == nil {
+			err = e
+		}
+	}()
+	if body, err = io.ReadAll(resp.Body); err != nil {
+		slog.Error("sendOne ReadAll", "method", method, "path", path, "error", err)
+		return nil, err
+	}
+	slog.Debug("Response", "body", string(body))
+	switch resp.StatusCode {
+	case 429:
+		e := decode429(body)
+		time.Sleep(time.Duration(e.Error.Data.RetryAfter * float64(time.Second)))
+		return c.sendOne(method, path, payload)
+	}
+	return body, nil
+}
diff --git a/golang/pkg/api/client.go b/golang/pkg/api/client.go
new file mode 100644
index 0000000..70f3e68
--- /dev/null
+++ b/golang/pkg/api/client.go
@@ -0,0 +1,75 @@
+package api
+
+import (
+	"container/heap"
+	"context"
+	"net/http"
+	"time"
+)
+
+type Client struct {
+	baseURL    string
+	channel    chan *Request
+	ctx        context.Context
+	headers    *http.Header
+	httpClient *http.Client
+	pq         *PriorityQueue
+}
+
+func NewClient(ctx context.Context) *Client {
+	pq := make(PriorityQueue, 0)
+	heap.Init(&pq)
+	client := &Client{
+		baseURL: "https://api.spacetraders.io/v2",
+		channel: make(chan *Request),
+		ctx:     ctx,
+		headers: &http.Header{
+			"Content-Type": {"application/json"},
+		},
+		httpClient: &http.Client{
+			Timeout: time.Minute,
+		},
+		pq: &pq,
+	}
+	go queueProcessor(client)
+	return client
+}
+
+func (c *Client) Close() {
+	close(c.channel)
+}
+
+func (c *Client) SetToken(token string) {
+	c.headers.Set("Authorization", "Bearer "+token)
+}
+
+func queueProcessor(client *Client) {
+	var ok bool
+	for {
+		// The queue is empty so we do this blocking call
+		req := <-client.channel
+		heap.Push(client.pq, req)
+		// we enqueue all values read from the channel and process the queue's
+		// contents until empty. We keep reading the channel as long as this
+		// emptying goes on
+		for {
+			select {
+			case req = <-client.channel:
+				heap.Push(client.pq, req)
+			default:
+				if client.pq.Len() == 0 {
+					break
+				}
+				// we process one
+				if req, ok = heap.Pop(client.pq).(*Request); !ok {
+					panic("queueProcessor got something other than a Request on its channel")
+				}
+				response, err := client.sendOne(req.method, req.path, req.payload)
+				req.resp <- &Response{
+					Response: response,
+					Err:      err,
+				}
+			}
+		}
+	}
+}
diff --git a/golang/pkg/api/errors.go b/golang/pkg/api/errors.go
new file mode 100644
index 0000000..d39a205
--- /dev/null
+++ b/golang/pkg/api/errors.go
@@ -0,0 +1,23 @@
+package api
+
+import (
+	"encoding/json"
+	"fmt"
+	"time"
+)
+
+type RateLimitError struct {
+	LimitType      string    `json:"type"`
+	RetryAfter     float64   `json:"retryAfter"`
+	LimitBurst     int       `json:"limitBurst"`
+	LimitPerSecond int       `json:"limitPerSecond"`
+	Remaining      int       `json:"remaining"`
+	Reset          time.Time `json:"reset"`
+}
+
+func decode429(msg []byte) (e APIMessage[any, RateLimitError]) {
+	if err := json.Unmarshal(msg, &e); err != nil {
+		panic(fmt.Sprintf("Failed to decode419: %+v", err))
+	}
+	return e
+}
diff --git a/golang/pkg/api/priority_queue.go b/golang/pkg/api/priority_queue.go
new file mode 100644
index 0000000..077c8f7
--- /dev/null
+++ b/golang/pkg/api/priority_queue.go
@@ -0,0 +1,44 @@
+package api
+
+type Request struct {
+	index    int
+	priority int
+
+	method  string
+	path    string
+	payload any
+	resp    chan *Response
+}
+
+type PriorityQueue []*Request
+
+func (pq PriorityQueue) Len() int {
+	return len(pq)
+}
+
+func (pq PriorityQueue) Less(i, j int) bool {
+	return pq[i].priority < pq[j].priority
+}
+
+func (pq PriorityQueue) Swap(i, j int) {
+	pq[i], pq[j] = pq[j], pq[i]
+	pq[i].index = i
+	pq[j].index = j
+}
+
+func (pq *PriorityQueue) Push(x any) {
+	n := len(*pq)
+	item := x.(*Request)
+	item.index = n
+	*pq = append(*pq, item)
+}
+
+func (pq *PriorityQueue) Pop() any {
+	old := *pq
+	n := len(old)
+	item := old[n-1]
+	old[n-1] = nil  // avoid memory leak
+	item.index = -1 // for safety
+	*pq = old[0 : n-1]
+	return item
+}
diff --git a/golang/pkg/api/register.go b/golang/pkg/api/register.go
new file mode 100644
index 0000000..4f95e2f
--- /dev/null
+++ b/golang/pkg/api/register.go
@@ -0,0 +1,20 @@
+package api
+
+type RegisterMessage struct {
+	//agent
+	//contract
+	//faction
+	//ship
+	Token string `json:"token"`
+}
+
+func (c *Client) Register(faction, symbol string) (APIMessage[RegisterMessage, any], error) {
+	type RegisterRequest struct {
+		Faction string `json:"faction"`
+		Symbol  string `json:"symbol"`
+	}
+	return Send[RegisterMessage](c, "POST", "/register", RegisterRequest{
+		Faction: faction,
+		Symbol:  symbol,
+	})
+}
-- 
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